JP2002319539A - Specification deciding method and computer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for deciding a specification, together with a system for realizing it, capable of simplifying a manufacturing process of a projection optical system and surely attaining a target which is achieved by the projection optical system with an optical device. SOLUTION: A computer system 10 comprises a first computer 120 into which a target information to be attained by optical devises 1221 -1223 is inputted, and a second computer 130 to decide the specification of the projection optical system, being a wavefront aberration which the projection optical system should meet, based on the target information received from the first computer 120 through a communication path. By adjusting the projection optical system based on a measurement result of wavefront aberration to meet a decided specification when manufacturing the projection optical system, not only a low-order aberration but high-order aberration are simultaneously corrected, for a simplified manufacturing process. By the manufactured projection optical system, the target which an aligner should meet is surely attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a specification determining method and a computer system, and more particularly, to a specification determining method for determining specifications of a projection optical system provided in an optical device, and suitable for implementing the specification determining method. Related to computer systems. INDUSTRIAL APPLICABILITY The present invention can be suitably applied to determination of specifications of a projection optical system of an exposure apparatus used in a lithography step particularly when manufacturing a semiconductor element or a liquid crystal display element.

[0002]

2. Description of the Related Art Conventionally, semiconductor devices (CPU, DRA)
M), an image pickup device (CCD or the like), a liquid crystal display device, a thin film magnetic head, etc., in a lithography process, various exposure apparatuses for forming a device pattern on a substrate are used. In recent years, with the high integration of semiconductor elements and the like, a step-and-repeat type reduction projection exposure apparatus (so-called stepper) capable of forming a fine pattern with high throughput on a substrate such as a wafer or a glass plate with high precision and A projection exposure apparatus such as a step-and-scan type scanning exposure apparatus (a so-called scanning stepper) obtained by improving this stepper is mainly used.

In the case of manufacturing a semiconductor device or the like, it is necessary to form different circuit patterns on the substrate in a number of layers. Therefore, a reticle (or a mask) on which the circuit pattern is drawn and a substrate It is important to accurately overlap the pattern already formed in each shot area. In order to perform such superimposition with high accuracy, the optical characteristics of the projection optical system are accurately measured, and are measured in a desired state (for example, a magnification error of a transfer image of a reticle pattern with respect to a shot area (pattern) on a substrate). Need to be adjusted and managed. When transferring the reticle pattern of the first layer to each shot area on the substrate, the image forming characteristics of the projection optical system are required to transfer the reticle patterns of the second and subsequent layers to each shot area with high accuracy. Is desirably adjusted.

Conventionally, as a method for measuring the optical characteristics (including the imaging characteristics) of a projection optical system, exposure is performed using a measurement reticle on which a predetermined measurement pattern that is remarkably responsive to a specific aberration is formed. A method of calculating optical characteristics based on a measurement result obtained by measuring a resist image obtained by developing a substrate onto which a projection image of a measurement pattern is transferred (hereinafter, referred to as a “printing method”) is mainly used. .

In a conventional exposure apparatus, low-order aberrations such as spherical aberration, coma, astigmatism, field curvature, and distortion (distortion), which are so-called Seidel's five aberrations, are measured by the printing method described above. Adjustment and management of the various aberrations of the projection optical system based on the measurement results have been mainly performed.

For example, when measuring the distortion of a projection optical system, for example, 100
Using a measurement reticle on which a μm square inner box mark and a 200 μm square outer box mark are formed, one mark is transferred via a projection optical system onto a wafer having a surface coated with a resist, and then the wafer stage To transfer the other mark over the wafer via the projection optical system. Assuming that the projection magnification is, for example, 1/5, after developing the wafer, a resist image of a box-in-box mark in which a 20 μm square box mark is arranged inside a 40 μm square box mark is formed. Become. Then, the distortion of the projection optical system is measured based on the positional relationship between the two marks and the shift amount from the reference point of the stage coordinate system.

For example, when measuring the coma aberration of the projection optical system, a mark for measurement having a line width of 0.9, for example, is used.
Using a measurement reticle on which a line and space (hereinafter referred to as “L / S”) pattern having five μm line patterns is formed, a resist is applied to the surface of the mark through a projection optical system. Transferred onto the wafer. Assuming that the projection magnification is, for example, 1/5, a resist image of an L / S pattern having a line width of 0.18 μm is formed after developing the wafer. For example, assuming that the line widths of the line patterns at both ends are L1 and L5,
A coma aberration is measured by obtaining an abnormal line width value represented by the following equation (1). Line width abnormal value = (L1−L5) / (L1 + L5) (1)

For example, to measure the best focus position of the projection optical system, the wafer is moved to a plurality of positions in the optical axis direction of the projection optical system at a predetermined step pitch, and the L / S pattern is projected at each position. Are sequentially transferred to different areas on the wafer through the, and the position of the wafer where the line width of the resist image formed after developing the wafer is maximized is measured as the best focus position.

When measuring spherical aberration, the above-described best focus position is measured using a plurality of types of L / S patterns having different duty ratios, and the spherical aberration is determined based on the difference between the best focus positions. Is measured.

In the measurement of the field curvature, the above-described best focus position is measured for each of a plurality of measurement points in the field of view of the projection optical system, and the field curvature is calculated by the least square method based on the measurement results. .

For example, the astigmatism of the projection optical system is determined for each of the two types of periodic patterns whose periodic directions are orthogonal to each other, and the astigmatism is calculated based on the difference between the two.

Heretofore, the specifications (specifications) of the projection optical system at the time of manufacturing an exposure apparatus have also been determined based on the same standards as in the management of the optical characteristics of the projection optical system. That is, the specification is determined so that the above-mentioned five aberrations obtained by the printing method or a simulation substantially equivalent thereto are equal to or less than a predetermined value.

[0013]

However, semiconductor elements are becoming highly integrated year by year, and as a result, the exposure apparatus is required to have even higher precision exposure performance. It is not sufficient to measure only low-order aberrations and adjust the optical characteristics of the projection optical system based on the measurement results. The reason is as follows.

That is, a measurement pattern, for example, L / S
In the case of a pattern, the aerial image has a spatial frequency component (a natural frequency component) of a fundamental wave corresponding to the period of L / S and a harmonic thereof, and these spatial frequency components pass through a pupil plane of the projection optical system. Information is determined by the pattern. on the other hand,
Various patterns exist on a reticle used in actual device manufacturing, and the aerial image includes countless spatial frequency components. Therefore, in the above-mentioned conventional aberration measurement method, aberrations are specified and adjusted based on limited information passing through the pupil plane, but this requires achieving the exposure accuracy required now or in the future. Is difficult.

In this case, in order to detect the missing information, it is necessary to measure a reticle pattern having a natural frequency that compensates for the missing information. However, the measurement requires a very large amount of measurement. Are also huge and are almost unrealistic.

Further, since the object to be measured is a resist image, measurement accuracy, inherent characteristics of the resist, etc. are interposed, and it is necessary to establish measurement data after establishing a correlation between the resist image and an optical image (aberration) in advance. was there.

If the aberration is large, the resist image loses linearity with respect to the spatial image of the pattern, and it becomes difficult to accurately measure the aberration. In such a case, accurate aberration measurement is performed by changing the pitch, line width, etc. (spatial frequency) of the measurement pattern on the reticle to a level at which the above-described intrinsic characteristics of the resist can be measured (the linearity is maintained). We needed to be able to do it.

For the same reason, the method of determining the specifications of the projection optical system based on the above-mentioned standard has reached its limit. This is because, even if a projection optical system that satisfies the determined specifications is manufactured, it is clear that the required exposure accuracy at present or in the future cannot be achieved.

In consideration of such circumstances, when manufacturing a projection optical system in accordance with the above determined specifications, in the manufacturing stage, after assembling the projection optical system, the aberration of the projection optical system is measured by the printing method described above. Based on the measurement result, the assembling of the lens elements and the like are adjusted so that Seidel's five aberrations (low-order aberrations) satisfy the determined specification. After that, the remaining higher-order aberrations are detected by a method such as ray tracing, and the lens elements are further assembled (if necessary, such as aspherical surface processing, etc.) so that the higher-order aberrations become as small as possible. A method of adjusting the projection optical system at the manufacturing stage by a procedure of performing reworking (including reworking) has recently been adopted (Japanese Patent Laid-Open No. 10-15465).
No. 7).

However, the above-described method of manufacturing a projection optical system requires at least two-stage aberration adjustment of correction of low-order aberration and subsequent adjustment of high-order aberration, and uses a high-speed computer called ray tracing. However, it took several days to perform the operation.

Conventionally, a measurement pattern (a pattern that remarkably reacts to each aberration), which is considered to be optimal for the measurement of each aberration, regardless of the user of the exposure apparatus to which the apparatus is delivered. As a target pattern, specification of a projection optical system, management of optical characteristics, and the like have been performed.

However, the influence of each aberration of the projection optical system on the imaging characteristics of various patterns is not uniform. For example, the contact hole pattern is particularly affected by the effect of astigmatism. Further, a line and space pattern having a small line width is greatly affected by coma aberration. Also, for example, the best focus position differs between the isolated line pattern and the line and space pattern.

Accordingly, it is a reality that required optical characteristics (such as aberration) of the projection optical system and other performances of the exposure apparatus are different for each user.

The present invention has been made under such circumstances, and a first object of the present invention is to simplify a manufacturing process for manufacturing a projection optical system according to determined specifications and to manufacture the projection optical system. It is an object of the present invention to provide a method for determining the specifications of a projection optical system that enables an optical device to reliably achieve a target to be achieved by the projection optical system.

A second object of the present invention is to simplify a manufacturing process for manufacturing a projection optical system according to determined specifications, and to achieve an optical device by the manufactured projection optical system. An object of the present invention is to provide a computer system capable of reliably achieving a goal.

It is a third object of the present invention to provide a computer system capable of setting an optimum exposure condition almost automatically.

[0027]

According to a _first aspect of the present invention, there is provided a specification determining method for determining a specification of a projection optical system (PL) used in an optical device (122 _{1 to} 122 ₃ ). A first step of obtaining target information to be achieved by the optical device; and a second step of determining a specification of the projection optical system based on the target information with a wavefront aberration to be satisfied by the projection optical system as a standard value. ;including.

In this specification, the target information includes resolution (resolution), minimum line width, wavelength (center wavelength and wavelength width, etc.) of illumination light incident on the projection optical system, information on a pattern to be projected, and other information. Means some information about the projection optical system that determines the performance of the optical device and can be a target value.

According to this, the specification of the projection optical system is determined based on the target information to be achieved by the optical device, with the wavefront aberration to be satisfied by the projection optical system as a standard value. That is,
The specification of the projection optical system is determined using the information of the wavefront on the pupil plane of the projection optical system, that is, the comprehensive information that passes through the pupil plane and is different from the limited information as the standard value. Therefore, when manufacturing the projection optical system according to the determined specification, by adjusting the projection optical system based on the measurement result of the wavefront aberration, it is possible to simultaneously correct not only the low-order aberration but also the high-order aberration. The manufacturing process is obviously simplified. Moreover, the target to be achieved by the optical device is reliably achieved by the manufactured projection optical system.

In this case, various methods are conceivable for determining the specifications of the projection optical system using the wavefront aberration as a standard value. For example, as in the specification determining method according to claim 2, in the second step, a specific term selected based on the target information among coefficients of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system. The specification of the projection optical system can be determined by using the coefficient as a standard value. Alternatively, as in the specification determining method according to claim 3, in the second step, an RMS value (Root-means-square valuation) of a coefficient of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system.
e: square root of the root mean square) as a standard value, and the specifications of the projection optical system can be determined so that the RMS value in the entire field of view of the projection optical system does not exceed a predetermined allowable value. . Alternatively, as in the specification determining method according to claim 4, in the second step, the values of the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system are set as standard values, and the coefficients are individually determined. The specifications of the projection optical system can be determined so as not to exceed the respective allowable values. Alternatively, as in the specification determining method according to claim 5, in the second step, among coefficients of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system,
The RMS value of the coefficient of the n-order mθ term corresponding to the particular aberration of interest in the field of view of the projection optical system is defined as a standard value, and the specification of the projection optical system is set so that the RMS value does not exceed a predetermined allowable value. Can be determined. In addition, as in the specification determining method according to claim 6, in the second step, among the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system, each term corresponding to a particular aberration of interest. Is divided into a plurality of groups for each mθ term, and the RMS value of the coefficient of each term included in each group in the field of view of the projection optical system is defined as a standard value, and the RM of each group is
The specifications of the projection optical system may be determined so that the S value does not exceed each individually determined allowable value.

In addition, as in the specification determining method according to claim 7, in the second step, weighting is performed according to the target information by weighting a coefficient of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system. RMS of the coefficient of each of the following terms
Value as a standard value, and the R
The specifications of the projection optical system may be determined so that the MS value does not exceed a predetermined allowable value.

In each of the specification determining methods according to the first to seventh aspects, the target information includes information on a pattern to be projected by the projection optical system as in the specification determining method according to the eighth aspect. It can be.

In this case, as in the specification determining method according to the ninth aspect, the second step is formed on an image plane when the pattern is projected by the projection optical system based on the information on the pattern. Performing a simulation for obtaining an aerial image; and analyzing the simulation result to determine a wavefront aberration allowed for the projection optical system as a standard value so that the pattern can be transferred well. Can be included.

In this case, as in the specification determining method according to the tenth aspect, in the simulation, when the pattern is set as a target pattern, a specific aberration is determined according to the pattern for a specific aberration. Sensitivity of the coefficients of each term of the Zernike polynomial with expanded wavefront (Zernik
e Sensitivity) and the aerial image can be determined based on a linear combination of coefficients of each term of a Zernike polynomial obtained by expanding the wavefront of the projection optical system.

Here, the "Zernike Sensitivity" of the coefficient of each term of the Zernike polynomial refers to the imaging performance of the projection optical system, such as various aberrations (or their index values), under predetermined exposure conditions. 1 of each term of Zernike polynomial
It means the amount of change per λ. In this specification, in this sense, the sensitivity of the coefficient of each term of the Zernike polynomial (Zernike
ike Sensitivity).

In each of the specification determining methods according to the first to tenth aspects, various optical devices can be considered as the optical device.
For example, the optical device may be an exposure device that transfers a predetermined pattern onto a substrate via the projection optical system.

According to a twelfth aspect of the present invention, there is provided a computer system for determining specifications of a projection optical system used in an optical device (122 _{1 to} 122 ₃ ), wherein target information to be achieved by the optical device is provided. A first computer (120) to which is input; a first computer connected to the first computer via a communication path, based on the target information received from the first computer via the communication path,
A second computer (13) for determining the specifications of the projection optical system with the wavefront aberration to be satisfied by the projection optical system as a standard value;
0) and;

According to this, the target information to be achieved by the optical device is input to the first computer, and the projection optical system is formed by the second computer based on the target information received from the first computer via the communication path. The specifications of the projection optical system are determined using the satisfactory wavefront aberration as a standard value. That is, the specification of the projection optical system is determined using the information of the wavefront on the pupil plane of the projection optical system, that is, the comprehensive information that passes through the pupil plane and is different from the limited information as the standard value.
Therefore, when manufacturing the projection optical system according to the determined specification, by adjusting the projection optical system based on the measurement result of the wavefront aberration, it is possible to simultaneously correct not only the low-order aberration but also the high-order aberration. The manufacturing process is obviously simplified. Moreover, the target to be achieved by the optical device is reliably achieved by the manufactured projection optical system.

In this case, as in the computer system according to the thirteenth aspect, the target information includes information on a pattern to be projected by the projection optical system, and the second computer performs processing based on the information on the pattern. Performing a simulation for obtaining an aerial image formed on an image plane when the pattern is projected by the projection optical system, and analyzing the simulation result to obtain a good transfer of the pattern. The wavefront aberration allowed for the optical system can be determined as a standard value.

[0040] In this case, as in the computer system according to claim 14, the second computer includes:
The sensitivity (Zernike Sensitivity) of the coefficient of each term of the Zernike polynomial which is obtained by expanding the wavefront of the projection optical system, which is determined according to the pattern with respect to a specific aberration when the pattern is a target pattern, and the projection optical system The aerial image can be obtained based on a linear combination of the Zernike polynomial with the coefficient of each term obtained by expanding the wavefront.

In each of the computer systems according to the twelfth to fourteenth aspects, various types of optical devices can be used. For example, as in the computer system according to the fifteenth aspect, the optical device is capable of forming a predetermined pattern. The exposure device may be an exposure device that transfers the image onto a substrate via the projection optical system.

A computer system according to a sixteenth aspect of the present invention includes a first computer connected to an exposure apparatus main body that transfers a predetermined pattern onto a substrate via a projection optical system; and a communication path to the first computer via a communication path. Connected, based on the information of the pattern received from the first computer via the communication path and the known aberration information of the projection optical system, when the pattern is projected by the projection optical system on an image plane A second computer that performs a simulation for obtaining an aerial image to be formed, analyzes the simulation result, and determines the best exposure condition.

According to this, in the second computer, based on the information of the pattern received from the first computer via the communication path and the known aberration information of the projection optical system,
A simulation for obtaining an aerial image formed on an image plane when the pattern is projected by a projection optical system is performed, and the simulation result is analyzed to determine the best exposure condition. Therefore, the setting of the optimum exposure condition can be performed almost fully automatically.

In this case, as in the computer system according to the seventeenth aspect, the information on the pattern may be input to the first computer as a part of the exposure condition. In a case where the information processing apparatus further includes an information reading device that reads information on the pattern recorded on the mask on a transport path of the mask to the exposure apparatus main body, such as the computer system according to 18, the information on the pattern is The data may be input to the first computer via a reading device.

In each of the computer systems according to claims 16 to 18, as in the computer system according to claim 19, the second computer transmits the determined best exposure condition to the first computer via the communication path. It can be sent to a computer.

In this case, as in the computer system according to the twentieth aspect, the first computer includes:
The best exposure condition may be set as the exposure condition of the exposure apparatus body.

In each of the computer systems according to claims 16 to 20, as in the computer system according to claim 21, when the pattern is a target pattern, the second computer performs the above-described processing for a specific aberration. The sensitivity (Zernike) of the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system, which is determined according to the pattern
Sensitivity) and the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system obtained based on the measurement result of the wavefront of the projection optical system transmitted from the first computer via the communication path. The aerial image may be determined based on a linear combination.

In this case, as in the computer system according to claim 22, the measurement result of the wavefront may be input to the first computer, or the computer according to claim 23. When the system further includes a wavefront measuring device that measures the wavefront of the projection optical system, such as a system, the measurement result of the wavefront is obtained by the first computer as the measurement result of the wavefront by the wavefront measuring device. There may be.

In each of the computer systems according to the sixteenth to twenty-third aspects, various conditions can be considered as the best exposure conditions. For example, as in the computer system according to claim 24, the best exposure condition can include information on a pattern suitable for exposure by the exposure apparatus body. Alternatively, as in the computer system according to claim 25, the best exposure condition can include at least one of an illumination condition for transferring the predetermined pattern and a numerical aperture of the projection optical system.

Alternatively, as in the computer system according to the twenty-sixth aspect, the best exposure condition can include an aberration of the projection optical system when transferring the predetermined pattern.

In each of the computer systems according to claims 16 to 26, as in the computer system according to claim 27, the projection system provided in the exposure apparatus main body connected to the second computer via the communication path. The image processing apparatus may further include an adjusting device that adjusts a state of formation of the projection image of the pattern by an optical system, and the second computer may control the adjusting device based on the determined best exposure condition.

In each of the computer systems according to claims 12 to 27, the communication path may be a local area network as in the computer system according to claim 28, or the computer system according to claim 29 As in the system, the communication path may include a public line. Alternatively, as in the computer system according to claim 30, the communication path may include a wireless line.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG.

FIG. 1 shows the overall configuration of a computer system according to an embodiment of the present invention.

A computer system 10 shown in FIG. 1 includes a lithography system 112 in a semiconductor factory of a device maker (hereinafter, appropriately referred to as “manufacturer A”) which is a user of a device manufacturing apparatus such as an exposure apparatus, and a lithography system. An exposure apparatus manufacturer (hereinafter, referred to as an exposure apparatus manufacturer) connected to a part of the system 112 through a communication path including a public line 116.
Computer system 11 (referred to as “maker B” as appropriate)
4 is provided.

The lithography system 112 includes a first communication server 120 as a first computer, a first exposure apparatus 122 ₁ as an optical apparatus, and a second exposure apparatus interconnected via a local area network (LAN) 118.
It is configured to include an exposure device 122 ₂ , a third exposure device 122 ₃ , a first authentication proxy server 124, and the like.

It is assumed that addresses AD1 to AD4 for identification are assigned to the first communication server 120 and the first to third exposure devices 122 _{1 to} 122 ₃ , respectively.

The first authentication proxy server 124 includes:
It is provided between the LAN 118 and the public line 116, and here functions as a kind of firewall. That is, the first authentication proxy server 124
8 to prevent leakage of communication data to the outside, pass only information from the outside with addresses AD1 to AD4, and prevent other information from passing, thereby preventing the LAN 118 from unauthorized access from outside. Protected from ingress.

The computer system 114 has a LA
A second authentication proxy server 128 and a second communication server 130 as a second computer are connected to each other via N126. Here, the second
It is assumed that an address AD5 for identification is assigned to the communication server 130.

The second authentication proxy server 128
Like the first authentication proxy server 124 described above, L
It has a role of a kind of firewall that prevents communication data flowing on the AN 126 from leaking to the outside and protects the LAN 126 from unauthorized entry from outside.

In this embodiment, the first to third exposure devices 12
2 _{1-122 3} transmission of data to the outside from is performed via the first communication server 120 and the first authentication proxy server 124, the first to third exposure apparatus 122 ₁ from the outside
The transmission of data to 122 ₃ is performed directly via the first authentication proxy server 124 or via the first authentication proxy server 124 and the first communication server 120.

FIG. 2 shows a schematic configuration of the first exposure apparatus 122 ₁ . The exposure apparatus 122 ₁ is a step-and-repeat reduction projection exposure apparatus using a pulse laser light source as an exposure light source (hereinafter, “light source”), that is, a so-called stepper.

The exposure device 122 ₁ is an illumination system including a light source 16 and an illumination optical system 12 and a mask stage for holding a reticle R as a mask illuminated by exposure illumination light EL as an energy beam from the illumination system. A reticle stage RST, a projection optical system PL for projecting the exposure illumination light EL emitted from the reticle R onto a wafer W (on an image plane) as a substrate, and a wafer on which a Z tilt stage 58 for holding the wafer W is mounted. A stage WST and a control system for these are provided.

Here, as the light source 16, a pulsed ultraviolet light source for outputting pulsed light in a vacuum ultraviolet region such as an F ₂ laser light source (output wavelength 157 nm) or an ArF excimer laser light source (output wavelength 193 nm) is used. .
Note that, as the light source 16, a light source that outputs pulsed light in the ultraviolet region, such as a KrF excimer laser light source (output wavelength 248 nm), may be used.

The light source 16 is actually used for the illumination optical system 1.
2 is installed in a low-clean service room separate from the clean room in which the chamber 11 in which the exposure apparatus main body including the reticle stage RST, the projection optical system PL, and the wafer stage WST is housed. Further, it is connected to the chamber 11 via a light transmitting optical system (not shown) including at least a part of an optical axis adjusting optical system called a beam matching unit. This light source 16
Then, based on the control information TS from the main controller 50,
The on / off of the output of the laser beam LB, the energy per pulse of the laser beam LB, the oscillation frequency (repetition frequency), the center wavelength, the spectrum half width (wavelength width), and the like are controlled by an internal controller. ing.

The illumination optical system 12 includes a cylinder lens,
A beam shaping / illuminance uniforming optical system 20 including a beam expander (both not shown) and an optical integrator (homogenizer) 22; an illumination system aperture stop plate 24;
A first relay lens 28A, a second relay lens 28B, a reticle blind 30, a mirror M for bending an optical path, a condenser lens 32, and the like are provided. Note that a fly-eye lens, a rod integrator (internal reflection type integrator), a diffractive optical element, or the like can be used as the optical integrator. In the present embodiment, since a fly-eye lens is used as the optical integrator 22, it is also referred to as a fly-eye lens 22 below.

The beam shaping / illuminance uniforming optical system 20
Is connected to a light transmission optical system (not shown) via a light transmission window 17 provided in the chamber 11. This beam shaping
The illuminance equalizing optical system 20 shapes the cross-sectional shape of the laser beam LB that is pulsed by the light source 16 and enters through the light transmission window 17 using, for example, a cylinder lens or a beam expander. Then, the fly-eye lens 22 located on the exit end side inside the beam shaping / illuminance uniforming optical system 20
In order to illuminate the reticle R with a uniform illuminance distribution, a laser beam whose cross-sectional shape is shaped is incident on its exit-side focal plane, which is arranged to substantially coincide with the pupil plane of the illumination optical system 12. A surface light source (secondary light source) composed of a number of point light sources (light source images) is formed. Hereinafter, the laser beam emitted from the secondary light source is referred to as “illumination light EL”.

An illumination system aperture stop plate 24 made of a disc-shaped member is arranged near the exit-side focal plane of the fly-eye lens 22. The illumination system aperture stop plate 24 is provided at substantially equal angular intervals, for example, an aperture stop (normal stop) formed of a normal circular aperture, and an aperture stop (small size) formed of a small circular aperture for reducing the σ value which is a coherence factor. σ stop), a ring-shaped aperture stop for annular illumination (ring stop), and a modified aperture stop (two types in FIG. 1) in which a plurality of apertures are eccentrically arranged for the modified light source method. (Only the aperture stop is shown). The illumination system aperture stop plate 24 is configured to be rotated by a driving device 40 such as a motor controlled by a main controller 50, so that one of the aperture stops is selectively placed on the optical path of the illumination light EL. And the shape of the light source surface in Koehler illumination, which will be described later, is limited to an annular zone, a small circle, a large circle, a fourth circle, or the like.

In place of the aperture stop plate 24 or in combination therewith, for example, a plurality of diffractive optical elements which are exchangeably arranged in the illumination optical system, a prism (cone which is movable along the optical axis of the illumination optical system) A light source 16 and an optical integrator 22 including at least one of a prism, a polyhedral prism, and the like, and a zoom optical system.
When the optical integrator 22 is a fly-eye lens, the intensity distribution of illumination light on the incident surface thereof, and when the optical integrator 22 is an internal reflection type integrator, the illumination light is incident on the incident surface. By making the angle range and the like variable, it is possible to suppress the light amount distribution of the illumination light on the pupil plane of the illumination optical system (the size and shape of the secondary light source), that is, the light amount loss accompanying the change in the illumination condition of the reticle R. desirable. In the present embodiment, a plurality of light source images (virtual images) formed by the internal reflection type integrator are also referred to as secondary light sources.

Illumination light EL emitted from illumination system aperture stop plate 24
Reticle blind 30 on the optical path of
A relay optical system including a relay lens 28A and a second relay lens 28B is provided. The reticle blind 30 is arranged on a conjugate plane with respect to the pattern surface of the reticle R, and has a rectangular opening defining a rectangular illumination area IAR on the reticle R. Here, as the reticle blind 30, a movable blind having a variable opening shape is used, and the main controller 50 sets the opening based on blind setting information also called masking information.

On the optical path of the illumination light EL behind the second relay lens 28B constituting the relay optical system, a bending mirror M for reflecting the illumination light EL passing through the second relay lens 28B toward the reticle R is arranged. And this mirror M
The condenser lens 32 is arranged on the optical path of the rear illumination light EL.

In the above configuration, the fly-eye lens 2
2 is optically set to be conjugate to each other, and the light source surface (pupil of the illumination optical system) is formed on the exit-side focal plane of the fly-eye lens 22. Plane), and the Fourier transform plane (exit pupil plane) of the projection optical system PL are optically set to be conjugate to each other, forming a Koehler illumination system.

The operation of the illumination system configured as described above will be briefly described. The laser beam LB pulse-emitted from the light source 16 is incident on the beam shaping / illuminance uniforming optical system 20 and its cross-sectional shape is shaped. After, fly eye lens 2
2 is incident. As a result, the above-described secondary light source is formed on the emission-side focal plane of the fly-eye lens 22.

The illumination light EL emitted from the secondary light source
After passing through one of the aperture stops on the illumination system aperture stop plate 24, passing through the first relay lens 28A, passing through the rectangular opening of the reticle blind 30, passing through the second relay lens 28B, and turning on the mirror M After the optical path is bent vertically downward, the rectangular illumination area IAR on the reticle R held on the reticle stage RST is illuminated with a uniform illuminance distribution via the condenser lens 32.

A reticle R is mounted on the reticle stage RST, and is held by suction via an electrostatic chuck (or vacuum chuck) not shown. The reticle stage RST is driven in a horizontal plane (XY
It is configured to be capable of minute driving (including rotation) within a plane. Note that the position of reticle stage RST is measured at a predetermined resolution (for example, a resolution of about 0.5 to 1 nm) by a position detector (not shown), for example, a reticle laser interferometer. It is being supplied.

The material used for the reticle R needs to be properly used depending on the light source used. That is, Ar
F excimer laser, when the KrF excimer laser light source, synthetic quartz, fluoride crystal such as fluorite or a fluorine-doped quartz or the like can be used, in the case of using the F ₂ laser, fluorite, etc. Fluoride crystals,
It must be formed of fluorine-doped quartz or the like.

As the projection optical system PL, for example, a both-side telecentric reduction system is used. The projection magnification of the projection optical system PL is, for example, 1/4, 1/5 or 1/6.
And so on. Therefore, as described above, when the illumination area IAR on the reticle R is illuminated by the illumination light EL, the pattern formed on the reticle R is reduced by the projection optical system PL at the projection magnification to the surface. Exposure area IA on wafer W coated with resist (photosensitive agent)
(Usually coincident with the shot area) and transferred.

As shown in FIG. 2, as the projection optical system PL, a refraction system including only a plurality of, for example, about 10 to 20 refraction optical elements (lens elements) 13 is used. Of a plurality of lens elements 13 that constitute the projection optical system PL, a plurality of the object plane side (reticle R side) (here, four in order to simplify the description) lens elements 13 _1, 13 ₂ , 13 ₃ , and 13 ₄ are movable lenses that can be driven externally by the imaging characteristic correction controller 48. Lens elements _131-134 is held lens holder having a double structure (not shown) to the barrel through, respectively. Of these, the lens elements 13 ₁ , 13 ₂ , 13 ₄
These are held by an inner lens holder that holds them, and the inner lens holder is supported by the drive lens (not shown), for example, a piezo element, at three points in the direction of gravity with respect to the outer lens holder. Then, by independently adjusting the applied voltages to these drive elements, the lens element 13 is adjusted.
₁ , 13 ₂ , and 13 ₄ are represented by Z, which is the optical axis direction of the projection optical system PL.
The shift driving in the axial direction and the driving in the tilt direction with respect to the XY plane (that is, the rotating direction around the X axis and the rotating direction around the Y axis) are possible (tilt possible). Further, the lens element 13 ₃ is held inside the lens holder (not shown), a driving element such as a piezoelectric element at approximately 90 ° intervals for example between the outer surface and the inner circumferential surface of the outer lens holder of the inner lens holder are arranged, the two drive elements facing each other as a set, respectively, by adjusting the voltage applied to the actuating element, the lens element 13 ₃ XY
The configuration is such that shift driving can be performed two-dimensionally in a plane.

The other lens elements 13 are held in a lens barrel via a normal lens holder. The present invention is not limited to the lens element _131-134, the pupil plane vicinity of the projection optical system PL, and
Or a lens arranged on the image plane side, or the projection optical system P
An aberration correction plate (optical plate) for correcting the aberration of L, particularly its non-rotationally symmetric component, may be configured to be drivable.
Further, the degrees of freedom (movable directions) of these drivable optical elements are not limited to two or three, but may be one or four or more.

In the vicinity of the pupil plane of the projection optical system PL,
A pupil aperture stop 15 capable of continuously changing the numerical aperture (NA) within a predetermined range is provided. This pupil aperture stop 15
For example, a so-called iris diaphragm is used.
The pupil aperture stop 15 is controlled by the main controller 50.

When ArF excimer laser light or KrF excimer laser light is used as the illumination light EL, each lens element constituting the projection optical system PL may be made of a fluoride crystal such as fluorite or the above-mentioned fluorine-doped quartz. In addition, synthetic quartz can also be used, but when F ₂ laser light is used, the material of the lens used for the projection optical system PL is all fluoride crystals such as fluorite or fluorine-doped quartz. Can be

The wafer stage WST is freely driven in an XY two-dimensional plane by a wafer stage driving section 56 including a linear motor and the like. A wafer W is held on a Z tilt stage 58 mounted on the wafer stage WST by electrostatic suction (or vacuum suction) via a wafer holder (not shown).

The Z tilt stage 58 is positioned on the wafer stage WST in the XY directions, and is configured to be movable in the Z-axis direction and tilted with respect to the XY plane by a drive system (not shown). Thus, the surface position (the position in the Z-axis direction and the inclination with respect to the XY plane) of the wafer W held on the Z tilt stage 58 is set to a desired state.

Further, a movable mirror 52W is fixed on the Z tilt stage 58, and the wafer mirror interferometer 54W disposed outside is used to move the Z mirror in the X-axis direction.
The positions in the Y-axis direction and the θz direction (the rotation direction around the Z-axis) are measured, and the position information measured by the interferometer 54W is supplied to the main control device 50. The main control device 50
Based on the measurement value of interferometer 54W, wafer stage WST (and Z tilt stage 58) includes wafer stage drive unit 56 (which includes all of the drive system of wafer stage WST and the drive system of Z tilt stage 58). ) Control.

On the Z-tilt stage 58, a reference mark plate FM on which reference marks such as a so-called baseline measurement reference mark have been measured is arranged so that its surface is substantially at the same height as the surface of the wafer W. Fixed.

A detachable portable wavefront aberration measuring device 80 is attached to the side surface of the Z tilt stage 58 on the + X side (the right side in FIG. 2).

As shown in FIG. 3, the wavefront aberration measuring device 80 is a light receiving optical system composed of a hollow housing 82 and a plurality of optical elements arranged in a predetermined positional relationship inside the housing 82. 84, and a light receiving unit 86 disposed at the + Y side end inside the housing 82.

The housing 82 is made of a member having an L-shaped YZ cross section and having a space formed therein. At the top (the end in the + Z direction), light from above the housing 82 is provided. Circular opening 82a so as to be incident toward the internal space of
Are formed. A cover glass 88 is provided to cover the opening 82a from the inside of the housing 82. On the upper surface of the cover glass 88, a light-shielding film having a circular opening in the center is formed by vapor deposition of a metal such as chrome, and the light-shielding film eliminates unnecessary light from the surroundings when measuring the wavefront aberration of the projection optical system PL. Light is blocked from entering the light receiving optical system 84.

The light receiving optical system 84 includes an objective lens 84a, a relay lens 84b, a bending mirror 84c, and a folding mirror 84c, which are arranged below the cover glass 88 in the housing 82 in order from top to bottom. A collimator lens 84d and a microlens array 84e are sequentially arranged on the + Y side. The bending mirror 84c is inclined at an angle of 45 °, and the objective lens 84c is vertically moved downward from above by the bending mirror 84c.
The optical path of the light incident on a is a collimator lens 84d.
It is designed to be bent toward. Each optical member constituting the light receiving optical system 84 is fixed to the inside of the wall of the housing 82 via a holding member (not shown). The micro lens array 84e is configured by arranging a plurality of small convex lenses (lens elements) in an array on a plane orthogonal to the optical path.

The light receiving section 86 comprises a light receiving element comprising a two-dimensional CCD or the like and an electric circuit such as a charge transfer control circuit. The light receiving element has an area sufficient to receive all of the light beams that enter the objective lens 84a and exit from the micro lens array 84e. The measurement data from the light receiving unit 86 is output to the main controller 50 via a signal line (not shown) or by wireless transmission.

By using the above-described wavefront aberration measuring device 80, the wavefront aberration of the projection optical system PL can be measured on-body. The method of measuring the wavefront aberration of the projection optical system PL using the wavefront aberration measuring device 80 will be described later.

Referring back to FIG. 2, the exposure apparatus 122 of the present embodiment
₁ has a light source whose ON / OFF is controlled by the main controller 50, and emits an image forming light beam for forming images of a large number of pinholes or slits toward the image forming surface of the projection optical system PL. An irradiation system 60a for irradiating the axis AX from an oblique direction.
And an incident light type multi-point focal position detection system (hereinafter, simply referred to as a "focus detection system") comprising a light receiving system 60b for receiving the reflected light beams of the image forming light beams on the surface of the wafer W. ing. As the focus detection system (60a, 60b), one having the same configuration as that disclosed in, for example, JP-A-6-283403 is used.

The main controller 50 controls the Z position and XY of the wafer W such that the defocus becomes zero based on the defocus signal (defocus signal) from the light receiving system 60b, for example, the S-curve signal at the time of exposure or the like. By controlling the inclination with respect to the surface via the wafer stage drive unit 56, auto focus (automatic focusing) and auto leveling are executed. The main controller 50 also measures and aligns the Z position of the wavefront aberration measuring device 80 using the focus detection system (60a, 60b) when measuring the wavefront aberration described later. At this time, the inclination of the wavefront aberration measuring device 80 may be measured as needed.

Further, exposure apparatus 122 ₁ is used for off-axis (off-axis) used for position measurement of alignment marks on wafer W held on wafer stage WST and reference marks formed on reference mark plate FM. axis) type alignment system ALG. As the alignment system ALG, for example, a broadband detection light beam that does not expose the resist on the wafer is irradiated on the target mark, and an image of the target mark formed on the light receiving surface by reflected light from the target mark and an index (not shown) (Field Image Alignment) of an image processing system that captures an image of the image using an image sensor (CCD) or the like and outputs an image signal of the image.
A system of sensors is used. In addition to the FIA system, a target mark is irradiated with coherent detection light to detect scattered light or diffracted light generated from the target mark, or two diffracted lights (for example, the same order) generated from the target mark.
Of course, it is possible to use an alignment sensor for detecting the interference by interference alone or in an appropriate combination.

Further, in the exposure apparatus 122 ₁ of the present embodiment, although not shown, a reticle R on the reference mark plate corresponding to the reticle mark on the reticle R is projected above the reticle R via the projection optical system PL. TTR (Through The Re) using light of the exposure wavelength to observe the reference mark at the same time
ticle) A pair of reticle alignment microscopes each including an alignment optical system are provided. As these reticle alignment microscopes, for example, Japanese Patent Laid-Open No. 7-176
A configuration similar to that disclosed in Japanese Patent No. 468 or the like is used.

The control system shown in FIG.
Mainly constituted by 0. Main controller 50 is a CPU
(Central processing unit), a so-called workstation (or microcomputer) including a ROM (read only memory), a RAM (random access memory), etc., and performs the various control operations described above. It controls the entire device. The main control device 50
For example, in order to perform the exposure operation accurately, for example, the inter-shot stepping of the wafer stage WST, the exposure timing, and the like are collectively controlled.

The main controller 50 includes, for example, a storage device 42 composed of a hard disk, an input device 45 including a pointing device such as a keyboard and a mouse, and a CRT display (or a liquid crystal display).
, A display device 44 such as a CD-ROM, a DVD-RO
A drive device 46 for an information recording medium such as M, MO or FD is externally connected. Further, main controller 50 is connected to LAN 118 described above.

An information recording medium (CD-ROM for convenience in the following description) set in the drive unit 46 includes:
A conversion program (hereinafter referred to as a “first program” for convenience) that converts the amount of positional deviation measured using the wavefront aberration measuring device 80 into a coefficient of each term of the Zernike polynomial as described later.
) Is stored.

The second and third exposure devices 122 ₂ and 122 ₃
Is configured similarly to the above-described first exposure apparatus 122 ₁ .

Next, a first operation performed during maintenance or the like is performed.
The method of measuring wavefront aberration in the third to third exposure apparatuses 122 _{1 to} 122 ₃ will be described. In the following description, for simplification of the description, it is assumed that the aberration of the light receiving optical system 84 in the wavefront aberration measuring device 80 is so small as to be negligible.

As a premise, the first program in the CD-ROM set in the drive device 46 is stored in the storage device 42.
It is assumed that it is installed in

During normal exposure, the wavefront aberration measuring device 80
Is removed from the Z tilt stage 58,
When measuring the wavefront, first, a service engineer or an operator (hereinafter referred to as “service engineer, etc.”
The operation of attaching the wavefront aberration measuring device 80 to the side surface of the Z tilt stage 58 is performed. At the time of this attachment, the wavefront aberration measuring device 80 at the time of wavefront measurement,
Wafer stage WST (Z-tilt stage 58) is fixed to a predetermined reference surface (here, the surface on the + X side) via a bolt or a magnet so as to fit within the movement stroke of wafer stage WST (Z tilt stage 58).

After completion of the above mounting, in response to the input of a measurement start command by a service engineer or the like, main controller 50 drives wafer stage so that wavefront aberration measuring device 80 is positioned below alignment system ALG. The wafer stage WST is moved via the unit 56. Then, main controller 50 detects an alignment mark (not shown) provided on wavefront aberration measuring device 80 by the alignment system, and detects the detection result and laser interferometer 54W at that time.
Then, the position coordinates of the alignment mark are calculated based on the measured values, and the accurate position of the wavefront aberration measuring device 80 is obtained. After measuring the position of the wavefront aberration measuring device 80, the main controller 50
Then, the measurement of the wavefront aberration is executed as follows.

First, main controller 50 loads a not-shown measurement reticle (hereinafter, referred to as a “pinhole reticle”) on which a pinhole pattern has been formed by a not-shown reticle loader onto reticle stage RST. This pinhole reticle has an illumination area IAR on its pattern surface.
This is a reticle in which pinholes (pinholes which become almost ideal point light sources and generate spherical waves) are formed at a plurality of points in the same region.

Incidentally, the pinhole reticle used here is provided with a diffusing surface on the upper surface or the like so that the projection optical system P
All N.L. A. So that the wavefront of the light beam passing through the projection optical system PL can be determined.
A. It is assumed that the wavefront aberration over the range is measured.

After loading the pinhole reticle, main controller 50 detects the reticle alignment mark formed on the pinhole reticle using a reticle alignment microscope (not shown), and based on the detection result, determines the pinhole reticle. Is positioned at a predetermined position. Thereby, the center of the pinhole reticle and the optical axis of the projection optical system PL substantially match.

Thereafter, main controller 50 gives control information TS to light source 16 to emit laser light. Thereby, the illumination light EL from the illumination optical system 12 is applied to the pinhole reticle. Then, light emitted from the plurality of pinholes of the pinhole reticle is condensed on the image plane via the projection optical system PL, and an image of the pinhole is formed on the image plane.

Next, main controller 50 controls wavefront aberration measuring device 80 at an image formation point where an image of any pinhole (hereinafter, referred to as a focused pinhole) on the pinhole reticle is formed. The wafer stage WST is moved via the wafer stage driving unit 56 while monitoring the measurement value of the wafer laser interferometer 54W so that the center of the opening 82a is substantially coincident. At this time, the main controller 50 adjusts the upper surface of the cover glass 88 of the wavefront aberration measuring device 80 to the image plane on which the pinhole image is formed based on the detection result of the focus detection system (60a, 60b). The Z tilt stage 58 is minutely driven in the Z-axis direction via the wafer stage driving unit 56. As a result, the image light flux of the pinhole of interest enters the light receiving optical system 84 via the central opening of the cover glass 88 and is received by the light receiving element constituting the light receiving section 86.

More specifically, a spherical wave is generated from the pinhole of interest on the pinhole reticle, and this spherical wave constitutes the projection optical system PL and the light receiving optical system 84 of the wavefront aberration measuring device 80. Into a parallel light beam via an objective lens 84a, a relay lens 84b, a mirror 84c, and a collimator lens 84d.
Is irradiated. Thereby, the pupil plane of the projection optical system PL is relayed to the microlens array 84e and divided. Then, each light is condensed on the light receiving surface of the light receiving element by each lens element of the micro lens array 84e,
Pinhole images are respectively formed on the light receiving surfaces.

At this time, if the projection optical system PL is an ideal optical system having no wavefront aberration, the wavefront on the pupil plane of the projection optical system PL becomes an ideal wavefront (here, a plane). The parallel light beam incident on the microlens array 84e becomes a plane wave, and its wavefront should be an ideal wavefront. In this case, as shown in FIG. 4A, a spot image (hereinafter, also referred to as “spot”) is formed at a position on the optical axis of each lens element constituting the microlens array 84e.

However, since the projection optical system PL usually has a wavefront aberration, the wavefront of the parallel light beam incident on the microlens array 84e deviates from the ideal wavefront, and the deviation, that is, the inclination of the wavefront with respect to the ideal wavefront. Accordingly, as shown in FIG. 4B, the image forming position of each spot is shifted from the position on the optical axis of each lens element of the microlens array 84e. In this case, the displacement of each spot from the reference point (the position of each lens element on the optical axis) corresponds to the inclination of the wavefront.

The light (light flux of the spot image) incident on each light condensing point on the light receiving element constituting the light receiving section 86 is photoelectrically converted by the light receiving element, and the photoelectric conversion signal is subjected to main control via an electric circuit. The main controller 50 calculates the image forming position of each spot based on the photoelectric conversion signal, and further uses the calculation result and the position data of the known reference point to perform the position shift ( Δξ, Δη) to calculate R
Store in AM. At this time, the main control unit 50, the measurement value at that time of the laser interferometer 54W (X _i, Y _i) is supplied.

As described above, when the measurement of the displacement of the spot image by the wavefront aberration measuring device 80 at the focus point of one pinhole image of interest is completed, the main controller 5
At 0, the wafer stage WST is moved such that the center of the opening 82a of the wavefront aberration measuring device 80 substantially coincides with the image forming point of the next pinhole image. When this movement is completed, the main controller 50 emits a laser beam from the light source 16 in the same manner as described above, and similarly, the main controller 50 calculates the imaging position of each spot. Thereafter, the same measurement is sequentially performed at other image forming points of the pinhole image. At the time of the above measurement, the reticle blind 30 is used, and only the pinhole of interest on the reticle or at least a part of the region including the pinhole of interest is irradiated with the illumination light E.
For example, the position and size of the illumination area on the reticle may be changed for each pinhole so as to be illuminated with L.

When the necessary measurement is completed in this way, the RAM of main controller 50 stores the positional deviation data (Δξ, Δ
η) and the coordinate data of each imaging point (measured values (X _i , Y _i ) of the laser interferometer 54W at the time of measurement at the imaging point of each pinhole image) are stored.

Next, the main controller 50 loads the first program into the main memory, and stores the displacement data (ΔΔ) at the imaging point of each pinhole image stored in the RAM.
ξ, Δη) and the coordinate data of each imaging point, corresponding to the imaging point of the pinhole image according to the principle described below, that is, the first measurement point to the first measurement point in the field of view of the projection optical system PL.
Wavefront corresponding to the n measurement points (wavefront aberration), where the coefficients of the terms of the Zernike polynomial of equation (4) described later, for example, the coefficients Z ₃₇ coefficient Z ₂ ~ paragraph 37 of the second Section 1 Calculate according to the program.

In the present embodiment, the above positional deviation (Δξ,
Based on Δη), the wavefront of the projection optical system PL is obtained by calculation according to the first program. That is, the displacement (Δξ, Δη) is a value that directly reflects the inclination of the wavefront with respect to the ideal wavefront, and the wavefront can be restored based on the displacement (Δξ, Δη). Note that, as is clear from the physical relationship between the above-described positional deviation (Δξ, Δη) and the wavefront, the principle of calculating the wavefront in the present embodiment is as follows.
This is the well-known Shack-Hartmann wavefront calculation principle.

Next, a method of calculating the wavefront based on the above-described positional deviation will be briefly described.

As described above, the positional deviation (Δξ, Δη) corresponds to the inclination of the wavefront, and the shape of the wavefront (strictly speaking, the deviation from the reference plane (ideal wavefront)) is obtained by integrating this. . The equation for the wavefront (the deviation of the wavefront from the reference plane) is
(X, y) and the proportional coefficient is k, the following equation (2):
A relational expression such as (3) holds.

[0119]

(Equation 1)

Since it is not easy to integrate the inclination of the wavefront given only by the spot position as it is,
It is assumed that the surface shape is developed into a series and fits the series. In this case, the series should be orthogonal. The Zernike polynomial is a series suitable for the expansion of an axisymmetric surface, and expands to a triangular series in the circumferential direction. That is, if the wavefront W is represented by a polar coordinate system (ρ, θ), it can be expanded as in the following equation (4).

[0121]

(Equation 2)

Since the system is an orthogonal system, the coefficient Z _i of each term can be determined independently. Cutting i by an appropriate value corresponds to performing some sort of filtering. Incidentally, consisting of f _i up to the items 1 to 37, wherein as an example To illustrate with Z _i, as shown in the following Table 1.

[0123]

[Table 1]

In practice, the differentiation is detected as the above-mentioned positional deviation, so that the fitting needs to be performed on the derivative. Polar coordinate system (x = ρcosθ, y = ρsi
nθ) are expressed as in the following equations (5) and (6).

[0125]

(Equation 3)

Since the differential form of the Zernike polynomial is not an orthogonal system, the fitting must be performed by the least square method. Since information (shift amount) of the image forming point of one spot image is given in the X and Y directions, the number of pinholes is set to n (n
Is, for example, about 81 to 400), the number of observation equations given by the above equations (2) to (6) is 2n (=
162 to 800).

Each term of the Zernike polynomial corresponds to an optical aberration. Moreover, the low-order term (the term with a small i) substantially corresponds to Seidel aberration. By using the Zernike polynomial, the wavefront aberration of the projection optical system PL can be obtained.

The calculation procedure of the first program is determined according to the above-described principle, and the first program in the field of view of the projection optical system PL is calculated by the calculation processing according to the first program.
Information of the wavefront corresponding to the measurement points through n th measurement point (wavefront aberration), where the coefficients of the terms of the Zernike polynomial, for example, the second term of the coefficient Z ₂ - coefficient Z ₃₇ of paragraph 37 is obtained.

In the following description, the data of the wavefront (wavefront aberration) corresponding to the above-described first to n-th measurement points will be described.
It is represented by a column matrix Q as in the following equation (7).

[0130]

(Equation 4)

In the above equation (7), the elements P _{1 to} P _n of the matrix Q are column matrices (vertical) each consisting of the coefficients (Z _{2 to} Z ₃₇ ) of the second to 37th terms of the Zernike polynomial. Vector).

In this way, the wavefront data (the coefficients of each term of the Zernike polynomial, for example, the coefficient Z _{2 of} the second term to the third term,
When the coefficient Z ₃₇ ) of the seven terms is obtained, the main controller 50 stores the data of the wavefront in the storage device 42.

Further, as will be described later, main controller 50 responds to an inquiry from first communication server 120,
The wavefront data is read from the storage device 42 and
8 to the first communication server 120 described above.

Returning to FIG. 1, the first to third exposure apparatuses 1 are stored inside a hard disk or the like of the first communication server 120.
22 _{1-122 3} target information to be accomplished by, for example, resolution (resolving power), practically minimum line width (device rule), the wavelength of the illumination light EL, the pattern of the transfer target information, the other exposure apparatus 122 ₁ to 122 ₃ Stored is any information on the projection optical system that determines performance, which can be a target value. Further, inside the hard disk or the like provided in the first communication server 120, target information of an exposure apparatus to be introduced in the future, for example, information of a pattern to be used is stored as target information.

On the other hand, inside the hard disk or the like provided in the second communication server 130, an adjustment amount calculation program for calculating the adjustment amount of the imaging characteristic based on the coefficient of each term of the Zernike polynomial (hereinafter referred to as “second program for convenience”) ), A best exposure condition setting program for setting the best exposure condition (hereinafter referred to as a “third program” for convenience), and a second
Contains the database that accompanies the program.

Next, the database will be described. This database includes the above-mentioned movable lens element (hereinafter, referred to as a “movable lens”) 13 ₁ for adjusting the imaging characteristic according to the input of the optical characteristic of the projection optical system, here, the measurement result of the wavefront aberration. , 13 ₂ , 13 ₃ , and 13 ₄ are databases each including numerical data of a parameter group for calculating target drive amounts (target adjustment amounts). This database stores a plurality of measurement points in the field of view of the projection optical system PL when the movable lenses 13 ₁ , 13 ₂ , 13 ₃ , and 13 ₄ are driven by unit adjustment amounts in each of the degrees of freedom (driving directions). , Specifically, data on the wavefront, for example, data on how the coefficients of the second to 37th terms of the Zernike polynomials change, is a model substantially equivalent to the projection optical system PL. And a data group in which the fluctuation amounts of the imaging characteristics obtained as a result of the simulation are arranged according to a predetermined rule.

Here, the procedure for creating this database will be briefly described. First, in the simulation computer in which specific optical software is installed, first, exposure conditions, that is, design values (numerical aperture NA, data of each lens, etc.) of the projection optical system PL and illumination conditions (coherence factor σ value, (The wavelength λ of the illumination light, the shape of the secondary light source, etc.). Next, data of an arbitrary first measurement point in the field of view of the projection optical system PL is input to the simulation computer.

Next, data of a unit amount in each direction of freedom (movable direction) of the movable lens is input. For example, if you enter a command that the movable lens 13 ₁ is driven by a unit amount with respect to the + direction of the Y-direction tilt, the simulation computer, the first wave front of the first measurement point determined in advance within the field of projection optical system PL The data of the change amount from the ideal wavefront, for example, the change amount of the coefficient of each term (for example, the second to 37th terms) of the Zernike polynomial is calculated, and the data of the change amount is displayed on the screen of the display of the simulation computer. At the same time, the amount of change is stored in the memory as a parameter PARA1P1.

[0139] Then, by entering the command of the movable lens 13 ₁ is driven by a unit amount with respect to the + direction of the X-direction tilt, the simulation computer, first
The data of the second wavefront at the measurement point, for example, the amount of change of the coefficient of each term of the Zernike polynomial is calculated, the data of the amount of change is displayed on the screen of the display, and the amount of change is used as a parameter PARA2P1. Stored in memory.

[0140] Then, by entering the command of the movable lens 13 ₁ is driven by a unit amount with respect to the + direction of the Z-direction shift, the simulation computer, first
The data of the third wavefront at the measurement point, for example, the amount of change in the coefficient of each term of the Zernike polynomial is calculated, the data of the amount of change is displayed on the screen of the display, and the amount of change is used as a parameter PARA3P1. Stored in memory.

Thereafter, in the same procedure as above, the second measurement point to
Input of each measurement point to the n measurement points is performed, the movable lens 13 ₁ in the Y-direction tilt, X-direction tilt, every time the command input Z-direction shift is performed, respectively, at each measurement point by simulation computer The data of the first wavefront, the second wavefront, and the third wavefront, for example, the amount of change in the coefficient of each of the above terms of the Zernike polynomial is calculated, and the data of each amount of change is displayed on the screen of the display, and the parameters PARA1P2 and PARA2P2 are displayed. , PARA3P
2, ..., PARA1Pn, PARA2Pn, PARA
3Pn is stored in the memory.

For the other movable lenses 13 ₂ , 13 ₃ , and 13 ₄ , the input of each measurement point and the command input for driving in the + direction by a unit amount in each of the degrees of freedom are performed in the same procedure as described above. Is performed, and in response to this, the movable computer 13 ₂ , 13 ₃ , 1
3 ₄ wavefront data for each of the first to n measurement points when driving by a unit amount to each degree of freedom directions, e.g. the amount of change in terms of the Zernike polynomial is calculated, the parameter (PARA4P1, PARA5P1, PARA6
, PARAmP1), parameters (PARA
4P2, PARA5P2, PARA6P2, ..., PA
RAmP2), parameters (PARA4Pn, P
ARA5Pn, PARA6Pn, ..., PARAmP
n) is stored in the memory. Then, a column matrix (vertical vector) PARA comprising the variation of the coefficient of each term of the Zernike polynomial stored in the memory in this manner.
Data of a matrix (matrix) O represented by the following equation (8) having 1P1 to PARAmPn as elements is stored inside the hard disk or the like provided in the second communication server 130 as the database. In this embodiment, since there are three lenses movable in the three-degree-of-freedom direction and one lens movable in the two-degree-of-freedom direction, m = 3 × 3 + 2 × 1
= 11.

[0143]

(Equation 5)

[0144] Next, a description will be given first to a method of adjusting the third exposure apparatus 122 ₁ to 122 ₃ is provided with the projection optical system PL of this embodiment. In the following, the _first to third exposure devices 122 ₁ to 122 _1, except for the case where distinction is particularly necessary.
It describes an exposure apparatus 122 22 ₃ representatively.

As a premise, at the time of periodic maintenance of the exposure apparatus 122 or the like, the main controller 50 of the exposure apparatus 122 controls the projection optical system PL using the above-described wavefront aberration measuring device 80 in response to a measurement instruction from a service engineer or the like. It is assumed that the measurement of the wavefront aberration is performed, and the data of the measured wavefront is stored in the storage device 42.

First, in the first communication server 120, measurement data of a new wavefront that has not yet been received (the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront corresponding to the first to nth measurement points, for example, the second An inquiry is made at predetermined intervals as to whether or not the coefficient Z _{2 of} the term to the coefficient Z ₃₇ of the thirty-seventh term is present in the storage device 42 of the exposure apparatus 122. Here, the exposure device 122 (actually, the first to third exposure devices 122 ₁ to 122 ₁₎
22 new wavefront measurement data in the storage device 42 either) comprises ₃ is assumed to be stored. Therefore,
The main controller 50 of the exposure device 122 has a LAN
The measurement data of the wavefront is transmitted to the first communication server 120 via 118.

The first communication server 120 transmits the received wavefront measurement data to the second communication server 130.
It is transmitted together with an instruction to automatically adjust the projection optical system PL (or an instruction to calculate the adjustment amount of the projection optical system PL). As a result, these data pass through the first authentication proxy server 124 via the LAN 118, and further pass through the public line 11
6 to the second authentication proxy server 128. The second authentication proxy server 128 confirms the transmission destination address attached to the data, recognizes that the data has been transmitted to the second communication server 130,
The message is sent to the second communication server 130 via 126.

The second communication server 130 receives the transmitted data, displays that fact on the display together with the source of the data, and stores the wavefront measurement data on a hard disk or the like. Then, as it follows, and calculates the adjustment amount of the projection optical system PL, ie the adjustment amount of each optional direction of the movable lens _131-134 described above.

First, the second communication server 130 loads the second program from the hard disk or the like into the main memory, and according to the second program, moves the movable lens 13 described above.
Calculating a _1-13 adjustment amount of each degree of freedom directions of _4. Specifically, the second communication server 130 performs the following calculation.

The data Q of the wavefront (wavefront aberration) corresponding to the first to nth measurement points and the matrix O stored in the hard disk as the above-mentioned database
And the adjustment amount P of each of the movable lenses 13 _{1 to} 13 _{4 in} the respective degrees of freedom.
And the following equation (9) holds.

Q = O · P (9) In the above equation (9), P is represented by the following equation (10).
A column matrix (ie, a vertical vector) consisting of a number of elements.

[0152]

(Equation 6)

Accordingly, from the above equation (9), by performing the operation of the following equation (11), each element A of P is obtained by the least square method.
DJ1～ADJm, i.e. can be determined adjustment amount of each optional direction of the movable lens _131-134 (target adjustment amounts).

[0154] ^{P = (O T · O)} -1 · O T · Q ...... (11) the above equation in (11), O ^T is the transpose matrix of matrix ^{O, (O T · O)} -1 is the inverse matrix of (O ^T · O).

That is, the second program is expressed by the above equation (1)
This is a program for performing the least square calculation of 1) using a database. Therefore, in the second communication server 130, the database in the hard disk is sequentially read into the RAM according to the second program, and the adjustment amount A
DJ1 to ADJm are calculated.

Next, the second communication server 130 transmits the data of the calculated adjustment amounts ADJ1 to ADJm to the main control device 50 of the exposure device 122. As a result, the data of the adjustment amounts ADJ1 to ADJm are
6, through the second authentication proxy server 128,
Further, it reaches the first authentication proxy server 124 via the public line 116. In the first authentication proxy server 124,
The address assigned to the data of the adjustment amounts ADJ1 to ADJm is confirmed to recognize that the data has been transmitted to the exposure apparatus 122, and is transmitted to the exposure apparatus 122 via the LAN 118. In practice, the adjustment amounts ADJ1 to ADJ1
When the address given to the data of Jm is AD2, the data is sent to the first exposure device 122 ₁ , and when the address is AD3, the data is sent to the second exposure device 122 ₂ . It sent, if the address is AD4, the data is sent to the third exposure apparatus 122 _3.

Here, the second communication server 130 can also send the data of the calculated adjustment amounts ADJ1 to ADJm to the first communication server 120. In this case, the first communication server 120 sends the data of the adjustment amounts ADJ1 to ADJm to the main controller 50 of the exposure apparatus 122 to which the wavefront data has been sent earlier.

In any case, the adjustment amounts ADJ1-AJ
The main controller 50 of exposure apparatus 122 that has received the data of DJM, according to the data of the adjustment amount ADJ1～ADJm, the command value to the effect that drives the movable lens _131-134 to each degree of freedom directions, imaging characteristics This is given to the correction controller 48. Thus, the image forming characteristics correction controller 48, the voltage applied to the actuating element for driving the movable lens _131-134 to each of the degrees of freedom is controlled, at least the position and orientation of the movable lens _131-134 One is adjusted almost simultaneously, and the imaging characteristics of the projection optical system PL, such as distortion, curvature of field, coma, spherical aberration,
And astigmatism are corrected. As for coma, spherical aberration and astigmatism, not only low-order but also high-order aberrations can be corrected.

[0159] As apparent from the above description, in the present embodiment, the movable lens _131-134, driving elements for driving these movable lenses, the imaging characteristic correction controller 48,
The main controller 50 forms an imaging characteristic adjusting mechanism as an adjusting device.

As described above, in the present embodiment, when adjusting the projection optical system PL during normal use of the exposure apparatus,
A service engineer or the like attaches the wavefront aberration measuring device 80 to the Z-tilt stage 58 and inputs a measurement command of the wavefront aberration via the input device 45. The image characteristics are adjusted with high precision.

In the above description, the projection optical system is automatically adjusted. However, the automatic adjustment may include an aberration that is difficult to correct. In consideration of such a case, a skilled technician of the second communication server 130 displays the measurement data of the wavefront stored in the hard disk of the second communication server 130 on a display, and analyzes the display contents. Therefore, when the problem is grasped and the aberration which is difficult by the automatic adjustment is included, the instruction content of the appropriate countermeasure is inputted from the keyboard or the like of the second communication server 130 and the exposure device 122 of the exposure device 122 is communicated by the communication. It is also possible to display on the screen of the display device 44. A service engineer or the like on the maker A side can adjust the projection optical system in a short time by finely adjusting the assembly of the lens based on the contents displayed on this screen.

[0162] Next, an exposure apparatus 122 (122 ₁ to 12
The setting of the best exposure condition in 2 ₃ ) will be described with reference to the flowchart of FIG. 5 showing the main control algorithm of the CPU of the second communication server 130. It is assumed that the projection optical system PL using the wavefront aberration measuring device 80 described above is used by the main controller 50 of the first exposure device 122 ₁ in response to a measurement instruction from a service engineer or the like during regular maintenance of the exposure device 122 or the like. Is measured, and the data of the measured wavefront is obtained by the same procedure as described above.
It is assumed that it is stored inside the hard disk of the first communication server 120 or the like. In the case of setting the best exposure condition, the first communication server 120 or the exposure apparatus 120 ₁
Communication of data between the communication server and the second communication server 130 is performed in the same manner as described above, but for simplification of description, description of communication such as a communication path will be omitted below.

The flowchart of FIG. 5 starts when the first communication server 120 specifies the exposure apparatus for which the best exposure condition is to be determined from the first communication server 120 to the second communication server 130 in accordance with the instruction of the operator on the maker A side. In this case, the instruction for determining the best exposure condition including the third program is loaded by the second communication server 130 into the main memory. Therefore, the processing after step 202 in FIG. 5 is actually performed according to the third program.

First, in step 202, after instructing the first communication server 120 to input a condition, step 20 is executed.
Go to step 4 and wait for the condition to be input.

At this time, the first communication server 120 responds to the instruction from the operator to determine the best exposure conditions, for example, the information on the reticle to be used next in the exposure device 122 ₁ , for example, the exposure device 122 _{1 1 to} 122
_An inquiry is made to a host computer (not shown) that manages ₃ and a predetermined database is searched based on the information of the reticle to obtain the pattern information. Also,
In the first communication server 120, it is assumed that the exposure apparatus 122 ₁ for example to the main controller 50 queries the setting information such as current lighting conditions, such information is stored in the memory.

[0166] Alternatively, the above-mentioned pattern information and information such as lighting conditions can be manually input by the operator to the first communication server 120 via the input device.

In any case, the information of the pattern to be simulated obtained above (for example, in the case of a line and space pattern, the line width, pitch, duty ratio, etc. (or design data of the actual pattern, etc. )) Together with information of a preset target imaging characteristic (including an index value of the imaging characteristic: hereinafter, referred to as “target aberration”), for example, information of a line width abnormal value, etc. 1
It will be input by the communication server 120.

As described above, when the first communication server 120 inputs a condition and instructs completion of the input, the process proceeds to step 206 in FIG.
After setting the conditions for creating the Zernike change table of the target aberration input in step, the process proceeds to the next step 208. The target aberration information input in step 204 is not limited to one type. That is, the projection optical system PL
Can be simultaneously designated as the objective aberration.

In step 208, the input of information regarding the projection optical system PL of the exposure device 122 ₁ is performed by the first communication server 1.
After instructing 20, the process proceeds to step 210 to wait for the input of the information. Then, by the first communication server 120,
When information about the projection optical system PL, specifically, information such as a numerical aperture (NA), illumination conditions (for example, setting of an illumination system aperture stop, or a coherence factor σ value), wavelength, and the like are input, Proceeding to step 212, the input information is stored in the RAM, and information on the aberration to be given is set. As an example, the values of the coefficients of the terms of the Zernike polynomial, for example, as the coefficient Z ₃₇ coefficient Z ₂ ~ paragraph 37 of the second term, the same value, for example, 0.05λ
Are set individually.

In the next step 214, aberration information set based on the input pattern information and information on the projection optical system PL, for example, one target aberration corresponding to 0.05λ or its index value ( For example, a graph (for example, a Zernike change table (calculation table) such as an abnormal line width value) having a vertical axis representing a line width abnormal value which is an index of coma aberration and a horizontal axis representing a coefficient of each term of the Zernike polynomial was prepared. rear,
Proceed to step 216.

Here, the Zernike change table refers to a specific aberration when the input pattern is set as a target pattern, that is, the above-mentioned target aberration (including its index value).
This is nothing but table data including the sensitivity (Zernike Sensitivity) of the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system PL. This Zernike change table is based on the information on the input pattern, the information on the projection optical system PL, and the information on the set aberration, and the type of each lens element constituting the projection optical system for the same type of projection optical system. It is uniquely determined based on the design information including the location and the layout. Therefore, based on the specification of the exposure apparatus for which the best exposure condition is to be determined (for example, the specification of the model name), a database or the like in the company of the maker B is searched to confirm the type of the projection optical system of the exposure apparatus. Thus, a Zernike change table corresponding to the target aberration can be created.

In the next step 216, the above step 2
It is determined whether or not a Zernike change table has been created for all target aberrations input in step 04. If this determination is denied, the process returns to step 214 to create a change table for the next target aberration.

Then, when the creation of the change tables for all target aberrations is completed, and the determination in step 216 is affirmed, the flow advances to the next step 218. In step 218,
After instructing the first communication server 120 to input the wavefront measurement data, the process proceeds to step 220 and waits for the input of the measurement data. Then, the first communication server 12
Coefficients of the terms of the measurement data of the wavefront from 0 stored in the hard disk (Zernike polynomial expand corresponding wavefront to the first measurement point to the n measurement points, for example, the coefficient Z ₂ - paragraph 37 of the second term When the coefficient Z ₃₇ ) is input, the process proceeds to step 222, where a calculation such as the following expression (12) is performed for each measurement point using the previously created Zernike change table (calculation table). One of the target aberrations previously input in step 204 is calculated and stored in the RAM.

A = K ・ {Z ₂ · (value of change table) + Z ₃ · (value of change table) +... + Z ₃₇ · (value of change table)} (12)

Here, A is a target aberration of the projection optical system PL, for example, astigmatism, curvature of field, or the like, or an index of the target aberration, for example, an abnormal line width which is an index of the coma aberration. K is a proportional constant determined according to the resist sensitivity and the like.

Here, for example, considering the case where A is an abnormal line width value, for example, when the pattern is an L / S pattern having five lines, the abnormal line width value is obtained by the above-described equation. It can be expressed by (1). As is apparent from the equation (1), the calculation of the above equation (12) is nothing but a calculation of converting a pattern into an aerial image (projection image).

In the next step 224, it is determined whether or not all target aberrations (conditionally set aberrations (imaging characteristics)) have been calculated.
Returning to 22, the next target aberration is calculated and stored in the RAM.

When the calculation of all target aberrations is completed in this way, the process proceeds to step 226, where the calculation results of all target aberrations stored in the RAM are stored on a hard disk or the like, and then the next step 228 is performed. Proceed to.

In step 228, information on the projection optical system PL, specifically, numerical aperture (NA), illumination conditions (for example, setting of an illumination system aperture stop, or a coherence factor σ value, etc.), wavelength, etc. Part, first step 2
After the content is changed to a content different from that input in step 10, the process proceeds to the next step 230, and it is determined whether or not the content change of the expected number of times is completed. Here, since the information regarding the projection optical system PL has been changed only once,
This determination is denied, and the process returns to step 214, and thereafter, the processing and determination after step 214 are repeated. At this time, in step 214, a Zernike change table is created. At this time, a Zernike change table is created based on the information on the projection optical system PL changed in step 228. In this way, while sequentially changing the illumination conditions, the numerical aperture, the wavelength, and the like, Steps 214 to 2
When the processing and determination of Step 30 are repeated, and the change of the lighting condition and the like for the predetermined number of times is repeated, the determination in Step 230 is affirmed, and the process proceeds to the next Step 232. At this point, the calculation result of the target aberration under the condition setting of the expected number is stored in a hard disk or the like.

In the next step 232, conditions (illumination conditions, numerical aperture, wavelength, etc.) relating to the projection optical system such that the target aberration stored inside the hard disk or the like is optimized (for example, zero or minimum). Is determined, and the condition is determined as the best exposure condition.

At the next step 234, after transmitting the determined best exposure condition to the first communication server 120, a series of processing of this routine is ended.

The first communication server 120 which has received the data on the best exposure condition sends command data for setting the best exposure condition to the main control device 50 of the exposure device 122 ₁ as necessary. At 50, the best exposure condition is set according to the data. Specifically, the main controller 50 changes (sets) the illumination conditions by changing the aperture stop of the illumination system aperture stop plate 24, or the main controller 50 shown in FIG.
The numerical aperture of the projection optical system PL can be adjusted by adjusting the pupil aperture stop 15 of the projection optical system PL shown in FIG. Alternatively, the main controller 50 can set the exposure wavelength by giving the light source 16 information for changing the wavelength of the illumination light EL as the control information TS.

Note that the second communication server 130 transmits the instruction data for instructing the setting of the best exposure condition to the direct exposure apparatus 12.
By providing two _1, it is possible to set the best exposure conditions of the exposure apparatus 122 _1.

Also, by making a slight change to the third program corresponding to the flowchart of FIG. 5, the pattern information is gradually changed while setting information other than the pattern information is fixed, and the same Zernike as described above is performed. By repeatedly creating the change table and calculating the target aberration (or aerial image) based on the wavefront measurement data, it is also possible to determine the optimal pattern setting information as the best exposure condition.

Similarly, by making a slight change to the third program corresponding to the flowchart of FIG. 5, while setting information other than the aberration information to be provided is fixed, while changing the information of the aberration to be provided, By repeatedly performing the creation of the Zernike change table and the calculation of the target aberration (or aerial image) based on the wavefront measurement data, as the best exposure conditions, the projection optical system for transferring the input pattern is used. It is also possible to determine the aberration to be applied. In such a case, the second communication server 130
An image is formed via the main controller 50 of the exposure device 122 ₁ so that the projection optical system PL is given such aberration (for example, the second term coefficient Z ₂ to the thirty-seventh coefficient Z ₃₇ of the Zernike polynomial). By controlling the correction controller 48, the imaging characteristics can be adjusted. Alternatively, the second communication server 130 may control the first communication server 120 and the main controller 5 so that the projection optical system PL is given such aberration.
The imaging characteristics can be adjusted by controlling the imaging correction controller 48 via the control unit 0.

The setting of the best exposure conditions in the other exposure apparatuses 122 ₂ and 122 ₃ is performed in exactly the same manner as described above.

In this embodiment, for example, at the time of periodic inspection of the exposure apparatus 122, a service engineer or the like performs condition setting input, information regarding the projection optical system, etc. from the first communication server 120 side. In response to the above, the second communication server 130 generates a similar Zernike change table in the same procedure as in the simulation at the time of setting the above-described best exposure condition by using another program obtained by partially changing the above-mentioned third program. Created. Then, the main controller 50 executes the measurement of the wavefront aberration based on the instruction of the service engineer or the like on the exposure apparatus 122 side, and when the resulting positional deviation data is transmitted via the first communication server 120, 2 communication server 130
Then, the target aberration is calculated in the same manner as described above. And
In the second communication server 130, the movable lens 13 ₁ whose target aberration is optimized (for example, zero or minimum).
To 13 ₄ of the driving amount of each optional direction, is calculated by the least square method using another program. Then, the second communication server 130 gives the calculated drive amount command value to the imaging characteristic correction controller 48 via the main controller 50. Thus, the image forming characteristics correction controller 48, the voltage applied to the actuating element for driving the movable lens _131-134 to each of the degrees of freedom is controlled, at least one position of the movable lens _131-134 and At least one of the postures is adjusted, and the desired imaging characteristics of the projection optical system PL, such as distortion, curvature of field, coma, spherical aberration, and astigmatism, are corrected. In addition,
As for coma, spherical aberration, and astigmatism, not only low-order aberrations but also high-order aberrations can be corrected. In this case, it is not always necessary to use the second program described above.

Further, in the present embodiment, the drive device 46
By installing another program obtained by partially changing the above-mentioned third program in the storage device 42 in advance, the projection device 122 itself performs projection when adjusting the projection optical system PL of the exposure device 122 during periodic maintenance or the like. Automatic adjustment of the imaging characteristics of the optical system PL can be easily realized. In this case, based on an operator's instruction (including condition setting input, input of information regarding the projection optical system, and the like), the CPU in the main control device 50 performs the same processing in the same procedure as the above-described simulation, and performs the same processing. A Zernike change table is created. Then, when the measurement of the wavefront aberration is executed and the data of the displacement is input, the CPU in the main control device 50 calculates the target aberration in the same manner as described above. After that, the CPU in the main control device 50
Their purpose aberration optimal (e.g. zero or minimal) become such movable lens _131-134 driving amount of each optional direction of _4, is calculated by the least square method using another program. The CPU in the main control device 50 transmits the calculated drive amount command value to the imaging characteristic correction controller 48.
Give to. Thereby, the imaging characteristic correction controller 48
Accordingly, the voltage applied to the actuating element for driving the movable lens _131-134 to each of the degrees of freedom is controlled,
At least one of the at least one of the position and orientation of the movable lens _131-134 is adjusted, the imaging characteristics for the purpose of projection optical system PL, for example, distortion, curvature of field,
Coma, spherical aberration, astigmatism and the like are corrected. As for coma, spherical aberration and astigmatism, not only low-order but also high-order aberrations can be corrected.

By the way, in the above description, the projection optical system P
The case where the measurement of the wavefront aberration of L is performed using the wavefront aberration measuring device 80 has been described. However, the present invention is not limited to this, and a measurement reticle R _T (hereinafter referred to as “reticle R _T ” as appropriate) will be described below.
) Can be used to measure the wavefront aberration.

FIG. 6 shows measurement reticle R_TOverview of
A perspective view is shown. FIG. 7 shows a reticle
Reticle R in a state loaded on page RST_TLight of
A schematic diagram of an XZ section near the axis AX is a schematic diagram of the projection optical system PL.
It is shown together with the equation diagram. FIG. 8 shows a reticle.
Reticle R loaded on stage RST _T
Is a schematic view of an XZ section near the −Y side end of the projection optical system P.
L is shown together with the schematic diagram.

As is clear from FIG. 6, the overall shape of the measurement reticle _RT is almost the same as that of a normal reticle with pellicle. This measurement reticle R _T
FIG. 3 shows a glass substrate 60, a lens mounting member 62 having a rectangular plate shape fixed to the center of the upper surface of the glass substrate 60 in FIG.
Spacer member 6 composed of a frame-shaped member having the same appearance as a normal pellicle frame attached to the lower surface of
4, and an opening plate 66 attached to the lower surface of the spacer member 64.

The lens mounting member 62 has n circular openings 63 _{i, j} (i = 1 to p, _i ) in a matrix arrangement over substantially the entire region except for some band-like regions at both ends in the Y-axis direction.
j = 1 to q, p × q = n) are formed. Inside each circular opening 63 _{i, j,} a condenser lens 65 _{i, j} composed of a convex lens having an optical axis in the Z-axis direction is provided (see FIG. 7).

The glass substrate 60 and the spacer member 64
As shown in FIG. 7, reinforcing members 69 are provided at predetermined intervals inside a space surrounded by the opening plate 66 and the opening plate 66.

Further, on the lower surface of the glass substrate 60, measurement patterns 67i _{, j} are formed opposite to the condenser lenses 65i _{, j} , respectively, as shown in FIG. In addition, as shown in FIG. 7, pinhole-shaped openings 70 _{i, j} are formed in the opening plate 66 so as to face the respective measurement patterns 67 _{i, j} . The pinhole-shaped openings 70 _{i, j} have a diameter of, for example, about 100 to 150 μm.

Returning to FIG. 6, the lens holding member 62
An opening 7 is provided at the center of a part of the band-shaped region at both ends in the axial direction.
2 _1, 72 ₂ are respectively formed. As shown in FIG. 8, the lower surface of the glass plate 60 (pattern surface), the reference pattern 74 ₁ opposite the one opening 72 ₁ is formed. Although not shown, the other opening 72
₂ , the lower surface (pattern surface) of the glass plate 60
A reference pattern similar to the reference pattern 74 ₁ (for convenience,
“Reference pattern 74 ₂ ” is formed.

As shown in FIG. 6, a pair of reticle alignment marks RM1, RM1, symmetrically arranged with respect to the center of the reticle, on both sides of the lens holding member 62, on the X axis passing through the center of the reticle of the glass substrate 60. RM2 is formed.

Here, in the present embodiment, a mesh-like (street line) pattern as shown in FIG. 9A is used as the measurement pattern 67 _{i, j} .
In correspondence with this, as the reference pattern 74 _1, 74 _2, as shown in FIG. 9 (B), measurement pattern 67
A two-dimensional lattice pattern in which square patterns are arranged at the same pitch as _{i and j} is used. Incidentally, using the pattern shown in FIG. 9 (A) as the reference pattern 74 _1, 74 _2, it is possible to use a pattern shown as a measurement pattern in FIG. 9 (B). The measurement pattern 67
_{i and j} are not limited to these, and patterns of other shapes may be used. In that case, a pattern having a predetermined positional relationship with the measurement pattern may be used as the reference pattern. That is, the reference pattern may be any pattern that serves as a reference for the displacement of the measurement pattern.
Although the shape or the like does not matter, in order to measure the imaging characteristics (optical characteristics) of the projection optical system PL, a pattern in which the pattern is distributed over the entire image field or the exposure area of the projection optical system PL is required. desirable.

Next, the exposure device 122 (exposure device 122 ₁
- 122 ₃₎ in the measurement of the wavefront aberration of the projection optical system PL in the case of using the reticle R _T is described.

First, using the measurement reticle _RT , the wavefront aberration is measured at a plurality of (here, n) measurement points in the field of view of the projection optical system PL as follows.

First, when a wavefront aberration measurement command is input by an operator (including a service engineer) via the input device 45, the main controller 50 controls the measurement reticle _RT via a reticle loader (not shown). Load on reticle stage RST. Next, main controller 50 moves wafer stage WST via wafer stage driving unit 56 while monitoring the output of laser interferometer 54W, and determines a pair of reticle alignment reference marks on reference mark plate FM in advance. To the specified reference position. Here, the reference position is, for example, a position where the center of the pair of second reference marks coincides with the origin on the stage coordinate system defined by the laser interferometer 54W.

Next, in main controller 50, a pair of reticle alignment marks RM1 and RM1 on measurement reticle _RT are provided.
The reticle alignment marks RM1 and RM2 are simultaneously observed by using the reticle alignment microscope described above.
The reticle stage RST is minutely driven in an XY two-dimensional plane via a drive system (not shown) so that the displacement between the projected image of M2 on the reference plate FM and the corresponding reference mark is both minimized. Thus, the reticle alignment is completed, and the center of the reticle substantially coincides with the optical axis of the projection optical system PL.

Next, main controller 50 loads wafer W having a surface coated with a resist (photosensitive agent) on Z tilt stage 58 using a wafer loader (not shown).

[0203] Then, the main controller 50, a condenser lens 65 _i of measurement reticle R _T, includes all _j, and does not include the opening 72 _1, 72 _2, the X-axis direction of the lens holding member 62 In order to form a rectangular illumination area having a length within the maximum width in the X-axis direction, an opening of the reticle blind 30 is set via a drive system (not shown). At the same time,
The main control device 50 rotates the illumination system aperture stop plate 24 via the drive device 40 to set a predetermined aperture stop, for example, a small σ stop on the optical path of the illumination light EL.

After such preparation work, main controller 50
Then, the control information TS is supplied to the light source 16, the laser beam LB is emitted, and the reticle _RT is irradiated with the illumination light EL to perform exposure. As a result, as shown in FIG. 7, the measurement patterns 67 _{i, j} are simultaneously transferred via the corresponding pinhole-shaped openings 70 _{i, j} and the projection optical system PL. As a result, the resist layer on the wafer W is
A reduced image (latent image) 67 ′ _{i, j} of each measurement pattern 67 _{i, j} as shown in (A) is formed at predetermined intervals at predetermined intervals along the XY two-dimensional direction.

Next, main controller 50 determines, based on the measured value of a reticle laser interferometer (not shown) and the positional relationship between the reticle center and one reference pattern 74 ₁ in design.
Reticle stage RS via a drive system (not shown) so that the center position of reference pattern 74 ₁ coincides with optical axis AX.
T is moved a predetermined distance in the Y-axis direction. Then, the main controller 50, a rectangular region of a predetermined area on the lens holding member 62 including the opening 72 ₁ after the transfer (this region, either not applied to the condenser lens) only illumination of the illumination light EL An opening of the reticle blind 30 is set via a drive system (not shown) to define an area.

[0206] Next, the main controller 50, the wafer W latent image 67 _'1,1 of the first measurement pattern 67 _1,1 are formed
The wafer stage WST is moved while monitoring the measurement value of the laser interferometer 54W such that the center of the upper region substantially coincides with the optical axis of the projection optical system PL.

The main controller 50 controls the control information T
S is applied to the light source 16 to emit a laser beam LB, and the reticle _RT is irradiated with illumination light EL to perform exposure.
As a result, the reference pattern 74 ₁ is transferred so as to be superimposed on a region (referred to as a region S _1,1 ) where the latent image of the measurement pattern 67 _1,1 of the resist layer on the wafer W is already formed. As a result, the latent image 67 ′ _1,1 of the measurement pattern 67 _1,1 is placed in the region S _1,1 on the wafer W, as shown in FIG.
The latent image 74 _'1 of the reference pattern 74 ₁ is formed in a positional relationship as in FIG.

Next, main controller 50 controls reticle R
_Based on the arrangement pitch of the measurement patterns 67 _{i, j} on _T and the projection magnification of the projection optical system PL _, a design arrangement pitch p of the measurement patterns 67 _{i, j} on the wafer W is calculated, and the pitch is calculated. By moving the wafer stage WST in the X-axis direction by p, the center of the region on the wafer W where the latent image of the second measurement pattern 67 _1,2 is formed (referred to as a region S _1,2 ). Is moved on the wafer stage WST so as to substantially coincide with the optical axis of the projection optical system PL.

[0209] Then, main controller 50 controls control information T.
S is applied to the light source 16 to emit a laser beam LB, and the reticle _RT is irradiated with illumination light EL to perform exposure.
As a result, the reference pattern 74 ₁ is transferred onto the region S _1,2 on the wafer W in an overlapping manner.

[0210] Thereafter, by repeating a stepping operation between similar regions as above, the exposure operation, the area S _i on the wafer _W, in _j, FIG. 10 (B) and the same measurement pattern and the reference pattern A latent image is formed.

When the exposure is completed, the main controller 50 unloads the wafer W from the Z-tilt stage 58 via a wafer loader (not shown), and is connected to the chamber 11 in-line. It is sent to a coater / developer not shown (hereinafter abbreviated as “C / D”). Then, the development of the wafer W is performed in the C / D, and after the development, measurement is performed on the wafer W in the areas S _{i, j} arranged in a matrix in the same arrangement as in FIG. A resist image of the use pattern and the reference pattern is formed.

Thereafter, the wafer W after the development is completed
D, a registration error is measured for each region S _{i, j} using an external registration measurement device (registration measurement device), and based on the result, each measurement pattern 67 _{i is} measured. _the position error for the corresponding reference pattern 74 ₁ of the resist image of _j (positional deviation) is calculated. In addition, various methods of calculating the displacement are conceivable, but in any case, it is desirable to perform a statistical calculation based on the measured raw data from the viewpoint of improving accuracy.

Thus, for each area S _{i, j} ,
The displacement (Δξ ′, Δη ′) of the measurement pattern relative to the reference pattern in the X and Y two-dimensional directions is obtained. Then, the respective areas S _i, position shift of _j (.DELTA..xi ', delta
The data of η ′) is input to the main controller 50 via the input device 45 by the above-described service engineer or the like. It is also possible to input the data of the calculated displacement (Δξ ′, Δη ′) for each of the regions S _{i, j} to the main controller 50 online from an external overlay measuring instrument.

In any case, in response to the above input,
The CPU in the main controller 50 loads an arithmetic program similar to the first program described above into the main memory,
Based on the displacement (Δξ ′, Δη ′), each region S _{i, j}
, Ie, the wavefront (wavefront aberration) corresponding to the first to n-th measurement points in the field of view of the projection optical system PL, here, the coefficient of each term of the Zernike polynomial, for example, the coefficient Z _{2 of} the second term the coefficients Z ₃₇ th to 37 wherein calculating according to the above operation program.

As described above, the CPU in main controller 50 performs the projection optical system PL based on the above-mentioned positional deviation (Δξ ′, Δη ′) by performing the calculation according to the predetermined calculation program.
Here, the physical relationship between the displacement (Δξ ′, Δη ′) and the wavefront, which is a premise of the calculation, will be briefly described with reference to FIGS. 7 and 8.

[0216] Figure 7, measurement pattern 67 _k, for _l, as representatively shown, measurement pattern 67 _{i, j}
Out of the diffracted light generated in the above, the pinhole-shaped openings 70 _{i, j}
The position at which the light passes through the pupil plane of the projection optical system PL differs depending on at which position the light originates from the measurement pattern 67 _{i, j} . In other words, the wavefront at each position on the pupil plane corresponds to the measurement pattern 67 corresponding to that position.
It corresponds to the wavefront of light through the positions of _{i and j} . And
Supposing it is assumed there is no aberration in the projection optical system PL, these wavefront in the pupil plane of projection optical system PL, all ideal wavefront as indicated at F ₁ (here planar) should be. However, since absolutely no projection optical system aberrations not actually exist, in the pupil plane, for example, a curved wavefront F ₂ as shown by dotted lines. Therefore, measurement pattern 67 _{i, j} image of is imaged at a position shifted in accordance with the inclination with respect to the ideal wavefront of wavefront F ₂ on the wafer W.

On the other hand, the reference pattern 74 ₁ (or 7
The diffracted light generated from 4 ₂ ) is, as shown in FIG.
The light is directly incident on the projection optical system PL without being restricted by the pinhole-shaped opening, and is imaged on the wafer W via the projection optical system PL. Further, the reference pattern 74
_Since the exposure using ₁ is performed in a state where the center of the reference pattern 74 ₁ is positioned on the optical axis of the projection optical system PL, the imaging light flux generated from the reference pattern 74 ₁ hardly has the aberration of the projection optical system PL. , And forms an image on a minute area including the optical axis without displacement.

Therefore, the displacement (Δξ ′, Δη ′) is
The value directly reflects the inclination of the wavefront with respect to the ideal wavefront. Conversely, the wavefront can be restored based on the displacement (Δξ ′, Δη ′). It should be noted that the above displacement (Δ
ξ ′, Δη ′) and the wavefront, as is apparent from the physical relationship between the wavefront and the wavefront according to the present embodiment.
It is the principle of ack-Hartmann's wavefront calculation.

Note that a mask having a special structure similar to that of the measurement reticle _RT is used, and a plurality of measurement patterns on the mask are sequentially passed through individually provided pinholes and a projection optical system. The reference pattern on the mask is printed on the substrate via the projection optical system without passing through the condensing lens and the pinhole, and the resist for a plurality of measurement patterns obtained as a result of each printing is printed. By measuring the displacement of the reference pattern of each image with respect to the resist image and performing a predetermined calculation,
An invention relating to a technique for calculating wavefront aberration is disclosed in U.S. Pat. No. 5,978,085.

Incidentally, the exposure apparatus 122 _{1 of the} present embodiment is described.
In - 122 _3, at the time of fabrication of semiconductor devices, a reticle R for device manufacturing is loaded on the reticle stage RST, thereafter, the reticle alignment and the so-called baseline measurement, and EGA (Enhanced Global Alignment) wafer alignment such as such Preparation work is performed.

Note that the above-mentioned preparation work such as reticle alignment and baseline measurement is described in, for example,
JP-A-324923 and the like, and the subsequent EGA is disclosed in detail in JP-A-61-44429 and the like, and therefore, detailed description will be omitted.

Thereafter, exposure is performed in the same step-and-repeat manner as when measuring the wavefront aberration using the measurement reticle _RT described above. However, in this case, the stepping is performed based on the wafer alignment result.
The operation at the time of exposure and the like are not different from those of a normal stepper, and a detailed description thereof will be omitted.

Next, the exposure apparatus 122 (122 ₁ to 122)
2 ₃₎ the production method of the projection optical system PL to be performed during manufacture will be described.

A. Determination of Specifications of Projection Optical System In determining these specifications, first, an exposure apparatus should be achieved by the technician on the manufacturer A side as a user to the first communication server 120 via an input / output device (not shown). Target information, for example, information such as an exposure wavelength, a minimum line width (or resolution), and a target pattern is input. Next, the engineer or the like instructs the first communication server 120 to transmit the target information via the input / output device.

As a result, in the first communication server 120,
An inquiry is made to the second communication server 130 as to whether or not data can be received. Upon receiving an answer from the second communication server 130 indicating that the data can be received, the target information is transmitted to the second communication server 130. Send to

The second communication server 130 receives the above target information, analyzes it, and based on the analysis result,
One of the seven specification determination methods described below is selected, and the specification is determined.
Store in AM.

Here, prior to the description of the specification determining method,
A brief description will be given of what type of aberration is related to the coefficient Z _i of each term of the Zernike polynomial (fringe Zernike polynomial) obtained by expanding the wavefront of the projection optical system, which is expressed by the above-described equation (4). Each term is f, as shown in Table 1 above.
_i (ρ, θ) term, that is, the highest order of ρ is n order, θ
Is a term including an n-th order mθ term where m is a coefficient applied to.

The 0th-order 0θ term (coefficient Z ₁ ) indicates the position of the wavefront, and has almost no relation to aberration. 1
The next 1θ term (coefficient (Z ₂ , Z ₃ )) indicates a distortion component. The second-order 0θ term (coefficient Z ₄ ) indicates a focus component. Coefficients (Z ₉ , Z ₁₆ ,
Z ₂₅ , Z ₃₆ , Z ₃₇ )) indicate spherical aberration components. The coefficient of the 2θ term ((Z ₅ , Z ₆ , Z ₁₂ , Z ₁₃ , Z ₂₁ , Z ₂₂ , Z ₃₂ ,
Z ₃₃ )) and the coefficient of the 4θ term ((Z ₁₇ , Z ₁₈ , Z ₂₈ , Z
₂₉ )) shows astigmatism components. Third or higher order 1θ terms (coefficients _{(Z 7, Z 8, Z} 14, Z 15, Z 23, Z 24, Z 34,
Z ₃₅ ), the coefficient of the 3θ term ((Z ₁₀ , Z ₁₁ , Z ₁₉ , Z ₂₀ ,
Z ₃₀ , Z ₃₁ )) and the 5θ term (coefficients (Z ₂₆ , Z ₂₇ ))
Indicates a coma aberration component.

In the following, seven specification determining methods will be described. In each of these methods, the specification of the projection optical system is determined using the wavefront aberration to be satisfied by the projection optical system as a standard value.

<First Method> This is based on the coefficient (value) of a specific term selected based on target information among the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system as a standard value. This is a method for determining the specifications of the projection optical system. In the first method, for example, when the target information includes, for example, a resolution, for example, the coefficients Z ₂ and Z ₃ corresponding to the distortion component are selected, and the values of these coefficients themselves are set as standard values in the visual field. Is used when the specification of the projection optical system is determined so that these values are each equal to or less than a predetermined value.

<Second Method> This method uses the RMS value (Root-means-square value) of the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system as a standard value, The RM in the entire field of view of the optical system
This is a method of determining the specifications of the projection optical system so that the S value does not exceed a predetermined allowable value. According to the second method, for example, aberrations defined over the entire visual field, such as curvature of field, are suppressed. This second method can be suitably applied regardless of the target information. Of course, the RMS value of the coefficient of each term within the field of view may be used as the standard value.

<Third Method> This is a method in which a coefficient value of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system is set as a standard value, and the coefficient does not exceed each individually set allowable value. The method for determining the specifications of the projection optical system will now be described. In the third method, each allowable value can be set as the same value, or a different value can be set arbitrarily. Of course, some of them may have the same value.

<Fourth Method> In the fourth method, among the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system, the field of view of the coefficient of the n-th order mθ term corresponding to the particular aberration of interest In this method, the specification of the projection optical system is determined such that the RMS value within the range is a standard value and the RMS value does not exceed a predetermined allowable value. According to the fourth method, for example, when pattern information is included in target information, in order to analyze the pattern information and form a projected image of the pattern on an image plane in a good state, the method is particularly restricted. What needs to be done is to guess which aberration is, and based on the estimation result, the RMS value of the coefficient of the n-order mθ term is normalized as follows, for example.

The RMS value A ₁ for Z ₂ and Z ₃ in the visual field is defined as a standard value, and the standard value A ₁ ≦ permissible value B ₁ is satisfied. The RMS value A ₂ of Z _{4 in} the visual field is defined as a standard value, and the standard value A ₂
≦ the allowable value B _2. The RMS value A ₃ about Z _5, Z ₆ within the field and standard value, the standard value A ₃ ≦ tolerance B _3. The RMS value A ₄ about Z _7, Z ₈ within the field and standard value, the standard value A ₄ ≦ tolerance B _4. The RMS value A ₅ of Z ₉ and standard values within the field, the standard value A ₅ ≦ tolerance B _5. RMS for Z ₁₀ and Z ₁₁ in the field of view
The value A ₆ is a standard value, and the standard value A ₆ ≦ permissible value B ₆ . The RMS value A ₇ about Z _12, Z ₁₃ within the field and standard value, the standard value A ₇ ≦ tolerance B _7. Z in the field of view
_The RMS value A ₈ relating to ₁₄ and Z _{15 is} defined as a standard value, and the standard value A ₈
≦ the allowable value B _8. RMS value A ₉ of Z _{16 in} the visual field
Is the standard value, and the standard value A ₉ ≦ the allowable value B ₉ is satisfied. The RMS value A ₁₀ about Z _17, Z ₁₈ within the field and standard value,
It is assumed that the standard value A ₁₀ ≦ the allowable value B ₁₀ . Z ₁₉ in the field of view,
The RMS value A ₁₁ for Z _{20 is} defined as a standard value, and the standard value A ₁₁ ≦
And tolerance B _11. The RMS value A ₁₂ about Z _21, Z ₂₂ within the field and standard value, the standard value A ₁₂ ≦ permissible value B _12. RMS value A ₁₃ for Z ₂₃ and Z ₂₄ in the visual field
Is the standard value, and the standard value A ₁₃ ≦ permissible value B ₁₃ is satisfied. The RMS value A ₁₄ of Z _{25 in} the visual field is defined as the standard value, and the standard value A ₁₄
≦ the allowable value B _14. The RMS value A ₁₅ for Z ₂₆ and Z ₂₇ in the visual field is defined as a standard value, and the standard value A ₁₅ ≦ permissible value B ₁₅
And RMS value A for Z ₂₈ and Z ₂₉ in the visual field
₁₆ is the standard value, and the standard value A ₁₆ ≦ the allowable value B ₁₆ is satisfied. The RMS value A ₁₇ about Z _30, Z ₃₁ within the field and standard value, the standard value A ₁₇ ≦ permissible value B _17. Z in the field of view
_The RMS value A ₁₈ for ₃₂ and Z ₃₃ is the standard value, and the standard value A
And ₁₈ ≦ permissible value B _18. The RMS value A ₁₉ for Z ₃₄ and Z ₃₅ in the visual field is set as a standard value, and the standard value A ₁₉ ≦ permissible value B
_{19 is} assumed. The RMS value A ₂₀ about Z _36, Z ₃₇ within the field and standard value, the standard value A ₂₀ ≦ permissible value B _20.

<Fifth Method> In the fifth method, of the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system, each term corresponding to the particular aberration of interest is divided into a plurality of mθ terms. And the RMS value in the field of view of the coefficient of each term included in each group is defined as a standard value, and the projection optical system is controlled so that the RMS value of each group does not exceed each individually set permissible value. This is the method for determining the specifications.

For example, the coefficients Z ₉ , Z
The RMS value C ₁ in the visual field for ₁₆ , Z ₂₅ , Z ₃₆ , and Z ₃₇ is set as a standard value, and the standard value C ₁ ≦ permissible value D ₁ . Coefficients Z ₇ , Z ₈ , Z ₁₄ , Z ₁₅ , Z ₂₃ , of 1θ terms of third order or higher
RMS value C ₂ in the field of view for Z ₂₄ , Z ₃₄ , Z ₃₅
Is the standard value, and the standard value C ₂ ≦ permissible value D ₂ . The RMS value C ₃ in the field of view for the coefficients Z ₅ , Z ₆ , Z ₁₂ , Z ₁₃ , Z ₂₁ , Z ₂₂ , Z ₃₂ , and Z ₃₃ of the 2θ term is defined as the standard value, and the standard value C ₃ ≦ permissible value D ₃ I do. 3θ term coefficients Z ₁₀ , Z ₁₁ , Z
_19, and Z _20, Z _30, standard value C ₄ of the RMS value within the field related to Z _31, a standard value C ₄ ≦ permissible value D _4. 4θ
The RMS value in the field of view for the coefficients Z ₁₇ , Z ₁₈ , Z ₂₈ , and Z ₂₉ of the term is defined as a standard value C ₅ , and the standard value C ₅ ≦ permissible value D ₅ . The RMS value in the field of view for the coefficients Z ₂₆ and Z ₂₇ of the 5θ term is defined as the standard value C ₆ , and the standard value C ₆ ≦ permissible value D ₆ .

In the fifth method, as can be understood from the meaning of the coefficients of the above-described terms, for example, when the target information includes the pattern information, the pattern information is analyzed and the projected image of the pattern is analyzed. In order to form on the image plane in a good state, it is possible to estimate which aberration should be particularly suppressed, and to perform based on the estimation result.

<Sixth Method> In the sixth method, the coefficients of each term in the Zernike polynomial obtained by expanding the wavefront of the projection optical system PL are weighted in accordance with the target information, and the coefficients of each weighted term are set to standard values. In this method, the specifications of the projection optical system are determined so that the RMS value of the coefficient of each term in the visual field after weighting does not exceed a predetermined allowable value. In the sixth method, for example, in the case where pattern information is included in target information, in order to analyze the pattern information and form a projected image of the pattern on an image plane in a good state, the method is particularly restricted. What needs to be done can be estimated based on the result of the estimation of the aberration.

<Seventh Method> This seventh method is a method used only when the target information includes information on a pattern to be projected by the projection optical system, and is based on the information on the pattern. Then, a simulation for obtaining an aerial image formed on an image plane when the pattern is projected by the projection optical system is performed, and the simulation result is analyzed, and the pattern is transferred to the projection optical system. The specification of the projection optical system is determined with the wavefront aberration to be used as a standard value. In this case, as a simulation method, for example, a Zernike change table similar to that described above is created in advance, and a specific aberration (including its index value) obtained from the Zernike change table when the pattern is set as a target pattern is used. A linear combination of the sensitivity (Zernike Sensitivity) of the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system and the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system, which is determined according to the pattern. The aerial image may be obtained based on

More specifically, various aberrations (including their index values) at n measurement points (evaluation points) in the visual field of the projection optical system, for example, a matrix of n rows and m columns composed of m types of aberrations f and the data of the wavefront aberration at the n measurement points, for example, the coefficient of each term of the Zernike polynomial in which the wavefront is expanded, for example, n rows and 36 columns of coefficients Z _{2 to} Z _{37 of} the second to 37th terms The matrix Wa and the data of the Zernike change table (that is, the coefficient of each term of the Zernike polynomial of m kinds of aberrations under predetermined exposure conditions, for example, the second
Of the coefficients Z _{2 to} Z ₃₇ of the term to the 37th term per 1λ (Z
For example, there is a relationship represented by the following equation (13) between the matrix ZS and the matrix ZS of 36 rows and m columns composed of ernike sensitivity.

F = Wa · ZS (13) Here, f, Wa, and ZS can be represented by the following equations (14), (15), and (16), for example.

[0242]

(Equation 7)

As is apparent from the above equation (13), the Zernike change table and the data of the wavefront aberration (for example, the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront, for example, the second to third terms)
By using 7 binomial coefficients of Z ₂ to Z ₃₇₎ and can be determined any aberration to a desired value. In other words, by giving a desired aberration value to f in the above equation (13), and solving the above equation (13) by the least square method using data of a known (pre-created) Zernike change table, It can be seen that the coefficients of each term of the Zernike polynomial at each point in the field of view of the projection optical system that make a specific aberration a desired value, for example, the coefficients Z _{2 to} Z ₃₇ of the second to 37th terms can be determined.

That is, in the seventh method, a spatial image of a pattern in which the line width abnormal value which is an index value of a specific aberration, for example, coma, is equal to or smaller than a predetermined value is obtained by the above simulation. Wavefront aberration when an aerial image is obtained (coefficient of each term of Zernike polynomial which expanded wavefront)
Is used as a standard value to determine the specifications of the projection optical system.

In any of the above-described first to seventh specification determination methods, the information on the wavefront on the pupil plane of the projection optical system, that is, the overall information passing through the pupil plane, is based on the target information to be achieved by the exposure apparatus. Since the specifications of the projection optical system are determined using the information as a standard value, if a projection optical system that satisfies the specifications is manufactured, the target to be achieved by the exposure apparatus can be surely achieved.

B. Manufacturing Process of Projection Optical System Next, according to the flowchart of FIG.
Will be described.

[Step 1] In step 1, first, each lens element as each optical member constituting the projection optical system PL, a lens holder for holding each lens, and a lens element according to a design value based on predetermined design lens data. A lens barrel for housing an optical unit including a lens holder is manufactured. That is, each lens element is processed from a predetermined optical material using a known lens processing machine so as to have a radius of curvature and an axial thickness according to a predetermined design value, and a lens holder for holding each lens, a lens element The lens barrel that houses the optical unit consisting of the lens and the lens holder is made of a predetermined holding material (stainless steel, brass,
From ceramics, etc.) into a shape having predetermined dimensions.

[Step 2] In step 2, the surface shape of the lens surface of each lens element constituting the projection optical system PL manufactured in step 1 is measured using, for example, a Fizeau interferometer. As the Fizeau interferometer, a He—Ne gas laser emitting light of a wavelength of 633 nm, a wavelength of 3
As the light source, an Ar laser emitting 63 nm light, an Ar laser having a wavelength of 248 nm, or the like is used. According to this Fizeau-type interferometer, the interference fringes due to the interference between the reference surface formed on the surface of the condenser lens arranged on the optical path and the reflected light from the surface of the lens element, which is the surface to be measured, are represented by C
By measuring with an imaging device such as a CD, the shape of the test surface can be accurately obtained. Note that it is known to determine the shape of the surface (lens surface) of an optical element such as a lens using a Fizeau-type interferometer.
JP-A-62-126305, JP-A-6-185997
The detailed description will be omitted because the information is disclosed in Japanese Patent No.

The measurement of the surface shape of the optical element using the above-mentioned Fizeau interferometer is performed on all lens surfaces of each lens element constituting the projection optical system PL. And
The respective measurement results are stored in a memory such as a RAM provided in the second communication server 130 or a storage device such as a hard disk via an input device (not shown) such as a console.

[Step 3] After the measurement of the surface shapes of all the lens surfaces of each lens element constituting the projection optical system PL in Step 2, the optical unit processed or manufactured according to the design values, that is, the lens, etc. A plurality of optical units each composed of the above optical element and a lens holder holding the optical element are assembled. Of this optical unit,
Plurality, for example four, movable lens _131-134 described above
The has respectively, in the optical unit having a movable lens _131-134, as described above, as the lens holder, the lens holder having a double structure is used. That is, the lens holder of the double structure has an inner lens holder for holding the movable lens _131-134, respectively, and an outer lens holder for holding the inner lens holder, respectively, inside the lens holder and the outer lens The positional relationship with the holder is adjustable via a mechanical adjustment mechanism. The drive elements described above are provided at predetermined positions in the lens holder having the double structure.

Then, the plurality of optical units assembled as described above are sequentially passed through the upper opening of the lens barrel.
It is assembled so that it is dropped into the lens barrel while interposing a spacer. Then, the optical unit first dropped into the lens barrel is supported via a spacer by a protrusion formed at the lower end of the lens barrel, and all the optical units are accommodated in the lens barrel. Is completed.
In parallel with this assembling process, information on the distance between the optical surfaces (lens surfaces) of the respective lens elements using a tool (micrometer or the like) while taking into account the thickness of the spacer housed in the lens barrel together with the optical unit. Is measured. Then, while alternately performing the assembly operation and the measurement operation of the projection optical system, the final interval of the optical surface (lens surface) of each lens element of the projection optical system PL at the stage when the assembly process of step 3 is completed is completed. Ask.

[0252] Incidentally, including the assembly process, each step of the manufacturing stage, the movable lens _131-134 described above are fixed to the neutral position. Although not described, the pupil aperture stop 15 is also incorporated in this assembling process.

During the above-mentioned assembling process or at the time of completion of the assembling, the measurement result regarding the distance between the optical surfaces (lens surfaces) of the lens elements of the projection optical system PL is input via an unillustrated input device such as a console. It is stored in a memory such as a RAM included in the second communication server 130 or a storage device such as a hard disk. In the above assembling process, the optical unit may be adjusted as needed.

At this time, for example, the relative distance between the optical elements in the optical axis direction is changed via a mechanical adjustment mechanism, or the optical elements are inclined with respect to the optical axis. Further, the lens barrel is configured such that the tip of a screw screwed through a female screw portion penetrating through the side surface of the lens barrel comes into contact with the lens holder, and the screw is moved via a tool such as a screwdriver, whereby the lens holder is moved. May be shifted in a direction orthogonal to the optical axis to adjust eccentricity and the like.

[Step 4] Next, in step 4, the wavefront aberration of the projection optical system PL assembled in step 3 is measured.

More specifically, the projection optical system PL is mounted on the body of a large-sized wavefront measuring device (not shown), and the wavefront aberration is measured. The principle of measuring the wavefront by this wavefront measuring device does not differ from that of the wavefront aberration measuring device 80 described above, and therefore, detailed description is omitted.

As a result of the measurement of the wavefront aberration, the coefficient Z _i (i) of each term of the Zernike polynomial (fringe Zernike polynomial) obtained by expanding the wavefront of the projection optical system by the wavefront measuring device.
= 1, 2,..., 37). Therefore, by connecting a wavefront measuring device to the second communication server 130, the coefficient Z _i of each term of the Zernike polynomial in a memory such as a RAM of the second communication server 130 (or storage device such as a hard disk) is automatically Is taken in. In the above description, the wavefront measuring device uses up to the 81st term of the Zernike polynomial, but this is used to calculate the higher order components of each aberration of the projection optical system PL. It is. However, as in the case of the above-mentioned wavefront aberration measuring instrument, it is also possible to calculate up to the 37th term,
Alternatively, 82 or more terms may be calculated.

[Step 5] In step 5, the wavefront aberration measured in step 4 is changed to the first to seventh waves described above.
The projection optical system PL is adjusted so as to satisfy the specifications determined according to the determination method selected from the specification determination methods.

First, prior to adjusting the projection optical system PL,
The second communication server 130 stores the information stored in the memory, that is, the information on the surface shape of each optical element obtained in step 2 and the optical information of each optical element obtained in the assembling process in step 3. The optical basic data stored in advance in the memory is corrected based on the information on the distance between the surfaces, and the optical data in the manufacturing process of the actually assembled projection optical system PL is reproduced. This optical data is used to calculate the adjustment amount of each optical element.

That is, in the hard disk of the second communication server 130, for all the lens elements constituting the projection optical system PL, the unit drive amount of each lens element in each of the six degrees of freedom and the coefficient of each term of the Zernike polynomial A basic database for adjustment obtained by calculating the relationship between the change amount of Z _{i and} the amount of change based on the design value of the projection optical system, that is, by expanding the above-described matrix O so as to include not only movable lenses but also non-movable lens elements. Are stored in advance. Therefore, the second communication server 130 corrects the adjustment basic database by a predetermined calculation based on the optical data in the process of manufacturing the projection optical system PL described above.

When any one of the above-described first to sixth methods is selected, the second communication server 1
In 30, the basic database after correction, the target value of the wavefront, i.e. the value coefficient Z _i is satisfactory in terms of the Zernike polynomial based on the selected specification determination method, was obtained as the measurement result of the wavefront measuring device Based on the actual measured value of the coefficient Z _i of each term of the Zernike polynomial, the adjustment amount of each lens element in each of the six degrees of freedom is calculated by, for example, the least square method according to a predetermined calculation program.

Then, the second communication server 130 displays on the screen of the display the information of the adjustment amount (including zero) of each lens element in each of the six degrees of freedom.

According to the display, each lens element is adjusted by a technician (operator). Thereby, the projection optical system PL is adjusted so as to satisfy the specifications determined according to the selected specification determining method.

Specifically, when the first method is selected as the specification determining method, based on the target information among the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system PL. The projection optical system PL is adjusted so that the coefficient of the selected specific term does not exceed a predetermined value. When the second method is selected, the projection is performed so that the RMS value of the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront in the entire field of view of the projection optical system PL does not exceed a predetermined allowable value. The optical system PL is adjusted. Further, when the third method is selected, the projection optical system PL is adjusted so that the coefficients of the terms of the Zernike polynomials obtained by expanding the wavefront of the projection optical system do not exceed respective individually set permissible values. Adjusted.
When the fourth method is selected, among the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system PL, the field of view of the coefficient of the n-th order mθ term corresponding to the particular aberration of interest The projection optical system PL is adjusted such that the RMS value within does not exceed a predetermined allowable value. When the fifth method is selected, among the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system PL, a plurality of terms corresponding to a particular aberration to be focused on are divided into a plurality of mθ terms. The projection optical system is divided into groups, and the projection optical system is adjusted so that the RMS value in the field of view of the coefficient of each term included in each group does not exceed each individually determined allowable value. When the sixth method is selected, the coefficients of the terms of the Zernike polynomials obtained by expanding the wavefront of the projection optical system PL are weighted in accordance with the target information. RMS
The projection optical system PL is adjusted so that the value does not exceed a predetermined allowable value.

On the other hand, when the seventh method is selected, the second communication server 130 sets the image when the pattern is projected by the projection optical system based on the information of the pattern included in the target information. A simulation for obtaining an aerial image formed on the surface is performed. The simulation result is analyzed, and the projection optical system PL is adjusted so as to satisfy the wavefront aberration allowed for the projection optical system PL in order to transfer a pattern well. adjust. In this case, in the second communication server 130, as a simulation method, for example, a Zernike change table similar to that described above is created in advance, and a specific aberration ( The sensitivity (Zernike Se) of each term of the Zernike polynomial which is obtained by expanding the wavefront of the projection optical system and is determined in accordance with the pattern (including the index value).
nsitivity) and a lens that obtains an aerial image based on a linear combination of coefficients of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system, and the aberration of interest does not exceed an allowable value based on the aerial image. The adjustment amount of the element is calculated by, for example, the least square method.

The second communication server 130 displays information on the adjustment amounts (including zero) of each lens element in each of the six degrees of freedom on the screen of the display. According to this display, each lens element is adjusted by a technician (operator). Thereby, the projection optical system PL can satisfy the specification determined according to the selected seventh specification determination method.
Is adjusted.

In any case, since the projection optical system PL is adjusted based on the measurement result of the wavefront of the projection optical system PL,
Not only low-order aberrations but also high-order aberrations can be adjusted simultaneously,
In addition, there is no need to consider the order of aberrations to be adjusted as in the related art. Therefore, the optical characteristics of the projection optical system can be easily adjusted with high accuracy. In this way, the projection optical system PL that almost satisfies the determined specifications is manufactured.

In this embodiment, after the wavefront aberration is measured in step 4, the projection optical system is adjusted after the projection optical system is incorporated into the exposure apparatus without adjusting the projection optical system. However, before the projection optical system is incorporated into the exposure apparatus, the projection optical system may be adjusted (such as rework or replacement of an optical element), and the adjusted projection optical system may be incorporated into the exposure apparatus. At this time, the projection optical system may be adjusted by, for example, an operator adjusting the position of the optical element without using the above-described imaging characteristic adjustment mechanism. Further, after incorporating the projection optical system into the exposure apparatus, the wavefront aberration is measured again using the above-described wavefront aberration measuring device 80 or the measurement reticle _RT , and the projection optical system is readjusted based on the measurement result. Is desirable.

The measurement of the wavefront aberration performed at the time of the adjustment of the projection optical system PL and the like is performed by using the wavefront measurement device as described above and based on the spatial image formed via the pinhole and the projection optical system PL. However, the present invention is not limited to this. For example, using a measurement reticle R _T and performing the measurement based on the result of printing a predetermined measurement pattern on the wafer W via the pinhole and the projection optical system PL. It is good.

In order to easily rework the optical element of the projection optical system PL, when the wavefront aberration is measured using the above-described wavefront measuring device, the optical element that needs to be reworked based on the measurement result. The presence or absence and position of the optical element may be specified, and the rework of the optical element and the readjustment of other optical elements may be performed in parallel. Further, when it is necessary to rework or replace the optical element of the projection optical system, it is preferable to perform rework or replacement before incorporating the projection optical system into the exposure apparatus.

Next, a method for manufacturing the exposure apparatus 122 will be described.

In manufacturing the exposure apparatus 122, first,
While assembling the illumination optical system 12 including a plurality of lens elements and optical elements such as mirrors as a unit,
The projection optical system PL is assembled as a single unit as described above. In addition, a reticle stage system, a wafer stage system, and the like including a large number of mechanical parts are assembled as units. Then, optical adjustment, mechanical adjustment, electrical adjustment, and the like are performed so as to exhibit desired performance as a unit alone. In this adjustment, the projection optical system PL is adjusted by the method described above.

Next, the illumination optical system 12, the projection optical system PL, and the like are assembled in the exposure apparatus main body, and the reticle stage system, the wafer stage system, and the like are attached to the exposure apparatus main body to connect wiring and piping.

Next, the illumination optical system 12 and the projection optical system PL
For, optical adjustment is further performed. This is because the imaging characteristics of those optical systems, particularly the projection optical system PL, are slightly changed before and after assembling to the exposure apparatus main body. In the present embodiment, when the projection optical system PL is optically adjusted after being incorporated into the exposure apparatus main body, the above-described wavefront aberration measuring device 80 is attached to the Z tilt stage 58, and the wavefront aberration is measured in the same manner as described above. The information on the wavefront at each measurement point obtained as a measurement result of the wavefront aberration is sent online from the main controller 50 of the exposure apparatus being manufactured to the second communication server 130. Then, in the same manner as in the above-described adjustment at the time of manufacturing the projection optical system PL alone, the second communication server 130 calculates the adjustment amount of each lens element in each of the six degrees of freedom by, for example, the least square method. The calculation result is displayed on the display.

Then, in accordance with this display, each lens element is adjusted by a technician (operator). This allows
The projection optical system PL that reliably satisfies the determined specifications is manufactured.

Note that the final adjustment in this manufacturing stage is as follows:
It is possible to perform the automatic adjustment of the projection optical system PL via the imaging characteristic correction controller 48 by the main controller 50 based on the instruction from the second communication server 130 described above. However, at the stage where the manufacture of the exposure apparatus has been completed, it is desirable to keep each movable lens at the neutral position in order to ensure a sufficient drive stroke of the drive element after delivery to the semiconductor manufacturing factory. Therefore, it is possible to determine that uncorrected aberrations, mainly high-order aberrations, are aberrations that are difficult to automatically adjust. Therefore, as described above, it is desirable to readjust the assembly of lenses and the like.

When desired performance cannot be obtained by the above readjustment, it is necessary to rework or replace some lenses. In order to easily rework the optical element of the projection optical system PL, as described above, the projection optical system P
Before assembling L into the exposure apparatus main body, the wavefront aberration of the projection optical system PL is measured using the above-described wavefront measurement device or the like, and based on the measurement result, the presence / absence, position, and the like of an optical element requiring rework are specified. It is good. Further, rework of the optical element and readjustment of another optical element may be performed in parallel.

The replacement may be performed for each optical element of the projection optical system PL, or may be performed for each lens unit in a projection optical system having a plurality of lens barrels. Further, in the reprocessing of the optical element, the surface may be processed to an aspherical surface as needed. Further, in the adjustment of the projection optical system PL, it is only necessary to change the position of the optical element (including the distance from other optical elements), the inclination, and the like. In particular, when the optical element is a lens element, the eccentricity is changed. Alternatively, it may be rotated about the optical axis AX.

Thereafter, comprehensive adjustments (electrical adjustment, operation confirmation, etc.) are further performed. Thus, it is possible to manufacture the exposure apparatus 122 of the present embodiment, which can transfer the pattern of the reticle R onto the wafer W with high accuracy using the projection optical system PL whose optical characteristics have been adjusted with high precision. . It is desirable that the manufacture of the exposure apparatus be performed in a clean room in which the temperature, cleanliness, and the like are controlled.

As described above in detail, according to the computer system 10 according to the present embodiment and the method for determining the specifications of the projection optical system performed by the computer system 10, based on the target information to be achieved by the exposure apparatus 122,
The specifications of the projection optical system PL are determined using the wavefront aberration that the projection optical system PL should satisfy as a standard value. That is, the specifications of the projection optical system PL are determined using the information on the wavefront on the pupil plane of the projection optical system PL as a standard value. Therefore, when the projection optical system PL is manufactured in accordance with the determined specification, the projection optical system PL is adjusted based on the measurement result of the wavefront aberration, thereby correcting not only low-order aberrations but also high-order aberrations at the same time. be able to. Therefore, in the manufacturing stage, after adjusting the projection optical system to correct low-order aberrations, high-order aberrations are detected by ray tracing, and based on the detection result, low-order aberrations are corrected. The manufacturing process of the projection optical system is obviously simplified as compared with the related art in which the adjustment of the projection optical system is performed again. Moreover, in this case, since the specifications are determined based on the target information, the target to be achieved by the exposure apparatus is reliably achieved by the resultant projection optical system.

According to the computer system 10 according to the above embodiment and the method for determining the best conditions performed by the computer system, the first communication server 120 is provided with a predetermined pattern by the host computer or the operator managing the exposure apparatus 122. When the exposure condition information including the information is input, the second communication server 130 transmits the pattern information and the projection optical system PL included in the exposure condition information received from the first communication server 120 via the communication path. Based on the known aberration information, the simulation for obtaining the aerial image formed on the image plane when the pattern is projected by the projection optical system PL is repeatedly performed, and the simulation result is analyzed to determine the best exposure condition. I do. Therefore, the setting of the optimum exposure condition can be performed almost fully automatically.

According to the computer system 10 of the present embodiment, when adjusting the projection optical system PL during maintenance of the exposure apparatus 122 or the like, a service engineer or the like moves the wavefront aberration measuring device 80 to the Z tilt stage 58. Just by inputting a wavefront aberration measurement command via the attachment and the input device 45, the second communication server 130 is almost fully automatic.
, The imaging characteristics of the projection optical system PL can be adjusted with high accuracy. Alternatively, a service engineer or the like uses the measurement reticle _RT to
The measurement of the wavefront aberration of the projection optical system PL of Step 2 is performed in the above-described procedure, and the data of the amount of displacement obtained as a result is input to the main controller 50 of the exposure apparatus 122. 2 By the remote control by the communication server 130, the imaging characteristics of the projection optical system PL can be adjusted with high accuracy.

According to the exposure apparatus 122 of the present embodiment, the projection optical system in which the best exposure conditions are set as described above and the image forming characteristics of the projection optical system PL are adjusted with high accuracy at the time of exposure. Since the pattern of the reticle R is transferred onto the wafer W via the system PL, it is possible to transfer the fine pattern onto the wafer W with high overlay accuracy.

In the above embodiment, the projection optical system PL
Has been described in which the adjusting device for adjusting the state of formation of the projected image of the pattern by the imaging characteristic adjustment mechanism for adjusting the imaging characteristic of the projection optical system PL has been described, but the present invention is not limited to this. is not. As the adjustment device, for example, a mechanism for driving at least one of the reticle R and the wafer W in the optical axis AX direction, a mechanism for shifting the wavelength of the illumination light EL, etc. May be used. For example, when a mechanism for shifting the wavelength of the illumination light EL is used together with the above-described imaging characteristic adjustment mechanism, a plurality of measurements in the field of view of the projection optical system PL with respect to the unit shift amount of the illumination light EL are performed as described above. Imaging characteristics corresponding to each point, specifically, data of the wavefront, for example, the second to third terms of the Zernike polynomial
By previously obtaining data on how the coefficient of the seven terms changes by simulation or the like, and including it as one of the parameters in the aforementioned database,
The same handling as the adjustment amount of each movable lens described above is possible. That is, the least square calculation according to the above-described second program is performed using the database, so that the calculation of the optimal shift amount of the wavelength of the illumination light EL for adjusting the image forming state of the pattern by the projection optical system is performed. This can be easily performed, and the wavelength can be automatically adjusted based on the calculation result.

In the above embodiment, the case where the exposure device is used as the optical device has been described. However, the present invention is not limited to this, and any optical device having a projection optical system may be used.

In the above embodiment, the computer in which the first communication server 120 as the first computer and the second communication server 130 as the second computer are connected via a communication path including a public line as a part thereof. While the system has been described, the invention is not so limited. For example, as shown in FIG. 12, a computer system in which the first communication server 120 and the second communication server 130 are connected via a LAN 126 ′ as a communication path may be used. As such a configuration, an in-house LAN system installed in a research and development department of an exposure apparatus maker can be considered.

When such an in-house LAN system is constructed, for example, the clean room side of the research and development department,
For example, the first communication server 120 is installed at a place where the assembly and adjustment of the exposure apparatus are performed (hereinafter, referred to as “site”), and the second communication server 130 is installed in a laboratory remote from the site. Then, a technician on the site side measures the above-described wavefront aberration, and transmits information (including pattern information) on exposure conditions of the exposure apparatus at the experimental stage via the first communication server 120 to the second communication on the laboratory side. Send to server 130. Then, the technician on the laboratory side uses the second communication server 130 in which the software program designed by himself / herself is installed in advance, based on the transmitted information, and projects the projection optical system PL of the exposure apparatus 122.
The automatic correction of the imaging characteristics is performed from a remote place, and the measurement result of the wavefront aberration of the projection optical system after the adjustment of the imaging characteristics is received, thereby confirming the effect of the adjustment of the imaging characteristics. It can also be used in software development stages.

Alternatively, a technician in the field sends pattern information and the like to the second communication server 130 to the first communication server 1.
By transmitting from the transmission unit 20, it is possible for the second communication server 130 to determine the specifications of the projection optical system optimal for the pattern.

In addition, the first communication server 120 and the second communication server 130 may be connected by a wireless line.

Also, in the above embodiment and the modified example, a plurality of exposure devices 122 are provided and the second communication server 130
However, a plurality of exposure apparatuses 122 _{1 to} 122 ₃ are connected via a communication path.
Has been described, the present invention is not limited to this, and a single exposure apparatus may be used.

In the above embodiment, the case where the specification of the projection optical system is determined by using the computer system 10 has been described. However, the technical idea of determining the specification of the projection optical system using the wavefront as the standard value is based on the computer. It can be used independently of the system 10. That is, in the negotiations between the maker A and the maker B, the maker A receives the provision of the pattern information and the like, and the maker B determines the specification of the projection optical system most suitable for the exposure of the pattern using the wavefront as the standard value. Is also good. Even in such a case, when the projection optical system is manufactured based on the specification determined using the wavefront as the standard value, there is an advantage that the manufacturing process is simplified as described above.

In the above embodiment, the exposure apparatus 12
2 based on the measurement result of the wavefront aberration of the projection optical system PL,
The second communication server 130 by using the second program to calculate the adjustment amount ADJ1~ADJm of the movable lens _131-134 transmits the data of the adjustment amount to the main controller 50 of exposure apparatus 122. Then, the adjustment amounts ADJ1 to ADJ
main controller 50 of exposure apparatus 122 that has received the data of m
But according to the data of the adjustment amount ADJ1～ADJm, by providing the movable lens _131-134 command value to the effect that the drive to each degree of freedom directions, the imaging characteristic correction controller 48, forming the projection optical system PL Adjustment of image characteristics was performed by remote control. However, the present invention is not limited to this.
22 may be configured to automatically adjust the imaging characteristics of the projection optical system based on the measurement result of the wavefront aberration using the same arithmetic program as the second program.

In the above embodiment, the case where the reference pattern is provided on the measurement reticle _RT along with the measurement pattern has been described. However, the reference pattern is an optical characteristic measurement mask (the measurement reticle R in the above embodiment). _T ) does not need to be provided. That is, the reference pattern may be provided on another mask, or may be provided on the substrate (wafer) side without providing the reference pattern on the mask side.
That is, using a reference wafer in which the reference pattern is formed in advance in a size corresponding to the projection magnification, applying a resist on the reference wafer, transferring the measurement pattern to the resist layer, developing, and developing By measuring the displacement between the resist image of the measurement pattern obtained later and the reference pattern, it is possible to perform substantially the same measurement as in the above embodiment.

In the above embodiment, after the measurement pattern and the reference pattern are transferred onto the wafer W, the wavefront aberration of the projection optical system PL is determined based on the measurement result of the resist image obtained by developing the wafer. It is assumed that the calculation is performed, but the invention is not limited to this.
Is projected onto a wafer, and the projected image (aerial image) is measured using an aerial image measuring instrument or the like, or the latent image of the measurement pattern and the reference pattern formed on the resist layer or the wafer is etched. The image may be measured. Even in such a case, if the positional deviation from the reference position of the measurement pattern (for example, the projected position of the measurement pattern in design) is measured, the projection optical system performs the same procedure as in the above embodiment based on the measurement result. It is possible to determine the wavefront aberration of the system. Instead of transferring the measurement pattern onto the wafer, a reference wafer on which the measurement pattern is formed is prepared in advance, and the reference pattern is transferred to the resist layer on the reference wafer to measure the positional deviation. Alternatively, an aerial image measuring device having a plurality of apertures corresponding to the measurement pattern may be used to measure the displacement between the two. Further, in the above-described embodiment, the above-described positional deviation is measured by using the overlay measuring device, but other than that, for example, an alignment sensor or the like provided in the exposure apparatus may be used.

In the above embodiment, up to the 37th term of the Zernike polynomial is used. However, the 38th term or more may be used. For example, using the up to the 81st term, each aberration of the projection optical system PL may be used. Higher order components may also be calculated. That is, the number and number of terms used in the Zernike polynomial may be arbitrary. Further, depending on the illumination conditions and the like, the aberration of the projection optical system PL may be positively generated. Therefore, in the above-described embodiment, not only the target aberration is always set to zero or minimum, but also the target aberration is set to a predetermined value. Alternatively, the optical element of the projection optical system PL may be adjusted.

[0296] In the above embodiment, the first communication server 120, for example, the information of a reticle used next in the exposure apparatus 122 ₁ is scheduled, for example, the exposure apparatus ₁₂₂ 1
122 ₃ inquiry to the host computer (not shown) to manage, on the basis of the information of the reticle, searches the predetermined database to obtain the pattern information, or the first pattern information via the operator input device
It is assumed that the information is manually input to the communication server 120. However, the present invention is not limited to this. A reading device BR such as a barcode reader indicated by a virtual line in FIG. 2 is provided in the exposure device, and the first communication server 120 is connected to the first communication server 120 via the main controller 50 using the reading device BR. However, the barcode or the two-dimensional code attached to the reticle R being conveyed to the reticle stage RST may be read to obtain the pattern information by itself.

When the measurement reticle described above is used for measuring the wavefront aberration, for example, the displacement of the latent image of the measurement pattern transferred and formed on the resist layer on the wafer with respect to the latent image of the reference pattern is determined. For example, it may be detected by an alignment system ALG provided in the exposure apparatus. When a wavefront aberration measuring device is used for measuring the wavefront aberration, for example, a wavefront aberration measuring device having an overall shape that can be exchanged with a wafer holder may be used as the wavefront aberration measuring device. In such a case, this wavefront aberration measuring instrument
Automatic transfer is possible using a transfer system (such as a wafer loader) for exchanging wafers or wafer holders. With such various measures, the computer system 10 can automatically perform the above-described automatic adjustment of the imaging characteristics of the projection optical system PL and the setting of the best exposure conditions without the intervention of an operator or a service engineer. It is also possible. In the above embodiment, the case where the wavefront aberration measuring device 80 is detachable from the wafer stage has been described. However, the wavefront aberration measuring device 80 may be permanently provided on the wafer stage. At this time, only a part of the wavefront aberration measuring device 80 may be placed on the wafer stage, and the rest may be placed outside the wafer stage. Further, in the above embodiment, the aberration of the light receiving optical system of the wavefront aberration measuring device 80 is neglected, but the wavefront aberration of the projection optical system may be determined in consideration of the wavefront aberration.

Further, all of the first to third programs described in the above embodiment and the database attached thereto are stored in advance in the information recording medium or the storage device 42 set in the drive device 46 of the exposure device 122. In addition, the exposure apparatus 122 alone can be used to automatically adjust the above-described imaging characteristics of the projection optical system PL and set the best exposure conditions. Further, a dedicated server (corresponding to the above-described second communication server 130) connected to the exposure apparatus via a LAN or the like is installed in the factory of the maker A, and the first to third programs and the like are stored in this dedicated server. good. In short, the present invention is not limited to the configuration of FIG.
The installation location of a computer (such as a server) for storing the program may be arbitrary.

In the above embodiment, the case where the stepper is used as the exposure apparatus has been described. However, the present invention is not limited to this. For example, the mask and the substrate disclosed in US Pat. No. 5,473,410 are moved synchronously. Alternatively, a scanning type exposure apparatus that transfers a mask pattern onto a substrate may be used.

The application of the exposure apparatus in this case is not limited to an exposure apparatus for manufacturing semiconductors. For example, an exposure apparatus for liquid crystal for transferring a liquid crystal display element pattern onto a square glass plate, or a thin film magnetic device. The present invention can be widely applied to an exposure apparatus for manufacturing a pad, a micro machine, a DNA chip, and the like. In addition, it manufactures reticles or masks used not only in microdevices such as semiconductor elements, but also in light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, and charged particle beam exposure apparatuses using electron beams or ion beams. Therefore, the present invention can be applied to an exposure apparatus that transfers a circuit pattern onto a glass substrate or a silicon wafer.

The light source of the exposure apparatus of the above embodiment is
F ₂ laser light source, ArF excimer laser light source is not limited to the ultraviolet pulsed light source such as KrF excimer laser light, a continuous light source, for example, g-line (wavelength 436 nm), i-line (wavelength 36
It is also possible to use an ultra-high pressure mercury lamp that emits a bright line such as 5 nm).

Further, a single-wavelength laser beam in the infrared or visible range oscillated from a DFB semiconductor laser or a fiber laser is amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium), and nonlinearly amplified. It is also possible to use a harmonic whose wavelength has been converted to ultraviolet light using an optical crystal. Further, the magnification of the projection optical system is not limited to the reduction system, and may be any one of the same magnification and the enlargement system. Further, the projection optical system is not limited to the refractive system, and a catadioptric system (catadioptric system) having a reflective optical element and a refractive optical element or a reflective system using only a reflective optical element may be used. When a catadioptric system or a catoptric system is used as the projection optical system PL, the position of a reflective optical element (such as a concave mirror or a reflective mirror) is changed as the above-mentioned movable optical element to change the imaging characteristics of the projection optical system. adjust. Further, as the illumination light EL, F ₂ laser light, Ar ₂ laser light, or EUV
When light or the like is used, the projection optical system PL may be an all-reflection system including only reflection optical elements. However, when Ar ₂ laser light or EUV light is used, the reticle R is also of a reflection type.

A semiconductor device has a step of designing the function and performance of the device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and a step of manufacturing a reticle by the exposure apparatus of the above-described embodiment. Transferring the pattern to the wafer,
It is manufactured through a device assembly step (including a dicing step, a bonding step, and a package step), an inspection step, and the like. According to this device manufacturing method, in the lithography step, exposure is performed using the exposure apparatus of the above-described embodiment, so that the imaging characteristics are adjusted according to the target pattern or the image formation is performed based on the measurement result of the wavefront aberration. Since the pattern of the reticle R is transferred onto the wafer W via the projection optical system PL whose image characteristics have been adjusted with high accuracy, it is possible to transfer the fine pattern onto the wafer W with high overlay accuracy. Therefore, the yield of devices as final products is improved, and the productivity thereof can be improved.

[0304]

As described above, according to each of the specification determining methods according to the first to eleventh aspects, when the projection optical system is manufactured according to the determined specifications, the manufacturing process can be simplified. At the same time, the target to be achieved by the optical device can be reliably achieved by the manufactured projection optical system.

Further, according to each of the computer systems according to the twelfth to fifteenth aspects, it is possible to determine specifications that can simplify the manufacturing process of the projection optical system, and to manufacture the projection optical system. The system allows the optical device to reliably achieve the goals to be achieved.

According to each of the computer systems according to the sixteenth to twenty-seventh aspects, the setting of the optimum exposure condition can be performed almost completely automatically.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a computer system according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a configuration of a _first exposure apparatus 1221 of FIG.

FIG. 3 is a sectional view showing an example of a wavefront aberration measuring device.

FIG. 4A is a diagram showing a light beam emitted from a microlens array when no aberration exists in the optical system, and FIG. 4B shows a case where aberration exists in the optical system. FIG. 3 is a diagram illustrating a light beam emitted from a microlens array.

FIG. 5 is a flowchart showing a control algorithm executed by a CPU in a second communication server when setting the best exposure condition of the exposure apparatus.

FIG. 6 is a schematic perspective view showing a measurement reticle.

FIG. 7 is a diagram showing a schematic diagram of an XZ section near the optical axis of the measurement reticle in a state where the reticle is mounted on a reticle stage, together with a schematic diagram of a projection optical system.

FIG. 8 is a diagram showing a schematic diagram of an XZ section near the −Y side end of the measurement reticle in a state where the reticle is mounted on a reticle stage, together with a schematic diagram of a projection optical system.

FIG. 9A is a diagram showing a measurement pattern formed on a measurement reticle of the present embodiment, and FIG.
FIG. 3 is a diagram showing a reference pattern formed on a measurement reticle of the present embodiment.

10A is a view showing a reduced image (latent image) of a measurement pattern formed at a predetermined interval on a resist layer on a wafer, and FIG. 10B is a view showing FIG. FIG. 7B is a diagram illustrating the positional relationship between the latent image of the measurement pattern and the latent image of the reference pattern.

FIG. 11 is a flowchart schematically showing a manufacturing process of the projection optical system.

FIG. 12 is a diagram illustrating a configuration of a computer system according to a modification.

[Explanation of symbols]

10 ... computer system, _131-134 ... (part of the adjustment device) movable lens, 48 ... (part of the adjustment device) imaging characteristic correction controller 50 ... (part of the adjustment device) main control unit, 120 ... first communication server (first computer) 122 ₁ to 122 ₃ ... exposure apparatus (optical apparatus), 13
0: second communication server (second computer), PL: projection optical system, W: wafer (substrate).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H087 KA21 NA01 NA04 NA09 2H097 CA13 GB01 LA10 5F046 AA28 BA04 BA05 CB12 CB25 DA13

Claims (30)

[Claims] 1. A specification determining method for determining specifications of a projection optical system used in an optical device, comprising: a first step of obtaining target information to be achieved by the optical device; A second step of determining the specifications of the projection optical system with the wavefront aberration to be satisfied by the optical system as a standard value. 2. In the second step, among the coefficients of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system, a coefficient of a specific term selected based on the target information is set as a standard value and the projection optical system is used. 2. The specification determining method according to claim 1, wherein the specification of the system is determined. 3. In the second step, an RMS value of a coefficient of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system is set as a standard value, and the RMS value in the entire visual field of the projection optical system is set to a predetermined value. 2. The specification determining method according to claim 1, wherein the specification of the projection optical system is determined so as not to exceed an allowable value. 4. In the second step, the value of the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system is set as a standard value, and the coefficient does not exceed each individually set allowable value. 2. The specification determination method according to claim 1, wherein the specification of the projection optical system is determined. 5. In the second step, among the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system, the coefficient of the n-th order mθ term corresponding to a particular aberration of interest of the projection optical system is obtained. 2. The specification determining method according to claim 1, wherein an RMS value in the field of view is a standard value, and the specification of the projection optical system is determined so that the RMS value does not exceed a predetermined allowable value. 6. In the second step, among the coefficients of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system, each term corresponding to a particular aberration of interest is divided into a plurality of groups for each mθ term. The RMS value of the coefficient of each term included in each group within the field of view of the projection optical system is defined as a standard value,
2. The specification determining method according to claim 1, wherein the specification of the projection optical system is determined such that the RMS value of each group does not exceed each individually determined allowable value. 7. In the second step, the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system is weighted according to the target information, and the RMS value of the coefficient of each term after weighting is set to a standard value. The specification determining method according to claim 1, wherein the specification of the projection optical system is determined such that an RMS value of the coefficient of each of the terms after the weighting does not exceed a predetermined allowable value. 8. The specification determining method according to claim 1, wherein the target information includes information on a pattern to be projected by the projection optical system. 9. The second step of performing a simulation for obtaining an aerial image formed on an image plane when the pattern is projected by the projection optical system based on the information on the pattern; Analyzing the simulation result to determine a wavefront aberration allowed for the projection optical system as a standard value so that the pattern is satisfactorily transferred, as a standard value. Method. 10. In the simulation, the sensitivity of the coefficient of each term of the Zernike polynomial obtained by expanding the wavefront of the projection optical system, which is determined according to the pattern with respect to a specific aberration when the pattern is a target pattern, 10. The specification determining method according to claim 9, wherein the aerial image is obtained based on a linear combination of coefficients of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system. 11. The specification determining device according to claim 1, wherein the optical device is an exposure device that transfers a predetermined pattern onto a substrate via the projection optical system. Method. 12. A computer system for determining specifications of a projection optical system used in an optical device, comprising: a first computer to which target information to be achieved by the optical device is input; and a communication to the first computer. And a specification of the projection optical system based on the target information received from the first computer via the communication path, with a wavefront aberration to be satisfied by the projection optical system as a standard value. And a second computer. 13. The target information includes information on a pattern to be projected by the projection optical system, wherein the second computer projects the pattern by the projection optical system based on the information on the pattern. A simulation for obtaining an aerial image formed on the image plane is performed, and the simulation result is analyzed to determine a wavefront aberration allowed for the projection optical system as a standard value so that the pattern is transferred well. The computer system according to claim 12, wherein: 14. The second computer, when the pattern is a target pattern, determines a coefficient of a coefficient of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system, which is determined according to the pattern with respect to a specific aberration. 14. The computer system according to claim 13, wherein the aerial image is obtained based on a linear combination of sensitivity and coefficients of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system. 15. The computer system according to claim 12, wherein the optical device is an exposure device that transfers a predetermined pattern onto a substrate via the projection optical system. . 16. A first computer connected to an exposure apparatus main body for transferring a predetermined pattern onto a substrate via a projection optical system; and a first computer connected to the first computer via a communication path, and via the communication path. A spatial image formed on an image plane when the pattern is projected by the projection optical system based on the information on the pattern received from the first computer and the known aberration information of the projection optical system. A second computer that performs the simulation of the above and analyzes the simulation result to determine the best exposure condition. 17. The computer system according to claim 16, wherein the information on the pattern is inputted to the first computer as a part of an exposure condition. 18. An information reading apparatus for reading information on the pattern recorded on the mask on a transport path of the mask to the exposure apparatus main body, wherein the information on the pattern is provided via the information reading apparatus. The computer system according to claim 1, wherein the computer system is input to a first computer. 19. The computer according to claim 16, wherein the second computer transmits the determined best exposure condition to the first computer via the communication path. system. 20. The computer system according to claim 19, wherein the first computer sets the best exposure condition as an exposure condition of the exposure apparatus main body. 21. The second computer calculates a coefficient of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system, which is determined according to the pattern with respect to a specific aberration when the pattern is a target pattern. Sensitivity and the first
The space based on a linear combination of coefficients of each term of a Zernike polynomial obtained by expanding a wavefront of the projection optical system obtained based on a measurement result of the wavefront of the projection optical system transmitted from the computer via the communication path. 21. The computer system according to claim 16, wherein an image is obtained. 22. The computer system according to claim 21, wherein the measurement result of the wavefront is input to the first computer. 23. The apparatus according to claim 23, further comprising a wavefront measuring device for measuring a wavefront of the projection optical system, wherein the measurement result of the wavefront is obtained by the first computer as a measurement result of the wavefront by the wavefront measuring device. 22. The computer system according to claim 21, wherein: 24. The computer system according to claim 16, wherein the best exposure condition includes information on a pattern suitable for exposure by the exposure apparatus main body. 25. The method according to claim 16, wherein the best exposure condition includes at least one of an illumination condition for transferring the predetermined pattern and a numerical aperture of the projection optical system.
24. The computer system according to any one of claims 23 to 23. 26. The computer system according to claim 16, wherein the best exposure condition includes an aberration of the projection optical system when transferring the predetermined pattern. 27. The image forming apparatus according to claim 27, further comprising an adjusting device that adjusts a state of forming the projection image of the pattern by the projection optical system included in the exposure apparatus main body connected to the second computer via the communication path, The computer system according to any one of claims 16 to 26, wherein the computer controls the adjusting device based on the determined best exposure condition. 28. The computer system according to claim 12, wherein said communication path is a local area network. 29. The computer system according to claim 12, wherein said communication path includes a public line. 30. The computer system according to claim 12, wherein said communication path includes a wireless line.