JP2003257841A - Method and device for detecting position of mark, for detecting position, and for exposure, and method of manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect positions of marks with accuracy regardless of types of the marks. <P>SOLUTION: A method of deciding a target focus position is selected in accordance with information on a shape of a mark to be detected, namely, a mark which becomes the target of position detection (steps 306-312). In addition, the target focus position at the time of detecting the position of the mark to be detected by means of an imaging type mark detecting system is decided in accordance with a selected deciding method (steps 316 and 320). Thereafter, positional information on the mark to be detected in a two-dimensional plane perpendicular to an optical axis of a detecting optical system is detected by using the mark detecting system, by controlling the position of an object (wafer) on which the mark to be detected is formed with respect to the optical axis of the detecting optical system based on the target focus position (steps 322-326). Therefore, positional information on the mark to be detected in a two-dimensional plane perpendicular to the optical axis of the detecting optical system can be detected with accuracy by means of the mark detecting system in an optimum focus state corresponding to the design of the mark. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mark position detecting method and device, a position detecting method and device, an exposure method and device, and a device manufacturing method, and more particularly, to position information of a mark formed on an object. Including a mark position detecting method suitable for implementing the method, a position detecting method including the mark position detecting method, a position detecting apparatus including the mark position detecting apparatus, and the position detecting method The present invention relates to an exposure method and an exposure apparatus including the position detection apparatus, and a device manufacturing method that uses the exposure apparatus in a lithography process.

[0002]

2. Description of the Related Art Conventionally, in a lithography process for manufacturing microdevices such as semiconductor elements and liquid crystal display elements,
Various exposure apparatuses are used. In recent years, for example, as a semiconductor exposure apparatus, a substrate such as a semiconductor wafer or a glass plate on which a fine pattern formed on a photomask or a reticle (hereinafter, referred to as “reticle”) is coated with a photosensitizer such as a photoresist. Transferring through a projection optical system (hereinafter collectively referred to as “wafer”),
A projection exposure apparatus such as an and repeat type reduction projection exposure apparatus (so-called stepper) or a step-and-scan type scanning projection exposure apparatus (so-called scanning stepper), which is an improvement of this stepper, is mainly used. ing.

By the way, when manufacturing a semiconductor device or the like, it is necessary to stack different layers of circuit patterns on a wafer. Therefore, the reticle on which the circuit patterns are formed and each shot area on the wafer are formed. It is important to exactly overlap the pattern already formed on the substrate.
Alignment of this reticle and wafer
The required accuracy has become severe with the miniaturization of patterns, and various measures have been taken for alignment.

The position of the wafer in the stepper or the like is detected by
This is performed by detecting the alignment mark (alignment mark) formed on the wafer. As a wafer alignment system that detects this alignment mark,
Various schemes are known. Recently, for example, a halogen lamp or the like is used as a light source to illuminate with light having a wide wavelength band, and C
An FIA (Fiel) that measures the mark position by image processing the image data of the alignment mark taken by a CD camera or the like.
Off-axis alignment systems such as d Image Alignment) are often used. According to this FIA type alignment sensor, it is possible to detect the position of an aluminum mark or an asymmetric mark with high accuracy without being affected by thin film interference due to the resist layer.

Similarly, the position of the reticle is detected by detecting the alignment mark (alignment mark) formed on the reticle. In this case, the exposure light is generally used as the detection light beam. Target. For example, there is known a VRA (Visual Reticle Alignment) type sensor that irradiates exposure light onto an alignment mark formed on a reticle, image-processes image data of the alignment mark captured by a CCD camera or the like, and measures the mark position. ing.

The alignment between the reticle and the wafer using these optical alignment sensors is generally performed in the following procedure. That is, first, the image of the alignment mark on the reticle is detected by the VRA sensor at the same time as the image of the reference mark on the wafer stage through the projection optical system, and the projection position of the reticle pattern is calculated based on the detection result. Next, the wafer stage is moved by, for example, a predetermined distance and F
The reference mark on the wafer stage is detected by the IA system sensor, and the FIA system baseline amount is obtained based on the detection result. Then, the alignment mark on the wafer is detected by a FIA sensor, and a predetermined calculation process is performed based on the detection result and the position coordinate of the wafer stage at that time to determine the position coordinate of each shot area on the wafer. Ask for.

Based on the above result, the relative positional relationship between the reticle (reticle stage) and the wafer (wafer stage) is controlled to perform exposure by the step-and-repeat method or the step-and-scan method. By doing so, the reticle patterns are sequentially superimposed and transferred to each shot area on the wafer.

However, when the position of the alignment mark formed on the object (wafer or the like) is detected by using the above-mentioned image-forming type alignment system, the position of the wafer or the like can be detected with high accuracy. In order to detect the position of the alignment mark, it is necessary to detect the alignment mark at the position where the optimum focus state is achieved.

The best focus position of the detection optical system is used as the focus position when detecting marks such as alignment marks. For example, while changing the optical axis direction (height direction) position of a reference mark provided on a wafer stage or the like, the reference mark is repeatedly imaged by using an imaging type alignment system, and the image pickup result is the optical axis direction. For example, the position of the reference mark in the optical axis direction corresponding to the image pickup signal having the maximum contrast among the image pickup signals obtained at the respective positions is set as the best focus position of the detection optical system. In this case, the best focus position can be made to coincide with the Gaussian image plane that is uniquely determined for the detection optical system depending on the reference mark used and the method of using the reference mark.

In addition to this, while changing the position in the optical axis direction of the object on which the mark for position detection is formed, an image of the mark is picked up by the alignment system, and the change in the shape of the picked-up signal is measured, It is also possible to determine the focus position when detecting the mark. In this case, the position detection is performed at a different focus position for each target mark.

[0011]

Conventionally, in the same exposure apparatus or the like, the focus position determined by any one of the above-mentioned various methods is designed for the mark to be detected. It has been used as the focus position of an image-forming alignment system when performing mark detection regardless of (type).

However, according to the experience of the present inventor, it is determined by the method of the mark design whether the focus position determined by which method is suitable for detecting the mark position with higher accuracy.
That is, it is known that the arrangement, the width, the cross-sectional shape, and the like are not always constant.

The present invention has been made under such circumstances, and a first object of the present invention is to provide a mark position detecting method and a mark position detecting device capable of accurately detecting the position regardless of the type of the mark. To provide.

A second object of the present invention is to provide a position detecting method and a position detecting device capable of accurately detecting the position information of an object on which a mark is formed.

A third object of the present invention is to provide an exposure method and an exposure apparatus capable of accurately transferring and forming a pattern on an object.

A fourth object of the present invention is to provide a device manufacturing method capable of improving the productivity of microdevices.

[0017]

As a result of repeating simulations on the assumption of various marks, the inventor has found that an image-forming mark detection system, based on the mark design (mainly two-dimensional or three-dimensional shape), For example, the above-mentioned F
Suitable for mark position detection by IA type sensor,
It was found that the focus position (including the focus position serving as a reference for the focus position) at the time of detecting the mark is different. A part of the above simulation will be described later. The present invention has been made on the basis of the novel findings of the inventor, and employs the following means (configuration or method).

According to a first aspect of the present invention, there is provided a mark position detecting method for detecting the position information of a mark formed on an object, wherein the target focus position is determined according to the shape information about the detected mark. A selection step of selecting; a target focus position at the time of detecting the position of the detected mark by an image-forming mark detection system that captures an image of the detected mark through a detection optical system according to the selected determination method. In a two-dimensional plane orthogonal to the optical axis by using the mark detection system by controlling the position of the object in the optical axis direction of the detection optical system based on the target focus position. And a detection step of detecting the position information of the detected mark.

According to this, according to the shape information regarding the detected mark, that is, the mark whose position is to be detected,
A method of determining the target focus position is selected (selection step). In this case, the optimum focus position of the image-forming mark detection system at the time of mark detection and its focus can be detected with high accuracy for various types of marks by simulation or experiment in advance. By obtaining the method of determining the position, the method of determining the mark is selected according to the shape information regarding the detected mark when the mark is detected.

Then, the target focus position when the position of the detected mark is detected by the image-forming mark detection system is determined according to the selected determination method (determination step). Then, the position of the object in the optical axis direction of the detection optical system is controlled based on the target focus position, and the position information of the detected mark in the two-dimensional plane orthogonal to the optical axis is detected using the mark detection system. It is detected (detection step).

Therefore, according to the mark position detecting method of the present invention, the position information of the detected mark in the two-dimensional plane orthogonal to the optical axis is detected by the mark detecting system in the optimum focus state according to the mark design. It is possible to detect with high accuracy, and as a result, it is possible to accurately detect the position information regardless of the type of mark.

In this case, as in the mark position detecting method according to the second aspect, in the selecting step, the shape information regarding the detected mark has a line width equal to or less than the resolution of the detection optical system. If it is information indicating that the detected mark is present or that the detected mark is formed as a set of minute marks having a resolution equal to or lower than the resolution, the first determination method is selected, and the shape relating to the detected mark is selected. When the information is information indicating that the detected mark has a line width exceeding the resolution of the detection optical system, a second determination method is selected, and in the determination step, the first determination method is selected. Is selected, the target focus position is dynamically determined based on the waveform of the imaging signal of the detected mark by the mark detection system, and the second determination method is selected. In this case, it can be decided to determine the predetermined focus position as the target focus position. It is based on the result of the simulation conducted by the inventor that it is confirmed that the optimum focus position determining method differs depending on the size of the line width of the detected mark, as described later.

In this case, as in the mark position detecting method according to the third aspect, in the determining step, when the target focus position is dynamically determined, the detection optical of the object on which the detected mark is formed is detected. An image of the detected mark is picked up using the mark detection system at a plurality of positions in the optical axis direction of the system, and the absolute value of the differential waveform of each picked-up signal of the detected mark at each position is maximum. The position in the optical axis direction of the object corresponding to the image pickup signal, and the position in the optical axis direction of the object corresponding to the image pickup signal having the maximum contrast among the image pickup signals, The target focus position can be set.

In the mark position detecting method according to the second aspect, as in the mark position detecting method according to the fourth aspect, in the determining step, the mark obtained in advance using the reference mark formed on the mark forming member is used. An image of the detected mark is captured by using the mark detection system at a fixed focus position of the detection optical system and at a plurality of positions in the optical axis direction of the detection optical system of the object on which the detected mark is formed. One of the focus position determined in advance based on the image pickup signal of the detected mark obtained for each position and the best focus position of the detection optical system obtained by simulation for the detected mark is set in advance. The target focus position may be determined.

In each of the mark position detecting methods described in claims 1 to 4, as in the mark position detecting method described in claim 5, in the detecting step, the target focus position determined in the center is set. The object is positioned at each of a plurality of positions in the optical axis direction of the detection optical system, position information in the two-dimensional plane of the detected mark is detected using the mark detection system, and each position in the optical axis direction is detected. The position information in the two-dimensional plane of the detected mark can be calculated based on an expression including a linear combination of the detection results obtained in the above. Alternatively, as in the mark position detecting method according to claim 6, in the detecting step, the object is respectively positioned at a plurality of positions in the optical axis direction of the detection optical system centered on the determined target focus position. Then, an image of the detected mark is picked up using the mark detection system, and the detected object in the two-dimensional plane is detected based on a combined signal obtained by combining the imaged signals obtained at each position in the optical axis direction. The position information of the mark can be calculated.

According to a seventh aspect of the present invention, there is provided a position detecting method for detecting position information of an object, wherein the position information in the two-dimensional plane of the position detection mark formed on the object is used. 6. The position detecting method according to any one of 6 to 6; and a step of calculating the position information of the object based on the position information of the detected position detecting mark; is there.

According to this, the position information in the two-dimensional plane of the position detecting mark formed on the object is detected by the mark position detecting method according to any one of claims 1 to 6. In this case, the position detection mark formed on the object is detected using the mark detection system in the optimum focus state for highly accurate position detection. This makes it possible to accurately detect the position of the position detection mark in the two-dimensional plane orthogonal to the optical axis. Then, since the position information of the object is calculated based on the position information of the position detection mark detected with high accuracy, it is possible to detect the position information within the two-dimensional plane of the object with high accuracy.

The present invention according to claim 8 is an exposure method for exposing an object to form a predetermined pattern on the object, wherein the position information in the moving plane of the object is used for the position information. And a step of detecting using a detection method; and a step of performing the exposure by controlling the position of the object in the moving surface based on the detected position information.

According to this, the position information in the moving plane of the object is detected by using the position detecting method according to the seventh aspect.
Therefore, the position information on the moving surface of the object is accurately detected. Then, at the time of exposure, the position of the object in the two-dimensional plane is controlled based on the detected position information of the object in the moving plane. Therefore, the position of the object at the time of exposure can be controlled with high accuracy, and high-precision exposure with an extremely small pattern formation position error becomes possible.

For example, when static exposure is performed by the projection exposure apparatus, the object (photosensitive substrate) can be accurately positioned at the exposure position (projection position of the mask pattern), and, for example, scanning exposure is performed. In this case, the relative positional relationship between the object (photosensitive substrate) and the mask can be maintained in a desired state. In any case, the pattern of the mask can be accurately superimposed and transferred to a desired divided area on the object (photosensitive substrate).

According to a ninth aspect of the present invention, there is provided a mark position detecting device for detecting position information of a mark formed on an object, which is an image-forming system for picking up an image of a detected mark through a detection optical system. Mark detection system; a selection device for selecting a target focus position determination method according to shape information about the detected mark; and a position of the detected mark by the mark detection system according to the method selected by the selection device. A focus position determining device for determining a target focus position at the time of detection; controlling the position of the object in the optical axis direction of the detection optical system based on the target focus position determined by the focus position determining device, A detection control device for detecting position information of the detected mark in a two-dimensional plane orthogonal to the optical axis by using the mark detection system; A position detecting device.

According to this, the selection device selects the method of determining the target focus position according to the shape information regarding the detected mark. In this case, the optimum focus position of the mark detection system at the time of mark detection and the method of determining the focus position can be detected with high accuracy for various types of marks by simulations or experiments in advance. According to the result, the selection criterion of the selection device is prepared as, for example, a software program or table data.

Then, by the focus position determining device,
The target focus position when the position of the detected mark is detected by the mark detection system is determined according to the method selected by the selection device. Then, in the detection control device, the position of the object in the optical axis direction of the detection optical system is controlled based on the target focus position determined by the focus position determination device, and the optical axis of the detected mark is detected using the mark detection system. The position information in the orthogonal two-dimensional plane is detected.

Therefore, according to the mark position detecting device of the present invention, the position information of the detected mark in the two-dimensional plane orthogonal to the optical axis is detected by the mark detecting system in the optimum focus state according to the mark design. It is possible to detect with high accuracy, and as a result, it is possible to accurately detect the position information regardless of the type of mark.

In this case, as in the mark position detecting device according to the tenth aspect, the shape information regarding the detected mark may be information provided from the outside,
Alternatively, as in the mark position detecting device according to claim 11, the shape information regarding the detected mark may be information obtained as a result of processing a waveform of an image pickup signal of the detected mark by the mark detection system. .

In each of the mark position detecting devices described in claims 9 to 11, like the mark position detecting device according to claim 12, the selection device is configured such that the shape information regarding the detected mark is the detected mark. Is information having a line width equal to or less than the resolution of the detection optical system and the detected mark being formed as a set of minute marks equal to or less than the resolution. If the shape information regarding the detected mark is information indicating that the detected mark has a line width exceeding the resolution of the detection optical system, the second determination method is selected. When the first determination method is selected, the focus position determination device determines the target focus based on the waveform of the image pickup signal of the detected mark by the mark detection system. Position dynamically determine, when the second determination method is selected, it can be decided to determine the predetermined focus position as the target focus position.

In this case, as in the mark position detecting device according to the thirteenth aspect, when the focus position determining device dynamically determines the target focus position,
Detected marks obtained at each of the positions by capturing an image of the detected mark using the mark detection system at a plurality of positions in the optical axis direction of the detection optical system of the object on which the detected mark is formed. The position in the optical axis direction of the object corresponding to the image pickup signal having the maximum absolute value of the differential waveform of the image pickup signals can be set as the target focus position. Alternatively, as in the mark position detection device according to claim 14, the focus position determination device dynamically determines the focus position,
The detected target image obtained by capturing images of the detected mark using the mark detection system at a plurality of positions in the optical axis direction of the detection optical system of the object on which the detected mark is formed. The position in the optical axis direction of the object corresponding to the image pickup signal having the maximum contrast among the image pickup signals of the mark can be set as the target focus position.

In each of the mark position detecting devices described in claims 12 to 14, like the mark position detecting device described in claim 15, the focus position determining device uses a reference mark formed on a mark forming member. The fixed focus position of the detection optical system obtained in advance can be set as the predetermined target focus position. Alternatively, as in the mark position detection device according to claim 16, the focus position determination device is such that the mark detection system is provided at a plurality of positions in the optical axis direction of the detection optical system of the object on which the detected mark is formed. A focus position determined in advance based on an image pickup signal of the detected mark obtained for each position by capturing an image of the detected mark using You can Alternatively, as in the mark position detection device according to claim 17, the focus position determination device is
The best focus position of the detection optical system obtained by simulation for the detected mark may be set as the predetermined target focus position.

In each of the mark position detecting devices described in claims 9 to 17, as in the mark position detecting device according to claim 18, the detection control device is configured to detect the target focus determined by the focus position determining device. Positioning the object at a plurality of positions in the optical axis direction of the detection optical system centered on a position, and detecting the position information in the two-dimensional surface of the detected mark using the mark detection system, The position information in the two-dimensional plane of the detected mark can be calculated based on an equation including a linear combination of detection results obtained for each position in the optical axis direction. Alternatively, as in the mark position detection device according to claim 19, the detection control device is arranged such that a plurality of positions in the optical axis direction of the detection optical system centered on the target focus position determined by the focus position determination device. The objects are respectively positioned at the respective positions, the image of the detected mark is picked up by using the mark detection system, and the image pickup signal obtained at each position in the optical axis direction is combined to generate the composite signal. It is possible to calculate position information of the detected mark in the dimension plane.

According to a twentieth aspect of the present invention, there is provided a mark position detecting device for detecting position information of a mark formed on an object, which is an imaging type for picking up an image of a detected mark via a detection optical system. A mark detection system for locating the object at a plurality of positions in the optical axis direction of the detection optical system centered on a predetermined target focus position, and using the mark detection system to form an image of the detected mark. A detection control device that captures an image and calculates position information of the detected mark in a two-dimensional plane orthogonal to the optical axis by using each imaging signal obtained for each position in the optical axis direction; It is a detection device.

According to this, in the detection control device, the object is respectively positioned at a plurality of positions in the optical axis direction of the detection optical system centered on the predetermined target focus position, and the mark detection system is used to detect the detected mark. The image of the image is captured, and the position information of the detected mark in the two-dimensional plane orthogonal to the optical axis is calculated using the respective image pickup signals obtained for each position in the optical axis direction. That is, even if the target focus position is deviated from the optimum focus position for detecting the detection target mark, the object is placed at a plurality of positions around the target focus position in the optical axis direction of the detection optical system. 2 is orthogonal to the optical axis by performing a predetermined process by using each image pickup signal of the detected mark obtained at each position in the optical axis direction.
By calculating the position information of the detected mark in the two-dimensional plane, the detected mark in the two-dimensional plane is used by using the imaging signal of the detected mark obtained by positioning the object only at the displaced target focus position. It is possible to detect the position information of the mark with higher accuracy than in the case of calculating the position information of.
As a result, accurate position detection can be performed regardless of the type of mark.

In this case, as in the mark position detection device according to the twenty-first aspect, the detection control device uses the image pickup signals to obtain position information of the detected mark in the two-dimensional plane in the optical axis direction. Can be calculated for each position of the object, and position information of the detected mark in the two-dimensional plane can be calculated based on an equation including a linear combination of the calculation results for each position. Alternatively, claim 2
As in the mark position detecting device described in 2, the detection control device may calculate the position information of the detected mark in the two-dimensional plane based on a combined signal obtained by combining the image pickup signals. it can.

The invention according to claim 23 is a position detecting device for detecting position information of an object, wherein the position detection mark formed on the object is the detected mark. A mark position detecting device according to any one of the preceding claims; and a calculating device that calculates the position information of the object in the two-dimensional plane based on the position information of the position detecting marks detected by the position detecting device. It is a position detection device.

According to this, the position information in the two-dimensional plane of the position detection mark formed on the object is accurately detected by the mark position detecting device according to any one of claims 9 to 22. Then, the position information in the two-dimensional plane of the object is calculated by the calculation device based on the position information of the position detection mark detected with high accuracy, so that the position information in the two-dimensional plane of the object is highly accurate. Can be detected.

The invention as set forth in claim 24 is an exposure apparatus which exposes an object to form a predetermined pattern on the object, and detects position information in a moving plane of the object. And a processing device that controls the position of the object in the moving surface based on the detected position information to perform the exposure.

According to this, the position information in the moving surface of the object can be accurately detected by the position detecting device according to the twenty-third aspect. Then, during the exposure, the processing device controls the position of the object in the two-dimensional plane on the basis of the position information in the moving surface of the object detected with high accuracy. Therefore, the position of the object at the time of exposure can be controlled with high accuracy, and high-precision exposure with an extremely small pattern formation position error becomes possible.

A twenty-fifth aspect of the present invention is a device manufacturing method including a lithography step, wherein in the lithography step, exposure is performed using the exposure apparatus of the twenty-fourth aspect. Is.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG.
~ It demonstrates based on FIG. 9 (B).

FIG. 1 shows a mark position detecting method according to the present invention,
The schematic configuration of an exposure apparatus 100 suitable for carrying out the position detection method and the exposure method is shown. This exposure apparatus 10
Reference numeral 0 is a step-and-scan type projection exposure apparatus. The exposure apparatus 100 includes an illumination system 10, a reticle stage RST that holds a reticle R as a mask,
The projection optical system PL, a wafer stage WST on which a wafer W as an object is mounted, a stage control system 19 for controlling the reticle stage RST and the wafer stage WST, and a main control system 20 for collectively controlling the entire apparatus are provided.

The illumination system 10 is, for example, Japanese Patent Laid-Open No. 6-34.
As disclosed in Japanese Patent No. 9701 etc., it is configured to include a light source, an illumination uniformizing optical system including an optical integrator, a relay lens, a variable ND filter, a reticle blind, and a dichroic mirror (all not shown). There is. A fly-eye lens, a rod (internal reflection type) integrator, a diffractive optical element, or the like is used as the optical integrator. The illumination system 10 has a slit-shaped illumination area portion on a reticle R, which is defined by a reticle blind (not shown) and extends in the X-axis direction (horizontal direction in the plane of FIG. 1), with a substantially uniform illuminance by the illumination light IL. Illuminate. Here, as the illumination light IL, KrF excimer laser light (wavelength 248n
m) and other far-ultraviolet light, ArF excimer laser light (wavelength 1
93 nm) or vacuum ultraviolet light such as F ₂ laser light (wavelength 157 nm). As the illumination light IL,
Ultraviolet emission line (g line, i line, etc.) from ultra-high pressure mercury lamp
It is also possible to use.

On the reticle stage RST, a reticle R having a circuit pattern PA formed on its pattern surface (lower surface in FIG. 1) is fixed by, for example, vacuum suction. The reticle stage RST is within an XY plane perpendicular to the optical axis of the illumination system 10 (which coincides with the optical axis AX of the projection optical system PL described later) by the reticle stage drive unit 12 including an actuator such as a linear motor and a voice coil motor. And a predetermined scanning direction (here, Y which is a direction orthogonal to the paper surface in FIG. 1).
It is possible to drive at the scanning speed specified in the (axial direction).

The position of the reticle stage RST on the stage moving surface is moved by a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 16 via a moving mirror 15.
For example, it is always detected with a resolution of about 0.5 to 1 nm.
Position information of the reticle stage RST from the reticle interferometer 16 is supplied to the stage control system 19 and the main control system 20 via the stage control system 19. In accordance with an instruction from the main control system 20, the stage control system 19 drives and controls the reticle stage RST via the reticle stage drive unit 12 based on the position information of the reticle stage RST. The end surface of reticle stage RST may be mirror-finished to form a reflection surface (corresponding to the reflection surface of movable mirror 15 described above).

The projection optical system PL is arranged below the reticle stage RST in FIG. 1, and its optical axis AX is in the Z-axis direction. As the projection optical system PL, for example, a dioptric system that is both-side telecentric and has a predetermined reduction magnification (for example, 1/5 or 1/4) is used. Therefore, when the illumination light IL from the illumination optical system illuminates the illumination area of the reticle R, the illumination light IL passing through the reticle R causes the circuit of the reticle R in the illumination area via the projection optical system PL. A reduced image (partial inverted image) of the pattern PA is formed on the wafer W whose surface is coated with a resist (photosensitive agent).

The wafer stage WST is arranged on a base (not shown) below the projection optical system PL in FIG. 1, and a wafer table 25 is placed on the wafer stage WST. The wafer W is fixed on the wafer table 25 via a wafer holder (not shown) by, for example, vacuum suction. The wafer table 25 is projected onto the projection optical system P by a driving unit including a voice coil motor.
Can be tilted in any direction with respect to the plane orthogonal to the optical axis of L,
Moreover, it is configured to be finely movable in the optical axis AX direction (Z-axis direction) of the projection optical system PL. Also, this wafer table 2
No. 5 is also capable of a minute rotation operation around the Z axis.

Wafer stage WST is moved in the scanning direction so that not only the movement in the scanning direction (Y-axis direction) but also a plurality of shot areas on wafer W can be positioned in an exposure area conjugate with the illumination area. It is also configured to be movable in the non-scanning direction (X-axis direction) orthogonal to each other. Wafer stage WST is driven in the XY two-dimensional directions by a drive system including a motor and the like. As described above, the drive unit of wafer table 25 and the drive system of wafer stage WST are separately provided, but in FIG. 1, they are collectively shown as wafer drive device 24. Therefore, in the following, the wafer driving device 24 drives the wafer stage WST in the XY two-dimensional directions, and
The description will be made assuming that the wafer table 25 is finely driven in the directions of four degrees of freedom Z, θx, θy, and θz.

The position of wafer stage WST (and wafer table 25) in the XY plane is wafer table 25.
Wafer laser interferometer system 18 constantly detects it with a resolution of, for example, about 0.5 to 1 nm via movable mirror 17 provided above. Here, in practice, on the wafer table 25, a Y moving mirror having a reflecting surface orthogonal to the scanning direction (Y axis direction) and an X moving mirror having a reflecting surface orthogonal to the non-scanning direction (X axis direction). In correspondence with this, the wafer laser interferometer is also provided with a Y interferometer that irradiates the interferometer beam perpendicularly to the Y moving mirror and an X interferometer that irradiates the interferometer beam perpendicularly to the X moving mirror. However, Figure 1
These are typically shown as a moving mirror 17 and a wafer laser interferometer system 18. It should be noted that, for example, the end surface of the wafer table 25 is mirror-finished to have a reflecting surface (the moving mirror
7) may be formed. Further, the X interferometer and the Y interferometer are multi-axis interferometers having a plurality of length measuring axes,
In addition to the X and Y positions of the wafer table 25, rotation (yawing (θz rotation around the Z axis), pitching (X
It is also possible to measure the rotation about the axis (θx rotation) and the rolling (rotation about the Y axis about the θy rotation). Therefore, the wafer laser interferometer system 18 will be described below.
X, Y, θz, θy of the wafer table 25,
It is assumed that the position of θx in the 5-DOF direction is measured. In the present embodiment, the stationary coordinate system (orthogonal coordinate system) that defines the movement position of wafer stage WST is defined by the length measurement axes of the Y interferometer and X interferometer of wafer laser interferometer system 18. In the following, this stationary coordinate system is also referred to as "stage coordinate system". Also, the multi-axis interferometer is 45
The laser beam is irradiated onto the reflection surface installed on the pedestal (not shown) on which the projection optical system PL is mounted through the reflection surface installed on the wafer table 25 with a tilt, and the projection optical system PL is irradiated.
The relative position information regarding the optical axis direction (Z-axis direction) may be detected.

The position information (or speed information) of wafer stage WST on the stage coordinate system is the stage control system 1.
9 and the main control system 20 via this. The stage control system 19 responds to an instruction from the main control system 20 based on the position information (or speed information) of the wafer stage WST via the wafer driving device 24.
Control T.

A reference mark plate FM as a mark forming member is fixed near the wafer W on the wafer table 25. The surface of the reference mark plate FM is set at the same height as the surface of the wafer W, and a measurement mark for measuring the best focus position of an alignment microscope, which will be described later, a so-called baseline measurement reference is set on this surface. Marks, reference marks for reticle alignment, and other marks (typically shown as GM in FIG. 1)
Are formed.

Further, the exposure apparatus 100 includes an off-axis type alignment microscope A as a mark detection system.
It has S. The alignment microscope AS irradiates the mark on the reference mark plate FM or the alignment mark as a position detection mark on the wafer W (hereinafter, also referred to as “wafer mark”) with illumination light having a predetermined wavelength width. , The images of the marks and the images of the index marks on the index plate arranged in the plane conjugate with the wafer are imaged on the light receiving surface of the image pickup device (CCD, etc.) by the objective lens, etc. The position information of the detected mark with the center of the index mark as a reference is calculated by performing a predetermined process on the image pickup signal obtained as, and the position information is output to the main control system 20.

This alignment microscope AS includes, for example, a light source 103 such as a halogen lamp, a light guide 104 such as an optical fiber, an illumination aperture stop 127, a condenser lens 129, an illumination relay lens 105, a beam splitter 106, a first objective lens 107, and a reflection. Prism 10
8, second objective lens 111, index plate 112, relay lens system (113, 114), imaging aperture stop 130, beam splitter 115, Y direction CCD 116, X direction C
The CD 117 and the signal processing system 118 are provided.

The operation of the alignment microscope AS will be described. The alignment light AL from the light source 103 is guided to a predetermined position via the light guide 104. Alignment light A emitted from the emission end of the light guide 104
After being limited by the illumination aperture stop 127 as necessary, L becomes an illumination light flux having an appropriate cross-sectional shape and enters the condenser lens 129.

The alignment light AL emitted from the condenser lens 129 is once condensed and then enters the illumination relay lens 105 through an illumination field stop (not shown).
The alignment light AL that has become parallel light through the illumination relay lens 105 passes through the beam splitter 106 and then enters the first objective lens 107. The alignment light AL condensed by the first objective lens 107 is reflected vertically downward by the reflection surface of the reflection prism 108, and then, a mark to be detected on the wafer stage WST, for example, the above-mentioned mark on the reference mark plate FM. The measurement mark, other reference mark, or the alignment mark on the wafer W is illuminated.

The above-mentioned detected mark illuminated by the alignment light AL (hereinafter referred to as "mark M" for convenience).
The reflected light from is incident on the beam splitter 106 via the reflecting prism 108 and the first objective lens 107. Then, the light reflected vertically upward by the beam splitter 106 passes through the second objective lens 111,
An image of the mark M is formed on the index plate 112 on which index marks (not shown) are formed.

The light emitted from the index plate 112 passes through the relay lens system (113, 114), is limited by the imaging aperture stop 130 as necessary during the passage, and enters the beam splitter 115. One of the lights (reflected light) split by the beam splitter 115 is C for Y direction.
The other light (transmitted light) is transmitted to the CD 116 by the CCD 1 for the X direction.
It is incident on 17.

In this way, the image of the mark M is formed together with the image of the index mark on the index plate 112 on the image pickup surfaces of the Y direction CCD 116 and the X direction CCD 117. Output signals from the Y-direction CCD 116 and the X-direction CCD 117 are supplied to the signal processing system 118, and the signal processing system 118 is supplied.
Predetermined signal processing (for example, noise removal) and A /
D conversion is performed, and the digitized image pickup signal, that is, image data is supplied to the main control system 20. The main control system 20 calculates the position of the mark M based on the center of the index mark based on the image pickup signal, and based on the calculation result and the measurement value of the interferometer system 18 at that time, the stage coordinate system. The position coordinates of the mark M on the top are calculated.

As can be seen from the above description, in the present embodiment, the light source 103, the light guide 104, the illumination aperture stop 127, the condenser lens 129, the illumination field stop (not shown), the illumination relay lens 105, and the beam splitter 10.
6, first objective lens 107, and reflection prism 108
An illumination optical system for irradiating the mark M with alignment light is constituted by. Also, the reflection prism 1
08, first objective lens 107, beam splitter 10
6, the second objective lens 111, the index plate 112, the relay lens system (113, 114), the imaging aperture stop 130, and the beam splitter 115 form a mark image based on the reflected light from the mark M with respect to the alignment light AL. An imaging optical system as a detection optical system is configured.

The exposure apparatus 100 further supplies an image forming light beam for forming a plurality of slit images toward the best image forming plane of the projection optical system PL from an oblique direction with respect to the optical axis AX direction. Illuminating optical system and the wafer W of the image forming light beam
An oblique-incidence type multi-point focus detection system including a light receiving optical system (not shown) that receives each reflected light beam on the surface of the lens is fixed to a support portion (not shown) that supports the projection optical system PL. ing. As this multi-point focus detection system, for example, a structure similar to that disclosed in JP-A-6-283403 is used, and the stage control system 19 uses the wafer position information from the multi-point focus detection system. Based on the above, the wafer table 25 is driven in the Z direction and the tilt direction.

Further, the exposure apparatus 100 is further described in Japanese Patent Laid-Open No.
It also has an alignment focus detection system (not shown) provided in the alignment microscope AS known from 001-257157 and JP 2000-12445A. Therefore, in the exposure apparatus 100, when the wafer table 25 is driven in the Z direction, either the above-mentioned multipoint focus detection system or the alignment focus detection system is used.

The main control system 20 is constituted by including a microcomputer or a workstation, and controls each component of the apparatus as a whole. Further, the main control system 20 is supplied with a command for the illumination aperture stop 127 and a command for the imaging aperture stop 130 via an input device 126 such as a keyboard. Based on these commands, the main control system 20 drives the illumination aperture stop 127 via the drive system 128 and drives the imaging aperture stop 130 via the drive system 131.

Next, in the exposure apparatus 100 configured as described above, the operation in the exposure processing step when exposing the second and subsequent layers will be described.

First, under the control of the main control system 20, a reticle loader and a wafer loader (not shown) perform reticle load and wafer load.

Then, in response to an instruction from the main control system 20,
The wafer drive device 24 is controlled by the stage control system 19, and a pair of reticle alignment marks on the reticle R and a corresponding first reference mark for reticle alignment on the reference mark plate FM, which are not shown, are provided. At a position where it can be detected simultaneously by a pair of reticle microscopes,
Wafer stage WST is moved (positioned). Then, the main control system 20 detects the positional relationship between the reticle alignment mark and the corresponding first reference mark using the reticle microscope.

Next, based on an instruction from the main control system 20, the stage control system 19 controls the wafer drive unit 24 so that the alignment microscope AS can detect the second fiducial mark for baseline measurement on the fiducial mark plate FM. Wafer stage WST is moved to the position. Then, the main control system 20 detects the second fiducial mark using the alignment microscope AS.

Then, in the main control system 20, the positional relationship between the reticle alignment mark and the corresponding first reference mark, the center of the index mark of the alignment microscope AS, and the second position.
Based on the positional relationship with the reference mark, the measured values of the reticle interferometer 16 and the wafer laser interferometer system 18 at the time of each measurement, and the designed baseline distance, the baseline amount (the index center of the alignment microscope AS and the reticle The positional relationship with the projected position of the pattern) is calculated.

Thereafter, in the main control system 20, for example, EGA
Perform wafer alignment such as (enhanced global alignment).

Hereinafter, regarding the operation of detecting the position of the alignment mark performed at the time of this wafer alignment, along with the flowchart of FIG. 2 showing the processing algorithm of the CPU in the main control system 20, and referring to other drawings as appropriate. Explain. As a premise, alignment marks, that is, wafer marks (hereinafter referred to as “sample marks” as appropriate) attached to M (at least three, usually 8 to 10) shot areas (sample shots) selected in advance on the wafer W. It is assumed that the counter n indicating the order of calling) is initialized to 1.

First, in step 302, the wafer W (wafer stage WST) is moved to the stage control system 19 so that the n-th (here, first) sample mark is located within the detection field of view of the alignment microscope AS. )
Instruct to move. As a result, the stage control system 19 moves the wafer stage WST via the wafer drive device 24 so that the wafer W is positioned at the above position while monitoring the measurement value of the wafer laser interferometer system 18. After the movement (positioning) of wafer stage WST is completed, the process proceeds to step 304.

At step 304, it is judged whether the counter n is 1 or not. Here, the counter n is 1
Since it has been initialized to, the determination here is affirmative, and the routine proceeds to step 306. In this step 306, the n-th (here, first) sample mark is imaged using the alignment microscope AS.

At the next step 308, the image pickup signal of the sample mark obtained as a result of the image pickup is analyzed to obtain the shape information of the sample mark. Typical examples of the shape information obtained here are two-dimensional information such as the interval (mark pitch) between the lines forming the sample mark and the line width. Further, based on this shape information, the mark is formed as a set of fine patterns that cannot be resolved by the alignment microscope AS (that is, the resolution is not higher than the resolution of the detection optical system of the alignment microscope AS (imaging optical system described above)). It is also possible to judge whether or not it is a mark (segment mark).

Therefore, in the next step 310, it is determined whether or not the sample mark is a segment mark based on the shape information obtained in step 308. If this determination is affirmative, the routine proceeds to step 316 where the target focus position is dynamically determined based on the waveform of the image signal of the sample mark. The processing of this subroutine will be described later.

On the other hand, when the determination in step 310 is negative, the process proceeds to step 312, and the line width of the sample mark is detected based on the shape information acquired in step 308 and the detection optical system of the alignment microscope AS. It is determined whether the resolution is equal to or lower than the resolution of the above-mentioned image forming optical system. When this determination is affirmative, the process proceeds to a subroutine for dynamically determining the above-mentioned target focus position based on the waveform of the imaging signal of the sample mark in step 316, as in the above. On the other hand, if the determination in step 312 is negative, the process moves to step 320 and a predetermined focus position is determined as the target focus position of the alignment microscope AS at the time of detecting the position of the sample mark. A specific example of this step 320 will be described later.

In the present embodiment, the shape information of the detected mark, that is, the sample mark of which the position is to be detected, is obtained based on the analysis result of the image pickup signal that actually picks up the image of the sample mark. However, the operator may previously input the mark shape information via the input device 126 or the like and store it in the memory. When inputting from the outside in this way, the cross-sectional shape of the mark can be given in advance. Further, for example, whether or not it is a segment mark is determined at a stage of forming a layer (layer) for forming an alignment mark, for example, a reticle used for exposure of the first layer, and therefore the shape information about the segment mark can be used without any problem. It is possible to input in advance.

Here, as described above, the method for determining the focus position is selected on the basis of whether it is a segment mark or whether the line width of the mark is less than the resolution of the detection optical system. The reason for this is that, as a result of simulation performed by the inventor, it was found that when such a criterion is adopted, the position detection error becomes extremely small regardless of the type of mark.

The simulation performed by the above inventor will be described below.

An error factor in mark position measurement (detection) is a component (TIS: Tool I) caused by the manufacturing accuracy of the optical system.
nduced Shift) and the manufacturing accuracy of the detected mark itself (WI
S: Wafer Induced Shift). Therefore, the inventor performed a precision comparison simulation considering both TIS and WIS.

As the cause of TIS, a coma aberration and a spherical aberration are given as wavefront aberrations of an optical system for position detection (of the alignment microscope AS) (hereinafter referred to as "detection optical system"). Further, the pupil shift is given as a factor of TIS (error) other than the wavefront aberration.

The cause of WIS is as shown in FIG.
As shown in FIG. 5B, the mark cross section was distorted asymmetrically. In addition, in these FIG. 5 (A) and FIG. 5 (B), the height direction is expanded and represented. The absolute value of the error factor varies depending on the device and the mark, and it is difficult to accurately assume a reasonable amount.

Therefore, the magnitude of the error factor is adjusted so that the position measurement errors due to TIS and WIS are almost the same.

Since the simulation is generally performed on a mark having a low step, which makes it difficult to measure (detect) the position,
Mark of 5 nm step (about 25 times the step of 612 nm of halogen lamp as the illumination wavelength) (Fig. 5 (A))
(See reference).

As the marks, the line and space marks as shown in FIG. 6A, in which the distance between both ends of each line (left and right edge distance) is sufficiently larger than the resolution of the detection optical system, and both ends of each line are used. Assuming a multi-bar mark as shown in FIG. 7A in which the interval is less than or equal to the resolution of the detection optical system, the two were compared. In FIG. 6A, P1 = 9.6 μm and L1 = 4.8 μm.
Further, in FIG. 7A, P2 = 9.6 μm and L2 =
It is 0.96 μm. Note that FIG. 6B corresponds to FIG.
6 shows a cross section of the line and space mark of FIG.
(C) shows an example of an imaging signal obtained by imaging the mark. Similarly, FIG. 7B shows a cross section of the mark in FIG. 7A, and FIG. 7C shows an example of an image pickup signal obtained by picking up an image of the mark.

A mark having a large line width of several μm may not be practical due to the restriction of the surface processing by CMP. Therefore, the inside of the mark is filled with fine marks whose resolution is lower than that of the detection optical system. The mark (segment mark) having a cross-sectional shape as shown in FIG. Note that FIG. 6E illustrates an example of an imaging signal obtained by imaging the segment mark in FIG. 6D.

The focus positions for detecting (measuring) the positions of the marks include the case where the detected mark is on the Gaussian image plane of the detection optical system and the marks at a plurality of focus positions (positions in the optical axis direction of the detection optical system). Is compared with the case where the focus position is dynamically determined by processing the image pickup signal of the mark imaged by locating.

Here, as a method of dynamically determining the focus position, the differential value of the signal waveform of the image pickup signal is calculated in the area where the mark is present, and the absolute value of the focus position (position in the optical axis direction) is maximized. Position of the mark), that is, the focus position at which the steepest signal is obtained (hereinafter referred to as “edge tilt maximum focus position”).

When an average measurement error was determined for the above-mentioned three types of marks when a plurality of error factors existed, the results shown in (Table 1) were obtained.

[0095]

[Table 1]

As described above, the absolute value of the error is not important in this simulation. For each mark, it is important to compare which focus determination method can perform highly accurate position detection.

According to (Table 1), when the line width of the mark is less than the resolution of the detection optical system, and when the mark is formed as a set of minute marks whose resolution is less than the resolution, based on the signal waveform. It can be seen that when the focus is dynamically determined (for example, when the edge tilt maximum focus position is adopted), the position detection can be performed with higher accuracy than when the Gaussian image plane position is adopted.

From the above simulation results, the wavelength of the illumination light source is λ [nm], and the numerical aperture of the detection optical system (the above-mentioned imaging optical system) is N.V. A. As a. ~ C. It can be said that the mark position can be detected with high accuracy by determining the target focus position of the alignment microscope AS when performing position detection based on the reference.

A. When the line width of the detected mark is equal to or smaller than the resolution (λ / NA. / 2) of the detection optical system, the target focus position is dynamically determined from the mark signal waveform. b. When the line width of the detected mark is larger than the resolution of the detection optical system but each line is formed as a set of minute marks whose resolution is equal to or smaller than the resolution, the target focus position is dynamically determined from the mark signal waveform. c. Above a. And b. For other marks, the predetermined best focus position of the detection optical system (for example, the Gaussian image plane position) is set as the target focus position.

For this reason, in the present embodiment,
As described above, the method for determining the focus position for position detection is selected based on the line width of the mark and the presence / absence of segmentation.

Returning to the explanation of the subroutine 316 in FIG.
In this subroutine 316, as shown in FIG.
First, in step 342, the counter i is initialized to 1. In the next step 344, the stage control system 19 is instructed to set the Z-axis direction position (Z position) of the wafer W to Z _i (here, the first point Z ₁ ). As a result, in the stage control system 19, the wafer table 25 is transferred via the wafer drive device 24 based on the wafer position information from the multi-point focus detection system so that the Z position of the wafer W is set to the predetermined first point. Z
Drive in the axial direction.

In this embodiment, the wafer table 2 is used.
The position detection and position control in the Z-axis direction of No. 5 will be described as being performed by the multi-point focus detection system, but the present invention is not limited to this, and the position detection in the Z-axis direction using the alignment focus detection system described above is performed. Alternatively, position control may be performed.

In the next step 346, the light source 103 starts to emit light, and the image of the sample mark is picked up by using the alignment microscope AS as described above, and the picked-up image data (the picked-up signal) of the sample mark (and the index mark) is taken. ) Is received via the signal processing system 118 and stored in the memory.

At the next step 348, it is judged whether or not the counter i is equal to or more than a predetermined total number of steps m, and if this judgment is denied, the counter i is incremented by 1 at step 350 and then step 344. Return to.

In step 344, the Z position of the wafer W is set to Z ₂ (= Z ₁ + ΔZ) in the same manner as described above.
In the next step 346, the sample mark is imaged and the imaged signal is stored in the memory. Here, ΔZ is a predetermined step pitch.

Then, in the next step 348, it is judged whether or not the counter i is greater than or equal to m, and if this judgment is denied, the routine proceeds to step 350, and thereafter, until the judgment in step 348 is affirmed. Steps 344-350
The processing of the loop is repeated. In this way, while changing the Z position of the wafer W at the predetermined step pitch ΔZ,
The imaging signal of the sample mark (and the index mark) for each position is captured.

When the capture of the image pickup signal at the planned Z position and Z _{1 to} Z _m is completed, the determination at step 348 is affirmed and the routine proceeds to step 352. At this point, the image pickup signal (image data) of the sample mark (and the index mark) is stored in the memory in various defocus states.

At step 352, each image pickup signal Sg stored in the memory as shown in FIG.
_i (i = 1 to m) are sequentially taken out, and each is differentiated to obtain a differential signal Sg _i ′ as shown in FIG.
The maximum absolute value (maximum slope of edge) D _i of each differential signal Sg _i 'as shown in FIG. 8C is obtained. Then, of all D _i , the Z position Z _i corresponding to the maximum image pickup signal Sg _i is determined as the target focus position,
After storing in memory, step 322 of the main routine.
Return to.

FIG. 9A shows an example of the relationship between the maximum edge inclination of the image signal of the mark and the focus position. In FIG. 9A, Z = 0 μm represents a Gaussian image plane. In the example of FIG. 9A, from the Gaussian image plane −
The maximum edge tilt of the image pickup signal is obtained at the focus position of 5 μm.

In the above description of step 352, the focus determination method based on the differential value of the signal is adopted as the feature amount obtained from the image pickup signal as in the above-mentioned simulation. This is one method for obtaining the strength, and an index other than the differential value may be used. For example, in step 352, for example, the difference between the maximum value and the minimum value of the image pickup signal Sg _i of the mark or a value obtained by normalizing the difference with the average signal intensity, the contrast is set as an index value, and the contrast is The Z position Z _i corresponding to the maximum image pickup signal Sg _i may be determined as the target focus position. However, since the edge portion of the signal has the largest contribution to position detection, the focus position obtained from the signal edge inclination is more accurate than the focus position obtained from the contrast calculated from the entire signal waveform. Can be expected to improve.

In step 320 of FIG. 2, the predetermined focus position is determined as the target focus position.
Various focus positions may be used as the predetermined focus position. For example, from the result of the above-mentioned simulation, if the Gaussian image plane of the detection optical system (imaging optical system) of the alignment microscope AS is set to a predetermined focus position, accurate mark position detection can be expected. In this case, for example, when manufacturing or adjusting the alignment microscope AS, based on the signal waveform of the imaging signal obtained by imaging the reference mark formed on the wafer stage WST or the measurement wafer such as a super flat wafer. First, the best focus position of the alignment microscope AS is obtained. At this time, it is also possible to match the best focus position with the Gaussian image plane of the detection optical system by measuring an appropriate reference mark by an appropriate method.
The best focus position thus obtained, that is, the position of the Gaussian image plane, is stored in the memory in the main control system 20. In step 320, the position of the Gaussian image plane is read out from the memory and set (determined) as the target focus position of the alignment microscope AS when detecting the position of the sample mark.

In addition to the above, as a result of the above-mentioned simulation,
It was confirmed that the focus position obtained from the characteristics of the signal was constant depending on the mark design and did not change due to the slight deformation of the mark. Therefore, for the mark having the same design as the sample mark, the focus position may be obtained in advance based on the signal characteristics such as the maximum edge inclination and the maximum contrast described above, and the obtained focus position may be stored in the memory. good. in this case,
In step 320, the focus position stored for the mark of the same design is read out from the memory based on the shape information of the sample mark, and is set as the target focus position of the alignment microscope AS when detecting the position of the sample mark. Set (decide).

Alternatively, the focus position, which is expected to have the highest position detection accuracy, may be obtained in advance by simulation and stored in the memory. In this case, the best focus position of the detection optical system is made to coincide with the position of the Gaussian image plane, and the offset amount from the Gaussian image plane of the focus position expected to have the best position detection accuracy obtained by simulation is
It is desirable to obtain the offset amount in advance using the reference mark and store the offset amount in the memory. In this case, in step 320, the offset amount is read from the memory, and the target focus position of the alignment microscope AS at the time of detecting the position of the sample mark is determined (set) based on the offset amount. Accordingly, it is possible to accurately detect the mark position at the target focus position that is expected to have the highest detection accuracy.

When the method of storing a predetermined focus position (including the above offset) in the memory by the various methods described above is adopted, the measurement time for determining the focus position for each mark becomes unnecessary, and the exposure is performed. There is an advantage that the processing time can be shortened.

When the determination of the target focus position in step 320 is completed, the process proceeds to step 322.

In step 322, a command for the target focus position is given to the stage control system 19 in order to control the Z position of the wafer W based on the target focus position determined in step 316 or 320. As a result, the stage control system 19 drives the wafer table 25 in the Z-axis direction based on the wafer position information from the above-mentioned multi-point focus detection system, and the surface of the wafer W exactly matches the target focus position.

In the next step 324, the sample mark is imaged using the alignment microscope AS in the same manner as described above, and the image signals of the sample mark and the index mark are received from the signal processing system 118.

At the next step 326, the position coordinate of the sample mark on the stage coordinate system is calculated based on the above-mentioned image pickup signal and the measurement value of the wafer laser interferometer system 18 at the time of detecting the position and stored in the memory. . That is, the position (x, y) of the sample mark with respect to the center of the index mark is obtained based on the image pickup signal, and the position of the index mark with respect to the center is determined based on the measurement value of the wafer laser interferometer system 18 at the time of detection. It is converted into position coordinates (X, Y) on the system.

In this way, the n-th (here, n =
When the position detection of the sample marks of 1) is completed, the process proceeds to step 328, and the position detection of all the sample marks is performed by determining whether the counter n is equal to or more than the number M of the preselected sample shots. Determine if it is finished. Here, since the position detection of the first sample mark is only completed, this determination is denied,
After incrementing the counter n by 1 in step 330, the process returns to step 302, and stage control is performed in the same manner as described above so that the nth (here, second) sample mark is located within the detection field of view of the alignment microscope AS. After moving the wafer W (wafer stage WST) via the system 19, the process proceeds to step 304.

In this step 304, it is judged whether or not the counter n is 1, but since the counter n is 2, the judgment here is denied, and step 32
Jump to 2. And this step 322-32
In step 6, the position of the n-th (here, second) sample mark is detected by the same procedure as described above.

When the position detection of the second sample mark is completed, the process proceeds to step 328 to check whether or not the position detection of all the sample marks is completed by referring to the counter n as described above. If the determination is negative, the counter n is incremented by 1 in step 330, and then the process returns to step 302. After that, step 3
28 until the determination in 28 is affirmed.
By repeating the loop of 304 → 322 to 326 → 328 → 330, the position detection operation of the third to Mth sample marks is sequentially performed.

When the position detection of the planned number M of sample marks is completed, the determination at step 328 is affirmed,
A series of processing of this routine is finished.

Thereafter, the main control system 20 (the CPU therein) uses the least squares method disclosed in, for example, Japanese Patent Laid-Open No. 61-44429 by using the calculated position coordinates of the sample mark (wafer mark). The statistical calculation is performed, and the array coordinates of all shot areas on the wafer W are calculated by a predetermined calculation based on the calculation result.

As a result, the wafer alignment is completed, and thereafter, the step-and-scan type exposure operation is performed with the main control system 20 as the center as follows.

In this exposure operation, the stage control system 19 monitors the measurement value of the wafer laser interferometer system 18 in accordance with an instruction from the main control system 20 based on the result of the wafer alignment and the measurement result of the baseline, and the wafer W. Wafer stage WST is moved to the scan start position (acceleration start position) for the exposure of the first shot (first shot region) of.

Then, the stage control system 19 starts scanning the reticle stage RST and the wafer stage WST in the Y-axis direction via the reticle stage drive unit 12 and the wafer drive unit 24, and both stages RST and WST respectively. When the target scanning speed is reached, the pattern area of the reticle R starts to be illuminated by the illumination light IL, and scanning exposure is started.

In the stage control system 19, especially during the above scanning exposure, the moving speed Vr of the reticle stage RST in the Y-axis direction and the moving speed Vw of the wafer stage WST in the Y-axis direction.
The reticle stage RST and the wafer stage WST are synchronously controlled so that and are maintained at a speed ratio according to the projection magnification of the projection optical system PL.

Then, different areas of the pattern area of the reticle R are successively illuminated with the illumination light IL, and the illumination of the entire pattern area is completed, whereby the first shot scanning exposure on the wafer W is completed. As a result, the circuit pattern of the reticle R is reduced and transferred to the first shot via the projection optical system PL.

When the first shot scanning exposure is completed in this way, in response to an instruction from the main control system 20,
Wafer stage WST is step-moved in the X-axis and Y-axis directions by stage control system 19, and is moved to a scan start position for exposure of a second shot (second shot area).

Then, under the control of the main control system 20, the scanning exposure similar to the above is performed on the second shot.

In this way, the scanning exposure of the shot area on the wafer W and the stepping operation for the next shot area exposure are repeated, and the circuit pattern of the reticle R is formed on all the shot areas to be exposed on the wafer W. Transferred in sequence.

In the above simulation,
For example, the line width of the detected mark is the resolution (λ /
N. A. In the case of / 2) or less, when the mark is asymmetrically distorted, the relationship as shown in FIG. 9B is obtained as the relationship between the position detection result and the focus. In the case of FIG. 9B, the Gaussian image plane of the detection optical system (Z = 0 μ
A mark position detection error (positional error) at a focus position that is substantially symmetrical with respect to m) occurs symmetrically with respect to the true mark position.

Therefore, when detecting the position of the mark,
If, for example, an average value of the results of detecting the positions of the marks is obtained at a plurality of focus positions that are arranged at predetermined intervals within a predetermined range centered on the best focus of the detection optical system, the position detection accuracy will be improved by the averaging effect. Expected to improve. For example, centering on the Gaussian image plane, +6 μm, −
It is possible to detect the mark position at two focus positions of 6 μm, obtain a simple average value of the detection results, and use the average value as the final mark position detection result. Figure 9
In the example of (B), if this method is adopted, the position detection error can be reduced to 1 nm or less.

Therefore, instead of the steps 322 to 326 surrounded by the chain double-dashed line in FIG. 2 described above, for example, a processing algorithm such as steps 362 to 380 in FIG. 4 may be adopted. Referring to FIG. 4, FIG.
After the processing of step 316 or 320 of
At 2, the counter j is initialized to 1. Next step 36
4, the stage control system 19 is set so that the Z position of the wafer W is set to Z _j (here, the previously determined target focus position is Z and the first point Z ₁ represented by Z−ΔZ ′). Give instructions to. As a result, in the stage control system 19, the wafer table 25 is moved in the Z-axis direction via the wafer drive device 24 based on the wafer position information from the multipoint focus detection system so that the Z position of the wafer W is set to Z _1. To drive. Here, ΔZ ′ is a predetermined value, for example, 6 μm.

In the next step 366, the sample mark is imaged using the alignment microscope AS in the same manner as described above, and the image signals of the sample mark and the index mark are received from the signal processing system 118.

In the next step 368, the position of the sample mark on the stage coordinate system is determined based on the image pickup signal and the measurement value of the wafer laser interferometer system 18 at the time of detecting the position, in the same manner as in step 326 described above. Coordinates (X _j , Y _j ), that is, (X ₁ , Y ₁ ) are calculated and stored in the memory.

At the next step 370, the counter j is set to 2
Whether or not it is above is determined, but since j = 1 here, this determination is negative, the process moves to step 372, the counter j is incremented by 1, and the process returns to step 364.

In this step 364, the Z position of the wafer W is set to Z _j (here, the second point Z ₂ represented by Z + ΔZ ′) via the stage control system 19 as described above.

In the next step 366, the image of the sample mark is picked up using the alignment microscope AS in the same manner as described above, the image signals of the sample mark and the index mark are received from the signal processing system 118, and in the next step 368,
The position coordinates (X _j , Y _j ) of the sample mark on the stage coordinate system, that is, (X ₂ , Y ₂ ) are calculated based on the above-mentioned imaging signal and the measurement value of the wafer laser interferometer system 18 at the time of detecting the position. Calculate and store in memory.

At the next step 370, the counter j is set to 2
Whether or not it is above is determined. However, since j = 2 here, this determination is affirmative, and the processing proceeds to step 380.
A simple average value of position coordinates (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ),
That is, ((X ₁ + X ₂ ) / 2, (Y ₁ + Y ₂ ) / 2)
It is calculated as the XY position (X, Y) of the sample mark and stored in the memory.

Thereafter, the processing shifts to step 328 of FIG.

As a result, as described above, the position detection error of the sample mark is reduced by the averaging effect, and the position coordinate of the sample mark can be detected with high accuracy.

In step 380, the simple average value of the position coordinates of the sample marks detected at the focus positions of two points separated by the same distance in the + direction and the-direction with the predetermined target focus position as the center is finally determined. However, the present invention is not limited to this, and the weighted average value of the above position coordinates (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ) is used as the final sample mark. It may be the detection result of the position. For example, the weight can be determined according to the contrast and the amplitude of the image pickup signal in each of Z ₁ and Z ₂ . Further, the position of the sample mark is detected in the + direction, − with the target focus position determined in advance as the center.
A simple average value or a weighted average value of these calculation results is performed at the focus positions of 2p points (p is a natural number) which are symmetrical positions in the direction, and further at the focus position of (2p + 1) points obtained by adding the target focus position to this. May be used as the final detection result of the sample mark position.

That is, the position of the mark is detected at the plurality of focus positions, and the result calculated based on the expression including the linear combination of the obtained position detection results can be used as the final position detection result.

It is needless to say that the simple average value or the weighted average value may be calculated with respect to the calculation result of the position of the sample mark with the center of the index mark as a reference.

In addition to the above, (2p +) set within a predetermined range centered on a predetermined target focus position.
1) The position of the sample mark is detected at the focus positions of the points, the signal waveforms of the image pickup signals obtained at the respective focus positions are combined, and the sample with the center of the index mark as a reference is based on the obtained signal waveforms. The position of the mark or the position of the sample mark in the stage coordinate system may be calculated. In this case, the signals may be synthesized by softly synthesizing a plurality of signal waveforms in the main control system 20,
It may be performed on the CCD at the time of imaging. When synthesizing on the CCD, the wafer table 25 can be driven along the Z-axis direction within the mark observation time to capture the waveform of the average image pickup signal with continuously changed focus. .

Here, placing importance on the result of FIG. 9B, the line width of the detected mark is determined by the resolution (λ / NA) of the detection optical system.
/ 2) or less, that is, only when the target focus position is determined by the process of step 316, the 2p point or (2
A sequence for detecting the position of the detected mark using the image pickup signal of the detected mark at the focus position of (p + 1) point is adopted, and for other detected marks, that is, the target focus position is determined in step 320. In this case, a sequence may be adopted in which the Z position of the wafer is controlled based on the target focus position and the position of the detected mark is detected based on the image pickup signal of the detected mark at that position. .

As is apparent from the above description, in the present embodiment, the main control system 20, more specifically, the CPU and the software program realize the components of the mark position detecting device except the alignment microscope AS. Has been done. That is, steps 310 and 3 performed by the CPU
The selection device is realized by the process of 12, and step 31
6 (342 to 352) and 320 realize the focus position determination device, and steps 322 to 326.
The detection control device is realized by the processing of. In addition,
Of course, at least a part of the components realized by the above software program may be configured by hardware.

Further, in this embodiment, the main control system 20 constitutes a calculating device, and the calculating device and the mark position detecting device constitute a position detecting device.
Further, by the stage control system 19 and the main control system 20,
A processing device that constitutes an exposure device is configured.

As described in detail above, according to the mark position detecting apparatus (and the mark position detecting method therefor) which constitutes the exposure apparatus 100 according to the present embodiment, the main control system 2
By 0, the method of determining the target focus position is selected according to the shape information about the sample mark as the detected mark (steps 310 and 312), and the position of the sample mark is detected by the alignment microscope AS according to the selected method. The target focus position is determined (steps 316 and 320). Then, the main control system 20 controls the position of the wafer W in the optical axis direction (focus direction) of the detection optical system of the alignment microscope AS based on the determined target focus position, and uses the alignment microscope AS to sample marks. 2 orthogonal to the optical axis of
The position information in the dimension plane (XY plane) is detected.

Therefore, according to the mark position detecting apparatus of the present embodiment, the position information of the sample mark in the two-dimensional plane can be accurately detected by the alignment microscope AS in the optimum focus state according to the mark design. As a result, the position information can be accurately detected regardless of the type of mark.

Further, according to the position detecting device and the position detecting method thereof which constitute the exposure apparatus 100 of the present embodiment,
As described above, the mark position detection device accurately detects the position information of the wafer mark (sample mark) formed on the wafer W in the XY plane (in the two-dimensional plane orthogonal to the optical axis of the detection optical system). Then, based on the position information of the sample mark detected with high accuracy, the main control system 20
Since the position information of the wafer W in the XY plane, more specifically, the XY arrangement coordinates of each shot area on the wafer W are calculated,
The array coordinates of each shot area on the wafer W can be accurately calculated.

Further, according to the exposure apparatus 100 of the present embodiment, the wafer W detected by the main control system 20 and the stage control system 19 with high accuracy as described above at the time of exposure.
The position in the XY plane of the wafer W is controlled on the basis of the position information in the XY plane (moving surface), that is, the array coordinates (and the baseline amount) of each shot area on the wafer W. Therefore, the position of the wafer W at the time of exposure can be controlled with high accuracy, and highly accurate exposure with an extremely small pattern formation position error becomes possible.

That is, the relative positional relationship between the wafer W and the reticle R during scanning exposure can be maintained in a desired state, and the pattern of the reticle R is transferred onto each shot area on the wafer W with high precision. can do.

In the above embodiment, when performing the EGA type wafer alignment, only the first sample mark of the plurality of sample marks to be detected is detected by the alignment microscope AS at the time of position detection based on its shape information. When the focus position is determined and the positions of the remaining sample marks are detected, the determined focus position is directly detected as the target focus position. However, the present invention is not limited to this, and all sample marks or arbitrary sample marks are detected. Of course, the focus position of the alignment microscope AS at the time of position detection may be determined based on the shape information of a plurality of sample marks.

Further, in the above embodiment, in wafer alignment, after the target focus position of the alignment microscope AS at the time of detecting the mark position is determined based on the shape information of the sample mark, the wafer focus direction is determined based on the target focus position. The case where the position of the sample mark is adjusted to detect the position of the sample mark has been described, but the present invention is not limited to this. For example, when the position of the sample mark in the XY plane is detected by the processing algorithm shown in FIG. It is not always necessary to determine the target focus position.

That is, in place of steps 304 to 326 in FIG. 2 described above, step 3 in FIG.
62 to 380 may be adopted. in this case,
Z ₁ is the best focus of the detection optical system Z _best −Δ
It is desirable that Z ′ and Z ₂ be Z _best + ΔZ ′. In this way, in the main control system 20, the wafer W is respectively positioned at Z positions Z ₁ and Z ₂ around the predetermined target focus position, that is, the best focus position, and the detected mark is detected by using the alignment microscope AS. Image is captured, and the position information of the detected mark in the XY plane is calculated using each image pickup signal obtained for each Z position. That is, even if the target focus position (best focus position) is deviated from the optimum focus position for detecting the detected mark, the wafer is placed at a plurality of positions in the focus direction with the target focus position as the center. When the respective target positions are set and the image pickup signals of the detected mark obtained for each focus position are used to perform a predetermined process to calculate the position information of the detected mark in the XY plane, the misaligned target focus is calculated. It is possible to detect the position information of the mark with high accuracy compared to the case where the position information of the mark to be detected in the XY plane is calculated using the image pickup signal of the mark to be detected obtained by positioning the wafer only at the position. Become. As a result, accurate position detection can be performed regardless of the type of mark.

Also in this case, the position of the sample mark is detected at the focus positions of the above (2p + 1) points set within the predetermined range with the target focus position as the center, and the image pickup signals obtained at the respective focus positions are detected. It is also possible to synthesize the signal waveforms and calculate the position of the sample mark based on the center of the index mark or the position of the sample mark in the stage coordinate system based on the obtained signal waveform. In this case, the signals may be combined by software combining a plurality of signal waveforms in the main control system 20, or may be performed on the CCD during image pickup. When synthesizing on the CCD, the wafer table 25 can be driven along the Z-axis direction within the mark observation time to capture the waveform of the average image pickup signal with continuously changed focus. .

In the above embodiment, the case where the present invention is applied to the scanning stepper has been described, but the present invention is not limited to this, and can be applied to a static exposure apparatus such as a step-and-repeat type stepper. . In such a case, the wafer can be accurately positioned at the exposure position (projection position of the reticle pattern) when performing static exposure, and the reticle pattern is accurately superimposed and transferred onto a desired sectioned area on the wafer. can do.

The illumination optical system including a plurality of lenses, the projection optical system, and the alignment microscope AS are incorporated into the exposure apparatus main body for optical adjustment, and the reticle stage and wafer stage consisting of many mechanical parts are exposed. By attaching to the device body, connecting wiring and piping, and further performing comprehensive adjustment (electrical adjustment, operation check, etc.),
The exposure apparatus of the above embodiment can be manufactured. It is desirable that the exposure apparatus be manufactured in a clean room where the temperature and cleanliness are controlled.

The present invention is not limited to the exposure apparatus for manufacturing semiconductors, but may be used for manufacturing an exposure apparatus for transferring a device pattern onto a glass plate and a thin film magnetic head used for manufacturing a display including a liquid crystal display element or the like. An exposure device that transfers the used device pattern onto a ceramic wafer, an imaging device (CCD, etc.), a micromachine, and a D.
It can also be applied to an exposure apparatus used for manufacturing NA chips and the like. Moreover, not only microdevices such as semiconductor elements, but also optical exposure apparatuses, EUV exposure apparatuses, X
The present invention can also be applied to an exposure apparatus that transfers a circuit pattern onto a glass substrate, a silicon wafer, or the like in order to manufacture a reticle or mask used in a line exposure apparatus, an electron beam exposure apparatus, or the like. Here, DUV (far-ultraviolet) light or V
Generally, a transmissive reticle is used in an exposure apparatus that uses UV (vacuum ultraviolet) light, and the reticle substrate is made of quartz glass, fluorine-doped quartz glass, fluorite,
Magnesium fluoride, crystal, or the like is used. Further, a transmission type mask (stencil mask, membrane mask) is used in a proximity type X-ray exposure apparatus, an electron beam exposure apparatus, or the like, and a silicon wafer or the like is used as a mask substrate.

Furthermore, the mark position detecting apparatus and method, and the position detecting method and position detecting apparatus according to the present invention are not limited to the exposure apparatus, but can be applied as long as the apparatus has an image forming type mark detecting system. Is.

<< Device Manufacturing Method >> Next, an embodiment of a device manufacturing method using the above-described exposure apparatus 100 in a lithography process will be described.

FIG. 10 shows devices (semiconductor chips such as IC and LSI, liquid crystal panel, CCD, thin film magnetic head,
A flow chart of a manufacturing example of a micromachine etc. is shown.

As shown in FIG. 10, first, in step 201 (design step), function / performance design of a device (for example, circuit design of a semiconductor device) is performed, and pattern design for realizing the function is performed. To do. Subsequently, in step 202 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 203 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

Next, in step 204 (wafer processing step), the mask and wafer prepared in steps 201 to 203 are used to form an actual circuit or the like on the wafer by a lithography technique or the like, as described later. . Next, in step 205 (device assembly step), device assembly is performed using the wafer processed in step 204. In this step 205,
Steps such as a dicing step, a bonding step, and a packaging step (chip encapsulation) are included as necessary.

Finally, step 206 (inspection step)
In step 1, inspections such as an operation confirmation test and a durability test of the device created in step 205 are performed. After these steps, the device is completed and shipped.

FIG. 11 shows a detailed flow example of the above step 204 in the semiconductor device. In FIG. 11, in step 211 (oxidation step), the surface of the wafer is oxidized. Step 212 (CV
In step D), an insulating film is formed on the wafer surface. In step 213 (electrode forming step), electrodes are formed on the wafer by vapor deposition. Step 214
In the (ion implantation step), ions are implanted in the wafer. Each of the above steps 211 to 214 constitutes a pretreatment process in each stage of wafer processing, and is selected and executed in accordance with a required process in each stage.

At each stage of the wafer process, after the above-mentioned pretreatment process is completed, the posttreatment process is executed as follows. In this post-treatment process, first, step 2
In 15 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step 216 (exposure step), the circuit pattern of the mask is transferred onto the wafer by the exposure apparatus and the exposure method described above. next,
In step 217 (developing step), the exposed wafer is developed, and in step 218 (etching step), the exposed member other than the portion where the resist remains is removed by etching. Then, in step 219 (resist removing step), the unnecessary resist after etching is removed.

By repeating these pre-processing step and post-processing step, multiple circuit patterns are formed on the wafer.

When the device manufacturing method of this embodiment described above is used, the exposure apparatus of the above embodiment is used in the exposure step (step 216), so that the overlay accuracy of the reticle pattern and each shot area on the wafer W is high. Therefore, the reticle pattern can be transferred onto the wafer with high accuracy. Therefore, the yield of the final microdevice can be improved, and the productivity thereof can be improved.

[0172]

As described above, according to the mark position detecting method and the mark position detecting apparatus of the present invention, there is an effect that the position can be detected accurately regardless of the kind of the mark.

Further, according to the position detecting method and the position detecting device of the present invention, there is an effect that the position information of the object on which the mark is formed can be accurately detected.

Further, according to the exposure method and exposure apparatus of the present invention, there is an effect that a pattern can be transferred and formed on an object with high accuracy.

Further, according to the device manufacturing method of the present invention, there is an effect that the productivity of microdevices can be improved.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a CPU in a main control system 20 showing an operation of detecting a position of an alignment mark performed during wafer alignment.
3 is a flowchart showing the processing algorithm of FIG.

FIG. 3 is a flowchart showing the processing contents of a subroutine 316 of FIG.

FIG. 4 is a flowchart for explaining an embodiment in which the position of a sample mark is detected using image pickup signals at a plurality of focus positions.

5A and 5B are views showing an example of an alignment mark having an asymmetric cross-sectional shape.

FIG. 6A is a plan view showing an example of a mark having a line width larger than the resolution of the detection optical system, and FIG.
6A is a cross-sectional view of the mark in FIG. 6A and FIG.
FIG. 6B is a diagram showing an example of a signal waveform obtained from the mark having the sectional shape of FIG. 6B, FIG. 6D is a sectional view of the segment mark, and FIG. 6E is a signal obtained from the mark of FIG. 6D. It is a figure which shows the example of a waveform.

FIG. 7A is a plan view showing an example of a mark having a line width equal to or less than the resolution of the detection optical system, and FIG.
A cross-sectional view of the mark in FIG. 7A and FIG.
It is a figure which shows the example of the signal waveform obtained from the mark which has sectional shape of (B).

8A and 8B are views for explaining a method for obtaining a signal edge inclination from an image pickup signal, FIG. 8A is a diagram showing an example of a waveform of an image pickup signal, and FIG. 8A is a diagram showing a waveform of a differential signal of the image pickup signal of FIG. 8A, and FIG.
It is a figure which shows the waveform of the signal which took the absolute value of the waveform of (B).

9A is a diagram showing an example of the relationship between the signal edge inclination and the focus, and FIG. 9B is a diagram showing an example of the relationship between the mark position measurement error and the focus.

FIG. 10 is a flowchart for explaining an embodiment of a device manufacturing method according to the present invention.

11 is a flowchart showing a process in step 204 of FIG.

[Explanation of symbols]

19 ... Stage control system (part of processing device), 20 ... Main control system (selection device, focus position determination device, detection control device, calculation device, part of processing device), 106 ... Beam splitter (of detection optical system) 107 ... First objective lens (part of detection optical system), 108 ... Reflection prism (part of detection optical system), 111 ... Second objective lens (part of detection optical system), 112 ... Index plate (part of detection optical system), 11
3, 114 ... Relay lens (part of detection optical system), 11
5 ... Beam splitter (a part of detection optical system), 130 ...
Imaging aperture stop (a part of detection optical system), AS ... Alignment microscope (mark detection system), FM ... Reference mark plate (mark forming member), W ... Wafer (object).

Claims (25)

[Claims] 1. A mark position detecting method for detecting position information of a mark formed on an object, comprising: a selecting step of selecting a target focus position determining method according to shape information about a detected mark; A determining step of determining a target focus position at the time of detecting the position of the detected mark by an image-forming mark detection system that captures an image of the detected mark through a detection optical system according to the selected determination method; The position of the object in the optical axis direction of the detection optical system is controlled based on the target focus position, and the mark detection system is used to orthogonally intersect the optical axis.
A step of detecting the position information of the mark to be detected in the three-dimensional plane; 2. In the selecting step, the shape information regarding the detected mark has a line width of the detected mark that is less than or equal to the resolution of the detection optical system, and the detected mark is a minute mark that is less than or equal to the resolution. If it is information indicating that it is formed as a set of
If the shape information about the detected mark is information indicating that the detected mark has a line width exceeding the resolution of the detection optical system,
In the determining step, when the first determining method is selected, the target focus position is dynamically changed based on the waveform of the image pickup signal of the detected mark by the mark detection system. And when the second determination method is selected,
The mark position detecting method according to claim 1, wherein a predetermined focus position is determined as the target focus position. 3. The mark detecting system at the plurality of positions in the optical axis direction of the detection optical system of the object on which the detected mark is formed in dynamically determining the target focus position in the determining step. With respect to the optical axis direction of the object corresponding to the image pickup signal having the maximum absolute value of the differential waveform of the image pickup signals of the detected mark at each position. 3. The target focus position according to claim 2, wherein any one of a position and a position in the optical axis direction of the object corresponding to an image pickup signal having the maximum contrast among the image pickup signals is set. Mark position detection method. 4. In the determining step, a fixed focus position of the detection optical system, which is obtained in advance using a reference mark formed on a mark forming member, and the detection optical system of the detection optical system of the object on which the detected mark is formed. At a plurality of positions in the optical axis direction, a focus position determined in advance based on an image pickup signal of the detected mark obtained at each position by capturing an image of the detected mark using the mark detection system, and The mark position detecting method according to claim 2, wherein any one of the best focus positions of the detection optical system obtained by simulation for the detected mark is set as the predetermined target focus position. 5. In the detection step, the object is respectively positioned at a plurality of positions in the optical axis direction of the detection optical system centered on the determined target focus position, and the mark detection system is used. The positional information of the detected mark in the two-dimensional plane is detected, and the positional information of the detected mark in the two-dimensional plane is calculated based on an equation including a linear combination of detection results obtained for each position in the optical axis direction. The mark position detection method according to claim 1, wherein position information is calculated. 6. In the detection step, the object is respectively positioned at a plurality of positions in the optical axis direction of the detection optical system centered on the determined target focus position, and the mark detection system is used. An image of the detected mark is picked up, and position information of the detected mark in the two-dimensional plane is calculated based on a combined signal obtained by combining the image pickup signals obtained for each position in the optical axis direction. The mark position detecting method according to any one of claims 1 to 4. 7. A position detecting method for detecting the position information of an object, wherein the position information in the two-dimensional plane of the position detection mark formed on the object is given in any one of claims 1 to 6. A position detecting method including: a step of detecting the mark position detecting method described above; and a step of calculating the position information of the object based on the position information of the detected position detecting mark. 8. An exposure method for exposing an object to form a predetermined pattern on the object, wherein position information in a moving plane of the object is detected by using the position detection method according to claim 7. An exposure method including: a step of controlling the position of the object in the moving surface based on the detected position information to perform the exposure. 9. A mark position detection device for detecting position information of a mark formed on an object, comprising: an image-forming mark detection system for picking up an image of a detected mark through a detection optical system; A selection device for selecting a method of determining a target focus position according to shape information about the detected mark; a target focus for detecting the position of the detected mark by the mark detection system according to the determination method selected by the selection device. A focus position determining device for determining a position; controlling the position of the object in the optical axis direction of the detection optical system based on the target focus position determined by the focus position determining device, and using the mark detection system And a detection control device for detecting positional information of the detected mark in a two-dimensional plane orthogonal to the optical axis;
A mark position detecting device comprising: 10. The mark position detecting device according to claim 9, wherein the shape information regarding the detected mark is information provided from the outside. 11. The mark according to claim 9, wherein the shape information regarding the detected mark is information obtained as a result of processing a waveform of an image pickup signal of the detected mark by the mark detection system. Position detection device. 12. The selecting device according to claim 1, wherein the shape information regarding the detected mark has a line width of the detected mark which is equal to or lower than a resolution of the detection optical system, and the detected mark is a minute mark whose resolution is equal to or lower than the resolution. If it is information indicating that it is formed as a set of
If the shape information about the detected mark is information indicating that the detected mark has a line width exceeding the resolution of the detection optical system,
When the first determination method is selected, the focus position determination device determines the target focus position based on the waveform of the imaging signal of the detected mark by the mark detection system. 10. The determination is made dynamically, and when the second determination method is selected, a predetermined focus position is determined as the target focus position.
11. The mark position detection device according to any one of 11. 13. The focus position determining device dynamically determines the target focus position at a plurality of positions in the optical axis direction of the detection optical system of the object on which the detected mark is formed. The image of the detected mark is picked up using a detection system, and the light of the object corresponding to the picked-up signal whose absolute value of the differential waveform of each picked-up signal of the detected mark obtained at each position is maximum. The mark position detection device according to claim 12, wherein a position in the axial direction is set as the target focus position. 14. The focus position determining device dynamically determines the target focus position at a plurality of positions of the object on which the detected mark is formed in the optical axis direction of the detection optical system. An image of the detected mark is picked up using a detection system, and among the image pickup signals of the detected mark obtained at each of the positions, the contrast of the object is associated with the optical axis direction of the object corresponding to the image pickup signal having the maximum contrast. The mark position detecting device according to claim 12, wherein a position is set to the target focus position. 15. The focus position determining device sets a fixed focus position of the detection optical system, which is previously obtained by using a reference mark formed on a mark forming member, as the predetermined target focus position. Claim 1
The mark position detection device according to any one of 2 to 14. 16. The focus position determining device uses the mark detection system to form an image of the detected mark at a plurality of positions in the optical axis direction of the detection optical system of the object on which the detected mark is formed. 15. A focus position determined in advance based on an image pickup signal of the detected mark obtained at each position by image pickup is set as the predetermined target focus position, according to any one of claims 12 to 14. The mark position detection device according to the item. 17. The focus position determining device sets the best focus position of the detection optical system, which has been obtained by simulation for the detected mark, as the predetermined target focus position. 15. The mark position detecting device according to any one of 14. 18. The detection control device positions the object at a plurality of positions in the optical axis direction of the detection optical system centered on the target focus position determined by the focus position determination device, Position information in the two-dimensional plane of the detected mark is detected using a mark detection system, and the detected mark is detected based on an equation including a linear combination of detection results obtained for each position in the optical axis direction. 18. The mark position detection device according to claim 9, wherein position information in the two-dimensional plane is calculated. 19. The detection control device positions the object at a plurality of positions in the optical axis direction of the detection optical system centered on the target focus position determined by the focus position determination device, The image of the detected mark is picked up using a mark detection system, and the position of the detected mark in the two-dimensional plane is based on a combined signal obtained by combining the image pickup signals obtained for each position in the optical axis direction. The mark position detecting device according to claim 9, wherein the mark position detecting device calculates information. 20. A mark position detection device for detecting position information of a mark formed on an object, comprising: an image-forming mark detection system for picking up an image of a mark to be detected via a detection optical system; The object is respectively positioned at a plurality of positions in the optical axis direction of the detection optical system centered on the target focus position of, and an image of the detected mark is captured using the mark detection system, the optical axis direction 2 which is orthogonal to the optical axis by using each image pickup signal obtained at each position
And a detection control device that calculates position information of the detected mark in the dimension plane; 21. The detection control device calculates position information in the two-dimensional surface of the detected mark for each position of the object in the optical axis direction by using each of the image pickup signals, and for each position. 21. The mark position detecting apparatus according to claim 20, wherein the position information of the detected mark in the two-dimensional plane is calculated based on an equation including a linear combination of the calculation results. 22. The detection control device calculates position information of the detected mark in the two-dimensional plane based on a combined signal obtained by combining the image pickup signals. Mark position detection device. 23. A position detecting device for detecting position information of an object, wherein the position detection mark formed on the object is the detected mark. A position detecting device, which includes: a position detecting device; and a calculating device that calculates position information of the object in the two-dimensional plane based on the position information of the position detecting mark detected by the position detecting device. 24. An exposure apparatus for exposing an object to form a predetermined pattern on the object, wherein the position detecting apparatus according to claim 23 detects position information in a moving plane of the object. An exposure apparatus that controls the position of the object in the moving surface based on the detected position information to perform the exposure. 25. A device manufacturing method including a lithography process, wherein in the lithography process, exposure is performed using the exposure apparatus according to claim 24.