TWI689792B - Diffraction measurement target - Google Patents

Abstract

A diffraction measurement target that has at least a first sub-target and at least a second sub-target, and wherein (1) the first and second sub-targets each include a pair of periodic structures and the first sub-target has a different design than the second sub-target, the different design including the first sub- target periodic structures having a different pitch, feature width, space width, and/or segmentation than the second sub-target periodic structure or (2) the first and second sub-targets respectively include a first and second periodic structure in a first layer, and a third periodic structure is located at least partly underneath the first periodic structure in a second layer under the first layer and there being no periodic structure underneath the second periodic structure in the second layer, and a fourth periodic structure is located at least partly underneath the second periodic structure in a third layer under the second layer. A method of devising such a measurement target involving locating an assist feature at a periphery of the sub-targets, the assist feature being configured to reduce measured intensity peaks at the periphery of the sub-targets.

Description

Diffraction measurement target

The present invention relates to a metrology method, apparatus, and substrate that can be used for device manufacturing, for example, by lithography, and to a method of manufacturing devices using lithography.

A lithography apparatus is a machine that applies a desired pattern to a substrate (usually the target portion of the substrate). Lithography devices can be used, for example, in integrated circuit (IC) manufacturing. In that case, a patterned device (which is alternatively referred to as a reticle or proportional reticle) can be used to generate circuit patterns to be formed on individual layers of the IC. This pattern can be transferred to a target portion (for example, a portion containing a die, a die, or several dies) on a substrate (for example, a silicon wafer). Pattern transfer is usually performed by imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are sequentially patterned. Known lithography devices include: the so-called stepper, in which each target part is irradiated by exposing the entire pattern to the target part at once; and the so-called scanner, in which by being in a given direction ("scanning" direction) The scanning pattern through the radiation beam simultaneously scans the substrate in parallel or anti-parallel to this direction to irradiate each target portion synchronously. It is also possible to transfer the pattern from the patterned device to the substrate by imprinting the pattern onto the substrate.

To monitor the lithography program, one or more parameters of the patterned substrate are measured. Examples In other words, the parameters may include overlay errors between sequential layers formed in or on the patterned substrate, and the critical line width of the developed photosensitive resist. This measurement can be performed on the target surface of the product substrate and/or in the form of a dedicated metrology target. For example, metrology (or marking) may include a combination of horizontal and vertical bars that form, for example, periodic structures such as gratings.

In the lithography process (ie, the process of developing a device or other structure that involves lithography exposure, which can usually include one or more associated processing steps, such as resist development, etching, etc.), frequent Take measurements of the resulting structure, for example, for program control and verification. Various tools for making these measurements are known to me, including scanning electron microscopes, which are often used to measure critical dimensions (CD), and to measure stacking pairs (alignment accuracy of the two layers in the device) Special tools. Recently, various forms of scatterometers have been developed for use in the field of lithography. These devices direct the radiation beam onto the target and measure one or more properties of the scattered radiation - for example, the intensity at a single angle of reflection that varies according to the wavelength; one or more wavelengths that varies according to the angle of reflection The intensity under the light; or the polarization that changes according to the reflection angle-to obtain the "spectrum" of the attribute of interest that can be used to determine the target. The determination of the attribute of interest can be performed by various techniques: for example, the reconstruction of the target structure by an iterative approach such as tightly coupled wave analysis or finite element method; library search; and principal component analysis.

There is a need to provide a method and apparatus for improving yield, flexibility, and/or accuracy using a target measure. In addition, although not limited to this method and device, if the method and device can be applied to a small target structure that can be read using a technology based on dark field images, it will have great advantages.

In one embodiment, a method for measuring a parameter of a lithography process is provided. The method includes: illuminating a diffraction measurement target on a substrate using radiation, the measurement target including at least one first sub-target And at least one second sub-marker, wherein each of the first sub-marker and the second sub-marker includes a pair of periodic structures, and wherein the first sub-marker has a design different from the second sub-marker, the different design The periodic structure including the first sub-targets has a pitch, characteristic width, interval width, and/or segmentation different from the periodic structure of the second sub-targets; and detection by at least the first sub-target and the first The scattered radiation of the two sub-targets is measured by obtaining one of the parameters of the lithography program for the target.

In an embodiment, a substrate having a diffraction measurement target is provided, the measurement target includes at least a first sub-target and at least a second sub-target, wherein the first sub-target and the second sub-target A pair of periodic structures are included and wherein the first sub-target has a different design from the second sub-target, the different design includes the periodic structure of the first sub-targets is different from the periodic structure of the second sub-targets A pitch, feature width, gap width and/or segment.

In one embodiment, a method for measuring a parameter of a lithography process is provided. The method includes: illuminating a diffraction measurement target on a substrate using radiation, the measurement target including a first layer At least a first sub-label and at least a second sub-label, wherein the first sub-label includes a first periodic structure and the second sub-label includes a second periodic structure, wherein a third periodic structure is located in the One of the second different layers under the first layer is at least partially under the first periodic structure, and there is no periodic structure under the second periodic structure in the second layer, and one of the fourth cycles The sexual structure is at least partially under the second periodic structure in a third different layer below the second layer; and detecting radiation scattered from at least the first periodic structure to the fourth periodic structure to target The other One measurement of the parameter representing the lithography program is obtained.

In one embodiment, a substrate having a diffraction measurement target is provided, the measurement target includes at least a first sub-target and at least a second sub-target, wherein the first sub-target includes a first periodic structure And the second sub-target includes a second periodic structure, wherein a third periodic structure is at least partially located under the first periodic structure in a second different layer below the first layer, and in the first There is no periodic structure under the second periodic structure in the two layers, and a fourth periodic structure is at least partially located under the second periodic structure in a third different layer under the second layer.

In one embodiment, a method for measuring a parameter of a lithography process is provided. The method includes: illuminating a diffraction measurement target on a substrate using radiation, the measurement target including at least one first sub-target And at least one second sub-marker, wherein each of the first sub-marker and the second sub-marker includes a first pair of periodic structures having a feature extending in a first direction, and having a second different direction One of the extended features of the second pair of periodic structures, and wherein the first sub-target has a design different from that of the second sub-target; and detecting the scattered radiation from at least the first sub-target and the second sub-target The measurement of one of the parameters representing the lithography program is obtained by obtaining the target.

In an embodiment, a substrate having a diffraction measurement target is provided, the measurement target includes at least a first sub-target and at least a second sub-target, wherein the first sub-target and the second sub-target It includes a first pair of periodic structures with features extending in a first direction, and a second pair of periodic structures with features extending in a second different direction, and wherein the first sub-targets have different A design for the second sub-subject.

In one embodiment, a method for measuring a parameter of a lithography program is provided. The method includes: using radiation to illuminate a diffraction measurement target on a substrate, the measurement target Including at least one first sub-label and at least one second sub-label, wherein each of the first sub-label and the second sub-label includes a first pair of periodic structures having a feature extending in a first direction, and having a A second pair of periodic structures that extend in a second different direction, and wherein at least part of each of the periodic structures of the first sub-target and the second sub-target is on the substrate Within a contiguous area of less than or equal to 1000 square micrometers; and detecting the radiation scattered by at least the first sub-target and the second sub-target to obtain one of the parameters representing the lithography procedure for the measurement of the target.

In an embodiment, a substrate having a diffraction measurement target is provided, the measurement target includes at least a first sub-target and at least a second sub-target, wherein the first sub-target and the second sub-target It includes a first pair of periodic structures with features extending in a first direction, and a second pair of periodic structures with features extending in a second different direction, and wherein the first sub-target and the first At least part of each of the periodic structures of the two sub-targets is within an adjacent area on the substrate that is less than or equal to 1000 square microns.

In an embodiment, a method of designing a metric and weighing target is provided. The method includes: receiving an indication of the design for a diffractive metric and weighing target having one of a plurality of sub-targets, each sub-target includes a first direction One of the extended features, a first pair of periodic structures and one of the second pair of periodic structures having a feature extending in a second, different direction; the area, a size, or one of the two receiving the diffraction scale Constraints; and selecting a design of the diffraction metric with a processor based at least on the constraints.

In an embodiment, a diffraction measurement target is provided, which includes at least a first sub-target and at least a second sub-target, wherein the first sub-target and the second sub-target each include a pair of periodic structures, And where the first sub-target has a different A design in which the different designs include the periodic structures of the first sub-targets having a pitch, characteristic width, interval width, and/or segmentation different from the periodic structures of the second sub-targets.

In an embodiment, a diffraction measurement target is provided, which includes at least a first sub-target and at least a second sub-target in a first layer when on a substrate, wherein the first sub-target includes A first periodic structure and the second sub-target includes a second periodic structure; and includes a third periodic structure, when the third periodic structure is on the substrate Two different layers are at least partially below the first periodic structure, and there is no periodic structure under the second periodic structure in the second layer; and includes a fourth periodic structure, the fourth period The sexual structure is at least partially below the second periodic structure in a third different layer below the second layer when on the substrate.

In an embodiment, a diffraction measurement target is provided, which includes at least a first sub-target and at least a second sub-target, wherein each of the first sub-target and the second sub-target includes a first direction One of the extended features is a first pair of periodic structures, and one of the second pair of periodic structures has a feature extending in a second different direction, and wherein the first sub-target has a different one than the second sub-target design.

In an embodiment, a diffraction measurement target is provided, which includes at least a first sub-target and at least a second sub-target, wherein each of the first sub-target and the second sub-target includes a first One of the first pair of periodic structures extending upward, and the second pair of periodic structures having one characteristic extending in a second different direction, and wherein the first sub-target and the second sub-target At least part of each of the periodic structures is in an adjacent area on a substrate that is less than or equal to 1000 square microns.

In one embodiment, a method is provided, which includes using radiation to illuminate a diffraction measurement target on a substrate, the measurement target including at least a first sub-target, a second The sub-subject and the third sub-subject, wherein the first sub-subject, the second sub-subject and the third sub-subject are different in design.

In an embodiment, there is provided a diffractive metric target, which includes at least a first sub-target, a second sub-target and a third sub-target, wherein the first sub-target, the second sub-target and the third The sub-targets are different in design.

In one embodiment, a method is provided that includes measuring the overlap between two layers. The method includes: using radiation to illuminate a diffraction target on a substrate in which the substrate is in the two layers Each has a portion of the target, where the two layers are separated by at least one other layer.

In one embodiment, a method for designing a configuration of a diffraction measurement target is provided, the target includes a plurality of sub-targets, each sub-target includes a plurality of periodic structures, and each sub-target is designed to measure a different Layer pairing or measuring a different program stack. The method includes: locating the periodic structures of the sub-targets in a target area; and locating an auxiliary feature at a periphery of the sub-targets. It is configured to reduce one of the surrounding areas of the sub-targets to measure the intensity peak.

In an embodiment, a diffraction measurement target is provided, which includes: a plurality of sub-targets in a target area of the target, each sub-target includes a plurality of periodic structures and each sub-target is designed to measure a Different layer pairs or measuring a different program stack; and an auxiliary feature at the periphery of the sub-targets, the auxiliary feature is configured to reduce one of the surrounding features of the sub-targets to measure the intensity peak.

In one embodiment, a method of manufacturing a device is provided in which a device pattern is applied to a series of substrates using a lithography procedure, the method includes using one of the methods described herein to detect as part of or in addition to the device pattern The device pattern is formed outside At least one diffraction measurement target on at least one of the substrates; and controlling the lithography process for later substrates based on the results of the method.

In one embodiment, a patterned device is provided that is configured to at least partially form one of the diffraction measurement targets as described herein.

In one embodiment, there is provided a non-transitory computer program product containing machine-readable instructions for causing a processor to produce the performance of a method as described herein.

In one embodiment, there is provided a non-transitory computer program product containing machine-readable instructions for causing a processor to produce the performance of a method as described herein.

In one embodiment, a non-transitory computer program product is provided that includes machine-readable instructions or data defining one of the subject matter described herein.

In one embodiment, a substrate is provided, which includes one of the targets as described herein.

In one embodiment, a system is provided that includes: a detection device configured to provide a light beam on a diffraction measurement target on a substrate and detect the radiation diffracted by the target to determine A parameter of a lithography program; and a non-transitory computer program product as described in this article.

The features and/or advantages of embodiments of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail herein with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. These embodiments are presented herein for illustrative purposes only. Based on the teachings contained herein, additional embodiments will be apparent to those skilled in the relevant art.

0: Zero-order ray/diffraction ray/diffraction zero-order radiation

+1: first-order ray/diffraction ray

-1: first-order ray/diffraction ray/1-order radiance

+1(N): +1 diffracted ray

-1(S):-1 diffracted ray

11: output

12: lens

13: aperture plate

13E: aperture plate

13N: aperture plate

13NW: aperture plate

13SE: aperture plate

13S: aperture plate

13W: aperture plate

14: lens

15: 稜鏡

16: Receiving objective lens/lens

17: Beam splitter

18: Optical system

19: The first sensor

20: Optical system

21: aperture diaphragm

22: Optical system

23: Sensor

31: Measuring light spot / illuminated spot

32: periodic structure of components

33: periodic structure of components

34: periodic structure of components

35: periodic structure of components

41: Circular area

42: rectangular area/image

43: rectangular area/image

44: rectangular area/image

45: rectangular area/image

600: compound stack alignment

602: Periodic structural features/lines

604: Space

606: substrate

608: feature/line

610: Space

700: Subject

702: Curve

704: points

706: points

710: Available target area

720: Periodic structure

730: The resulting dark field image

740: Intensity level zone

750: intensity level zone

800: first extended operating range measurement and weighing target/second extended operating range measurement and weighing target

802: Diffraction sub-target/first sub-target

804: Diffraction sub-target/second sub-target

806: Diffraction sub-target

808: Diffraction sub-target

810: periodic structure

812: Periodic structure

820: clearance

900: The first extended operating range

902: The second extended operating range measurement target

904: first floor

906: Second floor

1000: the first extended operating range measurement standard

1002: The second extended operating range measurement standard

1004: Layer

1006: Layer

1008: Layer

1010: Layer

1200: Extended operating range measurement target/non-optimized target layout/target

1202: The first sub-target

1204: The second sub-target

1220: Extended operating range measurement standard

1222: The first sub-target

1224: The second sub-target

1240: Extended operating range measurement standard

1242: The first sub-target

1244: The second sub-target

1260: Extended operating range

1262: The first sub-target

1264: The second sub-target

1280: Extended operating range

1282: The first sub-target

1284: The second sub-target

1300: Design layout module

1302: Patterned device layout module

1304: Patterned device model module

1306: Optical model module

1308: Resist model module

1310: Program model module

1312: Weights and Measures Module

1314: Results module

1400: periodic structure

1410: Measurement tool driven optical proximity correction (MT-OPC) auxiliary features

1420: Measurement tool driven optical proximity correction (MT-OPC) auxiliary features

1430: Intensity measurement area

1440: Periodic structure area

1500: Extended operating range measurement standard

1502: Extended operating range

1504: Sub-target

1506: Sub-target

1508: Periodic structure/optional mark

1510: Periodic structure

1512: Periodic structure

1600: Extended operating range

1602: Extended operating range

1604: Sub-target

1606: Sub-target

1608: Sub-target

1610: Sub-target/target area

1612: Periodic structure

1614: Periodic structure

1616: Periodic structure

1618: Periodic structure

1620: Gap area

1635: Measurement tool driven optical proximity correction (MT-OPC) auxiliary features

1640: Measurement tool driven optical proximity correction (MT-OPC) auxiliary features

1650: Periodic structure

1700: Extended operating range

1702: Extended operating range

1704: Sub-target

1706: Sub-target

1708: Periodic structure

1710: Periodic structure

1800: Extended operating range

1802: Extended operating range

1804: Sub-target

1806: Sub-target

1808: Sub-target

1810: Sub-target

1812: Periodic structure

1814: Periodic structure

1816: Periodic structure

1818: Periodic structure

1820: periodic structural features

1830: Auxiliary feature of measurement tool driven optical proximity correction (MT-OPC)

1840: Features

1850: Measurement tool driven optical proximity correction (MT-OPC) auxiliary features

AD: adjuster

AS: Alignment sensor

B: radiation beam

BD: beam delivery system

BK: baking board

B1: Block

B2: Block

B3: Block

B4: Block

B5: Block

B6: Block

C: Target part

CH: cooling plate

CO: Concentrator

DE: Developer

DF: Image

D1: Step

D2: Step

D3: Step

D4: Step

I: Illuminating rays/incident rays/incident radiation

IF: position sensor

IL: Lighting system/illuminator

IN: integrator

I/O1: input/output port

I/O2: input/output port

L1: Lower layer

L2: Layer

LA: lithography device

LACU: lithography control unit

LB: loading box

LC: Lithography Manufacturing Cell

LS: level sensor

M ₁ : Mask alignment mark

M ₂ : Mask alignment mark

M1: Step

M2: Step

M3: Step

M4: Step

M5: Step

M6: Step

MA: patterned device

MT: patterned device support or support structure/reticle stage

O: optical axis

P ₁ : substrate alignment mark

P ₂ : substrate alignment mark

P1: Area of interest

P2: Area of interest

P3: Area of interest

P4: Area of interest

PM: the first locator

PS: projection system

PU: Image processor and controller

PW: second locator

RF: reference frame

RO: substrate handler or robot

ROI: area of interest

SC: spin coater

SCS: Supervisory Control System

SO: radiation source

T: target/measure target

TCU: control unit for coating and developing system

T1: Step

T2: Step

T3: Step

T4: Step

T5: Step

T6: Step

W: substrate

WTa: substrate table

WTb: substrate stage

The embodiments of the present invention will now be described with reference to the accompanying drawings as examples only. In these drawings: FIG. 1 depicts a lithography apparatus according to an embodiment of the present invention; FIG. 2 depicts an embodiment according to the present invention Lithography manufacturing unit or cluster; FIG. 3(a) is a schematic diagram of a dark field scatterometer used to measure a target using a first pair of illumination apertures that provide certain illumination modes according to an embodiment of the present invention; FIG. 3 (B) is a schematic detail of the diffraction spectrum of a periodic structure for a given illumination direction; Figure 3(c) is when a scatterometer is used for diffraction-based overlay measurement Provides a schematic illustration of the second pair of illumination apertures for additional illumination modes; Figure 3(d) is the first pair of apertures that provide additional illumination modes in combination when a scatterometer is used for diffraction-based overlay measurement A schematic illustration of the third pair of illuminated apertures with the second pair of apertures; Figure 4 depicts the form of multiple periodic structures (e.g. gratings) on the substrate and the outline of the measurement light spot; Figure 5 depicts the device of Figure 3 The obtained image of the target of FIG. 4; FIG. 6 is a flowchart showing the steps of the stacking measurement method using the device of FIG. 3 and applicable to the embodiment of the present invention; FIG. 7(a) to FIG. 7( c) Shows a schematic cross-section of a stack-pair periodic structure with different stack-pair values of approximately zero; FIG. 8 illustrates the principle of stack-pair measurement in an ideal target structure; FIG. 9 illustrates an embodiment according to the invention The extended operating range of measurement and weighing standards; FIG. 10 illustrates the use of an extended operating range metric for considering program stack changes according to an embodiment of the present invention; FIG. 11 illustrates an extended operating range metric for multi-stack measurement according to an embodiment of the present invention. Use of the target; FIGS. 12A to 12E illustrate the change of the extended operating range measurement target according to one embodiment of the present invention; FIG. 13(a) depicts an example of the layout of a non-optimized target; FIG. 13(b) depicts The resulting dark field images of the target layout of (a) of FIG. 13; (a) to (f) of FIG. 14 illustrate examples of non-optimized target layout and target layout according to an embodiment of the present invention, and the use of different amounts Examples of expected dark field images of these targets for measuring radiation wavelength; FIG. 15 illustrates a partial cross-section of a target according to an embodiment of the present invention; FIG. 16(a) illustrates an example of the layout of a non-optimized target; FIG. 16(b) illustrates an example of a target layout according to an embodiment of the present invention; FIG. 17 is a flowchart of a method of designing a target configuration according to an embodiment of the present invention; FIG. 18(a) to (f) illustrate An embodiment of the method depicted in FIG. 17 executed with a design target configuration; FIG. 19 schematically depicts a system for designing an extended operating range measurement target according to one embodiment of the present invention; FIG. 20 depicts a system according to the present invention A flowchart of a procedure for designing an extended operating range measurement and weighing target according to an embodiment; FIG. 21 depicts a flowchart illustrating a procedure according to an embodiment of the present invention. The extended operating range measurement and measurement target in the program is used to monitor performance and is used as the basis for controlling measurement, design, and/or production procedures; FIGS. 22(A) to 22(C) illustrate one embodiment of the present invention. The extended operating range measurement and weighing standard; FIGS. 23(A) to 23(C) illustrate the extended operating range measurement and weighing standard according to one embodiment of the present invention; FIGS. 24(A) to 24(C) illustrate the An extended operating range measurement scale of an embodiment; FIGS. 25(A) to 25(C) illustrate an extended operating range measurement scale of an embodiment of the present invention; and FIGS. 26(A) to 26(E) Explaining an extended operating range measurement scale according to an embodiment of the present invention.

Before describing the embodiments in detail, it is instructive to present an example environment in which the embodiments can be implemented.

Fig. 1 schematically depicts a lithography apparatus LA. The device includes: an illumination system (illuminator) IL configured to adjust the radiation beam B (eg, UV radiation or DUV radiation); a patterned device support or support structure (eg, reticle stage) MT, which is Constructed to support a patterned device (eg, reticle) MA, and connected to a first positioner PM configured to accurately position the patterned device according to certain parameters; substrate table (eg, wafer table) WT , Which is constructed to hold a substrate (eg, a resist-coated wafer) W, and is connected to a second positioner PW configured to accurately position the substrate according to certain parameters; and a projection system (eg, Refractive projection lens system) PS, which is configured to impart radiation to the radiation from the patterned device MA The pattern of the light beam B is projected onto the target portion C (for example, including one or more dies) of the substrate W.

The lighting system may include various types of optical components for directing, shaping, or controlling radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof.

The patterned device support holds the patterned device in a manner that depends on the orientation of the patterned device, the design of the lithography apparatus, and other conditions such as whether the patterned device is held in a vacuum environment. The patterned device support may use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterned device. The patterned device support may be, for example, a frame or a table, which may be fixed or movable as needed. The patterned device support can ensure that the patterned device (for example) is in a desired position relative to the projection system. It can be considered that any use of the terms "proportional reticle" or "reticle" herein is synonymous with the more general term "patterned device".

The term "patterned device" as used herein should be broadly interpreted as referring to any device that can be used to impart a pattern to the radiation beam in the cross-section of the radiation beam to create a pattern in the target portion of the substrate. It should be noted that, for example, if the pattern assigned to the radiation beam includes phase-shifting features or so-called auxiliary features, the pattern may not exactly correspond to the desired pattern in the target portion of the substrate. Generally, the pattern assigned to the radiation beam will correspond to a specific functional layer in the device (such as an integrated circuit) produced in the target portion.

The patterned device may be transmissive or reflective. Examples of patterned devices include photomasks, programmable mirror arrays, and programmable LCD panels. Masks are well known to me in lithography, and include mask types such as binary, alternating phase shift, and attenuation phase shift, as well as various hybrid mask types. One example of a programmable mirror array uses a matrix configuration of small mirrors Each of these small mirrors can be individually tilted to reflect the incident radiation beam in different directions. The inclined mirror surface gives a pattern to the radiation beam reflected by the mirror matrix.

As depicted here, the device is of the transmissive type (for example, using a transmissive mask). Alternatively, the device may be of the reflective type (for example, using a programmable mirror array of the type mentioned above, or using a reflective mask).

Lithography devices can also be of the type in which at least a portion of the substrate can be covered by a liquid (eg, water) with a relatively high refractive index in order to fill the space between the projection system and the substrate. The immersion liquid can also be applied to other spaces in the lithography device, for example, the space between the reticle and the projection system. Immersion technology is well known in the art for increasing the numerical aperture of projection systems. The term "immersion" as used herein does not mean that a structure such as a substrate must be immersed in liquid, but only means that the liquid is located between the projection system and the substrate during exposure.

Referring to Fig. 1, the illuminator IL receives a radiation beam from a radiation source SO. For example, when the radiation source is an excimer laser, the radiation source and the lithography device may be separate entities. Under these circumstances, the radiation source is not considered to form part of the lithography device, and the radiation beam is transferred from the radiation source SO to the illuminator IL by means of a beam delivery system BD including, for example, a suitable guide mirror and/or beam expander . In other situations, for example, when the radiation source is a mercury lamp, the radiation source may be an integral part of the lithography device. The radiation source SO and the illuminator IL together with the beam delivery system BD (when required) may be referred to as a radiation system.

The illuminator IL may include an adjuster AD for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer radial range and/or the inner radial range of the intensity distribution in the pupil plane of the illuminator can be adjusted (commonly referred to as σouter and σinner, respectively). In addition, the illuminator IL may include various other components, such as an integrator IN and a condenser CO. The illuminator can be adjusted The radiation beam is knotted to have the desired uniformity and intensity distribution in its cross-section.

The radiation beam B is incident on the patterned device (eg, photomask) MA held on the patterned device support (eg, reticle stage MT), and is patterned by the patterned device. After having traversed the patterned device (eg, photomask) MA, the radiation beam B passes through the projection system PS, which focuses the beam onto the target portion C of the substrate W. By virtue of the second positioner PW and the position sensor IF (for example, an interferometric measuring device, a linear encoder, a 2D encoder, or a capacitive sensor), the substrate table WT can be accurately moved, for example, so that the different target parts C It is located in the path of the radiation beam B. Similarly, the first positioner PM and another position sensor (which are not explicitly depicted in FIG. 1) can be used, for example, relative to the radiation beam after mechanical extraction from the reticle library or during scanning The path of B to accurately position the patterned device (eg, photomask) MA.

The mask alignment marks M ₁ , M ₂ and the substrate alignment marks P ₁ , P ₂ may be used to align the patterned device (eg, mask) MA and the substrate W. Although the illustrated substrate alignment marks occupy portions of dedicated targets, the marks may be located in the space between the target portions (these marks are referred to as scribe-lane alignment marks). Similarly, in the case where more than one die is provided on the patterned device (eg, photomask) MA, the patterned device alignment mark may be located between the die. Small alignment marks can also be included in the die among device features. In this case, the marks need to be as small as possible without any imaging or procedural conditions different from adjacent features. Examples of alignment systems that can detect alignment marks are described further below.

The depicted device can be used in at least one of the following modes:

1. In the step mode, when the entire pattern imparted to the radiation beam is projected onto the target portion C at one time, the patterned device support (for example, reticle stage) MT and the substrate stage WTa are kept substantially still (That is, a single static exposure). Next, place the substrate table WTa on The X and/or Y directions are shifted so that different target portions C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.

2. In the scanning mode, when the pattern imparted to the radiation beam is projected on the target portion C, the patterned device support (for example, reticle stage) MT and the substrate stage WTa (that is, single shot Dynamic exposure). The speed and direction of the substrate table WTa relative to the patterned device support (eg, reticle table) MT can be determined by the magnification (reduction rate) and image reversal characteristics of the projection system PS. In the scanning mode, the maximum size of the exposure field limits the width of the target portion in a single dynamic exposure (in the non-scanning direction), and the length of the scanning motion determines the height of the target portion (in the scanning direction).

3. In another mode, while projecting the pattern imparted to the radiation beam onto the target portion C, the patterned device support (eg, reticle stage) MT is kept substantially still, thereby holding the programmable pattern Device, and move or scan the substrate table WTa. In this mode, a pulsed radiation source is usually used, and the programmable patterned device is updated as needed after each movement of the substrate table WTa or between successive radiation pulses during a scan. This mode of operation can be easily applied to maskless lithography using programmable patterned devices such as the programmable mirror arrays of the type mentioned above.

Combinations and/or variations or completely different modes of use of the modes of use described above may also be used.

The lithography apparatus LA belongs to the so-called double stage type, which has at least two stations WTa, WTb (for example, a double substrate stage) and at least two stations-an exposure station and a measurement station-between the at least two stations At least one of these stations can be exchanged. For example, while exposing one substrate on one stage at the exposure station, another substrate can be loaded onto another substrate stage at the measurement station and various preliminary steps are performed. The preliminary step may include mapping using the level sensor LS The surface control of the substrate and the use of alignment sensors AS to measure the position of the alignment marks on the substrate are both supported by the reference frame RF. If the position sensor IF cannot measure the position of the stage when the stage is at the measuring station and at the exposure station, a second position sensor can be provided to enable tracking of the position of the stage at both stations. As another example, when exposing one substrate on one stage at the exposure station, the other without the substrate waits at the measurement station (where measurement activity may occur depending on circumstances). This other one has one or more measuring devices and optionally other tools (eg, cleaning device). When the substrate has been exposed, the stage without the substrate moves to the exposure station to perform, for example, measurement, and the stage with the substrate moves to the place where the substrate is unloaded and another substrate is loaded (eg, measurement station). These multiple configurations achieve a considerable increase in the output rate of the device.

As shown in FIG. 2, the lithography device LA forms a component of a lithography manufacturing unit LC (sometimes referred to as a cluster). The lithography manufacturing unit LC also includes one or more pre-exposure processes and post-exposure processes performed on the substrate Program device. Generally, such devices include one or more spin coaters SC for depositing a resist layer, one or more developers DE for developing the exposed resist, one or more cooling plates CH and one or Multiple baking boards BK. The substrate handler or robot RO picks up the substrate from the input/output ports I/O1, I/O2, moves the substrate between different program devices, and delivers the substrate to the loading cassette LB of the lithography apparatus. These devices, which are often collectively referred to as coating and development systems (tracks), are under the control of the coating and development system control unit TCU. The coating and development system control unit TCU itself is controlled by the supervisory control system SCS, and the supervisory control system SCS is also The lithography apparatus is controlled via the lithography control unit LACU. Therefore, different devices can be operated to maximize yield and processing efficiency.

In order to accurately and consistently expose the substrate exposed by the lithography device, the exposed substrate needs to be inspected to measure one or more attributes, such as overlay error between subsequent layers, line thickness Degrees, critical dimensions (CD), etc. If an error is detected, the exposure of one or more subsequent substrates can be adjusted, especially if the detection can be performed quickly and quickly enough so that another substrate of the same batch/batch remains to be exposed. In addition, the exposed substrate can be peeled and reworked (to improve the yield) or the exposed substrate can be discarded, thereby avoiding performing exposure on the known defective substrate. In the case where only some of the target parts of the substrate are defective, another exposure may be performed only on the good parts of those targets. Another possibility should be to adapt the settings of the subsequent process steps to compensate for the error. For example, the timing of the trim etching step can be adjusted to compensate for changes in the CD between substrates caused by the lithography process steps.

The detection device is used to determine one or more attributes of the substrate, and in detail, determine how one or more attributes of different substrates or different layers of the same substrate change between different layers and/or across a substrate. The detection device may be integrated into the lithography device LA or the lithography manufacturing unit LC, or may be a stand-alone device. In order to achieve the fastest measurement, the detection device needs to measure one or more attributes in the exposed resist layer immediately after the exposure. However, the latent image in the resist has very low contrast-there is only a very small refractive index difference between the portion of the resist that has been exposed to radiation and the portion of the resist that has not been exposed to radiation-and not all The detection devices have sufficient sensitivity to perform useful measurements of latent images. Therefore, measurements can be taken after the post-exposure baking step (PEB), which is usually the first step performed on the exposed substrate and adds the exposed and unexposed portions of the resist Contrast between. At this stage, the image in the resist may be called a semi-latent image. It is also possible to perform the measurement of the developed resist image--at this time, the exposed or unexposed portion of the resist has been removed--or to perform the developed resist after the pattern transfer step such as etching Measurement of etchant images. The latter possibility limits the possibility of rework of defective substrates, but for example, useful information can still be provided for process control purposes.

The targets used by conventional scatterometers include relatively large periodic structure (eg, grating) layouts, for example, 40 microns by 40 microns. In this situation, the measurement beam often has a spot size smaller than the periodic structure layout (that is, the periodic structure layout is underfilled). This situation simplifies the mathematical reconstruction of the subject, because the subject can be regarded as infinite. However, for example, the target can therefore be positioned in the product features rather than in the cutting lane. The size of the target has been reduced (for example) to 20 microns by 20 microns or less, or to 10 microns by 10 microns or less. In this case, the periodic structure layout can be made smaller than the measurement light spot (that is, the periodic structure layout is overfilled). Dark field scattering measurements are usually used to measure this target, where the zero diffraction order (corresponding to specular reflection) is blocked, and only the higher order is processed. Examples of dark field weights and measures can be found in PCT Patent Application Publication Nos. WO 2009/078708 and WO 2009/106279, the entire texts of these patent application publications are hereby incorporated by reference. Further development of the technology has been described in US Patent Application Publications US2011-0027704, US2011-0043791, and US2012-0242970, and the entire contents of these patent application publications are hereby incorporated by reference. The diffractive-based fold pair using the diffractive order dark field detection enables the measurement of the fold pair of smaller targets. These targets can be smaller than the illumination spot and can be surrounded by the product structure on the substrate. In one embodiment, multiple targets can be measured in one image.

FIG. 3(a) shows a dark field measurement and measurement device suitable for use in an embodiment of the present invention. FIG. 3(b) illustrates the target T (including the periodic structure) and the diffracted rays in more detail. The dark field metrology device may be a stand-alone device or, for example, incorporated into the lithography device LA at the measurement station or into the lithography manufacturing unit LC. The optical axis through which the device has several branches is indicated by the dotted line O. In this device, the radiation emitted by the output 11 (for example, a source such as a laser or xenon lamp, or an opening connected to the source) is passed by the optical system 15 including the lenses 12, 14 and the objective lens 16 through the lens 15 Guide onto the substrate W. These lenses are equipped with a double sequence of 4F configuration Set. Different lens configurations can be used, with the limitation that the lens configuration still provides the substrate image to the detector.

In an embodiment, the lens configuration allows access to the intermediate pupil plane for spatial frequency filtering. Therefore, the angular range at which the radiation is incident on the substrate can be selected by defining the spatial intensity distribution in a plane that presents the spatial spectrum of the substrate plane (referred to here as (conjugate) pupil plane). In detail, this selection can be made, for example, by inserting an aperture plate 13 of suitable form between the lenses 12 and 14 in the plane of the back-projected image that is the pupil plane of the objective lens. In the illustrated example, the aperture plate 13 has different forms (labeled 13N and 13S), allowing different lighting modes to be selected. The lighting system in this example forms an off-axis lighting mode. In the first illumination mode, the aperture plate 13N provides off-axis illumination from the direction indicated as "North" for descriptive purposes only. In the second illumination mode, the aperture plate 13S is used to provide similar illumination, but provides illumination from different (eg, relative) directions labeled "South". By using different apertures, other lighting modes are possible. The rest of the pupil plane is ideally dark, because any unnecessary radiation outside the desired illumination mode will interfere with the desired measurement signal.

As shown in FIG. 3( b ), the target T is placed with the substrate W substantially perpendicular to the optical axis O of the objective lens 16. The illumination ray I irradiated on the target T at an angle to the axis O causes a zero-order ray (solid line 0) and two first-order rays (dot chain line+1 and double dot chain line-1). In the case of using the overfilled small target T, these rays are only one of many parallel rays covering the substrate area including the target T and other features. In the case of providing a composite periodic structure target, each individual periodic structure within the target will cause its own diffraction spectrum. Because the aperture in the plate 13 has a finite width (necessary to receive a useful amount of radiation), the incident ray I will actually occupy an angular range, and the diffracted ray 0 and +1/-1 will spread slightly. According to the point spread function of the subscript, each order of +1 and -1 will spread further over a range of angles instead of a single ideal ray as shown. It should be noted that the periodic structure pitch and illumination angle can be designed or adjusted so that the first-order rays entering the objective lens are closely aligned with the central optical axis. The rays illustrated in FIGS. 3(a) and 3(b) are shown slightly off-axis to purely enable them to be more easily distinguished in the illustration.

At least the 0th order and the +1th order of the diffraction by the target on the substrate W are collected by the objective lens 16, and are returned and guided through the 珜鏡15. Returning to (a) of FIG. 3, both the first illumination mode and the second illumination mode are explained by indicating the completely relative (in this case) apertures marked as north (N) and south (S). When the incident ray I comes from the north side of the optical axis, that is, when the aperture plate 13N is used to apply the first illumination mode, the +1 diffracted ray marked as +1(N) enters the objective lens 16. In contrast, when the second illumination mode is applied using the aperture plate 13S, the -1 diffracted ray (labeled -1(S)) is the diffracted ray entering the lens 16. Therefore, in one embodiment, by measuring the target twice under certain conditions (such as rotating the target or changing the illumination mode or changing the imaging mode to separately obtain the -1 diffraction order intensity and +1 diffraction order After the intensity) to obtain the measurement results. Comparing these intensities for a given target provides a measure of the asymmetry in the target, and the asymmetry in the target can be used as an indicator of parameters such as the lithography process of overlay errors. In the situation described above, the lighting mode is changed.

The beam splitter 17 divides the diffracted beam into two measurement branches. In the first measurement branch, the optical system 18 uses a zero-order diffracted beam and a first-order diffracted beam to form a target diffraction spectrum (pupil) on the first sensor 19 (eg, CCD or CMOS sensor) Flat image). Each diffraction order hits a different point on the sensor so that image processing can compare and contrast several orders. The pupil plane image captured by the sensor 19 can be used for the focus measurement device And/or normalized first-order beam intensity measurement. The pupil plane image can also be used for asymmetry measurement and for many measurement purposes such as reconstruction, which will not be described in detail here. The first example to be described will use a second measurement branch to measure asymmetry.

In the second measurement branch, the optical systems 20 and 22 form an image of the target on the substrate W on the sensor 23 (for example, a CCD or CMOS sensor). In the second measurement branch, an aperture stop 21 is provided in a plane conjugate to the pupil plane. The aperture stop 21 is used to block the zero-order diffracted beam, so that the target image DF formed on the sensor 23 is formed by the -1 or +1 first-order beam. The images captured by the sensors 19 and 23 are output to the image processor and controller PU, and the functions of the image processor and controller PU will depend on the specific type of measurement being performed. It should be noted that the term "image" is used here in a broad sense. Therefore, if only one of the -1 and +1 order exists, the image of the characteristic of the target periodic structure will not be formed.

The specific forms of the aperture plate 13 and the diaphragm 21 shown in FIG. 3 are purely examples. In another embodiment, the target coaxial illumination is used, and an aperture stop with an off-axis aperture is used to deliver substantially only one first-order diffracted radiation to the sensor (in which case it is actually exchanged between 13 and (Aperture shown at 21). In still other embodiments, instead of or in addition to the first-order beam, the second-order beam, the third-order beam, and the high-order beam can also be used in the measurement (not shown in FIG. 3).

In order to adapt the illumination to these different types of measurements, the aperture plate 13 may contain several aperture patterns formed around a disc which is rotated to put the desired pattern in place. Alternatively or additionally, a set of plates 13 can be provided and exchanged to achieve the same effect. Programmable lighting devices such as deformable mirror arrays or transmissive spatial light modulators can also be used. As an alternative way to adjust the lighting mode, moving mirrors or prisms can be used.

As explained earlier regarding the aperture plate 13, instead, by changing the aperture stop 21, or by replacing the pupil stop with a different pattern, or by using a programmable spatial light modulator to replace the fixed field light The stop can achieve the choice of diffraction order for imaging. In that situation, the illumination side of the measurement optical system can be kept constant, while the imaging side has the first mode and the second mode. In practice, there are many possible types of measurement methods, and each type has its own advantages and disadvantages. In one method, the lighting mode is changed to measure different orders. In another method, the imaging mode is changed. In the third method, the illumination mode and imaging mode remain unchanged, but the target is rotated by, for example, 180 degrees. In each case, the desired effect is the same, that is, to select, for example, the first and second parts of non-zero-order diffraction radiation that are symmetrically opposed to each other in the target diffraction spectrum.

Although the optical system used for imaging in this example has a wide entrance pupil defined by the aperture stop 21, in other embodiments or applications, the entrance pupil size of the imaging system itself may be small enough to be limited to the desired order, And therefore also used as a field diaphragm. Different aperture plates are shown in (c) and (d) of FIG. 3, and these aperture plates can be used as described further below.

In general, the target will be aligned with its periodic structural features extending north-south or east-west. That is, the periodic structure (eg, grating) will be aligned in the X direction or the Y direction of the substrate W. But it can be at different angles, that is, at 45°. The aperture plate 13N or 13S is used to measure the periodic structure of the target oriented in one direction (for example, depending on the set X, Y, or other directions). For the measurement of periodic structures at another angle (e.g., substantially orthogonal), the target rotation may be implemented (e.g., for substantially orthogonal periodic structures, rotations of 90° and 270°). Or, illumination from another angle (for example, east or west) using the aperture plate 13E or 13W shown in FIG. 3(c) may be provided in the illumination optics, and the aperture plates may have an appropriate angle (for example, East or West) aperture. Separately forming and interchangeable aperture plates 13N to 13W, or the aperture plate 13N to 13W may be a single aperture plate that can be rotated up to an appropriate angle (for example, 90 degrees, 180 degrees, or 270 degrees).

Different aperture plates are shown in (c) and (d) of FIG. 3. Figure 3(c) illustrates the other two types of off-axis illumination modes. In the first illumination mode of (c) of FIG. 3, the aperture plate 13E provides off-axis illumination from the direction indicated as "east" relative to the "north" previously described for the sake of description only. As mentioned above, "East" may be at a different angle than that shown. In the second illumination mode of (c) of FIG. 3, the aperture plate 13W is used to provide similar illumination, but illumination from different (eg, relative) directions labeled "west". Figure 3(d) illustrates the other two types of off-axis illumination modes. In the first illumination mode of (d) of FIG. 3, the aperture plate 13NW provides off-axis illumination from directions indicated as "north" and "west" as previously described. In the second lighting mode, the aperture plate 13SE is used to provide similar lighting, but from different (eg, relative) directions of lighting labeled "South" and "East" as previously described. If the crosstalk between these different diffraction signals is not too large, then the measurement of the periodic structure extending in different directions (for example, both X and Y) can be performed without changing the illumination mode. For example, the use of these and many other variations and applications of devices are described in the previously published patent application publications mentioned above. As already mentioned, the off-axis aperture illustrated in (c) and (d) of FIG. 3 may be provided in the aperture stop 21 instead of the aperture plate 13. In that situation, the lighting will be coaxial.

FIG. 4 depicts an example compound metrology scale formed on a substrate. The composite target includes four periodic structures (eg, gratings) 32, 33, 34, 35 that are closely positioned together. In one embodiment, the periodic structures are positioned close enough together so that they are all within the measurement light spot 31 formed by the illumination beam of the metrology device. In that situation, the four periodic structures are therefore illuminated simultaneously and imaged on the sensors 19 and 23 simultaneously. Dedicated to In the example of stacked measurement, the periodic structures 32, 33, 34, 35 themselves are compound periodicities formed by overlaying periodic structures on another target patterned in different layers of the device formed on the substrate W structure. The target may have an external dimension within 20 microns x 20 microns or within 16 microns x 16 microns. In addition, all periodic structures are used to measure the overlap between a specific pair of layers. In order to facilitate the measurement of more than a single pair of layers, the periodic structures 32, 33, 34, 35 may have stacked offsets with different offsets in order to promote different layers formed with different parts of the composite periodic structure Measure the overlap between. Therefore, all periodic structures used for the target on the substrate will be used to measure a pair of layers, and all periodic structures used for another same target on the substrate will be used to measure another pair of layers, where the stacked pairs Biasing facilitates distinguishing layer pairs. The meaning of overlapping offsets will be explained with particular reference to FIG. 7 below.

7(a) to (c) show schematic cross-sections of stacked pairs of periodic structures with different offsets of T for different targets. These stacked pairs of periodic structures can be used on the substrate W, as seen in FIGS. 3 and 4. Only for the sake of example, a periodic structure having periodicity in the X direction is shown. Different combinations of these periodic structures with different biases and different orientations can be provided.

Beginning with (a) of FIG. 7, a composite overlay target 600 formed in two layers labeled L1 and L2 is depicted. In the lower layer L1, the first periodic structure is formed by features (eg, lines) 602 and spaces 604 on the substrate 606. In layer L2, the second periodic structure is formed by features (eg, lines) 608 and spaces 610. (The cross-section is drawn such that the features 602, 608 extend into the page). The periodic structure pattern repeats with a pitch P in the two layers. The lines 602 and 608 are mentioned only for the sake of example, and other types of features such as dots, blocks, and vias may be used. In the situation shown in FIG. 7(a), there is no overlay error and no offset, so that each periodic structure feature 608 is exactly at the lower periodicity Above the periodic structure feature 602 in the structure.

At (b) of FIG. 7, the same target with offset +d is depicted as the feature 608 of the upper periodic structure is shifted to the right by a distance d relative to the feature 602 of the lower periodic structure. That is, feature 608 and feature 602 are configured such that if both are printed exactly at their nominal locations, feature 608 will be offset from feature 602 by distance d. The offset distance d may be practically several nanometers, for example, 5 nanometers to 60 nanometers, and the pitch P is (for example) in the range of 300 nanometers to 1000 nanometers, for example, 500 nanometers or 600 nanometers . At (c) of FIG. 7, the same subject with the offset -d is depicted as the feature 608 is shifted to the left relative to the feature 602. For example, this type of offset subject shown at (a) to (c) of FIG. 7 is described in the patent application publication mentioned above.

In addition, although (a) to (c) of FIG. 7 depict a feature 608 (with or without a small offset of +d or -d applied) above the feature 602 (which is said to have a value of approximately zero Biased "online" (target), but the target may have a programmed offset of P/2 (which is half of the pitch) so that each feature 608 in the upper periodic structure is in the lower periodic structure Above the space 604. This target is called the "ditch on-line" target. In this case, a small offset of +d or -d can also be applied. The choice between "online" target or "ditch online" target depends on the application.

Returning to Figure 4, the periodic structures 32, 33, 34, 35 may also differ in their orientation (as shown) to diffract incident radiation in the X and Y directions. In one example, the periodic structures 32 and 34 are X-directional periodic structures with offsets of +d and -d, respectively. The periodic structures 33 and 35 may be Y-directional periodic structures with offsets +d and -d, respectively. Although four periodic structures are illustrated, another embodiment may include a larger matrix to obtain the desired accuracy. For example, a 3×3 array of nine composite periodic structures can have offsets of -4d, -3d, -2d , -D, 0, +d, +2d, +3d, +4d. The separated images of these periodic structures can be identified in the image captured by the sensor 23.

FIG. 5 shows that the target of FIG. 4 can be formed on and detected by the sensor 23 using the target of FIG. 4 in the device of FIG. 3 using the aperture plate 13NW or 13SE from FIG. 3(d). Examples of images. Although the sensor 19 cannot resolve different individual periodic structures 32 to 35, the sensor 23 can resolve different individual periodic structures 32 to 35. The cross-hatched rectangle represents the field of the image on the sensor. In this field, the illuminated spot 31 on the substrate is imaged into the corresponding circular area 41. In one embodiment, the field is dark. In this image, rectangular areas 42 to 45 represent images of periodic structures 32 to 35. If the periodic structure is located in the product area, the product features can also be seen in the periphery of this image field. Although the dark field image shown in FIG. 5 shows only a single compound grating target, in practice, a product manufactured by lithography can have many layers, and it is necessary to perform overlay measurement between different pairs of layers. For each overlay measurement between a pair of layers, one or more composite grating targets are used, and therefore, other composite targets may exist within the image field. The image processor and the controller PU use pattern recognition to process these images to identify the separated images 42 to 45 of the periodic structures 32 to 35. In this way, the images do not have to be aligned very precisely at specific locations within the sensor frame. This situation greatly improves the overall yield of the measuring device.

Once the separated images of the periodic structure have been identified, the intensity of their individual images can be measured, for example, by averaging or summing the intensity values of selected pixels within the identified area. The intensity and/or other attributes of the images can be compared with each other. These results can be combined to measure different parameters of the lithography program. Stacking efficiency is an example of this parameter. For example, comparing these strengths will reveal asymmetry that can be used as a measure of stacking. In another technique for measuring the asymmetry and therefore the stacking, the sensor 19 is used.

FIG. 6 illustrates the case where the method described in, for example, PCT Patent Application Publication No. WO 2011/012624 and US Patent Application Publication No. 2011/027704 and the device using (for example) FIGS. 3 and 4 are used , How does the overlay error between the two layers containing the periodic structures 32 to 35 pass through the periods as revealed by comparing the intensity of the periodic structures in the +1 and -1 order darkfield images The asymmetry of the sexual structure is measured.

In step M1, the substrate (eg, semiconductor wafer) is processed one or more times by the lithography manufacturing unit of FIG. 2 to produce a target structure including periodic structures 32 to 35 that form metrology targets. At M2, in the case of using the weighing and measuring device of FIG. 3, one of the first-order diffracted beams (such as -1) is used to obtain images of the periodic structures 32 to 35. In one embodiment, the first illumination mode (for example, the illumination mode generated using the aperture plate 13NW) is used. Then, whether by changing the illumination mode or the imaging mode, or by rotating the substrate W by 180° in the field of view of the metrology device, a periodic structure using another first-order diffracted beam (+1) can be obtained The second image (step M3). Therefore, +1 diffraction radiation is captured in the second image. In one embodiment, the illuminated mode is changed and the second illumination mode is used (for example, the illumination mode generated using the aperture plate 13SE). Whether all periodic structures can be captured in each image or whether relative movement between the measuring device and the substrate is required to capture these periodic structures in separate images is a matter of design choice. In either case, it is assumed that the first image and the second image of the periodic structure of all components are captured through the sensor 23.

It should be noted that by including only half of the first-order diffraction radiation in each image, the "image" mentioned here is not a conventional dark-field microscopy image. Because there is only one of the +1 and -1 order diffraction radiation, the individual periodic structural features are not resolved. Each periodic structure will simply be represented by a region of certain intensity level. In step M4, in each component The region of interest (ROI) is identified in the image of the periodic structure, and the intensity level will be measured from the region of interest. The reason for this identification is that, especially around the edges of individual raster images, the intensity value can usually be highly dependent on programming variables such as resist thickness, composition, line shape, and edge effects.

In cases where the regions of interest P1, P2, P3, P4 for each individual periodic structure 32 to 35 have been identified and their strength has been measured, the asymmetry of the periodic structure can then be determined and thus determined (e.g. ) Overlap error. This determination is made by the image processor and the controller PU in step M5 comparing the intensity values obtained for the +1 and -1 orders of each periodic structure 32 to 35 to identify any difference in intensity (ie, Asymmetry). The term "poor" is not intended to refer only to subtraction. The difference can be calculated as a ratio. Therefore, the intensity difference is calculated at step M5 to obtain a measure of asymmetry for each periodic structure. In step M6, use the knowledge of the measured asymmetry for several periodic structures together with (where applicable) the overlapping offset of their periodic structures to calculate one of the lithography procedures around the target T or Multiple performance parameters. The performance parameter of interest may be stacked pairs. Other performance parameters of the lithography program can be calculated, such as focus and/or dose. The one or more performance parameters can be fed back for the improvement of the lithography process, and/or for improving the measurement and calculation process of FIG. 6 itself.

In one embodiment for determining overlap pairs, FIG. 8 depicts the overlap error for the "ideal" target with zero offset and no characteristic asymmetry in the individual periodic structures forming the overlapped periodic structure A curve 702 between the OV and the measured asymmetry A. This graph is only used to explain the principle of judging only the pairing, and in each graph, the unit for measuring the asymmetry A and the pairing error OV is arbitrary.

In the "ideal" situation of (a) to (c) of FIG. 7, the curve 702 indicates that the measured asymmetry A has a sinusoidal relationship with the stack pair. The period P of the sinusoidal change corresponds to the period of the periodic structure (Spacing), which of course translates to the appropriate scale. The sinusoidal form is pure in this example, but may include harmonics in practical situations. For simplicity, it is assumed in this example that (a) only the first-order diffraction radiation from the target reaches the image sensor 23 (or the equivalent of the image sensor 23 in a given embodiment), and (b) The design of the experimental subject is such that in these first orders, there is a purely sinusoidal relationship between the strength and overlap between the results of the top periodic structure and the results of the bottom periodic structure. In practice, whether this situation is true depends on the function of the optical system design, the wavelength of the illumination radiation and the distance P between the periodic structures, and the design and stacking of the target.

As mentioned above, the biased periodic structure can be used to measure stack pairs rather than relying on a single measurement. This offset has a known value defined in the patterned device (eg, reticle) for generating the offset, and this value is used as a calibration on the substrate corresponding to the stacked pair of measurement signals. In this diagram, the calculation is explained graphically. In steps M1 to M5 of FIG. 6, asymmetry is obtained for the periodic structure of the device with offsets +d and -d, respectively (as shown, for example, in FIG. 7(b) and FIG. 7(c)) Measure A(+d) and A(-d). Fitting these measurements to a sinusoidal curve will give points 704 and 706 as shown. With a known offset, the true overlap error OV can be calculated. The design of the distance P between the sinusoids from the standard is known to me. The vertical scale of the curve 702 is not known to us at the beginning, but is an unknown factor that we can call the first-order harmonic proportional constant K ₁ .

In terms of equations, it is assumed that the relationship between the stack pair and the asymmetry is as follows: A = K ₁ sin( OV )

Where OV is expressed on a scale that makes the periodic structure pitch P correspond to an angle of 2π radians. In the case of using two measurements on periodic structures with different known offsets, one can solve the two equations to calculate the unknown K ₁ and the overlapping pair OV.

The metrics described above are designed for stacking with specific procedures (that is, procedures for constructing procedures and materials for a particular device or part of a layer, for example, one or material layer involved ( For example, its thickness and/or material type), a lithography exposure process, a resist development process, a baking process, an etching process, etc.) are associated with one or more specific layers, which have a metric and will be targeted to the program stack The nominal change provides flexibility in measuring stability. That is, using the knowledge of the program layer (eg, its material, thickness, etc.) applied to the processing steps of the layer, etc. to design the metrology target to obtain good parameters that will give the lithography program used for the measurement (if not (Best) the measurement result of the measurement.

However, during the development of the lithography program, the program stack for a certain layer can change significantly beyond the nominal. Existing targets cannot handle large changes in program stacks (ie, program changes). Therefore, multiple targets can be designed with the aim of changing these extreme values. This situation requires the design of the new target, which means that the program development must wait for a significant period of time before the new target (for example) is measured on the reticle; therefore, the development cycle time is significantly increased. In addition, multiple targets may mean a significant cost in producing different patterned devices (eg, photomasks) for each different target. Or, the space for accommodating the targets (ie, the available space on the patterned device pattern) may not be available and/or the output rate for measuring the targets may be significantly affected.

In addition, a typical diffraction-based stacking target is used to measure the stacking pair between a pair of layers. However, driving new programs (for example, multiple patterning programs, final via programs, etc.) requires not only overlay measurement between a single layer pair, but also overlay measurement among multiple layer pairs. Similar to the program development example discussed above, the solution for multi-layer pairs will increase the number of stacked targets (i.e., different targets required for different layer pairs), and therefore the number of measurements increases (also That is, the measurement of each pair of multi-layer combinations). Attributed to increase In addition, the target "occupied area" of the measurement time (that is, the available space on the patterned device pattern to accommodate these individual layer pairs) and the yield rate are the costs.

Therefore, according to an embodiment of the present invention, a diffractive metric target including a cluster of multiple periodic structure targets (a single cluster of periodic structures) including a set with a small total size but including a set of multiple design periodic structures is provided; for convenience of reference This target is called the extended operating range measurement and balance target. Therefore, for (for example) program development, a subset of the periodic structure from the extended operating range measurement target can be used for a certain program stacking condition, while the other (another ) The subset can be used for another program stacking condition, so significant changes in program stacking can be considered. Alternatively or additionally, for (for example) a multi-layered pair, a subset of the periodic structure from the extended operating range metric can be used for a certain layer pair, while the extended operating range metric can be used for another of the periodic structures (in addition Several) subsets can be used for another layer pair, so multiple stack pairs are implemented.

Therefore, in the case of significant program stack changes (for example, changes that cannot be properly handled by the specific periodic structure of the measurement target), the extended operating range of the measurement target allows placement of significantly different designs (both in the target Within a reasonable size), this will increase the chance of successfully measuring the results with changes to the program stack. This situation can be attributed to the existence of different designs that actively anticipate program stack changes, increasing the chance of successful first measurement. And in the case of multi-overlap measurement, the extended operating range measurement scale allows overlay measurements between multiple layers in one measurement sequence. That is, in one embodiment, multiple layer pairs can be measured in one measurement sequence, and in one embodiment, the diffraction data of multiple layer pairs can be simultaneously detected.

By having a different design periodicity in the extended operating range measurement The structure can be significantly changed by stacking and/or multiple layers by a single measurement target with different design sets in which there are periodic structures. In this way, the cost of generating different patterned devices (eg, photomasks) for each different individual target and/or the cost of measuring time can be significantly reduced. In addition, due to the relatively small size of the extended operating range measurement target, the "occupation area" of the target for multiple different individual targets due to the increased measurement time can be significantly reduced (i.e., to accommodate these individual layers The cost of the available space on the target patterned device pattern) and the yield rate. Therefore, the extended operating range measurement target can bring all of these multiple targets into a single target cluster that is sufficiently small in view of the occupied area and is also more advantageous in terms of measurement time than multiple individual targets.

Referring to FIG. 9, an embodiment of an extended operating range scale 800 is depicted. The extended operating range scale 800 includes a plurality of sub-targets, in this example, four diffractive sub-targets 802, 804, 806, and 808. If you should understand, you can provide a different number of sub-targets. For example, only two sub-targets can be provided. Alternatively, three, five, six, seven, eight, etc. sub-targets may be provided. In one embodiment, each sub-target 802 to 808 is separated from the adjacent sub-target by a gap 820. In one embodiment, the gap is 200 nanometers or greater, 250 nanometers or greater, 350 nanometers or greater, 500 nanometers or greater, 750 nanometers or greater, or 1 micrometer or greater. The gap promotes the reconstruction of the sub-targets, so that the sub-targets can be identified separately. In addition, gaps can help prevent crosstalk from diffraction from one sub-target to extend to another sub-target.

Each sub-target includes a periodic structure. In one embodiment, each sub-target includes at least one pair of periodic structures. In one embodiment, each sub-target includes at least two pairs of periodic structures. In one embodiment, the features (eg, lines) of the periodic structure in the sub-targets extend in the same direction. In an embodiment, at least one periodic structure of the sub-target may have There is a feature that extends in a direction (eg, substantially perpendicular) that is different from the direction in which the feature of another periodic structure of the sub-target extends. In one embodiment, the direction of the feature extension of the periodic structure of one sub-target may be different from the direction of the feature extension of the periodic structure of the other sub-target.

In one embodiment as shown in FIG. 9, each sub-target has a first pair of periodic structures 810 with features extending in a first direction (eg, X direction), and has a second different direction (eg, A second pair of periodic structures 812 that extend in a second direction that is substantially perpendicular to the first direction, such as the Y direction). As discussed above, one or more of the sub-targets need not extend the second pair of periodic structures in different directions, or the second different direction may be non-vertical and non-parallel to one or more of the sub-targets The first direction. In this example, each sub-target 802 to 808 has a general layout similar to the target of FIG. 4. That is, each sub-target has a first pair of periodic structures with features that extend in opposite corners in the X direction, and a pair of periodic structures that extend in the Y direction in opposite corners of the first pair of periodic structures The second pair of periodic features. However, the layout of the sub-targets may be different from the layout depicted in FIG. 9. For example, the location of the periodic structure may be different. As another example, the length and/or width of a pair of periodic structures may be different from the length and/or width of another pair of periodic structures. The relative angle of a pair of periodic structures extending to another pair of periodic structures may be different. Examples of different layouts for sub-targets are described with respect to FIGS. 12A to 12E.

The sub-targets 802 to 808 have a size such that they can fit completely or at least partially within the same contiguous area as the target of FIG. 4. For example, the extended operating range scale 800 may have within 25 microns x 25 microns or equal to 25 microns x 25 microns, within 20 microns x 20 microns or equal to 20 microns x 20 microns, within 16 microns x 16 microns Or equal to 16 microns × 16 microns, within 12 microns × 12 microns or equal to 12 microns × 12 microns, within 10 microns × 10 The external dimensions are within 10 microns x 10 microns or within 8 microns x 8 microns or within 8 microns x 8 microns. In one embodiment, at least part of each of the sub-targets is within a contiguous area of a certain size on the substrate. In an embodiment, at least part of each periodic structure of the plurality of sub-targets is within a contiguous area of a certain size on the substrate. In an embodiment, each periodic structure of the plurality of sub-targets is within a contiguous area of a certain size on the substrate. In an embodiment, the certain size is less than or equal to 1000 square micrometers, less than or equal to 900 square micrometers, less than or equal to 800 square micrometers, less than or equal to 700 square micrometers, less than or equal to 600 square micrometers, less than or equal to 500 square micrometers , Less than or equal to 450 square microns, less than or equal to 400 square microns, less than or equal to 350 square microns, less than or equal to 300 square microns, less than or equal to 250 square microns, less than or equal to 200 square microns, less than or equal to 150 square microns, Or less than or equal to 100 square microns. In an embodiment, each of the periodic structures of sub-targets 802 to 808 is not less than about 3 microns x 3 microns or not less than about 4 microns x 4 microns. In one embodiment, each of the periodic structures of sub-targets 802 to 808 is not less than about 9 square microns or not less than about 16 square microns.

In one embodiment, at least part of each of the sub-targets is within the area of the measurement light spot on the substrate (eg, within the width of the measurement light spot). In one embodiment, at least part of each periodic structure of the plurality of sub-targets is within the area of the measurement light spot on the substrate (eg, within the width of the measurement light spot). In one embodiment, each periodic structure of the plurality of sub-targets is within the area of the measurement light spot on the substrate (eg, within the width of the measurement light spot). In one embodiment, the measurement light spot has about 35 microns or less, about 30 microns or less, about 25 microns or less or about 20 microns or less, about 15 microns or less or about 10 microns or Smaller width (eg, diameter). Therefore, in one embodiment, Multiple sub-targets are measured in the measurement sequence, and in one embodiment, the diffraction data of multiple sub-targets can be detected simultaneously.

Similar to the target of FIG. 4, in an embodiment, the plurality of sub-targets at least partially overlap another periodic structure (only for clarity, FIG. 9 does not show the other periodic structure). In an embodiment, each of the sub-targets 802 to 806 at least partially overlaps a respective periodic structure. In one embodiment, the first extended operating range metric 800 overlaps the second extended operating range metric 800. In that case, each of the plurality of sub-targets 802 to 806 of the first extended operating range measurement target 800 will overlap each of the sub-targets 802 to 806 of the second extended operating range measurement target 800. In one embodiment, the first extended operating range metric 800 may be in one layer, and the second extended operating range metric 800 may be in another layer. In one embodiment, the first extended operating range metric 800 may be in one layer, and the second extended operating range metric 800 may have each of a plurality of sub-targets in different layers.

In addition, in addition to generating multiple sub-tags within a single layout, each of the plurality of sub-tags is also designed for (a) different program conditions and/or (b) for different layer pairs of a multi-layered pair. In other words, in an embodiment, the first sub-mark 802 of the plurality of sub-marks has a different design from the second sub-mark 804 of the plurality of sub-marks. In an embodiment, each of the sub-targets 802 to 808 may have a different design. In an embodiment, two or more sub-targets 802, 808 of the plurality of sub-subjects may have a different design than two or more other sub-targets 804, 806 of the plurality of sub-subjects.

Referring to FIG. 10, the use of examples of extended operating range metrics 900, 902 with a plurality of sub-targets (designed in FIG. 9) designed for different program conditions is depicted. For easy reference, the sub-targets 802, 804, 806, 808. As should be understood from the layout of FIG. 9, the sub-subjects 806 and 808 in FIG. 10 will actually be located “front” or “rear” of the sub-subjects 802 and 804 in FIG. 10, that is, in or out of the page, respectively. In addition, in this embodiment, the first extended operating range measurement target 900 is in one layer, and the second extended operating range measurement target 902 is in another layer. That is, in FIG. 10, each of the first extended operating range measurement scale 802, 804, 806, and 808 of the sub-target 900 is at the top layer, and the second extended operating range measurement scale 902 is the sub-standard 802. , 804, 806, and 808 are each in a single layer below 900 of the first extended operating range measurement target, such that each of the 802, 804, 806, and 808 of the child of the first extended operating range measurement target 900 One at least partially overlaps the 802, 804, 806, 808 of the respective sub-targets of the second extended operating range measurement target 902.

In the example of FIG. 10, each of the sub-targets 802, 804, 806, 808 is designed for different program stacks. In this example, the sub-target 802 is designed for a program stack with a first layer 904 of 100 nanometers and a second layer 906 of 100 nanometers, and the sub-target 804 is designed to have a 100 nanometer The different layers of the first layer 904 and the second layer 906 of 110 nm are stacked, and the sub-standard 806 is designed to be used for the difference between the first layer 904 of 110 nm and the second layer 906 of 110 nm The program stack, and the sub-subject 808 is designed for a program stack with a first layer 904 of 120 nm and a second layer 906 of 110 nm. As should be understood, the conditions for different program stacks can be different from the conditions used for the program stack in this example. For example, the program conditions may be other than the layer thickness. Other program conditions may include refractive index, layer material, etch rate, baking temperature, exposure focus, exposure dose, and so on. In addition, although in this embodiment, the extended operating range measurement target 900 differs from the overlapping extended operation range measurement target 902 in a different way It is designed (for example, in FIG. 10, the periodic structural features in the extended operating range measurement target 902 are segmented, while the periodic operating features in the extended operating range measurement target 900 are not segmented), but the extended type The operating range measurement target 900 and the extended operating range measurement target 902 may be the same. In addition, although four different program stacks can be successfully measured in FIG. 10, there may be a different number of program stacks that may be successfully measured.

In terms of design differences, the difference is the difference between the periodic structure between at least one of the sub-targets 802, 804, 806, and 808 and the other of the sub-targets 802, 804, 806, and 808. In one embodiment, the spacing is selected from the range of 100 nm to 1000 nm. In one embodiment, the design difference is a characteristic of a periodic structure between at least one of the sub-targets 802, 804, 806, and 808 and the other of the sub-targets 802, 804, 806, and 808 (eg, Line) or gap width. In one embodiment, the design difference is a characteristic of a periodic structure between at least one of the sub-targets 802, 804, 806, and 808 and the other of the sub-targets 802, 804, 806, and 808 (eg, The broken line is not the solid line). In one embodiment, the design difference is the offset of the periodic structure between at least one of the sub-targets 802, 804, 806, 808 and the other of the sub-targets 802, 804, 806, 808 (e.g. , Volume and/or direction). In one embodiment, the bias is selected to be in the range of 1 nanometer to 60 nanometers. The arrow depicts an embodiment of the offset direction. Make sure that no bias is required. In one embodiment, the difference in design is the difference in features or gap widths between the overlying extended operating range metrics (eg, the difference between "top CD and bottom CD"), for example, the first extended operating range metrics The characteristics or spacing widths of at least one of the sub-targets 802, 804, 806, and 808 are different from the characteristics of at least one of the associated sub-targets 802, 804, 806, and 808 that overlie the second extended operating range measurement and measurement target Or interval width. In one embodiment, the difference in design is between 802, 804, 806, 808 and their associated periodic structures Poor layout. See, for example, FIGS. 12A to 12E described below. In one embodiment, the difference in design is the best for measuring the beam between at least one of the sub-targets 802, 804, 806, 808 and the other of the sub-targets 802, 804, 806, 808 The difference in wavelength. In the case where the same wavelength measurement recipe is used for each of the sub-targets 802, 804, 806, and 808, the sub-target 802, 804, 806, and 808 can be optimized to accept the minimum performance for each sub-target loss. Or in one embodiment, multiple wavelengths can be used for multiple sub-targets, or wavelengths can be separated from the broadband radiation applied to the sub-targets. If you should understand, you can use a combination of design parameters.

Therefore, in one embodiment, in the first example, the extended operating range measurement target 900, 902 can be provided to the program stack with the characteristics of the sub-target 802, that is, the first layer 904 with 100 nm and the The stacking of the second layer 906 of 100nm. Therefore, when performing the measurement of 900, 902 of their extended operating range measurement standard, the measurement result of 802 from the sub-standard will be good for their program stacks, while the measurement results of 804, 806, and 808 from the sub-standard Will be less so good. However, conveniently, in the second example, 900, 902 of the same extended operating range measurement target can be provided to a program stack having the characteristics of sub-target 804, that is, having a first layer 904 of 100 nanometers and 110 nanometers The stacking of the second layer of 906 meters. Therefore, when the measurement of 900 and 902 of their extended operating range measurement targets are performed in this different program stack, the measurement result of 804 from the sub-target under this condition will be good for the other program stack, but from the sub-program. The measurement results of the target 802, 806 and 808 will be less good.

To determine whether the measurement results are good, one or more different techniques can be used. For example, in the first example mentioned above, there may simply not be any or significantly weaker measurement results from the sub-targets 804, 806, and 808 because it is actually not Measure. In another example, the residual (e.g., overlapping pairs of residuals) can be measured for each of the sub-targets, and the lower or lowest residual of one of the sub-targets can represent the amount from that sub-target The test results are good. In another example, the same parameter can be measured by another procedure (eg, overlapping pairs). As an example, an electrical test may be performed to determine a value for a parameter, and a sub-target having a value closest to the value measured by the electrical test may indicate that the measurement result from the sub-target is good.

Referring to FIG. 11, the use of an example of an extended operating range measurement target 1000, 1002 with a plurality of sub-targets (designed in FIG. 9) for multiple pairs is depicted. For ease of reference, the sub-targets 802, 804, 806, 808 are depicted in the form of columns in FIG. As should be understood from the layout of FIG. 9, the sub-subjects 806 and 808 in FIG. 11 will actually be located “front” or “rear” of the sub-subjects 802 and 804 in FIG. 11, that is, in or out of the page, respectively. In addition, in this embodiment, the first extended operating range measurement target 900 is at one layer, and the second extended operating range measurement target 902 has each of a plurality of sub-targets in different layers. That is, in FIG. 11, each of the 802, 804, 806, and 808 of the first extended operating range measurement and measurement target 900 is at the top layer, and the second extended operating range measurement and measurement target 802 is the sub-802 , 804, 806, 808 are in different layers below the first extended operating range measurement target 900, such that each of the 802, 804, 806, 808 of the child of the first extended operating range measurement target 900 One at least partially overlaps the 802, 804, 806, 808 of the respective sub-targets of the second extended operating range measurement target 902.

In the example of FIG. 11, each of the sub-targets 802, 804, 806, 808 is designed for different layers. In this example, the sub-target 802 is designed to measure the stacking pair for the top layer and the first layer pair of the layer 1010, and the sub-target 804 is designed to measure for the top The overlay of the second layer pair of the sub-layer and the layer 1008, the sub-target 806 is designed for measuring the overlay pair of the third layer pair of the top layer and the layer 1006, and the sub-target 808 is designed for the quantity It is measured for the top layer and the fourth layer pair of layer 1004. Although each sub-target in this example measures a different layer pair, in one embodiment, two or more of the sub-targets can measure the first layer pair, and one or more other sub-targets can measure Measure the second layer pair. In addition, although four different layer pairs can be measured in FIG. 11, there may be a different number of layer pairs that can be measured.

In this embodiment, each of the 802, 804, 806, and 808 of the 900 sub-targets of the first extended operating range metric has the same design, and the 802, 804, and 806 of the 900 sub-targets of the first extended operating range metric , 808 is the same in design as 802, 804, 806, 808 of the second extended operating range measurement standard 902 sub-target. However, as mentioned above, two or more of the 802, 804, 806, 808 sub-targets of the second extended operating range measurement target 902 are in different layers (and therefore have different designs) while still being The first extended operating range measures the bottom of the standard 900. In one embodiment, one or more of the 802, 804, 806, 808 of the 900 sub-targets of the first extended operating range metric may have 802, 804, 806, the One or more of the different designs in 808. In one embodiment, one or more of the 802, 804, 806, 808 of the sub-standard 900 of the first extended operating range metric may have 802, 804, 806, the sub-standard of the 902 sub-standard of the second extended operating range metric One or more of 808 have different designs.

In an embodiment, since the extended operating range measures the position of each of the 802, 804, 806, 808 of the sub-targets of the target, it is easy to perform stacking pairs for each specific different layer pair. In addition, because the extended operating range metrics have The 802, 804, 806, and 808 of different layer pairs can be measured in a plurality of different layer pairs in one measurement sequence. For example, the diffraction information of each of the different layer pairs can be captured immediately. Instead of using the measured overlay value of each different layer pair separately or in addition to the measured overlay value of each different layer pair, the average value, median value or the measurement of the sub-standard 802, 804, 806, 808 Other statistical values can also be used for program control. This situation may be useful in cases where there is a point of interest in one or more of the sub-targets 802, 804, 806, 808 due to its small specific reliability. Statistics can help eliminate anomalies.

12A-12E depict additional embodiments of extended operating range metrics. In one embodiment, these embodiments of the extended operating range metrics are designed for multi-layer pair measurement. However, additionally or alternatively, such extended operating range metrics can be used with appropriate modifications for program stack changes (ie, different sub-targets of the extended operating range metrics are designed for Different program stacking conditions). Of course, the design possibility of the extended operating range measurement scale is not limited to the design possibility of the extended operation range measurement scale described in FIGS. 9 and 12A to 12E. It is possible for different design changes of the extended operating range measurement target to accommodate, for example, different or more program stack changes, different amounts of layers, different layout constraints, and so on. In addition, each of the design of the extended operating range measurement target in FIGS. 12A-12E depicts two sub-targets. As should be understood, the extended operating range measurement target may have more than two sub-targets.

In one embodiment, the extended operating range scale is designed to maximize the number of features exposed to radiation. In one embodiment, the extended operating range scale is designed to maximize periodic structures of the same type (eg, same size, area, etc.). In one embodiment, the extended operating range metrics are designed to maximize Weighing. In one embodiment, the extended operating range measure is designed to maximize the size of the periodic structure of one sub-subject relative to the periodic structure of another sub-subject while maintaining each of its sub-subjects The diffraction efficiency is essentially the same or similar.

Referring to FIG. 12A, an embodiment of an extended operating range measurement target 1200 having a first sub-target 1202 and a second sub-target 1204 is depicted. Compared with the extended operating range measurement and weighing target of FIG. 9, the sub-targets are “interleaved” with each other, in which case the periodic structure of the second sub-target 1204 meets at the center of the extended operating range measurement and weighing target 1200, and The periodic structure of the first sub-target 1202 is arranged around the periphery. In this embodiment, the length L1 and width W1 of each periodic structure of the first sub-target 1202 are substantially the same as the length L2 (see FIG. 12B) and width W2 of each periodic structure of the second sub-target 1204. In one embodiment, the lengths L1, L2 are 8 microns, and the widths W1, W2 are 4 microns. In one embodiment, the feature length is in the range of 3500 nm to 4000 nm, for example, 3875 nm. In one embodiment, the interval between the adjacent sides of the periodic structure of the first sub-target and the second sub-target is in the range of 150 nm to 400 nm, for example, 250 nm. In an embodiment, the interval between all adjacent sides of the periodic structure of the first sub-target and the second sub-target is not uniform. In an embodiment, there may be an offset difference between the first sub-target 1202 and the second sub-target 1204. The arrow depicts an embodiment of the offset direction. Make sure that no bias is required. In one embodiment, the offset is less than or equal to 60 nanometers. In one embodiment, the extended operating range scale 1200 can measure stacks in the range of 30 nanometers or less.

Referring to FIG. 12B, an embodiment of an extended operating range measurement target 1220 having a first sub-target 1222 and a second sub-target 1224 is depicted. Each of these sub-targets is a different adjacent part of the extended operating range measurement target 1220. In this situation, the first sub-standard The 1222 is in the "top" section, and the second sub-target 1224 is in the "bottom" section. In this embodiment, the length L1 and width W1 of each periodic structure of the first sub-target 1222 are substantially the same as the length L2 and width W2 of each periodic structure of the second sub-target 1224. In one embodiment, the lengths L1, L2 are 8 microns, and the widths W1, W2 are 4 microns. In one embodiment, the feature length is in the range of 3500 nm to 4000 nm, for example, 3875 nm. In one embodiment, the interval between the adjacent sides of the periodic structure of the first sub-target and the second sub-target is in the range of 150 nm to 400 nm, for example, 250 nm. In an embodiment, the interval between all adjacent sides of the periodic structure of the first sub-target and the second sub-target is not uniform. In an embodiment, there may be an offset difference between the first sub-target 1222 and the second sub-target 1224. The arrow depicts an embodiment of the offset direction. Make sure that no bias is required. In one embodiment, the offset is less than or equal to 60 nanometers. In one embodiment, the extended operating range scale 1220 can measure stacks in the range of 30 nanometers or less.

Referring to FIG. 12C, an embodiment of an extended operating range measurement target 1240 having a first sub-target 1242 and a second sub-target 1244 is depicted. The design of FIG. 12C is similar to the design of FIG. 12A, because the sub-targets are “interlaced” with each other. In this case, the periodic structure of the 1244 of the second sub-target meets at the center of the scale 1240 of the extended operating range, and the first The periodic structure of a sub-target 1242 is arranged around the periphery. In this embodiment, the length L1 of each periodic structure of the first sub-target 1242 is different from the length L2 of each periodic structure of the second sub-target 1244, and the length of each periodic structure of the first sub-target 1242 The width W1 is substantially the same as the width W2 of each periodic structure of the second sub-target 1244. In one embodiment, the length L1 is 6 microns and the width W1 is 4.9 microns. In one embodiment, the length L2 is 10.4 microns and the width W2 is 4.9 microns. In one embodiment, the characteristic length is In the range of 3500 nm to 4000 nm, for example, 3875 nm. In one embodiment, the interval between the adjacent sides of the periodic structure of the first sub-target and the second sub-target is in the range of 150 nm to 400 nm, for example, 250 nm. In an embodiment, the interval between all adjacent sides of the periodic structure of the first sub-target and the second sub-target is not uniform. In an embodiment, there may be an offset difference between 1242 of the first sub-target and 1244 of the second sub-target. The arrow depicts an embodiment of the offset direction. Make sure that no bias is required. In one embodiment, the offset is less than or equal to 60 nanometers. In one embodiment, the extended operating range scale 1240 can measure stacks in the range of 30 nanometers or less. This embodiment may be advantageous for multi-layered pairs, where the 1244 of the second sub-target rather than the 1242 of the first sub-target is used for the lower layer, because the properties of the layer material, thickness, etc. are significantly attenuated or otherwise interfere with the diffraction from the lower layer radiation. The software used to design the extended operating range measurement standard (described in more detail below) can select the design parameters of the periodic structure of the first sub-target 1242 and the second sub-target 1244 based on the properties of the layer material, thickness, etc. ( For example, the characteristics and spacing width, spacing, layout, etc.) make the diffraction efficiency of each of the first sub-target 1242 and the second sub-target 1244 substantially the same or similar. This situation can help prevent the measurement sensor from clipping excessive diffraction radiation from the first sub-target 1242 or the second sub-target 1244.

Referring to FIG. 12D, an embodiment of an extended operating range measurement target 1260 having a first sub-target 1262 and a second sub-target 1264 is depicted. The design of FIG. 12D is similar to the design of FIG. 12C, with the difference that the design is more symmetrical. In this case, the 1264 of the second sub-target is in the form of a cross and the 1262 of the first sub-target is arranged around the periphery. In this embodiment, the length L1 of each periodic structure of the first sub-target 1262 is different from the length L2 of each periodic structure of the second sub-target 1264, and the length of each periodic structure of the first sub-target 1262 The width W1 is substantially the same as the width W2 of each periodic structure of the second sub-target 1264. In a In the embodiment, the length L1 is 5.4 microns, and the width W1 is 5.4 microns. In one embodiment, the length L2 is 7.5 microns and the width W2 is 5.4 microns. In one embodiment, the feature length is in the range of 3500 nm to 4000 nm, for example, 3875 nm. In one embodiment, the interval between the adjacent sides of the periodic structure of the first sub-target and the second sub-target is in the range of 150 nm to 400 nm, for example, 250 nm. In an embodiment, the interval between all adjacent sides of the periodic structure of the first sub-target and the second sub-target is not uniform. In an embodiment, there may be an offset difference between 1262 of the first sub-target and 1264 of the second sub-target. The arrow depicts an embodiment of the offset direction. Make sure that no bias is required. In one embodiment, the offset is less than or equal to 60 nanometers. In one embodiment, the extended operating range scale 1260 can measure stacks in the range of 30 nanometers or less. This embodiment may be advantageous for multi-layer pairs, where 1264 of the second sub-target is used for the lower layer instead of 1262 of the first sub-target, because the properties of the layer material, thickness, etc. are significantly attenuated or otherwise interfere with diffraction from the lower layer radiation. The software used to design the extended operating range measurement scale (described in more detail below) can select the design parameters of the periodic structure of 1262 of the first sub-target and 1264 of the second sub-target based on the properties of the layer material, thickness, etc. ( For example, the characteristics and spacing width, pitch, layout, etc.) make the diffraction efficiency of each of the first sub-target 1262 and the second sub-target 1264 substantially the same or similar. This situation can help prevent the measurement sensor from clipping excessive diffraction radiation from 1262 of the first sub-target or 1264 of the second sub-target. This design is slightly more balanced than the design of Figure 12C.

Referring to FIG. 12E, an embodiment of an extended operating range measurement target 1280 with a first sub-target 1282 and a second sub-target 1284 is depicted. The design of FIG. 12E is similar to the design of FIGS. 12C and 12D, because the periodic structure of the first sub-target 1282 and the second sub-target 1284 are different. In the design of FIG. 12E, the periodic structure of the first sub-target 1282 is focused on Inside, and the periodic structure of the first sub-target 1284 is arranged around the periphery. In this embodiment, the length L1 and width W1 of each periodic structure of the first sub-target 1282 are different from the length L2 and width W2 of each periodic structure of the first sub-target 1284. In one embodiment, the length L1 is 6.25 microns and the width W1 is 6.25 microns. In one embodiment, the length L2 is 12.5 microns and the width W2 is 7.5 microns. In one embodiment, the feature length is in the range of 3500 nm to 4000 nm, for example, 3875 nm. In one embodiment, the interval between the adjacent sides of the periodic structure of the first sub-target and the second sub-target is in the range of 150 nm to 400 nm, for example, 250 nm. In an embodiment, the interval between all adjacent sides of the periodic structure of the first sub-target and the second sub-target is not uniform. In an embodiment, there may be an offset difference between 1282 of the first sub-target and 1284 of the second sub-target. The arrow depicts an embodiment of the offset direction. Make sure that no bias is required. In one embodiment, the offset is less than or equal to 60 nanometers. In one embodiment, the extended operating range scale 1280 can measure stacks in the range of 30 nanometers or less. This embodiment may be advantageous for multi-layered pairs, where the first sub-target 1284 instead of the first sub-target 1282 is used for the lower layer. This is because the properties of the layer material, thickness, etc. are significantly attenuated or otherwise interfere with the diffraction from the lower layer radiation. The software used to design the extended operating range measurement target (described in more detail below) can select the design parameters of the periodic structure of the first sub-target 1282 and the second sub-target 1284 based on the properties of the layer material, thickness, etc. ( For example, the characteristics and spacing width, spacing, layout, etc.) make the diffraction efficiency of each of the first sub-target 1282 and the second sub-target 1284 substantially the same or similar. This situation can help prevent the measurement sensor from clipping excessive diffraction radiation from the first sub-target 1282 or the second sub-target 1284. This design is slightly more balanced than the design of Figure 12C. In addition, in this embodiment, 1282 of the first sub-target may be smaller than the measurement light point (that is, 1282 of the first sub-target is overfilled), and 1284 of the second sub-target will be larger than the measurement light point (also That is, 1284 of the second sub-target is underfilled). Although underfilled, 1284 enough for the second sub-target can be captured to take measurements.

Referring to FIGS. 22(A) to 22(C), the use of examples of extended operating range metrics 1500, 1502 with multiple sub-targets for a multi-layer pair is depicted. In this embodiment, the extended operating range metrics 1500, 1502 include sub-targets 1504 and 1506. The sub-target 1504 contains a periodic structure 1508, and the sub-target 1506 contains a periodic structure 1510.

In this example, FIG. 22(A) depicts the location of the periodic structure 1510 of 1504 designated as a sub-target in the lower layer of layer 1. FIG. 22(B) depicts the location of the periodic structure 1512 located above layer 1 and designated as the sub-label 1506 in the higher layer of layer 2. FIG. FIG. 22(C) depicts the location of the periodic structure of 1504 and 1506 located above layer 1 and layer 2 and designated as sub-targets in the higher layer of layer 3. FIG. These layers need not be in close proximity to each other. For example, one or more other layers may be provided between layer 1 and layer 2 or between layer 2 and layer 3, where these other layers will not have any of those shown in FIGS. 22(A) to 22(C) A periodic structure in which any of the periodic structures overlap. In an embodiment, the extended operating range scale 1500, 1502 may have one or more additional sub-targets. In an embodiment, each of the one or more additional sub-targets may be located in a separate one or more additional layers (and thus allow the measurement of additional layer pairs).

In addition, in practice, the periodic structure in FIG. 22(C) will at least partially overwrite the periodic structure in FIG. 22(A), and the periodic structure in FIG. 22(C) will at least partially overwrite FIG. 22(C). B) The periodic structure. In detail, the periodic structure 1510 in FIG. 22(C) will at least partially overwrite the periodic structure 1510 in FIG. 22(A). In addition, the periodic structure 1512 in FIG. 22(C) will at least partially overwrite the periodic structure 1512 in FIG. 22(B). In one embodiment, the order of the periodic structures in these layers can be changed. For example, Figure 22(C) It may be located at layer 2, and FIG. 22(B) may be located at layer 3 (in this case, FIG. 22(A) will be at layer 1) or may be located at layer 1 (in this case, FIG. 22(A) Will be at layer 3). In this situation, different combinations of layer pairs can be measured, that is, the layer pair between layer 1 and layer 2 and/or the layer pair between layer 2 and layer 3. Or for example, FIG. 22(C) may be located at layer 1 while FIG. 22(B) may still be located at layer 2 (and therefore FIG. 22(A) will be located at layer 3), or FIG. 22(B) may be Located at layer 3 (in this case Figure 22(A) will be located at layer 2).

In this embodiment, the features of the periodic structure 1510 of the sub-target 1504 extend in the first direction, which can be named the Y direction. The periodic structure 1510 can accordingly determine overlapping pairs in the second direction, which can be named the X direction, which is substantially orthogonal to the first direction. In addition, the characteristics of the periodic structure 1512 of the sub-target 1506 extend in the same first direction. Therefore, the periodic structure 1512 can also determine overlapping pairs in the X direction.

In one embodiment, the features of the periodic structure 1510 of the sub-target 1504 extend in the second direction. In that situation, the periodic structure 1510 can determine overlapping pairs in the Y direction. In addition, the characteristics of the periodic structure 1512 of the sub-target 1506 will extend in the same second direction. Therefore, the periodic structure 1512 will likewise be able to determine overlapping pairs in the Y direction.

Therefore, in the embodiment of FIG. 22, the extended operating range metrics 1500, 1502 allow the determination of the X direction (or Y direction) between layer 1 (FIG. 22(A)) and layer 3 (FIG. 22(C)). ), it also allows the determination of the overlapping pair in the X direction between layer 2 (FIG. 22(B)) and layer 3 (FIG. 22(C)). Therefore, in a single measurement sequence, overlapping pairs in the same direction between different layer pairs can be achieved.

In order to facilitate checking the alignment of periodic structures to help ensure that the appropriate periodic structure or structures at least partially overlap the associated periodic structure or structures, the selection criteria may be Note 1508 is provided at each of the plurality of layers. For example, a mark 1508 can be used to perform a rough alignment to, for example, help ensure that the periodic structure is substantially overlaid with other periodic structures (for example, if one mark 1508 is significantly misaligned with another mark, the mark cannot be used Target measurement). Additionally or alternatively, the mark 1508 may be used to facilitate alignment of the measuring beam spot in the middle of the target.

Referring to FIGS. 23(A) to 23(C), the use of examples of extended operating range metrics 1600, 1602 with multiple sub-targets for a multi-layer pair is depicted. In this embodiment, the extended operating range metrics 1600, 1602 include sub-targets 1604, 1606, 1608, 1610. Sub-target 1604 includes periodic structure 1612, sub-target 1606 includes periodic structure 1614, sub-target 1608 includes periodic structure 1616 and sub-target 1610 includes periodic structure 1618.

In this example, FIG. 23(A) depicts the location of the periodic structure 1614 of the sub-target 1606 in the lower layer designated as layer 1 and the location of the periodic structure 1616 of the sub-target 1608. FIG. 23(B) depicts the location of the periodic structure 1612 of the sub-target 1604 and the location of the periodic structure 1618 of the sub-target 1610 located above layer 1 in the higher layer designated as layer 2. FIG. 23(C) depicts the location of the periodic structure of 1604, 1606, 1608, 1610 located above layer 1 and layer 2 and designated as the neutron target of the higher layer of layer 3. FIG. These layers need not be in close proximity to each other. For example, one or more other layers may be provided between layer 1 and layer 2 or between layer 2 and layer 3, where these other layers will not have any of those shown in FIGS. 23(A) to 23(C) A periodic structure in which any of the periodic structures overlap.

In addition, in practice, the periodic structure in Figure 23(C) will at least partially overwrite the periodic structure in Figure 23(A), and the periodic structure in Figure 23(C) will at least partially overwrite Figure 23(C). B) The periodic structure. In detail, the periodic structure 1614 in FIG. 23(C) and 1616 will at least partially overlie the respective periodic structures 1614 and 1616 in FIG. 23(A). In addition, the periodic structures 1612 and 1618 in FIG. 23(C) will at least partially overwrite the respective periodic structures 1612 and 1618 in FIG. 23(B). In one embodiment, the order of the periodic structures in these layers can be changed. For example, FIG. 23(C) may be located at layer 2 and FIG. 23(B) may be located at layer 3 (in this case, FIG. 23(A) will be at layer 1) or may be located at layer 1 ( In this situation, FIG. 23(A) will be at layer 3). In this situation, different combinations of layer pairs can be measured, that is, the layer pair between layer 1 and layer 2 and/or the layer pair between layer 2 and layer 3. Or for example, FIG. 23(C) may be located at layer 1, while FIG. 23(B) may still be located at layer 2 (and therefore FIG. 23(A) will be located at layer 3), or FIG. 23(B) may be Located at layer 3 (in this case Figure 23(A) will be located at layer 2).

In this embodiment, the characteristic of the periodic structure 1612 of the sub-target 1604 extends in the first direction, which can be named Y direction. The periodic structure 1612 can accordingly determine overlapping pairs in the second direction, which can be named the X direction, which is substantially orthogonal to the first direction. In addition, the characteristics of the periodic structure 1614 of the sub-target 1606, the characteristics of the periodic structure 1616 of the sub-target 1608, and the characteristics of the periodic structure 1618 of the sub-target 1610 extend in the same direction. Therefore, the periodic structures 1614, 1616, and 1618 can also determine the overlapping pairs in the X direction, respectively.

In one embodiment, the features of the sub-target 1604 periodic structure 1612 extend in the second direction. In that situation, the periodic structure 1612 can determine overlapping pairs in the Y direction. In addition, the features of the periodic structures 1614, 1616, and 1618 will extend in the same second direction. Therefore, the periodic structures 1614, 1616, and 1618 will likewise be able to determine overlapping pairs in the Y direction.

Therefore, in the embodiment of FIG. 23, the extended operating range scale 1600, 1602 allows to determine the X direction (or Y direction) between layer 1 (FIG. 23(A)) and layer 3 (FIG. 23(C)). ) The above overlapping pair also allows to determine the overlapping pair in the X direction between layer 2 (FIG. 23(B)) and layer 3 (FIG. 23(C)). In addition, in this case, the overlapping pairs in the X direction (or Y direction) are measured at least twice for each layer pair due to one or more periodic structures in at least two sub-targets in each layer . For example, in one embodiment, the stacking pair in the X direction (or Y direction) between layer 1 and layer 3 is measured by at least each of sub-targets 1604 and 1610. Similarly, for example, in one embodiment, the stacking pair in the X direction (or Y direction) between layer 2 and layer 3 is measured by at least each of sub-targets 1606 and 1608. Therefore, in a single measurement sequence, for each layer pair, multiple overlapping pairs in the same direction between different layer pairs can be realized. The overlay results can be combined statistically (eg, average), or can be combined by weighting (eg, the overlay value measured for one layer pair using one sub-target is weighted more than the amount using another sub-target Measure the stacking value of the layer pair).

Referring to FIGS. 24(A) to 24(C), the use of examples of 1700, 1702 with extended operating range metrics for multiple sub-targets for a multi-layer pair is depicted. In this embodiment, the extended operating range metrics 1700, 1702 include sub-targets 1704 and 1706. Sub-target 1704 contains periodic structure 1708, while sub-target 1706 contains periodic structure 1710.

In this example, FIG. 24(A) depicts the location of the periodic structure 1708 of 1704 designated as the sub-target in the lower layer of layer 1. FIG. 24(B) depicts the location of the periodic structure 1710 located above layer 1 and designated as the sub-target 1706 in the higher layer of layer 2. FIG. FIG. 24(C) depicts the location of the periodic structure of 1704 and 1706 located above layers 1 and 2 and designated as the sub-targets in the higher layer of layer 3. FIG. These layers need not be in close proximity to each other. For example, one or more other layers may be provided between layer 1 and layer 2 or between layer 2 and layer 3, where these other layers will not have the same structure as those in FIG. 24(A) to FIG. 24(C) Periodic structure where any of the periodic structures overlap Structure.

In addition, in practice, the periodic structure in Figure 24(C) will at least partially overwrite the periodic structure in Figure 24(A), and the periodic structure in Figure 24(C) will at least partially overwrite Figure 24(C). B) The periodic structure. In detail, the periodic structure 1708 in FIG. 24(C) will at least partially overwrite the periodic structure 1708 in FIG. 24(A). In addition, the periodic structure 1710 in FIG. 24(C) will at least partially overwrite the periodic structure 1710 in FIG. 24(B). In one embodiment, the order of the periodic structures in these layers can be changed. For example, FIG. 24(C) may be located at layer 2 and FIG. 24(B) may be located at layer 3 (in this case, FIG. 24(A) will be at layer 1) or may be located at layer 1 ( In this case, FIG. 24(A) will be at layer 3). In this situation, different combinations of layer pairs can be measured, that is, the layer pair between layer 1 and layer 2 and/or the layer pair between layer 2 and layer 3. Or for example, FIG. 24(C) may be located at layer 1 while FIG. 24(B) may still be located at layer 2 (and therefore FIG. 24(A) will be located at layer 3), or FIG. 24(B) may be Located at layer 3 (in this case Figure 24(A) will be located at layer 2).

In this embodiment, the features of the periodic structure 1708 of the sub-target 1704 extend in the first direction, which can be named the Y direction. The periodic structure 1708 can accordingly determine overlapping pairs in the second direction, which can be named the X direction, which is substantially orthogonal to the first direction. In addition, the characteristics of the periodic structure 1710 of the sub-target 1706 extend in the second direction. The periodic structure 1710 can accordingly determine overlapping pairs in the Y direction.

In one embodiment, the features of the periodic structure 1708 of the sub-target 1704 extend in the second direction. In that situation, the periodic structure 1708 can determine overlapping pairs in the Y direction. In addition, under that condition, the features of the periodic structure 1710 of the sub-target 1706 will extend in the same second direction. Therefore, the periodic structure 1710 will similarly be able to determine the Y side Stack up right.

Therefore, in the embodiment of FIG. 24, the extended operating range metrics 1700 and 1702 allow the determination of the overlapping pair in the X direction between layer 1 (FIG. 24(A)) and layer 3 (FIG. 24(C)). At the same time, it also allows to determine the overlapping pair in the Y direction between layer 2 (FIG. 24(B)) and layer 3 (FIG. 24(C)). Or, for example, by shifting FIG. 24(B) to layer 1 and FIG. 24(A) to layer 2, the extended operating range metrics 1700, 1702 under that condition will allow determination of layer 1 The overlap in the Y direction with layer 3 also allows the determination of the overlap in the X direction between layer 2 and layer 3. Therefore, in a single measurement sequence, overlapping pairs in different directions between different layer pairs can be achieved.

Referring to FIGS. 25(A) to 25(C), the use of examples of 1800, 1802 with extended operating range metrics for multiple sub-targets of a multi-layer pair is depicted. In this embodiment, the extended operating range metrics 1800, 1802 include sub-targets 1804, 1806, 1810, and 1812. Sub-label 1804 includes periodic structure 1812, sub-label 1806 includes periodic structure 1814, sub-label 1808 includes periodic structure 1816, and sub-label 1810 includes periodic structure 1818.

In this example, FIG. 25(A) depicts the location of the periodic structure 1816 of the sub-label 1808 in the lower layer designated as layer 1 and the location of the periodic structure 1818 of the sub-label 1810. 25(B) depicts the location of the periodic structure 1812 of the sub-target 1806 located above the layer 1 designated as the sub-target in the higher layer of the layer 2, and the location of the periodic structure 1814 of the sub-target 1806. FIG. 25(C) depicts the location of the periodic structure of 1804, 1806, 1808, and 1810 located above layer 1 and layer 2 and designated as sub-targets in the higher layer of layer 3. FIG. These layers need not be in close proximity to each other. For example, one or more other layers may be provided between layer 1 and layer 2 or between layer 2 and layer 3, where these other layers will not have any of those shown in FIGS. 25(A) to 25(C) Periodic structure Periodic structure in which any one overlaps.

In addition, in practice, the periodic structure in FIG. 25(C) will at least partially overwrite the periodic structure in FIG. 25(A), and the periodic structure in FIG. 25(C) will overwrite at least partially over FIG. 25(C). B) The periodic structure. In detail, the periodic structures 1816 and 1818 in FIG. 25(C) will at least partially overwrite the associated periodic structures 1816 and 1818 in FIG. 25(A). In addition, the periodic structures 1812 and 1814 in FIG. 25(C) will at least partially overwrite the associated periodic structures 1812 and 1814 in FIG. 25(B). In one embodiment, the order of the periodic structures in these layers can be changed. For example, FIG. 25(C) may be located at layer 2 and FIG. 25(B) may be located at layer 3 (in this case, FIG. 25(A) will be at layer 1) or may be located at layer 1 ( In this situation, FIG. 25(A) will be at layer 3). In this situation, different combinations of layer pairs can be measured, that is, the layer pair between layer 1 and layer 2 and/or the layer pair between layer 2 and layer 3. Or for example, FIG. 25(C) may be located at layer 1 while FIG. 25(B) may still be located at layer 2 (and therefore FIG. 25(A) will be located at layer 3), or FIG. 25(B) may be Located at layer 3 (in this case Figure 25(A) will be located at layer 2).

In this embodiment, the features of the periodic structure 1812 of the sub-target 1804 and the features of the periodic structure 1814 of the sub-target 1806 extend in the first direction, which can be named the Y direction. The periodic structures 1812 and 1814 can respectively determine the overlapping pairs in the second direction, which can be named the X direction, which is substantially orthogonal to the first direction. In addition, the features of the periodic structure 1816 of the sub-target 1808 and the features of the periodic structure 1818 of the sub-target 1810 extend in the second direction. The periodic structures 1816 and 1818 can respectively determine the overlapping pairs in the Y direction accordingly.

In one embodiment, the features of the periodic structure 1812 of the sub-target 1804 and the features of the periodic structure 1814 of the sub-target 1806 extend in the second direction. In that situation, the periodic structures 1812 and 1814 can determine the overlapping pairs in the Y direction. In addition, in the situation Next, the features of the sub-standard 1808 periodic structure 1816 and the sub-standard 1810 periodic structure 1818 will extend in the first direction. Therefore, in that situation, the periodic structures 1816 and 1818 can determine the overlapping pairs in the X direction.

Therefore, in the embodiment of FIG. 25, the extended operating range metrics 1800, 1802 allow the determination of the overlapping pair in the X direction between layer 2 (FIG. 25(B)) and layer 3 (FIG. 25(C)). At the same time, it is also allowed to determine the overlap between the layer 1 (FIG. 25(A)) and the layer 3 (FIG. 25(C)) in the Y direction. Or, for example, by shifting FIG. 25(B) to layer 1 and FIG. 25(A) to layer 2, the extended operating range measurement scale 1800, 1802 under that condition will allow to determine layer 1 The overlap between the layer 3 and the X direction in the X direction also allows the determination of the overlap between the layer 2 and the layer 3 in the Y direction. In addition, in this case, the overlapping pairs in the X direction and the Y direction will be measured at least twice for each layer pair due to one or more periodic structures of at least two sub-targets in each layer. For example, in one embodiment, the overlap pair in the X direction between layer 2 and layer 3 is measured by at least each of sub-targets 1804 and 1806. Similarly, for example, in one embodiment, the overlap pair in the Y direction between layer 1 and layer 3 is measured by at least each of sub-targets 1808 and 1810. Therefore, in a single measurement sequence, overlapping pairs in different directions between different layer pairs can be realized multiple times for each layer pair. The overlay results can be combined statistically (eg, average), or can be combined by weighting (eg, the overlay value measured for one layer pair using one sub-target is weighted more than the amount using another sub-target Measure the stacking value of the layer pair).

Referring to FIGS. 26(A) to 26(E), the use of examples of 1800, 1802 with extended operating range metrics for multiple sub-targets of a multi-layer pair is depicted. In this embodiment, the extended operating range metrics 1800, 1802 include sub-targets 1804, 1806, 1810, and 1812. Sub-target 1804 contains periodic structure 1812, sub-target 1806 contains period Sexual structure 1814, sub-label 1808 includes periodic structure 1816, and sub-label 1810 includes periodic structure 1818.

In this example, FIG. 26(A) depicts the location of the periodic structure 1814 of 1806 designated as a sub-target in the lower layer of layer 1. FIG. 26(B) depicts the location of the periodic structure 1818 above the layer 1 designated as the sub-target 1810 in the higher layer of the layer 2. FIG. 26(C) depicts the location of the periodic structure 1816 above the layers 1 and 2 designated as the sub-target 1808 in the higher layer of layer 3. FIG. FIG. 26(D) depicts the location of the periodic structure 1812 located above layer 1 to layer 3 and designated as the sub-target 1804 in the higher layer of layer 4. FIG. FIG. 26(E) depicts the location of the periodic structure of 1804, 1806, 1808, and 1810 located above layers 1 to 4 and designated as sub-subjects in the higher layer of layer 5. FIG. These layers need not be in close proximity to each other. For example, one or more other layers may be provided between layer 1 and layer 2, between layer 2 and layer 3, between layer 3 and layer 4, and/or between layer 4 and layer 5, such other The layer will not have a periodic structure that overlaps with any of the periodic structures of FIGS. 26(A) to 26(E).

In addition, in practice, the periodic structure in Figure 26(E) will at least partially overwrite the periodic structure in Figure 26(A), and the periodic structure in Figure 26(E) will at least partially overwrite Figure 26(B). ), the periodic structure in FIG. 26(E) will at least partially overwrite the periodic structure in FIG. 26(C), and the periodic structure in FIG. 26(E) will overwrite at least partially The periodic structure in 26(D). In detail, the periodic structure 1814 in FIG. 26(E) will at least partially overwrite the periodic structure 1814 in FIG. 26(A). In addition, the periodic structure 1818 in FIG. 26(E) will at least partially overwrite the periodic structure 1818 in FIG. 26(B), and the periodic structure 1816 in FIG. 26(E) will at least partially overwrite FIG. 26(C). ) And the periodic structure 1812 in FIG. 26(E) will at least partially overwrite the periodic structure 1812 in FIG. 26(D). In one embodiment, the periodic structure in the layers can be changed sequence. For example, FIG. 26(E) may be located at layer 3, and FIG. 26(C) may be located at layer 5 or another layer (if the structure at another layer is moved to another layer). In this situation, different combinations of layer pairs can be measured, ie, the layer pair between layer 1 and layer 3, the layer pair between layer 2 and layer 3, the layer pair between layer 3 and layer 4, and/or Overlap between layer 3 and layer 5. Or, for example, FIG. 26(E) may be located at layer 2 and FIG. 26(B) may be located at layer 5 or another layer (if the structure at another layer is moved to another layer).

In this embodiment, the features of the periodic structure 1812 of the sub-target 1804 and the features of the periodic structure 1814 of the sub-target 1806 extend in the first direction, which can be named the Y direction. The periodic structures 1812 and 1814 can respectively determine the overlapping pairs in the second direction, which can be named the X direction, which is substantially orthogonal to the first direction. In addition, the features of the periodic structure 1816 of the sub-target 1808 and the features of the periodic structure 1818 of the sub-target 1810 extend in the second direction. The periodic structures 1816 and 1818 can respectively determine the overlapping pairs in the Y direction accordingly.

In one embodiment, the features of the periodic structure 1812 of the sub-target 1804 and the features of the periodic structure 1814 of the sub-target 1806 extend in the second direction. In that situation, the periodic structures 1812 and 1814 can determine the overlapping pairs in the Y direction. In addition, in that situation, the features of the periodic structure 1816 of the sub-target 1808 and the periodic structure 1818 of the sub-target 1810 will extend in the first direction. Therefore, in that situation, the periodic structures 1816 and 1818 can determine the overlapping pairs in the X direction.

Therefore, in the embodiment of FIG. 26, the extended operating range metrics 1800 and 1802 allow the determination of layer 1 (FIG. 26(A)) and layer 5 (FIG. 26(E)) and layer 4 (FIG. 26( D)) and layer 5 (FIG. 26(E)) in the X-direction overlap, while also allowing the determination of layer 2 (FIG. 26(B)) and layer 5 (FIG. 26(E)) And between layer 3 (Figure 26(C)) and layer 5 (Figure 26(E)) in the Y direction The stack is right. Or for example, by shifting FIG. 26(B) to layer 1 and FIG. 26(A) to layer 2, the extended operating range measurement scale of 1800, 1802 under that condition will allow to determine layer 2 The overlap between the layer 3 and the X direction in the X direction also allows the determination of the overlap between the layer 1 and the layer 5 in the Y direction. Or, for example, by shifting FIG. 26(C) to layer 4 and FIG. 26(D) to layer 3, the extended operating range measurement scale of 1800, 1802 under that condition will allow determination of layer 3 The overlap between the layer 5 and the X direction in the X direction also allows the determination of the overlap between the layer 4 and the layer 5 in the Y direction. Therefore, in a single measurement sequence, overlapping pairs in different directions between different layer pairs can be achieved.

In addition, in the embodiments of FIGS. 24 to 26, sub-subjects have been described and shown to include periodic structures that are characterized in a particular direction. There is no need for this situation. The fact is that in FIGS. 24 to 26, the sub-targets may include one or more periodic structures with features in the first direction and one or more periodic structures with features in the second different direction. For example, in FIG. 24, sub-target 1704 may include periodic structure 1708 and periodic structure 1710. Similarly, sub-target 1706 may include periodic structure 1708 and periodic structure 1710. The similar grouping can be applied in FIG. 25 and FIG. 26.

Therefore, the extended operating range measurement scale can open up a new way for the measurement scale to work during, for example, the program development stage and multi-layer measurement. In advanced nodes (having, for example, difficult and changing procedures and/or multiple layers for multiple patterning (eg, double patterning), device designers and manufacturers dynamically change the program stack and/or Use multiple layers and expect metrics to work. Therefore, the extended operating range measurement standard can bring more program stability to the measurement measurement and increase the chance of the first success of the measurement and measurement of relatively unknown program stacks. For example, if at least a part of each of the sub-targets of the extended operating range measurement target is within the area of the measurement light spot, the measurement from the measurement can be achieved The benefits of speed. If so, the extended operating range metrics can, for example, increase the chance of first success with metrics for program stacks whose program conditions may be unknown. In addition, the extended operating range measurement target can achieve rapid measurement of multiple layers and/or significant changes in the disposal process stack by reducing the cost of the target "occupied area", patterned device manufacturing, and/or yield. An extended operating range can be used at the development and/or manufacturing site using existing metrology and measurement equipment, and sensor hardware changes may not be required.

As described above, in one embodiment, a system and method for designing an extended operating range metric is provided. In one embodiment, the extended operating range metrics should be suitable for the expected stacking of different procedures and/or the desired multi-pair measurement. In addition, the extended operating range metrics should be able to cover typical program changes (which is different from the significant difference from different program stacks). Therefore, in one embodiment, a design method is used to help ensure the stability of the extended operating range metrics. That is, the extended operating range measurement scale (including its sub-targets and its associated periodic structure) can be designed by using program stack information calculation and/or simulation to help ensure the stability of the extended operating range measurement scale. In detail, for example, for the extended operating range measurement scale used for different program stacks, the stability of each sub-target can be determined for the expected typical program change associated with a specific different program stack. The stack is associated with the sub-target.

As mentioned, from both the printability and detectability perspectives, the design of the proposed metrology target can be subjected to testing and/or simulation in order to confirm its suitability and/or survivability. In a commercial environment, good overlap mark detectability can be considered as a combination of low total measurement uncertainty and short movement-acquisition-movement time, because slow acquisition is detrimental to the total output rate of the production line. Modern micro-diffraction-based stacked alignment (μDBO) can be approximately 10 μm on one side Meters to 20 microns, which provides inherently low detection signals compared to targets of 40 x 160 square microns (such as those used in the content background of monitor substrates).

In addition, once a metric that meets the above criteria has been selected, there is a possibility that the detectability will change relative to typical program changes, such as film thickness changes, various etch biases, and/or by etching And/or geometric asymmetry induced by polishing procedures. Therefore, it can be used to select targets that have low detectable changes relative to various program changes and low changes in measurement parameters of interest (eg, overlay, alignment, etc.). Similarly, the fingerprints (printing characteristics, including, for example, lens aberrations) of a particular machine to be used to produce the microelectronic device to be imaged will generally affect the imaging and production of metrology targets. Therefore, it may be useful to ensure that the metrology target is resistant to fingerprint effects because some patterns will be more or less affected by specific lithographic fingerprints.

Therefore, in one embodiment, a method for designing an extended operating range measurement and weighing standard is provided. In one embodiment, it is necessary to simulate the design of various extended operating range metrics to confirm the suitability and/or survivability of one or more of the proposed extended operating range metrics.

In a system for simulating manufacturing processes involving lithography and metrology, major manufacturing system components and/or processes can be described by, for example, various functional modules as illustrated in FIG. 19. Referring to FIG. 19, the functional module may include: a design layout module 1300, which defines the design target of the metrology (and/or microelectronic device); and a patterned device layout module 1302, which defines how the target-based design is polygonal Patterned device patterns; a patterned device model module 1304, which models the physical attributes of pixelated and continuous tone patterned devices to be used during the simulation process; an optical model module 1306, which defines lithography The performance of the optical components of the system; a resist model module 1308, which defines the given procedure The effectiveness of the resist utilized; a program model module 1310, which defines the effectiveness of the resist post-development process (eg, etching); and a metrology module 1312, which defines the effectiveness of the metrology system for the use of metrology targets and Therefore, the effectiveness of the metrology target when used in the metrology system is defined. The results of one or more of the simulation modules (eg, predicted contours and CD) are provided in the results module 1314.

Capture the properties of the lighting and projection optics in the optical model module 1306, including (but not limited to) the NA mean square deviation (σ) setting and any specific lighting source shape, where σ (or mean square deviation) is the illuminator's External radial extent. The optical properties of the photoresist layer coated on the substrate--that is, refractive index, film thickness, propagation, and polarization effects--can also be captured as part of the optical model module 1306, while the resist model module 1308 describes the effects of chemical procedures that occur during resist exposure, post-exposure bake (PEB), and development in order to predict, for example, the contours of resist features formed on the substrate. The patterned device model module 1304 captures how target design features are arranged in the pattern of the patterned device, and may include a representation of detailed physical attributes of the patterned device as described in, for example, US Patent No. 7,587,704. The target of the simulation is to accurately predict (for example) the edge placement and CD, and then the design of the edge placement and CD and the target can be compared. The target design is usually defined as a pre-OPC patterned device layout, and the target design will be provided in a standardized digital file format such as GDSII or OASIS.

Generally speaking, the connection between the optical model and the resist model is the simulated aerial image intensity in the resist layer, which results from the projection onto the substrate, the refraction at the resist interface, and the resist film Multiple reflections in the stack. The radiation intensity distribution (aerial image intensity) is changed into a latent "resist image" by the absorption of photons, and the latent resist image is further modified by a diffusion process and various loading effects. Fast enough for full chip applications The efficient simulation method used approximates the actual 3-dimensional intensity distribution in the resist stack by 2-dimensional aerial (and resist) images.

Therefore, the model formulates most, if not all, known physical and chemical methods of the overall program, and each of the model parameters ideally corresponds to a different physical or chemical effect. Therefore, the model formulation sets an upper limit on how well the model can be used to simulate the overall manufacturing process. However, sometimes the model parameters may be inaccurate due to measurement and reading errors, and other defects may exist in the system. In the case of precise calibration with model parameters, extremely accurate simulations can be performed.

In the manufacturing process, the change of various program parameters has a significant impact on the design of the appropriate target that can faithfully reflect the device design. These program parameters include (but are not limited to) the sidewall angle (determined by the etching or development process), the refractive index (of the device layer or resist layer), the thickness (of the device layer or resist layer), the incident radiation Frequency, etching depth, floor inclination, extinction coefficient for radiation source, coating asymmetry (for resist layer or device layer), change in erosion during chemical-mechanical polishing procedures, and the like By.

The design of the metrology target may be characterized by various parameters, such as target coefficient (TC), stack sensitivity (SS), stacking influence (OV), or the like. Stacking sensitivity can be understood as a measure of how much the strength of the signal changes as the stack of diffractions between the target (eg, grating) layers changes. The target coefficient can be understood as the measurement of the signal-to-noise ratio for a specific measurement time due to changes in photon collection by the measurement system. In one embodiment, the target coefficient can also be considered as the ratio of stack sensitivity to photon noise; that is, the signal (ie, stack sensitivity) can be divided by the photon noise measurement to determine the target coefficient. The measurement of the influence of stacking pair changes according to the design of the target.

This article describes the definition of manufacturing process models that are used or targeted in, for example, weights and measures system simulations A computer-implemented method of designing a metrology target to be used in (for example, using a lithography program to expose metrology targets, develop metrology targets, and etch targets, etc.). In an embodiment, one or more design parameters (eg, geometric dimensions) for the target may be specified, and additional discrete values or ranges of values may be specified for the one or more design parameters. In addition, the user and/or the system may impose one or more design parameters (e.g., the relationship between the spacing and the width of the gap in the same layer or between several layers based on, for example, the desired lithography program) Constraints on the limits of the pitch or the width of the gap, the relationship between the width of the feature (eg, line) (CD) and the pitch (eg, the width of the feature is less than the pitch, etc.). In an embodiment, one or more constraints may have specified one or more design parameters with respect to discrete values or ranges, or with respect to one or more other design parameters.

FIG. 20 schematically depicts a computer-implemented method for defining the design of an extended operating range measurement scale according to an embodiment. The method includes (at block B1) providing a range of values or a plurality of values for each of a plurality of design parameters (e.g., geometric dimensions) used to measure the scale.

In one embodiment, the user of the design system of the weighing scale can specify one or more of the design parameters (eg, geometric dimensions) of the weighing scale. For example, the user can specify the extended operating range measurement and weighing target. The user can further specify the number of child targets of the extended operating range measurement target. In addition, in an embodiment, the user may specify (e.g., select) one of the design parameters for the extended operating range measurement target, one or more sub-targets, and one or more periodic structures of the sub-target or The discrete value or range of values for each of the multiple. For example, a user may select a range or set of values for the width (interval), size, interval, spacing, etc. for the extended operating range measurement scale, etc. In the package of weights and measures In one embodiment containing multiple periodic structures (gratings) or segmented periodic structures (gratings), the user can select or provide a range or set of values for other design parameters (eg, common spacing).

In one embodiment, the design parameters may include any one or more geometric dimensions selected from the following: the distance between the target periodic structures, the target periodic structure feature (eg, line) width, the target periodic structure One or more segment parameters of the interval width and the characteristics of the periodic structure (depending on the segment type, the segment pitch/characteristic width/space width in the X and/or Y direction). In addition, parameters for a single layer or a plurality of layers (for example, two layers or two layers plus an intermediate shield layer) can be specified. For multiple layers, they can share the pitch. For, for example, focusing or aligning certain metrics of the target, other parameters may be used. Other design parameters may be physical limitations such as one or more selected from the following: wavelength of radiation used in the target weighing system, polarization of radiation used in the weighing system, numerical aperture of the weighing system, target Type, and/or program parameters. In one embodiment, non-uniform and asymmetric patterns can be provided, for example, modulated overlay targets and focused targets. Therefore, design parameters may vary and may not be uniform in a particular direction.

At block B2, one or more constraints on one or more design parameters of the metric are provided. Depending on the situation, the user can define one or more constraints. The constraint can be a linear algebraic expression. In an embodiment, the constraints may be non-linear. Some constraints may be related to other constraints. For example, the correlation of the feature width, the pitch, and the gap width makes it possible to completely determine the third party if any two of the three are known to us.

In one embodiment, the user can specify constraints on the area, size, or both of the extended operating range measurement target. The user can specify constraints on the number of sub-targets.

In an embodiment, the constraints may be weights and measures parameter constraints. For example, in some In the system of weights and measures, constraints can be placed on the physics of the system. For example, the wavelength of radiation used in the system may constrain the distance between target designs, for example, the lower limit. In one embodiment, there are (upper/lower) limits on the pitch that varies depending on the wavelength, the type of target, and/or the aperture of the metrology system. The physical limitations that can be used as constraints include one or more selected from the following: wavelength used to measure radiation in the weighing system, polarization used to measure radiation in the weighing system, numerical aperture of the weighing system, and/or target Types of. In an embodiment, the constraint may be a program parameter constraint (eg, a constraint that depends on the type of etching, development type, resist type, etc.).

Depending on the particular program used, in one embodiment, one or more constraints may be related to constraints between the design parameters (eg, geometric dimensions) of one layer and the design parameters (eg, geometric dimensions) of another layer.

At block B3, with a processor, the method solves and/or selects one or more designs with one or more constraints by sampling within a range of values or values for design parameters The design of a plurality of parameters of the parameters. For example, in one embodiment involving solving, one or more potential metric designs may be solved. That is, one or more potential weights and measures designs can be derived by using, for example, one or more equation constraints used to solve a particular value to solve the allowed value. For example, in one embodiment involving sampling, the convex polyhedron may be defined by various design parameters and constraints. The volume of the convex polyhedron can be sampled according to one or more rules to provide a design of sample measurement scale that meets all constraints. One or more sampling rules can be applied to the design of sample measurement standards.

However, it should be noted that not all the design of the measurement and measurement targets thus discovered also represents a change in the program. Thus, in an embodiment, the design of the metric and scale discovered using the method described herein may be further simulated at block B4 to determine (for example) the metric and scale The survivability and/or suitability of one or more of the designs. The simulated metric design can then be evaluated at block B5 to identify which one or more metric design is best or by design order of one or more metric targets based on, for example, the key performance index or robustness criteria It also means that the program changes. At block B6, a specific weights and measures design (for example) can be selected and used for measurement.

As mentioned above, it is necessary to make the metrology target (eg, overlay target, alignment target, focus target, etc.) smaller. This is to limit the "occupied area" consumption on, for example, each production substrate for metrology purposes. However, the small size may cause problems in detection (for example, image resolution).

In dark field measurement and measurement, single-stage radiation can be transmitted to the detector and produce a target gray-scale image. The individual periodic structure is smaller than the illuminated area at the time of reading of the metric scale, and therefore, the edge of the periodic structure is visible in the image. However, the edge of the periodic structure may exhibit a strength level that significantly deviates from the average periodic structure strength. This is called the "edge effect".

After the target pattern recognition step in the dark field image, a region of interest (ROI) is selected within an individual periodic structure, and the region of interest is used for signal estimation. In this way, the average periodic structural strength is extracted while eliminating the effects of edge effects. Therefore, the measurement signal may be based on only a few detector pixels corresponding to the center of the periodic structure in the image.

When designing the target, the target design can be based on the optimized "infinite" large periodic structure such as feature space size, spacing, sub-segmentation, etc. The periodic structure can be positioned around the center of the predefined periodic structure within the target. As a result, the target area is more or less efficiently filled depending on the distance between periodic structures and the size of the feature space.

In one embodiment, it is necessary to consider the layout of the entire target of the extended operating range measurement target relative to the configuration of the best or improved detectability by the measurement device (example For example, optimization) includes, for example, the distance between optimized periodic structures, the reduction of edge effects, and the maximization of available grating area. Failure to configure the best or improved detectability by measuring the device can cause one or more of the following problems:

1. The large edge effect at the periphery of each periodic structure can be observed in the dark field image. It can have one or more of the following effects:

‧The size of the region of interest (ROI) can be reduced (due to the image cropping used to exclude the edges of periodic structures), resulting in poor reproducibility of the calculated signal.

‧The accuracy of the calculated periodic structure signal (average intensity) can be reduced due to the contamination of the signal with optical crosstalk from the emission due to edge effects.

‧ Examples of pattern recognition failures can be attributed to the increase in images with obvious edge effects as the substrate and process time change.

‧The sensitivity of the calculated signal to ROI positioning error can be increased; for example, large edge strength can be accidentally included in the signal estimation.

‧The full-scale use of the detector (of the full dynamic grayscale range) can be reduced, resulting in reduced reproducibility and sensitivity to systemic nonlinear sensor problems at low gray levels.

2. The total area containing periodic structures is not maximized within the target area. Therefore, the maximum photon count is not reached (for example, it is not optimized for reproducibility).

FIG. 13(a) shows an example of the layout of the target 700 including four periodic structures 720. The dashed shape 710 represents the area of available targets. In (a) of FIG. 13, the layout of the target 700 is not optimized for the available target area 710. The calculation changes the number of periodic structural features that vary according to the spacing and available target area 710. Subsequently, the predefined periodic structure feature is centered on the midpoint of the predetermined periodic structure. This situation causes a non-optimized distance between periodic structures (that is, the space between periodic structures is not optimized within the target area). Description of (b) of Figure 13 The resulting dark field image 730 after detection of the target 700. The medium/high intensity level zone 750 can be seen at the location of the periodic structure. However, at the periphery of the periodic structure, there is an even higher intensity level region 740 caused by edge effects. This situation can make the target difficult to analyze using a pattern recognition program, resulting in pattern recognition that is prone to failure.

The detection device 700 used to measure the target actually acts as a band filter. When the measuring device measures a single periodic structure 720, it actually detects two structure types. The first structure is a structure containing repeated periodic structural features with a certain pitch. The second structure is a set of features regarded as a single entity with a certain size (half the pitch); this is because these periodic structures are so small that they can be regarded as a single structure and a periodic structure. Both of these "structures" give their own set of Fourier frequencies. If these two sets are not fitted together, it will produce a set of stepped Fourier frequencies. The final frequency set has one or more frequencies that pass the band filter of the measurement device. Unfortunately, the intensity of these frequencies is high, thereby causing edge effects. In many cases, the edge effect causes an intensity 2 to 4 times greater than the intensity of the maximum intensity grid.

In order to configure (for example, optimize) the target layout/design for improved measurement device detection, the embodiments described herein propose to use:

1. Consider the configuration of the target layout of all available target areas (for example, optimization).

2. Use a method similar to Optical Proximity Correction (OPC) to model (e.g., optimize) the layout of the target layout for computational lithography process response (e.g., except for improvement or optimization) In addition to the configuration of capabilities or to replace the configuration for improved or optimized capabilities, this configuration is used to print targets using the lithography program). The resulting target can use one or more measurement tools to drive optical proximity correction (MT-OPC) auxiliary features to assist in the improvement or optimization of the response of the metrology process. In one embodiment, the distance between MT-OPC auxiliary features And/or size is the sub-resolution used to weigh the device.

For example, the configuration of the target layout can be started by placing one or more MT-OPC auxiliary features at the periphery of the available target area in order to "isolate" the target from the environment and reduce the dark field image The edge effect of the periodic structure. One or more auxiliary features are not observed in the dark field image captured by the measurement device, because the high diffraction order of the one or more auxiliary features is usually not transmitted to the sensor (note that the zero order also Blocked).

In addition, periodic structure features are used to fill available target areas within one or more MT-OPC auxiliary features. For each periodic structure, this filling can be performed starting from the periphery in the direction toward the center. The periodic structure features can be located in this way, while adjusting the length of the periodic structure features as needed to fit the desired spacing and feature space values of adjacent periodic structures commensurately. One or more additional MT-OPC auxiliary features can be positioned between the periodic structures to reduce the periodic structure edge effects and separate the periodic structures in the dark field image. Therefore, in an embodiment, each periodic structure may have one or more MT-OPC auxiliary features around its entire perimeter. The layout of these targets helps improve pattern recognition and limit crosstalk. In an embodiment, the periodic structure of each sub-target of the extended operating range measurement target can be handled separately, such that, for example, the periodic structure of one sub-target is processed as described above, and then the Periodic structure.

Therefore, the configuration of the full standard design may include:

1. The configuration of the periodic structure relative to the design limit (for example, optimization). These design limits depend on the application given the specific product design, such as: feature width, sub-segment, "online", or "ditch online", etc.

2. The configuration of the entire target layout used for improved or optimal measurement and measurement procedures, In some situations, one or more MT-OPC assist features are used. Sub-segmentation and/or other design restrictions may be applied to MT-OPC auxiliary features as appropriate.

3. Perform one or more lithography OPC cycles on the entire target layout to help ensure that the desired target layout designed in steps 1 and 2 can be printed appropriately.

The target configuration may include any parameter or configuration of the target. For example, this configuration may include periodic structure pitch, MT-OPC auxiliary feature pitch, the length and width of any feature, periodic interval of periodic structure action, etc. The configuration program considers the entire available target area. In addition to or instead of using one or more MT-OPC auxiliary features, the length and length of one or more periodic structure features adjacent to the gap between adjacent periodic structures can also be modified Size (for example, CD). For example, the length of periodic structural features extending toward the gap can be shortened or extended. As another example, the features of the periodic structure extending along the gap may narrow or widen its size relative to other features of the periodic structure.

The layout of potential targets can be evaluated in a suitable measurement device simulation tool. It may require several iterations to achieve the desired (eg, optimal) target layout specific to the measurement device configuration. For example, in each iteration, the configuration of the target layout can be changed by, for example, changing the size, placement, number of features, spacing, etc. of one of the multiple MT-OPC auxiliary features to help achieve Improved or best weights and measures program detection. As should be understood, this change in configuration can be made automatically by software and/or the user can guide this change in configuration. In one embodiment, the simulation considers different layers of the extended operating range scale (eg, in terms of different refractive index, thickness, etc.). In one embodiment, the difference between the spacing, feature size (CD), etc. of the quantum targets is simulated.

Therefore, ideally, this configuration can be done in an automated manner. An "automation" Methods include (non-exclusively) (i) one or more accurate optical models that can accurately predict the response of the measurement device within an acceptable time frame, and (ii) well-defined criteria for configuration. For example, the criteria may include one or more selected from the following:

-The edge strength of the periodic structure with the same order of magnitude as the center strength of the periodic structure.

-The smallest change in the edge effect in the presence of overlapping, defocusing and/or aberrations of the measuring device. In one embodiment, regarding the stability of the measurement formulation (eg, wavelength, focus, etc.).

λ/2，其中λ表示量測輻射波長)。舉例而言，在超過強度臨限值之鄰近週期性結構區之間的感測器像素之至少1個線。 -Sufficient spacing between periodic structures for pattern recognition for improved or optimal targets for the relevant wavelength range (eg, spacing

λ/2, where λ represents the measured radiation wavelength). For example, at least one line of sensor pixels between adjacent periodic structure regions that exceed the intensity threshold.

-Maximum periodic structure area.

Ideally, these criteria are balanced when designing the final target configuration.

14 shows an example of an extended operating range measurement scale similar to the design of FIG. 12A. Of course, in one embodiment, different designs of extended operating range measurement and measurement may be used, such as the design of FIG. 9 or the design of any of FIGS. 12B-12E.

FIG. 14(a) shows an example non-optimized target layout 1200 that includes two sub-targets 1202 and 1204 of the extended operating range measurement target. The non-optimized target layout 1200 also includes four periodic structures 1400, and each periodic structure 1400 includes a portion of the sub-targets 1202 and 1204 in this case. Each periodic structure 1400 includes a plurality of periodic structure features (eg, raster lines). The calculation varies the number of periodic structural features depending on the pitch and the total predetermined grating area. In addition, the predefined periodic structure features The midpoint is the center. This situation causes non-matching and non-optimized distances between periodic structures observed by the device for weighing and weighing. FIG. 14(c) illustrates an example simulation of dark field images that can be caused by the targeted layout of FIG. 14(a) and clearly show visible edge effects. These edge effects can be regarded as extremely high-intensity measurement regions 1430 at the periphery of the periodic structure region 1440. In (c) to (f) of FIG. 14, areas with darker shadows indicate higher intensity. FIG. 14(e) illustrates another example simulation of a dark field image that can be caused by the target layout of FIG. 14(a) in the case where a wavelength different from that of (c) of FIG. 14(c) is used. It can be seen that the image of the periodic structure in (e) of FIG. 14 is not clearly delimited and therefore will not be easily recognized.

14(b) shows an improved version of the target layout 1200 of FIG. 14(a), which includes the same periodic structure 1400 as the periodic structure of the FIG. 14(a) configuration, and further includes one or more MT-OPC auxiliary features 1410, 1420. A first set of one or more MT-OPC auxiliary features 1410 is located at the periphery of the target (eg, to surround the target), and a second set of one or more MT-OPC auxiliary features 1420 is located among the plurality of periodic structures 1400 between. In one embodiment, each periodic structure 1400 is surrounded by a combination of one or more MT-OPC auxiliary features 1410, 1420. FIG. 14(d) illustrates an example simulation of dark field images that can be caused by the targeted layout of FIG. 14(b) and shows reduced edge effects. FIG. 14(f) illustrates another example simulation of a dark field image that can be caused by the target layout of FIG. 14(b) in the case where a wavelength different from that of FIG. 14(d) is used. It can be seen that the image of the periodic structure in (e) of FIG. 14 is fairly clearly delimited and therefore should be easily identifiable.

Therefore, the comparison between (c) of FIG. 14 and (d) of FIG. 14 shows that the intensity distribution in each periodic structure region in (d) of FIG. 14 is much more uniform, and there are fewer edge effects. The comparison between (e) of FIG. 14 and (f) of FIG. 14 shows that the enhanced dark-field image resolution of (f) of FIG. 14 compared to (e) of FIG. 14 is compared with the improved separation of the periodic structure ( That is, compared to (e) of FIG. 14, in (Lower intensity between periodic structures in (f) of FIG. 14), thus improving dark field pattern recognition.

In this example, one or more MT-OPC auxiliary features have a small pitch of, for example, approximately 160 nanometers, thereby causing fading waves. One or more MT-OPC auxiliary features provide edge effect reduction and separation of periodic structure and environment.

15 illustrates an enlarged partial view of a cross-section of a target 1200 that includes a periodic structure 1400 and one or more MT-OPC auxiliary features 1420. In one embodiment, one or more MT-OPC auxiliary features 1420 are positioned with periodic structure space-feature-space rhythms to avoid sudden steps (eg, sharp rectangular windows). In this way, one or more auxiliary features 1420 are positioned close to the periodic structure 1400 lines while destroying excitations caused by their finite size (eg, edge softening) within the periodic structure. FIG. 15 shows a representation of this matched positioning of the fundamental frequencies in periodic structure features and in one or more MT-OPC auxiliary features immediately adjacent to a 90° rotated periodic structure. In this example, the distance between the MT-OPC auxiliary features is such that the diffraction orders associated with the MT-OPC auxiliary features are not transmitted to the detector. Although FIG. 15 shows that the periodic structure of one or more MT-OPC auxiliary features 1420 has two features, it should be understood that it may have only one feature or more than two features.

Ensuring that the periodic structure 1400 and one or more MT-OPC auxiliary features 1420 are in phase with each other will help avoid "stepping frequency sets" that cause high-intensity edge effects. The periodic structure 1400 and the one or more MT-OPC auxiliary features 1420 are in phase with each other meaning that one or more MT-OPC auxiliary features 1420 extend the continuous surface of the periodic structure 1400. Although there are still edge effects, the high-intensity edge effects are outside the transmission band of the measurement device and are not detected by the measurement device. In this way, the peak intensity actually measured by the measuring device is reduced. Therefore, in one embodiment, one or more MT-OPC auxiliary features are such that the spectrum outside the transmission band of the measurement detector is strongly coupled to the periodic structure.

In one embodiment, the MT-OPC auxiliary feature should be in phase with its associated measurement periodic structure, but the design used to image the periodic structure and measure the periodic structure may make this situation impossible. As an example, the design of the sub-target of the extended operating range measurement and weighing target may be in the case of fitting the sub-target in its constrained area and fitting one or more auxiliary features at the periphery of the sub-target or between adjacent sub-targets Become problematic. This problem with MT-OPC auxiliary features can be solved by providing destruction in the middle of MT-OPC auxiliary features. For example, where the MT-OPC auxiliary feature includes a periodic structure of three or more features, one or more of the intermediate features may be amplified. Similarly, in the case where the MT-OPC auxiliary feature includes a periodic structure of two or more features, one or more of the intermediate spaces between the features can be enlarged. Therefore, the area consumed by the MT-OPC assist feature can be enlarged. The enlargement of features and/or spaces can be performed except in the middle. The enlargement of features and/or spaces and their parts are designed to facilitate improved (eg, best possible) matching of phases.

In one embodiment, for one or more auxiliary features located between adjacent periodic structures, the gap between the periodic structures is the cross size (CD) of the features of one or both of the adjacent periodic structures (CD ) Same or about the same. In an embodiment, for one or more auxiliary features located between adjacent periodic structures, the one or more auxiliary features are equal to or approximately equal to the cross dimension (CD) of the space between adjacent periodic structures, And in an embodiment, the cross-like sizes between the auxiliary features are equal or approximately equal.

In one embodiment, the light waves diffracted from these one or more auxiliary features 1420 generally do not carry any energy (decaying or destructive interference), or are transmitted to the detector's spectrum Part of the exterior (blocking the propagation wave). In this example, incident radiation I, diffracted zero-order radiation 0, and first-order radiation -1 are shown. The -1 order radiation diffracted by one or more auxiliary features 1420 is blocked, and only the -1 order radiation diffracted by the periodic structure 1400 is transmitted to the sensor. However, due to the limitation of one or more auxiliary features 1420, the "tail" reflected by the auxiliary features may leak into the spectrum transmitted to the sensor and will interact with the spectrum from periodic structural features.

For well-separated periodic structures in dark-field images, one or more MT-OPC auxiliary features 1420 in one embodiment fill the space between the periodic structures, the space having a width that is at least half the wavelength of the measurement device . The same situation holds true for the separation of the target from the environment and the reduction of crosstalk.

16(a) shows the configuration of the target of the extended operating range measurement target 1600, which includes two sub-targets 1202 and 1204. The target 1600 also includes four periodic structures 1650, and each periodic structure 1650 in this case includes a portion of the sub-targets 1202 and 1204. The target 1600 actually occupies the area 1610. The target layout includes a "clearance" area 1620 at the boundary of the target to improve dark field pattern recognition and reduce crosstalk from the environment. In FIG. 16(b), the target layout of FIG. 16(a) is replaced by the target layout 1630 optimized for the entire target area 1610. The target layout includes one or more MT-OPC auxiliary features 1635 at its surroundings, and another one or more MT-OPC auxiliary features 1640 between the plurality of periodic structures 1650. MT-OPC auxiliary features 1635, 1640 help ensure dark field pattern recognition performance and optical crosstalk reduction from the environment, so that no "gap" area 1620 will be needed. Therefore, the size and number of features and spacing of each periodic structure 1650 can be configured to the available target area 1610. The corresponding dark field image simulation results (not illustrated) will show a strong reduction in edge effects, while pattern recognition will go from periodic structure to peripheral Separation and improvement of periodic structure.

FIG. 17 is a flowchart illustrating a method of designing an extended operating range measurement scale configuration according to an embodiment. The method includes:

Step T1-Provide one or more MT-OPC auxiliary features with "sub-resolution" spacing and/or dimensions near and/or within the boundary of the design target area, for example. This situation defines the "available/blank" design target area. The characteristics of one or more auxiliary features (eg, feature width, shape...) can be selected to, for example, efficiently isolate the target from the environment in dark field images.

Step T2- Based on one or more MT-OPC auxiliary features placed at the boundary of the target, the periodic structure features of the first periodic structure are sequentially placed starting at the boundary in the direction toward the inside of the target area ( (Includes the characteristics of one or more of the extended operating range measurement and weighing targets). For example, the feature is placed until the part of the last placed feature is above the halfway point of the available target area in the direction of the periodic structure.

Step T3-Add an MT-OPC auxiliary feature (if needed) that has a form based on the size and pitch of adjacent periodic structure features and further has a "sub-resolution" pitch and/or size.

Step T4-Based on the latter one or more MT-OPC auxiliary features, the feature length of the next periodic structure (if applicable) is adapted to the remaining available target area.

Step T5- Repeat steps T2 to T4 for the remaining periodic structure.

Step T6-Depending on the situation, one or more MT-OPC auxiliary features are used to fill the central part of the target area.

An example application of this method is illustrated in Figure 18. (A) of FIG. 18 corresponds to step T1. One or more MT-OPC auxiliary features 1810 are drawn close to the boundaries of the available target area, where The spacing is selected to isolate the target from the environment and reduce periodic structure edge effects. (B) and (c) of FIG. 18 correspond to step T2, in which the periodic structure feature 1820 is placed to fill about one quarter of the target area assigned to the periodic structure. (D) of FIG. 18 corresponds to step T3, in which one or more additional MT-OPC auxiliary features 1830 are added to match the adjacent periodic structure features. Figure 18(d) also illustrates the beginning of step T4, where the length of feature 1840 has been adapted to the remaining available area. (E) of FIG. 18 corresponds to the intermediate point during step T5, in which two periodic structures are placed and the third periodic structure is started. FIG. 18(f) illustrates the completed target configuration in which one or more additional MT-OPC auxiliary features 1850 are placed in the center area of the target layout, as described in step T6. This method may require several iterations, where a metrology simulation tool is used to evaluate the configuration of each target obtained at step T6. Evaluation may include determining whether a particular configuration meets one or more predefined criteria, and/or comparing multiple different configurations designed according to this method to determine the best configuration (based on one or more predefined criteria).

Instead of using one or more additional MT-OPC auxiliary features 1850 to fill the center area of the target, a special target (cross shape) can be used to fill this area for performing patterned device write quality measurements.

Stacked metrology involves two stacked periodic structures (ie, double-layered). For such targets, the method of FIG. 18 can be used to design the layout of the lower targets. The layout of the upper target usually contains stack offsets in the range of five nanometers to tens of nanometers. In this configuration, the layout of the upper target can simply match the layout of the lower target, except for the offset. In one example, the bias may only be applied to periodic structural features in the layout of the superscript, where the bias is not applied to one or more MT-OPC auxiliary features in the layout of the superscript. In one example, the MT-OPC auxiliary feature can be omitted from the superscript layout, which can help avoid interference The asymmetric signal of the momentum measurement is especially applicable when the back reflection diffraction of the upper periodic structure is weak and the main back reflection diffraction originates from the lower periodic structure.

For the configuration of "ditch on-line" instead of "online", the layout of the upper target can be reversed to obtain the "ditch on-line" configuration. For a 50%-different action interval cycle, it is possible to design the layout of the upper target as an "online" version with a reverse action interval cycle (100%-action interval cycle), which is then inverted to obtain the "ditch" Go online" configuration. The design of MT-OPC auxiliary features in the situation where the working interval between the upper target layout and the lower target layout is cyclically different can lead to more complicated layout configuration processes, however, those skilled in the art will be able to implement and customize This method for these configurations.

To help ensure printability and compliance with semiconductor manufacturer design rules, the size of one or more MT-OPC auxiliary features may allow sub-segmentation of the one or more MT-OPC auxiliary features.

The size and/or shape of one or more MT-OPC auxiliary features can be customized according to the needs of the application. For example, in the example of FIG. 15, the MT-OPC auxiliary feature 1420 is represented by a "continuous rectangle" shape. However, the continuous rectangular shape can cause a charging effect on the reticle or printed circuit at the sharp edges. To overcome this problem, shape edges can be "deleted" from the layout.

In the example mentioned above, one or more MT-OPC auxiliary features have a "sub-resolution" (ie, have a smaller resolution than the resolution of the product features). However, depending on the application, one or more MT-OPC auxiliary features may have a size that is lower than, within, or above the resolution of the sensor. For example, one or more outer MT-OPC auxiliary features can be adapted to structures (eg, device features) located in the area surrounding the target. The distance between the features surrounding the target is lower than the detection range of the weighing device or In the case where the feature outside the detection range of the weighing and measuring device or around the target has approximately the same size as the MT-OPC auxiliary feature, the MT-OPC auxiliary feature may not need to be changed. If the distance between the features in the area surrounding the target is within the detection range of the weighing device or the features surrounding the target do not have about the same size as the nominal MT-OPC auxiliary feature, then the MT-OPC auxiliary feature can be The size is changed (eg, larger) to suppress the effect of one or more features in the area surrounding the target.

This method for configuring the layout/design of the target can be applied, for example, during the design/configuration process of the metrology target for all metrology applications (including alignment). For example, the method can be applied to alignment targets used in overlay correction systems and/or in advanced alignment systems.

As shown in the above example, one or more MT-OPC auxiliary features may be placed at the target boundary and/or may be placed around periodic structures in order to reduce edge effects. In addition to this placement, one or more MT-OPC auxiliary features can also be placed between periodic structure features (eg, for large-pitch periodic structures such as aligned periodic structures) to sharpen or soften the feature space change. This situation can help to enhance the diffraction efficiency to the ideal order by improving or optimizing the inherent diffraction efficiency for the detected order or improving or optimizing the energy to rank the relevant diffraction orders. This situation can aid the detectability of stacks with low "substrate quality". In addition, during readout and scanning throughout the target, especially for low substrate quality stacking, the gain set point in the alignment sensor electronics can be improved.

In addition, one or more MT-OPC auxiliary features need not be located in the same layer as the periodic structure. For example, one or more MT-OPC auxiliary features may be located in different layers ideally above the applicable periodic structure, and possibly below the applicable periodic structure. Make MT-OPC auxiliary features in different layers can promote manufacturability (eg, MT-OPC auxiliary features can (The projection settings for printing periodic structures are not used for printing, and these projection settings may be the projection settings for printing device patterns).

In addition, although embodiments of the MT-OPC assist feature have been described as being adjacent to the target periodic structure or a specific uniform periodic structure between the target periodic structures, the MT-OPC assist feature may take other forms. For example, the auxiliary feature may take the form as described in US Patent Application Publication No. 2013-0271740, the entire content of which is incorporated herein by reference.

This method can be combined with current methods used to improve parameter estimation in, for example, dark field metrology.

The method disclosed above causes a larger ROI, and therefore a larger photon count during intensity measurement. This situation improves the reproducibility of the area for constant targets. The improved reproducibility can also be caused by the reduction of edge effects, which reduces the inaccuracy of ROI positioning. In addition, due to the well-defined dark field target image, the reduction of the edge effect will improve pattern recognition. In addition, the full gray scale dynamic range of the sensor of the measurement device can be used, because the edge effect will not saturate the dark field image. Therefore, the reproducibility is further improved, and the non-linear sensor effect caused by the photon noise at low intensity is avoided. Photon noise is the square root of the number of photons. The number of measured photons is the product of the number of pixels used, gray scale and sensitivity. In order to obtain a more stable measurement, it is necessary to increase the number of pixels or the number of grayscales; to make the sensor sensitivity fixed. By using one or more MT-OPC auxiliary features, more gray levels can be obtained.

When each periodic structure is distributed separately among the device structures, adding one or more MT-OPC auxiliary features to the individual periodic structure improves the isolation from the intra-die environment. Therefore, the flexibility of the built-in die for the target/periodic structure is due to the period The sexual structure is isolated from the environment and improved.

In addition, by using one or more MT-OPC auxiliary features, the target area (that is, the size of the smaller target) can be reduced while maintaining the same reproducibility. The reduced size of the target enables denser field measurements. This situation improves, for example, the high-level overlay correction of the die on the substrate on the product, and the characterization of the performance of the lithography device.

One or more embodiments of these MT-OPC assisted feature technologies may be implemented, for example, at module 1312 of FIG. 19 and/or at blocks B2 to B5 of FIG. 20.

21 shows a flowchart illustrating a procedure in which the extended operating range measurement target is used to monitor performance and is used as a basis for controlling measurement, design, and/or production processes. In step D1, the substrate is processed to produce product features and one or more extended operating range metrics as described herein. At step D2, the method of (for example) FIG. 6 is used to measure and calculate the values of the lithography program parameters (for example, overlapping pairs). At step D3, the measured lithography program parameter (e.g., overlay) value (along with other information as available) is used to update the weights and measures formula. The updated weights and measures recipe is used to re-measure lithography process parameters and/or to measure lithography process parameters for subsequently processed substrates. In this way, the accuracy of the calculated lithography program parameters is improved. The update procedure can be automated as needed. In step D4, the lithography program parameter values are used to update the recipe controlling the lithography patterning step and/or other process steps in the device manufacturing process for reworking and/or for processing another substrate. Again, this update can be automated as needed.

Although the embodiments of the extended operating range measurement and weighing target described herein have been described mainly in terms of overlapping measurements, the embodiments of the extended operating range measuring and weighing target described herein may be used to measure one or more additional or alternative The lithography program parameters. For example, the extended operating range scale can be used to measure the exposure dose change and the exposure focus / Defocus etc. Therefore, in one embodiment, the same extended operating range scale can be used to measure a plurality of different parameters. For example, the extended operating range metric can be configured to measure stack pairs and measure one or more other parameters, such as critical size, focus, dose, etc. As an example, one or more of the sub-targets can be designed to measure stack-pairs (eg, have their associated periodic structures in different layers), and one or more other sub-targets can be designed to measure criticality Size and/or focus and/or dose etc. In one embodiment, specific sub-targets can be designed to measure two or more parameters, for example, overlapping pairs; and one or more other parameters, such as critical size, focus, dose, etc.

In an embodiment, the periodic structure is ideally longer than wide, as shown in (A) of FIG. 14, for example. FIG. 14(A) depicts each of the periodic structures 1202 and 1204 such as sub-targets whose length is greater than the width. This configuration helps reduce crosstalk between the X and Y directions. For smaller periodic structures as required by, for example, extended operating range metrics, crosstalk tends to be stronger because of the larger ratio between the grating side and the total surface area. The area that causes crosstalk is 0.5 times the wavelength times the grating side times 2. Therefore, periodic structures with a length greater than the width tend to reduce crosstalk and can therefore be more advantageous.

Although the target structure described above is a metrology target specifically designed and formed for the purpose of measurement, in other embodiments, the measurement properties of the target may be the functional component of the device formed on the substrate . Many devices have regular grating-like structures. The terms "target grating" and "target periodic structure" as used herein do not need to provide structure specifically for the measurements performed. In addition, the distance P between the scales is close to the resolution limit of the optical system of the scatterometer, but it can be much larger than the size of typical product features manufactured in the target part C by the lithography process. In practice, features and/or spaces of stacked periodic structures can be manufactured to include smaller structures that are similar in size to product features.

In an embodiment, the periodic structure of the sub-target of the extended operating range measurement target may be rotationally symmetrical. That is, there may be two or more sub-targets (eg, three or more, four or more, etc.) of two or more sub-targets of the extended operating range measurement target, where these sub-targets are configured to share There is a common center of symmetry and each pair of sub-targets rotates 180 degrees or more around the common center of symmetry unchanged. In addition, each sub-target may include two or more periodic structures (eg, three or more, four or more, etc.), where each of these periodic structures has a Individual symmetry centers, and each periodic structure pair does not change by 180 degrees or more around the individual symmetry centers.

However, in one embodiment, the periodic structure of the sub-target of the extended operating range scale may be rotationally asymmetric. This situation can be achieved in any of several ways. For example, one of the three sub-targets can be shifted (located) away from the common symmetry center of the other sub-targets. As another example, one or more of the features of one or more of the periodic structures of a sub-target may be relative to one or more of the features of one or more of the other periodic structures of the sub-target or It is slightly shortened, lengthened, or shifted relative to one or more of the features of one or more periodic structures of another sub-target. As another example, one or more dummy structures may be inserted between periodic structures of a sub-target or between sub-targets to break any symmetry. In one embodiment, one or more dummy structures are rotationally asymmetric. The displacement, shortening or lengthening can be lower than the measurable range of the measuring device. In one embodiment, the displacement, shortening, or lengthening is in the range of 1 nanometer or less. This change will have a negligible effect on the measurement reading. Similarly, the dummy structure may have a characteristic size or pitch lower than the effective measurement range of the measurement device. In an embodiment, the auxiliary feature described herein may be a dummy structure.

The term "structure" is used herein and is not limited to any particular form of structure, such as simple raster lines. In fact, rough structural features, such as grating lines and spaces, can be formed by a collection of finer substructures.

In association with the target physical periodic structure as implemented on a substrate and patterned device, an embodiment may include a computer program containing one or more sequences of machine-readable instructions that describe the design A method of marking a target on a substrate, a method of generating a target on a substrate, a method of measuring a target on a substrate, and/or a method of analyzing measurement to obtain information about a lithography process. An embodiment may include computer program code containing one or more sequences or data describing the machine-readable instructions of the subject. This computer program or program code can be executed, for example, in the unit PU in the device of FIG. 3 and/or in the control unit LACU of FIG. 2. It is also possible to provide a data storage medium (for example, semiconductor memory, magnetic disk, or optical disk, etc.) in which the computer program or code is stored. In the case where an existing weighing and measuring device of the type shown in FIG. 3, for example, is already in production and/or in use, one embodiment of the present invention can be implemented by supplying an updated computer program product, which is updated The computer program product is used to cause the processor to perform one or more of the methods described herein. The computer program or program code may be configured to control the optical system, substrate support, and the like, as the case may be, to perform a method of measuring the parameters of the appropriate plural lithography processes. The computer program or program code can update the lithography and/or weights and measures formula for the measurement of other substrates. The computer program or program code may be configured to control (directly or indirectly) the lithography device for patterning and processing of another substrate.

Additional embodiments according to the invention can be found in the following numbered entries:

1. A method for measuring a parameter of a lithography program, the method comprising: using radiation to illuminate a diffraction measurement target on a substrate, the measurement target includes At least a first sub-label and at least a second sub-label, wherein the first sub-label and the second sub-label each include a pair of periodic structures, and wherein the first sub-label has a different structure than the second sub-label A design, the different design includes that the periodic structures of the first sub-targets have a pitch, characteristic width, interval width and/or segmentation different from the periodic structures of the second sub-targets; The scattered radiation of a sub-target and the second sub-target is measured by obtaining one of the parameters of the lithography program for the target.

2. The method of clause 1, wherein the first sub-target at least partially overlaps a fifth periodic structure and the second sub-target at least partially overlaps a sixth periodic structure, wherein the fifth periodicity The structure is at a layer on the substrate different from the sixth periodic structure.

3. The method of clause 1 or 2, wherein the features of the pair of periodic structures of each of the first sub-subject and the second sub-subject extend in the same direction.

4. The method of clause 1 or 2, wherein each of the first sub-subject and the second sub-subject includes a first pair of periodic structures having a feature extending in a first direction, and having a second One of the features extending in different directions is the second pair of periodic structures.

5. The method of clause 2, wherein each of the first sub-label and the second sub-label includes a first pair of periodic structures having a feature extending in a first direction, and having a second different direction One of the second pair of periodic structures extending upward, wherein the fifth periodic structure has a characteristic extending in the first direction, and the sixth periodic structure has a characteristic extending in the second direction.

6. The method according to any one of clauses 1 to 5, further comprising at least a third sub-target and at least a fourth sub-target, wherein each of the third sub-target and the fourth sub-target includes a pair of periodicity structure.

7. The method of clause 6, wherein the third sub-target overlaps at least partially a ninth periodic structure and the fourth sub-target overlaps at least partially a tenth periodic structure, wherein the ninth periodicity The structure is on the substrate at a layer different from the tenth periodic structure.

8. The method of clause 6 or 7, wherein each of the third sub-target and the fourth sub-target includes a first pair of periodic structures having a feature extending in a first direction, and having a second One of the features extending in different directions is the second pair of periodic structures.

9. The method of clause 7, wherein each of the third sub-label and the fourth sub-label includes a first pair of periodic structures having a feature extending in a first direction, and having a second different direction One of the second pair of periodic structures extending upward, wherein the ninth periodic structure has a characteristic extending in the first direction, and the tenth periodic structure has a characteristic extending in the second direction.

10. The method of any one of clauses 1 to 9, wherein the parameters of the lithography program include overlapping pairs.

11. The method according to any one of items 1 to 10, wherein the illumination comprises: illuminating a measurement light spot on the diffraction measurement target, the measurement light spot covering the first sub-target and the first At least part of each of these periodic structures of the two sub-subjects.

12. The method of any one of clauses 1 to 11, wherein at least part of each of the periodic structures of the first sub-target and the second sub-target is less than or equal to the substrate In a contiguous area of 1000 square microns.

13. The method of any one of clauses 1 to 11, wherein at least part of each of the periodic structures of the first sub-target and the second sub-target is less than or equal to the substrate In a contiguous area of 400 square microns.

14. The method of any one of clauses 1 to 13, wherein each of the sub-subjects It is designed for one of the different stacking of the substrate.

15. The method of any one of clauses 1 to 14, wherein each of the sub-subjects is designed to measure a different layer pair of a multi-layer pair.

16. A diffraction measurement target, comprising at least a first sub-target and at least a second sub-target, wherein the first sub-target and the second sub-target each include a pair of periodic structures, and wherein the first The sub-marker has a design different from the second sub-marker, the different design includes that the periodic structure of the first sub-marker has a pitch, characteristic width, interval width and/or different from the periodic structure of the second sub-marker Or segment.

17. The subject matter of clause 16, wherein when on a substrate, the first sub-target at least partially overlaps a fifth periodic structure and the second sub-target at least partially overlaps a sixth periodic structure And the fifth periodic structure is at a layer different from the sixth periodic structure.

18. The subject of clause 16 or 17, wherein the characteristics of the pair of periodic structures of each of the first sub-subject and the second sub-subject extend in the same direction.

19. The subject of clause 16 or 17, wherein each of the first sub-subject and the second sub-subject includes a first pair of periodic structures having a feature extending in a first direction, and having a second One of the features extending in different directions is the second pair of periodic structures.

20. The subject of clause 17, wherein each of the first sub-subject and the second sub-subject includes a first pair of periodic structures having a feature extending in a first direction, and having a second different direction One of the second pair of periodic structures extending upward, wherein the fifth periodic structure has a characteristic extending in the first direction, and the sixth periodic structure has a characteristic extending in the second direction.

21. As the subject matter of any one of Articles 16 to 20, it further includes at least a third The sub-target and the at least one fourth sub-target, wherein each of the third sub-target and the fourth sub-target includes a pair of periodic structures.

22. The object of clause 21, wherein when on a substrate, the third sub-object at least partially overlaps a ninth periodic structure and the fourth sub-object at least partially overlaps a tenth periodic structure And the ninth periodic structure is at a layer different from the tenth periodic structure.

23. The subject of clause 21 or 22, wherein each of the third sub-subject and the fourth sub-subject includes a first pair of periodic structures having a feature extending in a first direction, and having a second One of the features extending in different directions is the second pair of periodic structures.

24. The subject of clause 22, wherein each of the third sub-subject and the fourth sub-subject includes a first pair of periodic structures having a feature extending in a first direction, and having a second different direction One of the second pair of periodic structures extending upward, wherein the ninth periodic structure has a characteristic extending in the first direction, and the tenth periodic structure has a characteristic extending in the second direction.

25. The subject of any one of clauses 16 to 24, wherein at least part of each of the periodic structures of the first sub-subject and the second sub-subject is on a substrate In a contiguous area of less than or equal to 1000 square microns on the substrate.

26. The subject of any one of clauses 16 to 24, wherein at least part of each of the periodic structures of the first sub-subject and the second sub-subject is on a substrate In an adjacent area on the substrate that is less than or equal to 400 square microns.

27. A method of measuring a parameter of a lithography program, the method comprising: using radiation to illuminate a diffraction measurement target on a substrate, the measurement target including at least a first sub-layer in a first layer Target and at least a second sub-target, where the first sub The target includes a first periodic structure and the second sub-target includes a second periodic structure, wherein a third periodic structure is at least partially located in the first period in a second different layer below the first layer And there is no periodic structure under the second periodic structure in the second layer, and a fourth periodic structure is at least partially located in a third different layer under the second layer Below the second periodic structure; and detecting radiation scattered from at least the first periodic structure to the fourth periodic structure to obtain a measurement of the parameter representing the lithography process for the target.

28. The method of clause 27, wherein the first sub-target has a design different from the second sub-target.

29. The method of clause 28, wherein the different design includes the first sub-mark having a pitch, feature width, space width, and/or segmentation that is different from the second sub-mark.

30. The method of any one of clauses 27 to 29, wherein each of the first sub-subject and the second sub-subject includes an additional period having a feature extending in a second direction different from a first direction Characteristics of the first periodic structure, the first periodic structure and the second periodic structure respectively extend in the first direction.

31. The method of any one of clauses 27 to 29, wherein the second periodic structure has a feature extending in a second direction that is different from a first direction in which a feature of the first periodic structure extends.

32. The method of clause 30 or 31, wherein the third periodic structure has a feature extending in the first direction, and the fourth periodic structure has a feature extending in the second direction.

33. The method of any one of clauses 27 to 29, wherein the characteristics of the periodic structures and the third periodic structure of each of the first sub-subject and the second sub-subject And the characteristics of the fourth periodic structure extend in the same direction.

34. The method of any one of clauses 27 to 33, further comprising at least a third sub-target and at least a fourth sub-target, wherein each of the third sub-target and the fourth sub-target includes a periodic structure .

35. The method of clause 34, wherein the third sub-target at least partially overlaps a fifth periodic structure on the substrate, and the fourth sub-target at least partially overlaps a sixth period on the substrate Sexual structure, wherein the fifth periodic structure is at a layer different from the sixth periodic structure.

36. The method of clause 34 or 35, wherein the third sub-target includes a periodic structure having a feature that extends in a first direction, and the fourth sub-target includes a second structure that extends in a second different direction One of the characteristics of the periodic structure.

37. The method of clause 35, wherein the third sub-target includes a periodic structure having a feature that extends in a first direction, and the fourth sub-target includes a feature that extends in a second different direction A periodic structure, wherein the fifth periodic structure has a feature extending in the first direction, and the sixth periodic structure has a feature extending in the second direction.

38. The method of any one of clauses 27 to 37, wherein the parameters of the lithography program include overlapping pairs.

39. The method of any one of clauses 27 to 38, wherein the illumination comprises: illuminating a measurement light spot on the diffraction measurement target, the measurement light spot covering the first sub-target and the first At least part of each of these periodic structures of the two sub-subjects.

40. The method of any one of clauses 27 to 39, wherein at least part of each of the periodic structures of the first sub-target and the second sub-target is a small one on the substrate In an adjacent area equal to or equal to 1000 square microns.

41. The method of any one of clauses 27 to 39, wherein at least part of each of the periodic structures of the first sub-subject and the second sub-subject is less than or equal to the substrate In a contiguous area of 400 square microns.

42. The method of any one of clauses 27 to 41, wherein each of the sub-subjects is designed for a different process stacking of the substrate.

43. The method of any one of clauses 27 to 42, wherein each of the sub-subjects is designed to measure a different layer pair of a multi-layer pair.

44. A diffraction measurement target including at least a first sub-target and at least a second sub-target in a first layer when on a substrate, wherein the first sub-target includes a first periodicity Structure and the second sub-target includes a second periodic structure; and includes a third periodic structure, the third periodic structure when on the substrate is at least in a second different layer below the first layer Partially under the first periodic structure, and there is no periodic structure under the second periodic structure in the second layer; and includes a fourth periodic structure, the fourth periodic structure should be in the A third different layer under the second layer is at least partially under the second periodic structure on the substrate.

45. The subject of clause 44, wherein the first sub-subject has a design different from that of the second sub-subject.

46. The subject of clause 45, wherein the different design includes that the first sub-subject has a pitch, characteristic width, interval width, and/or segmentation that is different from the second sub-subject.

47. The subject of any one of clauses 44 to 46, wherein each of the first sub-subject and the second sub-subject includes an additional period having a feature extending in a second direction different from a first direction Sexual structure, the first periodic structure and the second periodic structure of the The other features extend in the first direction.

48. The subject matter of any one of clauses 44 to 47, wherein the second periodic structure has a feature extending in a second direction that is different from a first direction in which a feature of the first periodic structure extends.

49. The subject matter of clause 47 or 48, wherein the third periodic structure has a feature extending in the first direction, and the fourth periodic structure has a feature extending in the second direction.

50. The subject of any one of clauses 44 to 46, wherein the characteristics of the periodic structures of each of the first sub-subject and the second sub-subject and the third periodic structure and the sub-subject The characteristics of the four periodic structures extend in the same direction.

51. The subject of any one of clauses 46 to 50, further comprising at least a third sub-subject and at least a fourth sub-subject, wherein each of the third sub-subject and the fourth sub-subject includes a periodic structure .

52. The object of clause 51, wherein when on a substrate, the third sub-object at least partially overlaps a fifth periodic structure on the substrate, and the fourth sub-object at least partially overlaps A sixth periodic structure on the substrate, and the fifth periodic structure is at a layer different from the sixth periodic structure.

53. The subject of clause 51 or 52, wherein the third sub-subject includes a periodic structure with a feature extending in a first direction, and the fourth sub-subject includes a second structure extending in a second different direction One of the characteristics of the periodic structure.

54. The subject of clause 52, wherein the third sub-subject includes a periodic structure having a feature extending in a first direction, and the fourth sub-subject includes a feature extending in a second different direction A periodic structure, wherein the fifth periodic structure has Features extending in the first direction, and the sixth periodic structure have features extending in the second direction.

55. The subject of any one of clauses 44 to 54, wherein at least part of each of the periodic structures of the first sub-subject and the second sub-subject is on a substrate Within a contiguous area less than or equal to 1000 square microns.

56. The subject of any of clauses 44 to 55, wherein at least part of each of the periodic structures of the first sub-subject and the second sub-subject is on a substrate Within a contiguous area less than or equal to 400 square microns.

57. A method of measuring a parameter of a lithography program, the method comprising: using radiation to illuminate a diffraction measurement target on a substrate, the measurement target including at least a first sub-target and at least a second Sub-target, wherein each of the first sub-label and the second sub-label includes a first pair of periodic structures having one of the features extending in a first direction, and one of the features having a second extending in a different direction A second pair of periodic structures, and wherein the first sub-target has a design different from that of the second sub-target; and detecting the scattered radiation from at least the first sub-target and the second sub-target to obtain the target It represents the measurement of one of the parameters of the lithography program.

58. The method of clause 57, wherein at least one of the periodic structures of the first sub-target has a first period and a first characteristic or interval width, wherein the periods of the second sub-target At least one of the sexual structures has a second period and a second feature or interval width, and wherein the different designs include the first period, the first feature or interval width, or both are different from the second period , The second feature or space width, or both.

59. The method of clause 57 or 58, wherein at least part of the first sub-target overlaps A ninth periodic structure and the second sub-target at least partially overlap a tenth periodic structure, wherein the ninth periodic structure is at a layer on the substrate different from the tenth periodic structure.

60. The method of clause 59, wherein the features of the ninth periodic structure extend in the first direction, and the features of the tenth periodic structure extend in the second direction.

61. The method of clause 60, further comprising at least a third sub-target and at least a fourth sub-target, wherein each of the third sub-target and the fourth sub-target includes a periodic structure.

62. The method of clause 61, wherein the third sub-target at least partially overlaps a thirteenth periodic structure and the fourth sub-target at least partially overlaps a fourteenth periodic structure, wherein the tenth The three periodic structures are at a layer on the substrate different from the fourteenth periodic structure, and the thirteenth periodic structure and the fourteenth periodic structure are different from the ninth periodic structure and the third At the layer of ten periodic structures.

63. The method of any one of clauses 57 to 62, wherein the measurement target fits within an area of 400 square microns.

64. The method of any one of clauses 57 to 63, wherein the parameters of the lithography program include overlapping pairs.

65. The method of any one of clauses 57 to 64, wherein each of the sub-subjects is designed for a different process stacking of the substrate.

66. The method of any one of clauses 57 to 65, wherein the illumination comprises: illuminating a measurement light spot on the diffraction measurement target, the measurement light spot covering the first sub-target and the first At least part of each of these periodic structures of the two sub-subjects.

67. A diffraction measurement target, which includes at least a first sub-target and at least a first Two sub-targets, wherein each of the first sub-target and the second sub-target includes a first pair of periodic structures having a feature extending in a first direction, and a first pair of features having a feature extending in a second different direction Two pairs of periodic structures, and wherein the first sub-target has a design different from that of the second sub-target.

68. The subject matter of clause 67, wherein when on a substrate, the first sub-target at least partially overlaps a ninth periodic structure and the second sub-target at least partially overlaps a tenth periodic structure And the ninth periodic structure is on a different layer from the tenth periodic structure on the substrate.

69. The subject matter of clause 68, wherein the features of the ninth periodic structure extend in the first direction, and the features of the tenth periodic structure extend in the second direction.

70. The subject of clause 69, further comprising at least one third sub-subject and at least one fourth sub-subject, wherein each of the third sub-subject and the fourth sub-subject includes a periodic structure.

72. The subject of clause 70, wherein when on a substrate, the third sub-target at least partially overlaps a thirteenth periodic structure and the fourth sub-target at least partially overlaps a fourteenth cycle Structure, wherein the thirteenth periodic structure is at a layer on the substrate different from the fourteenth periodic structure, and the thirteenth periodic structure and the fourteenth periodic structure are different from the thirteenth periodic structure At the layer of the nine periodic structure and the tenth periodic structure.

73. The target of any one of clauses 67 to 72, wherein the fit of the measurement target is within an area of 400 square microns when on a substrate.

74. The target of any one of clauses 67 to 73, wherein at least one of the periodic structures of the first sub-target has a first period and a first feature or interval width, wherein the second At least one of the periodic structures of the sub-target has a second period and A second feature or interval width, and wherein the different designs include the first period, the first feature or interval width, or both are different from the second period, the second feature, or interval width, or both.

75. The subject of any one of clauses 67 to 74, wherein each of the sub-subjects is designed for a different process stacking of a lithographic substrate.

76. A method of measuring a parameter of a lithography program, the method comprising: using radiation to illuminate a diffraction measurement target on a substrate, the measurement target including at least a first sub-target and at least a second Sub-target, wherein each of the first sub-target and the second sub-target includes a first pair of periodic structures having a feature extending in a first direction, and a first pair of features having a feature extending in a second different direction Two pairs of periodic structures, and wherein at least a part of each of the periodic structures of the first sub-target and the second sub-target is within an adjacent area on the substrate that is less than or equal to 1000 square microns And detecting the scattered radiation from at least the first sub-target and the second sub-target to obtain a measurement of one of the parameters of the lithography program obtained for the target.

77. The method of clause 76, wherein the first sub-target has a design different from the second sub-target.

78. The method of clause 77, wherein the different design includes a pitch, feature width, interval width, and/or segmentation of the first sub-mark different from the second sub-mark.

79. The method of any one of clauses 76 to 78, wherein the first sub-target at least partially overlaps a ninth periodic structure and the second sub-target at least partially overlaps a tenth periodic structure, The ninth periodic structure is at a layer on the substrate different from the tenth periodic structure.

80. The method of clause 79, wherein the features of the ninth periodic structure extend in the first direction, and the features of the tenth periodic structure extend in the second direction.

81. The method of clause 80, further comprising at least a third sub-target and at least a fourth sub-target, wherein each of the third sub-target and the fourth sub-target includes a periodic structure.

82. The method of clause 81, wherein the third sub-target overlaps at least partially a thirteenth periodic structure and the fourth sub-target overlaps at least partially a fourteenth periodic structure, wherein the tenth The three periodic structures are at a layer on the substrate different from the fourteenth periodic structure, and the thirteenth periodic structure and the fourteenth periodic structure are different from the ninth periodic structure and the third At the layer of ten periodic structures.

83. The method of any one of clauses 76 to 82, wherein the parameters of the lithography program include overlapping pairs.

84. The method of any one of clauses 76 to 83, wherein the illumination comprises: illuminating a measurement light spot on the diffraction measurement target, the measurement light spot covering the first sub-target and the first At least part of each of these periodic structures of the two sub-subjects.

85. The method of any one of clauses 76 to 84, wherein at least part of each of the periodic structures of the first sub-target and the second sub-target is less than or equal to the substrate In a contiguous area of 400 square microns.

86. The method of any one of clauses 76 to 85, wherein each of the sub-subjects is designed for a different process stacking of the substrate.

87. The method of any one of clauses 76 to 86, wherein each of the sub-subjects is designed to measure a different layer pair of a multi-layer pair.

88. A diffraction measurement target, comprising at least a first sub-target and at least a first Two sub-targets, wherein the first sub-target and the second sub-target each include a first pair of periodic structures having one of the features extending in a first direction, and one of the features having a second extending in a different direction A second pair of periodic structures, and wherein at least part of each of the periodic structures of the first sub-target and the second sub-target is an adjacent area on a substrate that is less than or equal to 1000 square microns Inside.

89. The subject of clause 88, wherein the second sub-subject has a design different from that of the first sub-subject.

90. The subject of clause 88 or 89, wherein when on a substrate, the first sub-target at least partially overlaps a ninth periodic structure and the second sub-target at least partially overlaps a tenth period And the ninth periodic structure is at a layer on the substrate different from the tenth periodic structure.

91. Subject matter of clause 90, wherein the features of the ninth periodic structure extend in the first direction, and the features of the tenth periodic structure extend in the second direction.

92. The subject of clause 91, further comprising at least a third sub-subject and at least a fourth sub-subject, wherein each of the third sub-subject and the fourth sub-subject includes a periodic structure.

93. The subject of clause 92, wherein when on a substrate, the third sub-target at least partially overlaps a thirteenth periodic structure and the fourth sub-target at least partially overlaps a fourteenth period Structure, wherein the thirteenth periodic structure is on the substrate at a layer different from the fourteenth periodic structure, and the thirteenth periodic structure and the fourteenth periodic structure are different from the thirteenth periodic structure At the layer of the nine periodic structure and the tenth periodic structure.

94. The subject of any one of clauses 88 to 93, wherein when on a substrate, at least part of each of the periodic structures of the first sub-subject and the second sub-subject It is within a contiguous area of 400 square microns or less.

95. A method of designing a metrology target, the method comprising: receiving an indication of one of the designs for a diffraction metrology target having one of a plurality of sub-targets, each sub-target including one of the features extending in a first direction A first pair of periodic structures and one of the second pair of periodic structures having features extending in a second different direction; receiving a constraint on the area, a size, or one of the diffraction scales; and by A processor selects a design of the diffraction metric based on at least the constraint.

96. The method of clause 95, wherein the constraints on the area, a size, or both of the diffraction scale include: the periodic structures of the first sub-target and the second sub-target At least part of each is in an adjacent area on the substrate that is less than or equal to 1000 square microns.

97. The method of clause 95 or 96, further comprising receiving information about at least two different program stacks, and wherein the design of the diffraction measurement target includes each of the sub-targets designed for use A different program is stacked.

98. The method of any one of clauses 95 to 97, further comprising receiving information about a plurality of layer pairs to be measured by the diffraction metric, and wherein the design of the diffraction metric includes the Each of the equal sub-targets is designed for a different layer pair.

99. The method of any one of clauses 95 to 98, wherein the design of the diffraction scale includes the first sub-mark having a pitch, characteristic width, space width and/or different from the second sub-mark Segment.

100. A method comprising: using radiation to illuminate a diffractive measurement target on a substrate, the measurement target including at least a first sub-target, a second sub-target and a third sub-target, wherein the first A sub-subject, the second sub-subject and the third sub-subject are different in design.

101. The method of clause 100, wherein the different design includes one of the first sub-subject to the third sub-subject having a different one from the first sub-subject to the other of the third sub-subject Spacing, feature width, spacing width and/or segmentation.

102. The method of clause 100 or 101, wherein the first sub-target at least partially overlaps a first periodic structure, the second sub-target at least partially overlaps a second periodic structure, and the third A sub-target at least partially overlaps a third periodic structure, wherein the first periodic structure is at a layer on the substrate different from the second periodic structure and the third periodic structure, and the second period The sexual structure is at a layer on the substrate different from the first periodic structure and the third periodic structure.

103. The method of any one of clauses 100 to 102, wherein the illumination comprises: illuminating a measurement light spot on the diffraction measurement target, the measurement light spot covering the first sub-target to the first At least part of each of the periodic structures of one of the three sub-targets.

104. The method of any one of clauses 100 to 103, wherein at least part of the periodic structure of one of each of the first sub-subject to the third sub-subject is less than or equal to 400 on the substrate In a contiguous area of square microns.

105. The method of any one of clauses 100 to 104, wherein each of the first sub-subject to the third sub-subject is designed for a different process stacking of the substrate.

106. The method of any one of clauses 100 to 105, wherein each of the first sub-subject to the third sub-subject is designed for measuring a different layer pair of a multi-layer pair.

107. A diffractive metrology target, which includes at least a first sub-target, a second sub-target and a third sub-target, wherein the first sub-target, the second sub-target and the third sub-target are by design different.

108. The subject of clause 107, wherein the different design includes one of the first sub-subject to the third sub-subject having a different one from the first sub-subject to the other of the third sub-subject Spacing, feature width, spacing width and/or segmentation.

109. The subject of clause 107 or 108, wherein at least part of one of the periodic structures of each of the first sub-subject to the third sub-subject is within an adjacent area of less than or equal to 400 square microns.

110. The subject of any one of clauses 107 to 109, wherein each of the first sub-subject to the third sub-subject is designed for a different process stacking of a substrate.

111. The subject of any one of clauses 107 to 110, wherein each of the first sub-subject to the third sub-subject is designed to measure a different layer pair of a multi-layer pair.

112. A method including measuring the overlap between two layers, the method comprising: using radiation to illuminate a diffraction measurement target on a substrate, the substrate having on each of the two layers A part of the subject in which the two layers are separated by at least one other layer.

113. The method of clause 112, wherein a first layer of the two layers includes at least a first sub-target and a second sub-target, wherein a first periodic structure is in the second layer of the two layers Is at least partially under the first sub-target, and there is no periodic structure under the second sub-target in the second layer.

114. The method of clause 113, wherein the first sub-subject and the second sub-subject are different in design.

115. The method of clause 114, wherein the different design includes a pitch, feature width, interval width, and/or segmentation of the first sub-mark that is different from the second sub-mark.

116. The method of any one of clauses 113 to 115, wherein a second periodic structure is at least partially below the second sub-target in the at least one other layer.

117. The method of any one of clauses 113 to 116, wherein the illumination comprises: illuminating a measurement light spot on the diffraction measurement target, the measurement light spot covering the first sub-target and the first At least part of each of the periodic structures of one of the two sub-targets.

118. The method of any one of clauses 113 to 117, wherein at least part of one of the periodic structures of each of the first sub-subject and the second sub-subject is less than or equal to 400 on the substrate In a contiguous area of square microns.

119. The method of any one of clauses 113 to 118, wherein each of the first sub-subject and the second sub-subject is designed for a different process stacking of the substrate.

120. The method of any one of clauses 113 to 119, wherein each of the first sub-subject and the second sub-subject is designed for measuring a different layer pair of a multi-layer pair.

121. A method of designing a configuration of a diffraction measurement target, the target includes a plurality of sub-targets, each sub-target includes a plurality of periodic structures, and each sub-target is designed to measure a different layer pair or measurement A different procedure stacking, the method comprising: locating the periodic structures of the sub-targets in a target area; and locating an auxiliary feature at the periphery of at least one of the sub-targets It is configured to reduce the measured intensity peak at one of the surroundings of the at least one sub-target.

122. The method of clause 121, wherein the auxiliary feature adjacent to a specific periodic structure of a sub-target and oriented with the specific periodic structure of the sub-target is positioned in phase with that periodic structure.

123. The method of clause 121 or 122, wherein the auxiliary feature includes a plurality of auxiliary features, and the target area is defined by the plurality of auxiliary features substantially surrounding the target area.

124. The method of clause 123, wherein the auxiliary feature includes a plurality of additional auxiliary features provided between each sub-target within the target area.

125. The method of clause 124, wherein the additional plurality of auxiliary features are positioned to fill a space between the sub-targets that includes at least half of a wavelength of the relevant detection wavelength.

126. The method of any of clauses 121 to 125, wherein each sub-subject is substantially surrounded by the auxiliary feature so as to isolate each sub-subject from its surrounding environment.

127. The method of any one of clauses 121 to 126, wherein the auxiliary feature comprises a feature having a pitch substantially smaller than a pitch of a periodic structure of a sub-tag of a plurality of sub-tags.

128. The method of any one of clauses 121 to 127, wherein a spacing of the plurality of structures of the auxiliary feature is such that the auxiliary feature is not detected during the detection of the target using a weighing procedure.

129. The method of any one of clauses 121 to 128, wherein the auxiliary feature is positioned next to each outermost substructure of each sub-target.

130. The method of any one of clauses 121 to 129, further comprising: modeling a resulting image obtained by performing the detection of the target using a measurement and measurement procedure based on diffraction; and evaluating the configuration of the target Whether it is optimized for detection using this diffraction-based measurement procedure.

131. The method of clause 130, wherein the method is repeated iteratively to optimize the target configuration.

132. The method of clause 130 or 131, wherein one of the criteria for considering whether a particular target configuration is considered to be optimized includes one or more of the following: when using the diffraction-based metrics When the program is tested, it is determined whether the intensity at the periphery of the sub-target has the same order of magnitude as the intensity at the center of the sub-target; when the measurement and measurement program based on diffraction is used to detect, it is determined that there is overlap and defocus And/or aberrations, whether there is a minimum intensity change at the periphery of the sub-target; for the relevant detection wavelength range, determine whether there is a sufficient interval between the sub-targets for identification of the best target; and/or determine Whether the total raster area is maximized.

133. The method of any one of clauses 121 to 132, wherein the target includes two or more stacked target layers, wherein an upper target layer includes a stacked pair offset and the auxiliary feature, and wherein the No bias is applied to the auxiliary feature in the upper layer.

134. The method of any one of clauses 121 to 132, wherein the target includes two or more stacked target layers, wherein an upper target layer includes a stacked pair offset, and wherein the upper layer does not include Any auxiliary features.

135. The method of any one of clauses 121 to 132, wherein the auxiliary feature is located in a layer different from the at least one sub-target.

136. A diffraction measurement target, comprising: a plurality of sub-targets in a target area of the target, each sub-target includes a plurality of periodic structures and each sub-target is designed to measure a different layer pair or quantity Measuring a different distance Order stacking; and an auxiliary feature at the periphery of at least one of the sub-targets, the auxiliary feature configured to reduce one of the measured intensity peaks at the periphery of the sub-targets.

137. The subject of clause 136, wherein the auxiliary feature includes a feature having a pitch that is substantially smaller than a pitch of a periodic structure of a subtag of a plurality of subtags.

138. As defined in clause 136 or 137, wherein each sub-target is substantially surrounded by the auxiliary feature so as to isolate each sub-target from its surrounding environment.

139. The target of any one of clauses 136 to 138, wherein the auxiliary feature includes a plurality of auxiliary features, and the plurality of auxiliary features substantially surround the target area.

140. The subject of clause 139, wherein the auxiliary feature includes a plurality of additional auxiliary features provided between each sub-subject within the area of the subject.

141. The target of any one of clauses 136 to 140, wherein one of the features of the auxiliary feature is spaced such that the auxiliary feature is not detected during the detection of the target using a weighing procedure.

142. The target of any one of clauses 136 to 141, wherein the auxiliary feature is configured to reduce the peak diffraction intensity at the periphery of each sub-target.

143. The target of any one of clauses 136 to 142, wherein the auxiliary feature is positioned immediately adjacent to each outermost substructure of each subtarget.

144. The target of any one of clauses 136 to 143, wherein the auxiliary feature adjacent to a specific periodic structure of a sub-target and oriented with the specific periodic structure of the sub-target is positioned to The sexual structure is in phase.

145. A method of manufacturing a device, wherein a device pattern is applied to a series of substrates using a lithography procedure, the method includes using items 1 to 9, 15 to 24, 31 to 37, The method of any one of 43 to 51, 61 to 67, or 73 to 81 to detect at least one diffraction measurement formed on at least one of the substrates as part of or in addition to the device pattern Target; and control the lithography process for the substrate later based on the results of the method.

146. A non-transitory computer program product containing machine-readable instructions used to cause a processor to generate items such as items 1 to 9, 15 to 24, 31 to 37, 43 to 51, 56 to 67. The effectiveness of the method of any one of 73 to 81 or 82 to 96.

147. A non-transitory computer program product, which includes machine-readable instructions defining any of the objectives of items 10 to 14, 25 to 30, 38 to 42, 52 to 55, 68 to 72, or 97 to 105 Or information.

148. A substrate comprising the target of any one of items 10 to 14, 25 to 30, 38 to 42, 52 to 55, 68 to 72, or 97 to 105.

149. A patterned device configured to at least partially form a diffraction amount such as any one of items 10 to 14, 25 to 30, 38 to 42, 52 to 55, 68 to 72, or 97 to 105 Targeted.

150. A system, comprising: a detection device configured to provide a light beam on a diffraction measurement target on a substrate and detect radiation diffracted by the target to determine a lithography procedure A parameter; and a non-transitory computer program product such as item 146 or 147.

151. The system of clause 150, further comprising a lithography device, the lithography device comprising: a support structure configured to hold a patterned device for modulating a radiation beam; and a projection optics A system configured to project the modulated radiation beam onto a radiation-sensitive substrate.

Although the above may specifically refer to the use of embodiments of the present invention in the context of optical lithography, it should be understood that the present invention can be used in other applications (for example, imprinting lithography), and does not Limited to optical lithography. In embossed lithography, the configuration in the patterned device defines the pattern generated on the substrate. The configuration of the patterned device may be pressed into the resist layer supplied to the substrate, where the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist is cured, the patterned device is removed from the resist, leaving a pattern therein.

The terms "radiation" and "beam" as used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g., having or about 365 nanometers, 355 nanometers, 248 nanometers, 193 nanometers, 157 Nanometer or 126 nanometer wavelength) and extreme ultraviolet (EUV) radiation (for example, having a wavelength in the range of 5 nanometers to 20 nanometers), and particle beams (such as ion beams or electron beams).

The term "lens" may refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components, as the context permits.

The foregoing description of specific embodiments reveals the general nature of the embodiments of the present invention so that others can easily target a variety of applications by applying the knowledge of those skilled in the art without departing from the general concept of the present invention Modify and/or adapt these specific embodiments without undue experimentation. Therefore, based on the teachings and guidance presented herein, such adaptations and modifications are intended to be within the meaning and scope of equivalents of the disclosed embodiments. It should be understood that the wording or terminology herein is for, for example, description and not limitation, so that the terminology or wording in this specification is to be interpreted by those skilled in the art in accordance with the teachings and the guidance.

The breadth and scope of the present invention should not be limited by any of the above exemplary embodiments Should only be defined based on the scope of patent applications and their equivalents below.

802: Diffraction sub-target/first sub-target

804: Diffraction sub-target/second sub-target

806: Diffraction sub-target

808: Diffraction sub-target

1000: the first extended operating range measurement standard

1002: The second extended operating range measurement standard

1004: Layer

1006: Layer

1008: Layer

1010: Layer

Claims (11)

A diffraction measurement target including at least a first sub-target and at least a second sub-target, wherein the first sub-target and the second sub-target each include a pair of periodic structures, wherein the first The periodic structure of the sub-marks is configured adjacent to the periodic structure of the second sub-mark, and wherein the first sub-mark has a design different from that of the second sub-mark, the different design includes the periodicity of the first sub-marks The structure has a pitch, characteristic width, space width and/or segmentation different from the periodic structure of the second sub-targets, and wherein each of the first sub-target and the second sub-target has a diffraction efficiency Essentially the same or similar. As claimed in claim 1, wherein when on a substrate, the first sub-target at least partially overlaps a fifth periodic structure and the second sub-target at least partially overlaps a sixth periodic structure, and The fifth periodic structure is at a layer different from the sixth periodic structure. As claimed in item 1 or 2, the features of the pair of periodic structures in each of the first sub-subject and the second sub-subject extend in the same direction. As the subject of claim 1 or 2, wherein each of the first sub-subject and the second sub-subject includes a first pair of periodic structures having a feature extending in a first direction, and having a second different direction One of the extended features is the second pair of periodic structures. As the subject of claim 2, wherein the first sub-subject and the second sub-subject each include a first pair of periodic structures having a feature extending in a first direction, and having a second different direction extending One of the features of the second pair of periodic structures, wherein the fifth periodic structure has a feature extending in the first direction, and the sixth periodic structure has a feature extending in the second direction. As the target of claim 1 or 2, it further includes at least a third sub-target and at least a fourth sub-target, wherein each of the third sub-target and the fourth sub-target includes a pair of periodic structures. As the subject of claim 6, wherein when on a substrate, the third sub-target at least partially overlaps a ninth periodic structure and the fourth sub-target at least partially overlaps a tenth periodic structure, and The ninth periodic structure is at a layer different from the tenth periodic structure. As claimed in claim 6, wherein each of the third sub-mark and the fourth sub-mark includes a first pair of periodic structures having a feature extending in a first direction, and having a second different direction extending One of the characteristics of the second pair of periodic structures. As the subject of claim 7, wherein the third sub-subject and the fourth sub-subject each include a first pair of periodic structures having a feature extending in a first direction, and having a second different direction extending One of the characteristics of the second pair of periodic structures, wherein the ninth periodic structure has a feature extending in the first direction, and the tenth periodic structure has The feature extending in the second direction. As the subject of claim 1 or 2, wherein when on a substrate, at least part of each of the periodic structures of the first sub-subject and the second sub-subject is less than or on the substrate In a contiguous area equal to 1000 square microns. As the subject of claim 1 or 2, wherein when on a substrate, at least part of each of the periodic structures of the first sub-subject and the second sub-subject is less than or on the substrate In an adjacent area equal to 400 square microns.

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