JP2003214984A - Optical characteristic measuring method and optical characteristic measuring device, adjusting method of optical system and exposing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely measure the optical characteristic of an optical system to be inspected. <P>SOLUTION: A mask RT having a prescribed pattern formed thereon is irradiated through a light diffusing member DF, at least one position of the light diffusing member DF, the mask RT, and a light receiving opening 91a is changed, and the light through the light receiving opening 9a is wave- surfacewise divided to form a plurality of pattern images. Successively, the position information of each of the formed pattern images is detected. Consequently, position information for a plurality of spot images in the state where the diffusion unevenness of light by the light diffusing member is reduced by a certain sort of averaging effects is detected. On the basis of the detected position information for the spot images, the optical characteristic of the optical system to be inspected PL is calculated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical characteristic measuring method, an optical characteristic measuring apparatus, an optical system adjusting method, and an exposure apparatus, and more particularly to an optical characteristic measuring method for measuring an optical characteristic of a test optical system. The present invention relates to a method and an optical characteristic measuring device, an adjusting method of an optical system using the optical characteristic measuring method, and an exposure apparatus including the optical characteristic measuring device.

[0002]

2. Description of the Related Art Conventionally, in a lithography process for manufacturing a semiconductor device, a liquid crystal display device, etc., a pattern (hereinafter also referred to as a "reticle pattern") formed on a mask or a reticle (hereinafter collectively referred to as "mask"). A substrate such as a wafer or a glass plate coated with a resist or the like through a projection optical system (hereinafter collectively referred to as “substrate” as appropriate)
An exposure device that transfers images onto the top is used. As such an exposure apparatus, a static exposure type exposure apparatus such as a so-called stepper and a scanning exposure type exposure apparatus such as a so-called scanning stepper are mainly used.

In such an exposure apparatus, it is necessary to faithfully project the pattern formed on the reticle onto the substrate with high resolution. Therefore, the projection optical system is designed to have good optical characteristics in which various aberrations are sufficiently suppressed.

However, it is difficult to manufacture the projection optical system exactly as designed, and various aberrations due to various factors remain in the actually manufactured projection optical system.
Therefore, the optical characteristics of the projection optical system actually manufactured are
It will be different from the designed optical characteristics.

Therefore, various techniques have been proposed for measuring optical characteristics such as aberrations of an optical system to be tested such as an actually manufactured projection optical system. Among the various proposed technologies, (1) a spherical wave generated by using a pinhole is incident on a test optical system, and a pinhole image after passing through the test optical system is once converted into parallel light. And (2) forming a spot image for each of the divided wavefronts and measuring the wavefront aberration of the optical system under test based on the spot image formation position for each divided wavefront. Wavefront aberration measurement technology is drawing attention.

In a wavefront aberration measuring apparatus using such a wavefront aberration measuring technique, for example, as a wavefront dividing element that divides the wavefront of incident light to form a spot image for each divided wavefront, two parallel light beams are formed. By adopting a microlens array in which a large number of minute lenses are arranged along a dimensional plane, it is possible to easily configure. In this case, a large number of spot images formed by the microlens array are picked up by an image pickup device such as CCD, and the center of gravity of the image pickup waveform of each spot image is obtained by the center of gravity method, or the image pickup waveform of each spot image and the template waveform are obtained. The spot image position is detected by, for example, obtaining the maximum correlation position of by the correlation method.
Then, from the deviation of each detected spot image position from the design position, for example, the coefficient in the Zernike polynomial expansion of the wavefront shape is calculated to obtain the wavefront aberration.

When the measurement of the wavefront aberration is applied to, for example, a bilateral telecentric projection optical system in an exposure apparatus, the light passing through the pinhole pattern of the reticle is focused after passing through the projection optical system, and then the wavefront. Splitting is done. Then, a spot image is formed for each divided wavefront, the inclination of the wavefront is obtained from the positional relationship of the multiple spot images, and the wavefront aberration can be obtained by reconstructing the wavefront. Using the pinhole pattern of such a reticle, the numerical aperture (hereinafter referred to as “N
Light having a uniform intensity can be incident on a projection optical system in an exposure apparatus having a large size (also referred to as “A”) in a wide range by diffraction.

However, since the NA of the projection optical system is large, the size of the pinhole pattern on the reticle is
It is necessary to make the size of the wavelength of the measuring light, that is, the wavelength of the exposure light. Therefore, the amount of light that passes through the pinhole pattern and enters the projection optical system becomes extremely small, and the required measurement time becomes extremely long. Therefore, in order to secure both the amount of light incident on the projection optical system and the incidence of highly uniform light on the projection optical system over a wide range, instead of using the pinhole pattern, the wavelength of the measuring light should be about the same. A method has been proposed in which an opening pattern having a larger diameter is formed on a reticle, and illumination light is applied to the reticle after passing through a diffusion plate such as a lemon skin plate.

[0009]

In the conventional wavefront aberration measuring method using the above-mentioned diffusing plate, since an aperture pattern larger than the wavelength of the measuring light is used, the light which is not diffracted by the projection optical system is not detected. It will be incident. For this reason, in the pupil plane of the projection optical system, unevenness of the light amount distribution inevitably occurs due to uneven diffusion of light by the diffusion plate.

When such nonuniformity of the light quantity distribution occurs in the divided wavefront, the shape of the spot image on the divided wavefront changes depending on the nonuniformity of the light quantity distribution. As a result, the detection accuracy of the spot image position deteriorates, which in turn lowers the measurement accuracy of the wavefront aberration.

[0011] By the way, due to the demand for improvement of exposure accuracy accompanying the progress of high integration in semiconductor devices in recent years, there is a strong demand for improvement in accuracy of wavefront aberration measurement of a projection optical system in an exposure apparatus. Therefore, there is a strong demand for a technique capable of preventing the measurement accuracy of the wavefront aberration from being reduced due to the uneven diffusion caused by the diffusion plate.

The present invention has been made under such circumstances, and a first object thereof is an optical characteristic measuring method and an optical characteristic measuring method capable of measuring the optical characteristic of an optical system to be tested quickly and accurately. It is to provide a characteristic measuring device.

A second object of the present invention is to provide an optical system adjusting method capable of adjusting the optical characteristics of the optical system quickly and accurately.

A third object of the present invention is to provide an exposure apparatus capable of accurately transferring a predetermined pattern onto a substrate.

[0015]

According to the optical characteristic measuring method of the present invention, a light diffusing member (DF), a mask (PT, PT ') on which a predetermined pattern is formed, and an optical system (PL) to be tested are sequentially arranged. An optical characteristic measuring method for measuring the optical characteristic of the optical system to be tested based on the light having reached the light receiving opening (91a) after passing through the light receiving opening (91a). Positions of at least one of the light diffusing member, the mask, and the light receiving opening are changed, the light passing through the light receiving opening is wavefront-divided to form a plurality of pattern images, and the positions of the plurality of pattern images A pattern image position detecting step of detecting information; and an optical characteristic calculating step of calculating optical characteristics of the optical system to be inspected based on position information of each of the plurality of pattern images detected in the pattern image position detecting step. Is a method for measuring optical characteristics.

According to this, in the pattern image position detecting step, the mask on which a predetermined pattern is formed is irradiated through the light diffusing member, and at least one position of the light diffusing member, the mask and the light receiving opening is set. The light passing through the light-receiving opening is changed to be wavefront-divided to form a plurality of pattern images. Then, the position information of each of the plurality of pattern images is detected. As a result, it is possible to quickly detect the positional information of the plurality of spot images in a state where the unevenness of light diffusion by the light diffusing member is reduced by a kind of averaging effect.

Subsequently, in the optical characteristic calculating step, the optical characteristic of the optical system to be tested is calculated based on the position information of the plurality of spot images detected in the pattern image position detecting step. In the calculation result of the optical characteristic, the decrease in accuracy of the measurement result of the optical characteristic due to the uneven diffusion of light by the light diffusion member is suppressed.

Therefore, according to the optical characteristic measuring method of the present invention, the optical characteristic of the optical system to be tested can be measured quickly and accurately.

In the optical characteristic measuring method of the present invention, in the relative position changing step, while maintaining the conjugate positional relationship between the mask and the light receiving aperture with respect to the optical system under test,
The mask and the light diffusing member may be moved relative to each other.

Here, the predetermined pattern may be a circular opening, and the stroke of the relative movement may be about the diameter of the circular opening.

Further, in the optical characteristic measuring method of the present invention, in the pattern image position detecting step, the mask and the light receiving opening are relatively moved while maintaining the positional relationship between the light diffusing member and the mask. Can be Here, the predetermined pattern is defined as a plurality of openings, and the relative movement of the mask and the light receiving opening is relatively moved such that the light receiving opening sequentially goes around a conjugate position of each of the plurality of openings with respect to the test optical system. Can be

Further, in the optical characteristic measuring method of the present invention, the pattern image can be a spot image.

In the optical characteristic measuring method of the present invention, the optical characteristic can be wavefront aberration.

The optical characteristic measuring apparatus of the present invention uses the light reaching the light receiving opening (91a) after sequentially passing through the mask (PT, PTA) on which a predetermined pattern is formed and the test optical system (PL). An optical characteristic measuring device for measuring the optical characteristic of the optical system to be inspected based on a light diffusing member (DF) for diffusing incident light and emitting the light toward the mask.
An image information detecting device (90) having the light receiving opening, dividing the light passing through the light receiving opening into wavefronts to form a plurality of pattern images, and detecting information of the plurality of pattern images. For the light reaching the light receiving opening, the light diffusing member,
A drive device (23, 24) for changing the position of at least one of the mask and the image detection device; a position for calculating position information of each of the plurality of pattern images based on a detection result by the image information detection device An information calculation device (32); based on the position information of each of the plurality of pattern images calculated by the position information calculation device,
An optical characteristic measuring device comprising: an optical characteristic calculating device (33) for calculating the optical characteristic of the test optical system.

According to this, the light is transmitted through the light diffusing member to the mask, and the driving device changes at least one position of the light diffusing member, the mask, and the image information detecting device (that is, the light receiving opening). Let In this state, the image detection device forms a plurality of pattern images by dividing the light that has passed through the light receiving opening into wavefronts. Then, the position information calculation device detects the position information of each of the formed plurality of pattern images. Subsequently, the optical characteristic calculation device calculates the optical characteristic of the test optical system based on the position information of the plurality of spot images detected by the position information calculation device. That is, the optical characteristic measuring apparatus of the present invention can measure the optical characteristic of the test optical system by using the optical characteristic measuring method of the present invention described above.

Therefore, according to the optical characteristic measuring apparatus of the present invention, the optical characteristic of the optical system to be tested can be measured quickly and accurately.

In the optical characteristic measuring apparatus of the present invention, the image information detecting apparatus divides the light passing through the light receiving opening into wavefronts to form the plurality of patterns.
And an image detecting device (9) for detecting the plurality of pattern images.
5) and; can be provided.

Here, the wavefront splitting member may be a microlens array in which a plurality of lens elements (94a) are arranged.

In the optical characteristic measuring device of the present invention, the optical characteristic can be wavefront aberration.

The optical system adjusting method of the present invention is an optical system adjusting method for adjusting the optical characteristics of an optical system, wherein the optical characteristics of the optical system are measured using the optical characteristic measuring method of the present invention. An optical system adjusting method comprising: an optical characteristic measuring step; and an optical characteristic adjusting step of adjusting an optical characteristic of the optical system based on a measurement result in the optical characteristic measuring step.

According to this, in the optical characteristic measuring step, the optical characteristic of the optical system is accurately measured by the optical characteristic measuring method of the present invention. Then, in the optical characteristic adjusting step, the optical characteristic of the optical system is adjusted based on the accurately measured optical characteristic. Therefore, the desired optical characteristics of the optical system can be adjusted quickly and accurately.

The exposure apparatus of the present invention is an exposure apparatus which transfers a predetermined pattern onto the substrate (W) by irradiating the substrate with the exposure light, and is a projection optical system arranged on the optical path of the exposure light. (PL); and an optical characteristic measuring device of the present invention, which uses the projection optical system as an optical system to be tested.

According to this, a predetermined pattern is formed by using the projection optical system in which the optical characteristic measuring device of the present invention accurately measures the optical characteristic and the optical characteristic is guaranteed to be well adjusted. It can be transferred to a substrate. Therefore, the predetermined pattern can be accurately transferred to the substrate.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION << First Embodiment >> A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the schematic arrangement of an exposure apparatus 100 according to the first embodiment of the present invention. The exposure apparatus 100 is a step-and-scan type projection exposure apparatus. The exposure apparatus 100 includes an exposure apparatus main body 6
0 and the wavefront aberration measuring device 70.

The exposure apparatus main body 60 includes an illumination system 10, a holding member DFH holding a lemon skin plate DF as a light diffusing member, and a reticle stage RS holding a reticle R.
T, projection optical system PL as a test optical system, substrate (object)
Wafer stage WST as a stage device on which the wafer W as a substrate is mounted, an alignment detection system AS, a reticle stage RST and a stage control system 19 for controlling the position and orientation of the wafer stage WST, and a main control system for integrally controlling the entire device. Equipped with 20 etc.

The illumination system 10 includes a light source, an illuminance uniformizing optical system including an optical integrator such as a fly-eye lens, a relay lens, a variable ND filter, a reticle blind, and a dichroic mirror (all not shown). Has been done. The configuration of such an illumination system is disclosed in, for example, Japanese Patent Laid-Open No. 10-112433. In this illumination system 10, a slit-shaped illumination area portion defined by a reticle blind on a reticle R on which a circuit pattern or the like is drawn is illuminated with illumination light IL with a substantially uniform illuminance.

A lemon skin plate DF can be fixed on the holding member DFH by, for example, vacuum suction. The holding member DFH has a hollow rectangular shape in plan view, and the illumination light IL via the lemon skin plate DF passes through the hollow portion of the holding member DFH. Further, the holding member DFH is fixed to a casing member (not shown) in the exposure apparatus main body 60. The lemon skin plate D is used only when measuring the wavefront aberration of the projection optical system PL.
F is mounted on the holding member DFH, and the lemon skin plate DF is removed from the holding member DFH for the pattern transfer exposure operation.

The reticle R is fixed on the reticle stage RST by, for example, vacuum suction. The reticle stage RST is an optical axis of the illumination system 10 (an optical axis of a projection optical system PL described later) for positioning the reticle R by a reticle stage drive unit (not shown) including a magnetically levitated two-dimensional linear actuator. It can be finely driven in the XY plane perpendicular to AX) and has a predetermined scanning direction (here, the Y direction).
It can be driven at the scanning speed specified in. Further, in the present embodiment, the magnetic levitation type two-dimensional linear actuator is provided with Z drive coil in addition to X drive coil and Y drive coil.
Since it includes a driving coil, it can be finely driven also in the Z direction.

The position of the reticle stage RST on the stage moving surface is constantly detected by a reticle laser interferometer (hereinafter referred to as "reticle interferometer") 16 via a moving mirror 15 with a resolution of, for example, about 0.5 to 1 nm. To be done. Position information (or speed information) of the reticle stage RST from the reticle interferometer 16 is sent to the main control system 20 via the stage control system 19, and the main control system 20 uses the position information (or speed information) as a basis. Reticle stage R via stage control system 19 and reticle stage drive unit 23
Drive ST.

The projection optical system PL is arranged below the reticle stage RST in FIG. 1, and its optical axis AX is in the Z-axis direction. The projection optical system PL is, for example, a both-side telecentric reduction system, and is composed of a plurality of lens elements (not shown) having a common optical axis AX in the Z-axis direction. In addition, this projection optical system P
As L, the projection magnification β is, for example, 1/4, 1/5, 1 /
Something like 6 is used. Therefore, as described above, when the illumination area on the reticle R is illuminated by the illumination light (exposure light) IL, the pattern formed on the reticle R is reduced by the projection optical system PL at the projection magnification β. The image (partially inverted image) is projected and transferred onto a slit-shaped exposure area on the wafer W having a resist (photosensitive agent) applied on its surface.

In this embodiment, among the plurality of lens elements described above, specific lens elements (for example, five predetermined lens elements) can be independently moved. Such movement of the lens element is performed by driving elements such as three piezo elements provided for each specific lens, which support a lens supporting member that supports the specific lens element and are connected to the lens barrel portion. There is. That is, the specific lens elements can be independently moved in parallel along the optical axis AX according to the displacement amount of each drive element, or a desired inclination can be given to a plane perpendicular to the optical axis AX. You can also do it. Then, the drive instruction signals given to these drive elements are controlled by the imaging characteristic correction controller 51 based on the instruction MCD from the main control system 20, whereby the displacement amount of each drive element is controlled. ing.

In the projection optical system PL thus constructed,
By controlling the movement of the lens element via the imaging characteristic correction controller 51 by the main control system 20, optical characteristics such as distortion, field curvature, astigmatism, coma, or spherical aberration can be adjusted.

The wafer stage WST is arranged on a base (not shown) below the projection optical system PL in FIG. 1, and the wafer holder 2 is placed on the wafer stage WST.
5 is placed. The wafer W is fixed on the wafer holder 25 by, for example, vacuum suction. The wafer holder 25 can be tilted in an arbitrary direction with respect to a plane orthogonal to the optical axis of the projection optical system PL by a drive unit (not shown), and can be finely moved in the optical axis AX direction (Z direction) of the projection optical system PL. ing. Further, the wafer holder 25 is also capable of a minute rotation operation around the optical axis AX.

On the + Y direction side of wafer stage WST, a bracket structure for attaching / detaching a wavefront sensor 90 described later is formed.

The wafer stage WST is not only moved in the scanning direction (Y direction), but is also perpendicular to the scanning direction so that a plurality of shot areas on the wafer W can be positioned in an exposure area conjugate with the illumination area. Direction (X direction), the operation of scanning and exposing each shot area on the wafer W and the operation of moving to the exposure start position of the next shot are repeated. Perform scan operation. This wafer stage WST
Is XY by the wafer stage drive unit 24 including a motor and the like.
It is driven in two dimensions.

The position of wafer stage WST in the XY plane is adjusted by a wafer laser interferometer (hereinafter referred to as “wafer interferometer”) 18 via a movable mirror 17 to, for example, 0.5.
It is constantly detected with a resolution of about 1 nm. Position information (or speed information) of wafer stage WST is sent to main control system 20 via stage control system 19, and main control system 20
Performs drive control of wafer stage WST via stage control system 19 and wafer stage drive unit 24 based on this position information (or speed information).

The alignment detection system AS is arranged on the side surface of the projection optical system PL, and in the present embodiment, an image formation alignment for observing the street lines and the position detection marks (fine alignment marks) formed on the wafer W. An off-axis type detection system including a sensor is used. The detailed configuration of this alignment detection system AS is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-219354. The observation result by the alignment detection system AS is supplied to the main control system 20.

Further, the apparatus shown in FIG. 1 has an oblique incident light type focus detection system (focus) for detecting the position in the Z direction (optical axis AX direction) inside the exposure area on the surface of the wafer W and in the vicinity thereof. A multi-point focus position detection system (21, 22), which is one of the detection systems), is provided. The multi-point focus position detection system (21, 22) is an irradiation optical system 21 including an optical fiber bundle, a condenser lens, a pattern forming plate, a lens, a mirror, and an irradiation objective lens (all not shown).
And a light receiving optical system 22 including a condenser objective lens, a rotation direction vibrating plate, an image forming lens, a light receiving slit plate, and a light receiver (not shown) having a large number of photosensors. This multi-point focus position detection system (21,
22), for details of the configuration, refer to, for example, Japanese Patent Laid-Open No. 6-2
It is disclosed in Japanese Patent No. 83403. The detection result of the multipoint focus position detection system (21, 22) is supplied to the stage control system 19.

The wavefront aberration measuring device 70 comprises a wavefront sensor 90 and a wavefront data processing device 80.

As shown in FIG. 2, the wavefront sensor 90 includes a marking plate 91, a collimator lens 92, and a lens 93.
A relay lens system 93 including a and a lens 93b, a microlens array 94 as a wavefront dividing element, and a CCD 95 as an image pickup device are provided, and are arranged in this order on the optical axis AX1. In addition, the wavefront sensor 90
Is a mirror 96a, 96b, 96c for setting the optical path of the light incident on the wavefront sensor 90, and a collimator lens 9
2, relay lens system 93, microlens array 94,
A storage member 97 for storing the CCD 95 and the mirrors 96a, 96b, 96c is further provided.

The marking plate 91 is made of, for example, a glass substrate as a base material, and is arranged at the same height position (Z direction position) as the surface of the wafer W fixed to the wafer holder 25 so as to be orthogonal to the optical axis AX1. (See Figure 1). This signboard 91
As shown in FIG. 3, an opening 91a is formed in the center of the surface of the. In addition, three or more pairs (in FIG.
A pair of two-dimensional position detection marks 91b are formed. In this embodiment, a combination of a line and space mark 91c formed along the X direction and a line and space mark 91d formed along the Y direction is used as the two-dimensional position detection mark 91b. ing. The line and space marks 91c, 91
d can be observed by the alignment detection system AS described above. The surface of the marking plate 91 except for the opening 91a and the two-dimensional position detecting mark 91b is processed to have a reflecting surface. Such reflection surface processing is performed, for example, by depositing chromium (Cr) on a glass substrate.

Returning to FIG. 2, the collimator lens 92 is
Converts the light incident through the opening 91a into a plane wave.

As shown in FIG. 4, the microlens array 94 has a large number of square microlenses 94a having a positive refracting power arranged densely in a matrix. Here, the optical axes of the microlenses 94a are substantially parallel to each other. In FIG. 4, the microlenses 94a arranged in a 7 × 7 matrix are shown as an example. The microlenses 94a are not limited to have a square shape, but may have a rectangular shape, and all the microlenses 94a do not have to have the same shape. The microlenses 94a in the microlens array 94 may be arranged in a non-uniform pitch arrangement or may be arranged in a diagonal arrangement.

The microlens array 94 as described above is formed by subjecting a parallel flat glass plate to an etching process. The microlens array 94 forms an image of the opening 91a at different positions for each microlens 94a on which light is incident via the relay lens system 93.

The collimator lens 92, the relay lens system 93, the microlens array 94, and the mirror 96.
The optical system composed of a, 96b, and 96c is hereinafter referred to as "wavefront aberration measuring optical system".

Returning to FIG. 2, the CCD 95 has an image forming surface on which an image of an aperture pattern, which will be described later, formed in the aperture 91a by each microlens 94a of the microlens array 94 is formed, that is, a wavefront aberration measuring optical system. Has a light receiving surface on the conjugate surface of the formation surface of the opening 91a, and picks up images of a large number of aperture patterns formed on the light receiving surface. The imaging result is supplied to the wavefront data processing device 80 as imaging data IMD.

The housing member 97 has a support member (not shown) for supporting the collimator lens 92, the relay lens system 93, the microlens array 94, and the CCD 95 therein. Incidentally, the mirrors 96a, 96
b and 96c are attached to the inner surface of the storage member 97. Further, the outer shape of the storage member 97 has a shape that fits with the bracket structure of the wafer stage WST described above, and is detachable from the wafer stage WST.

The wavefront data processing device 80, as shown in FIG. 5, comprises a main control device 30 and a storage device 40. The main controller 30 (a) controls the entire operation of the wavefront data processing device 80 under the control of the main control system 20, and supplies the wavefront measurement result data WFA to the main control system 20, and ( b) an imaging data collection device 31 that collects the imaging data IMD from the wavefront sensor 90,
(C) a position calculation device 32 as a position information calculation device that calculates the position of the spot image based on the image data;
A wavefront aberration calculation device 33 that calculates the wavefront aberration of the projection optical system PL based on the spot image position detected by the position detection device 32 is included.

The storage device 40 also includes (a) an image data storage area 41 for storing image data, and (b) a spot image position storage area 4 for storing the calculated spot image position.
2 and (c) a wavefront aberration data storage area 43 for storing wavefront aberration data.

In this embodiment, the wavefront data processing device 80
As described above, various types of devices are combined, but the wavefront data processing device 80 is configured as a computer system, and the functions of the above-described devices that form the main controller 30 are built into the wavefront data processing device 80. It is also possible to realize by the program.

The exposure operation of the exposure apparatus 100 of this embodiment will be described below with reference to the flowchart shown in FIG.
Description will be given with reference to other drawings as appropriate.

As a premise of the following operation, it is assumed that the wavefront sensor 90 is mounted on the wafer stage WST and the wavefront data processing device 80 and the main control system 20 are connected.

Further, the opening 91a of the marking plate 91 of the wavefront sensor 90 mounted on the wafer stage and the wafer stage W
It is assumed that the positional relationship with ST is accurately obtained by observing the two-dimensional position mark 91b with the alignment detection system AS. That is, based on the position information (speed information) output from the wafer interferometer 18, the opening 91
It is assumed that the XY position of a can be accurately detected, and the opening 91a can be accurately positioned at a desired XY position by controlling the movement of the wafer stage WST via the wafer stage drive unit 24. In this embodiment, the positional relationship between the opening 91a and the wafer stage WST is determined by the four two-dimensional position marks 91 by the alignment detection system AS.
Based on the detection result of the position of b, Japanese Patent Laid-Open No. 61-4442.
It is accurately detected using a statistical method such as so-called enhanced global alignment (hereinafter, referred to as “EGA”) disclosed in Japanese Patent Publication No. 9 and the like.

In the processing shown in FIG. 6, first, in the subroutine 101, the wavefront aberration of the projection optical system PL is measured. In the measurement of this wavefront aberration, as shown in FIG. 7, first, in step 111, the lemon skin plate DF is placed on the holding member DFH, and the wavefront shown in FIG. The measurement reticle RT for aberration measurement is loaded on the reticle stage RST. As shown in FIG. 8, the measurement reticle RT has a plurality (9 in FIG. 8) of opening patterns PH ₁
.About.PH _N (N = 9 in FIG. 8) are formed in a matrix along the X direction and the Y direction. Note that the opening patterns PH _{1 to} PH _N are formed in the area having the size of the slit-shaped illumination area shown by the dotted line in FIG. 8. Moreover, in this embodiment, each of the opening patterns PH _{1 to} PH _N is a circular opening pattern. The diameter of the circular opening pattern is set to about the wavelength of the illumination light IL or less than the wavelength. In the present embodiment, the diameter of the circular opening pattern may be set so as to pass light that can be regarded as a spherical wave within the range of NA of the optical system to be tested, and is set larger than the wavelength of the illumination light IL. .

Subsequently, reticle alignment using a reference mark plate (not shown) arranged on wafer stage WST, and baseline amount measurement using alignment detection system AS are performed. Then, reticle stage RST is moved so that the first aperture pattern PH _{1 for} which aberration measurement is performed is located on optical axis AX of projection optical system PL. Such movement is performed by the main control system 20 controlling the reticle drive unit 23 via the stage control system 19 based on the position information (speed information) of the reticle stage RST detected by the reticle interferometer 16.

[0067] Returning to FIG. 7, then, in step 112, when the opening 91a of marking plate 91 of the wavefront sensor 90, the conjugate position relative to the projection optical system PL of the opening pattern PH ₁ in (opening pattern PH _1, the light Wafer stage WST is moved to the measurement initial position on axis AX), that is, with respect to opening pattern PH ₁ . This movement is performed by the main control system 20.
, But the wafer stage WST detected by the wafer interferometer 18
Based on the position information (speed information) of the stage control system 1
This is performed by controlling the wafer stage drive unit 24 via the control unit 9. At this time, the main control system 20 uses the wavefront sensor 9 on the image plane on which the image of the aperture pattern PH ₁ is formed, based on the detection results of the multipoint focus position detection system (21, 22).
The wafer stage WST is finely driven in the Z-axis direction via the wafer stage drive unit 24 so that the upper surface of the marking plate 91 of 0 is aligned.

As described above, the first opening pattern P
The arrangement of each optical device for measuring the wavefront aberration of the projection optical system PL regarding the spherical wave from H ₁ is completed. Regarding such an optical arrangement, the optical axis AX1 of the wavefront sensor 90 is
FIG. 9 shows the projection optical system PL and the projection optical system PL developed along the optical axis.

In such an optical arrangement, when the illumination light IL is emitted from the illumination system 10, the light that reaches the first aperture pattern PH ₁ of the measurement reticle RT becomes a spherical wave and is emitted from the aperture pattern PH. Then, after passing through the projection optical system PL, the opening 9 of the marking plate 91 of the wavefront sensor 90.
It is focused on 1a. The light that has passed through the opening patterns PH _{2 to} PH _N other than the first opening pattern PH ₁ does not reach the opening pattern 91a. The wavefront of the light focused on the opening 91a in this manner includes the wavefront aberration of the projection optical system PL.

In addition to the wavefront aberration of the projection optical system PL, the image plane on which the pinhole image of the pinhole pattern PH ₁ is formed (the image plane of the projection optical system PL) is formed on the wavefront of the light.
X between the wavefront sensor 90 and the upper surface of the marking plate 91,
There is a possibility that it includes a positional deviation component in the Y and Z directions (for example, a tilt component, a positional deviation component in the optical axis direction, etc.). Therefore, the above-mentioned positional deviation component is calculated from the wavefront aberration data obtained by the wavefront aberration measuring device 70, and the position of wafer stage WST is controlled based on this positional deviation component.
Thereby, highly accurate wavefront aberration measurement can be performed.

The light passing through the opening 91a is converted into substantially parallel light by the collimator lens 92, further passes through the relay lens system 93, and then enters the microlens array 94. Here, the wavefront of the light incident on the microlens array 94 reflects the wavefront aberration of the projection optical system PL. That is, when the projection optical system PL has no wavefront aberration, the wavefront WF is a plane orthogonal to the optical axis AX1 as shown by the dotted line in FIG. 9, but the projection optical system PL has wavefront aberration. In fact, as indicated by the chain double-dashed line in FIG. 9, the wavefront WF ′ is inclined at an angle according to the position.

In the microlens array 94, the image of the opening 91a is formed on the conjugate plane of the marking plate 91, that is, the image pickup plane of the CCD 95, for each microlens 94a. When the wavefront of the light incident on the microlens 94a is orthogonal to the optical axis AX1, a spot image centered on the intersection of the optical axis of the microlens 94a and the image pickup surface is formed on the image pickup surface. In addition, when the wavefront of the light incident on the microlens 94a is tilted, only a distance corresponding to the tilt amount,
A spot image centered on a point deviated from the intersection of the optical axis of the microlens 94a and the image pickup surface is formed on the image pickup surface.

Returning to FIG. 7, next, at step 113, the CCD 95 captures the image formed on the image capturing surface while performing the synchronous movement while maintaining the conjugate positional relationship between the aperture pattern PH ₁ and the aperture 91a. . Such synchronous movement causes the reticle stage RST to move in the + Y direction or −Y direction.
While being moved at a velocity V _R direction is performed by moving the wafer stage WST in the reticle stage RST in the driving direction of the opposite direction to the speed _{V W (= β · V R} ). Here, movement of reticle stage RST is performed by main control system 20 controlling reticle stage drive unit 23 via stage control system 19. Further, the movement of wafer stage WST is performed by main control system 20.
Is controlled by controlling the wafer stage drive unit 24 via the stage control system 19.

Incidentally, in the synchronous movement of reticle stage RST and wafer stage WST in step 113, the movement distance of reticle stage RST may be at least about the diameter of opening pattern PH ₁ . Further, the above-mentioned speeds V _R and V _W are determined based on the moving distance of reticle stage RST and the moving distance of wafer stage WST, and the light receiving time (imaging time) required for CCD 95 to image a spot image.

In the imaging performed as described above, the light that is wavefront-divided by the microlens array 94, that is, the aperture pattern PH ₁ , the projection optical system PL, and the marking plate 91.
The non-uniformity of the light intensity distribution caused by the uneven diffusion of the lemon skin plate DF in the light sequentially passing through the opening 91a, the collimator lens 92, and the relay optical system is reduced by the synchronous movement in the imaging period described above. As a result, a spot image is formed at a position that accurately reflects the wavefront shape.

Imaging data IMD obtained by this imaging
Are supplied to the wavefront data processing device 80. In the wavefront data processing device 80, the imaging data collection device 31 collects the imaging data IMD and stores the collected imaging data in the imaging data storage area 41.

Next, in step 114, the position information of each spot image is detected based on the image pickup result. In calculating the position information, the position calculation device 32 reads the image pickup result data from the image pickup data storage area 41. Subsequently, the position calculation device 32 calculates the center position of each spot image by calculating the center of gravity of the light intensity distribution of each spot image formed on the image pickup surface of the CCD 95 by the microlens array 94. The position calculation device 32
The center position of each spot image thus obtained is stored in the spot image position storage area 42 as position information of each spot image formed on the image pickup surface of the CCD 95 by the microlens array 94.

Next, in step 115, the wavefront aberration calculation device 33 reads the detection result of the spot image position from the spot image position storage area 42, and projects the light through the first aperture pattern PH ₁ in the measurement reticle RT. The wavefront aberration of the optical system PL is calculated. The calculation of the wavefront aberration is performed by obtaining the coefficient of the Zernike polynomial from the difference between each spot image position expected when there is no wavefront aberration and the detected spot image position. The wavefront aberration thus calculated is stored in the wavefront aberration data storage area 43 together with the position of the aperture pattern PH ₁ .

Next, at step 116, it is judged if the wavefront aberration of the projection optical system PL has been calculated for all the aperture patterns. At this stage, since the wavefront aberration of the projection optical system PL is only measured for the first aperture pattern PH ₁ , a negative determination is made, and the processing shifts to step 117.

In step 117, the aperture 91a of the marking plate 91 of the wavefront sensor 90 moves the wafer stage WST to the conjugate position of the next aperture pattern PH ₂ with respect to the projection optical system PL, that is, the measurement initial position with respect to the aperture pattern PH ₂ . . This movement is performed by the main control system 20 controlling the wafer stage drive unit 24 via the stage control system 19 based on the position information (speed information) of the wafer stage WST detected by the wafer interferometer 18. . At this time also, the main control system 20 causes the wavefront sensor 9 to be formed on the image plane on which the image of the aperture pattern PH ₂ is formed, based on the detection result of the multipoint focus position detection system (21, 22).
If necessary, the wafer stage WST is finely driven in the Z-axis direction via the wafer stage drive unit 24 in order to make the upper surfaces of the marking plates 91 of 0 coincide with each other.

Even when the upper surface of the marking plate 91 of the wavefront sensor 90 is moved to the image plane on which the pinhole image of the pinhole pattern PH ₂ is formed, as described above, the wavefront aberration measured by the wavefront aberration measuring device 70 is obtained. The above-described position shift component is calculated from the data, and the position of wafer stage WST is controlled based on this position shift component. It is desirable to perform such control for each pinhole pattern.

Then, the wavefront aberration of the projection optical system PL is measured in the same manner as in the case of the above-mentioned aperture pattern PH ₁ . Then, the measurement result of the wavefront aberration is the aperture pattern PH.
It is stored in the wavefront aberration data storage area 43 together with the position ₂ .

Thereafter, similarly to the above, the wavefront aberration of the projection optical system PL for all the aperture patterns is sequentially measured, and the measurement result for each aperture pattern is stored in the wavefront aberration data storage area 43 together with the position of the aperture pattern. It
When the wavefront aberration of the projection optical system PL for all the aperture patterns is measured in this way, a positive determination is made in step 117. Then, the control device 39 reads the measurement result of the wavefront aberration from the wavefront aberration data storage area 43 and supplies it to the main control system 20 as the wavefront measurement result data WFA. After this, the processing shifts to step 102 in FIG.

In step 102, the main control system 20 determines, based on the wavefront measurement result data WFA supplied from the control device 39, whether or not the measurement of the wavefront aberration of the projection optical system PL is below the allowable value. . If this determination is affirmative, the process proceeds to step 104. On the other hand, if the result of the judgment is negative, the procedural steps proceed to step 103. At this stage, the following description will be made assuming that the determination is negative and the process has proceeded to step 103.

In step 103, the main control system 20 reduces the wavefront aberration that is currently occurring based on the measurement result of the wavefront aberration of the projection optical system PL.
Adjust the wavefront aberration of. For the adjustment of the wavefront aberration, the control device 39 controls the movement of the lens element via the image formation characteristic correction controller 51, and in some cases, manually, in the XY plane of the lens element of the projection optical system PL. This is done by moving or replacing the lens element.

Continuing, in subroutine 101,
The wavefront aberration relating to the adjusted projection optical system PL is measured in the same manner as above. After that, the adjustment of the wavefront aberration of the projection optical system PL (step 103) and the measurement of the wavefront aberration (step 101) are repeated until a positive determination is made in step 102. Then, if a positive determination is made in step 102, the lemon skin plate DF is removed from the holding member DFH, and then the process proceeds to step 104.

In step 104, the wavefront sensor 90 is removed from the wafer stage WST, the connection between the wavefront data processing device 80 and the main control system 20 is cut off, and then the main control system 2
Under the control of 0, the reticle R on which the pattern to be transferred is formed is loaded onto the reticle stage RST by a reticle loader (not shown). Further, the wafer W to be exposed is moved to the wafer stage WS by a wafer loader (not shown).
Loaded into T.

Next, in step 105, exposure preparation measurement is performed under the control of the main control system 20. That is, preparatory work such as reticle alignment using a reference mark plate (not shown) arranged on wafer stage WST and measurement of a baseline amount using alignment detection system AS are performed. Further, when the exposure of the wafer W is the exposure of the second layer or later, in order to form the circuit pattern with a high overlay accuracy with the already formed circuit pattern, the above-mentioned EGA measurement using the alignment detection system AS is performed. The array coordinates of the shot areas on the wafer W are detected with high accuracy.

Next, in step 106, exposure is performed. In this exposure operation, first, wafer stage WST is moved so that the XY position of wafer W becomes the scanning start position for the exposure of the first shot area (first shot) on wafer W. Position information (velocity information) and the like from the wafer interferometer 18 (in the case of exposure of the second and subsequent layers, the detection result of the positional relationship between the reference coordinate system and the array coordinate system, the position information from the wafer interferometer 18 ( (Speed information) and the like) by the main control system 20 via the stage control system 19 and the wafer stage drive unit 24. At the same time, the reticle stage RST is moved so that the XY position of the reticle R becomes the scanning start position. This movement is performed by the main control system 20 via the stage control system 19 and a reticle drive unit (not shown).

Next, the stage control system 19 operates the main control system 2
In response to an instruction from 0, the multi-point focus position detection system (2
Wafer position information detected by reticle R, XY of reticle R measured by reticle interferometer 16
Based on the position information and the XY position information of the wafer W measured by the wafer interferometer 18, the reticle R and the reticle R are adjusted while adjusting the surface position of the wafer W via a reticle drive unit and a wafer stage drive unit 24 (not shown). Scan exposure is performed by relatively moving the wafer W.

Thus, when the exposure of the first shot area is completed, the wafer stage WST is moved to the scanning start position for the exposure of the next shot area and the XY position of the reticle R is scanned. Reticle stage RST is moved to the position. Then, scanning exposure for the shot area is performed in the same manner as the above-described first shot area. Thereafter, scanning exposure is similarly performed for each shot area, and the exposure is completed.

Then, in step 107, the exposed wafer W is unloaded from the wafer holder 25 by an unloader (not shown). Thus, the exposure process for one wafer W is completed.

In the subsequent exposure of the wafer, the step 10 is performed while the wavefront aberration of the projection optical system PL in steps 101 to 103 is measured and adjusted as needed.
Wafer exposure operations 4 to 107 are performed.

As described above, in the first embodiment, the measurement reticle RT and the light receiving opening 91a in the wavefront aberration measuring apparatus 70 are moved synchronously while maintaining the conjugate positional relationship with respect to the projection optical system PL. In the meantime, the wavefront division is performed on the light through the lemon skin plate DF, the aperture pattern formed on the measurement reticle RT, the projection optical system PL, the aperture 91a, the collimator lens 92, and the relay optical system 93 in sequence. Then, the position information of the spot image formed for each divided wavefront is detected. As a result, lemon skin plate DF
It is possible to suppress a decrease in the accuracy of the detection result of the spot image position information due to the uneven diffusion of light due to, and it is possible to quickly and accurately detect the position information of each spot image.

Then, in this embodiment, the wavefront aberration of the projection optical system PL is obtained based on the detection result of the position information of each spot image detected with high accuracy. Therefore, according to the present embodiment, the wavefront aberration characteristic which is the optical characteristic of the projection optical system PL can be measured quickly and accurately.

Further, the projection optical system PL which is accurately obtained
The aberration of the projection optical system PL is adjusted based on the wavefront aberration of the projection optical system PL, and the predetermined pattern formed on the reticle R is projected onto the surface of the wafer W by the projection optical system PL having various aberrations sufficiently reduced. The pattern can be transferred onto the wafer W with high accuracy.

In the first embodiment, only the aperture patterns PH _{1 to} PH _N for measuring the wavefront aberration of the projection optical system PL are formed on the measurement reticle RT, but the wavefront sensor 90 itself causes the wavefront aberration. In order to measure, the opening pattern significantly larger than the opening patterns PH _{1 to} PH _N may be formed on the measurement reticle RT as a calibration opening pattern. Even when using such a calibration opening pattern,
Diffusion unevenness caused by the lemon skin plate DF is caused by the wavefront sensor 90.
Although the measurement accuracy of the measurement result of the wavefront aberration is deteriorated, as in the case of the wavefront aberration measurement of the projection optical system PL described above, the lemon skin through which the light reaching the opening 91a of the wavefront sensor 90 passes. By changing the area of the plate DF and picking up the spot image by the CCD 95, the spot image formed at a position accurately reflecting the wavefront shape can be picked up. As a result, the wavefront aberration of the wavefront sensor 90 used for the calibration of the wavefront sensor 90 can be measured with high accuracy, and the wavefront aberration of the projection optical system PL can be measured with high accuracy. The sign board 9
If the calibration aperture pattern image formed at 1 is sufficiently larger than the aperture 91a, only the wavefront sensor 90 is moved in order to change the region of the lemon skin plate DF through which the light reaching the aperture 91a passes. Can be

Further, in the first embodiment, when the spot image is picked up, the lemon skin plate DF is fixed, and the measurement reticle RT and the light receiving opening 91a in the wavefront aberration measuring device 70 are moved synchronously. It was On the other hand, the positions of the imaging measurement reticle RT and the light receiving opening 91a of the wavefront aberration measuring device 70 may be fixed, and the lemon skin plate DF may be moved. Such movement of the lemon skin plate DF makes the holding member DFH movable. For example, the holding member DFH is moved by a voice coil motor or a piezo element.
Should be driven.

The lemon skin plate DF may be moved in a direction parallel to the pattern forming surface of the measurement reticle RT, or may be moved in a direction perpendicular to the pattern forming surface of the measurement reticle RT. It may be.

Further, the synchronous movement of the measurement reticle RT and the light receiving opening 91a of the wavefront aberration measuring apparatus 70 and the movement of the lemon skin plate DF may be combined.

Further, in the first embodiment, based on the total amount of light continuously received by each pixel of the CCD 95 during the synchronous movement of the measuring reticle RT and the light receiving aperture 91a in the wavefront aberration measuring apparatus 70. Then, the spot image position was obtained. On the other hand, the plurality of measurement reticles RT and the wavefront aberration measuring device 70 are arranged such that the measurement reticle RT and the light receiving opening 91a of the wavefront aberration measuring device 70 are at conjugate positions with respect to the projection optical system PL. CCD in each positional relationship with the opening 91a for
It is also possible to perform image pickup by 95 and calculate the sum of the same pixel positions for a plurality of image pickup results, and then obtain the spot image position based on the calculated sum image. Further, it is also possible to calculate the spot image candidate position for each of a plurality of image pickup results and obtain the average of these spot image candidate positions as the spot image position.

<< Second Embodiment >> Next, a second embodiment of the present invention will be described. In the description of the present embodiment, elements that are the same as or equivalent to those in the case of the first embodiment will be assigned the same reference numerals and redundant description will be omitted.

FIG. 10 shows the schematic arrangement of an exposure apparatus 100A according to the second embodiment of the present invention. This exposure apparatus 100A is a step-and-scan projection exposure apparatus, like the exposure apparatus 100 of the first embodiment described above. This exposure apparatus 100A includes an exposure apparatus main body 60A and a wavefront aberration measuring apparatus 70A.

The exposure apparatus main body 60A has the above-mentioned first structure.
Compared with the exposure apparatus main body 60 (see FIG. 1) of the embodiment,
The only difference is that the holding member DFH is not provided.

The wavefront aberration measuring device 70A comprises a wavefront sensor 90 and a wavefront data processing device 80A. That is, the wavefront aberration measuring device 70A includes a wavefront sensor 90 configured similarly to the case of the first embodiment, and a wavefront data processing device 80A having a different configuration from the wavefront data processing device 80 of the first embodiment. Is equipped with.

The wavefront data processing device 80A is shown in FIG.
As shown in, the main controller 30A and the storage device 40A
It has and. The main control device 30A controls the entire operation of the wavefront data processing device 80A under the control of (a) the main control system 20, and supplies the wavefront measurement result data WFA to the main control system 20, and (a) b) an imaging data collection device 31 that collects the imaging data IMD from the wavefront sensor 90, and (c) a position information calculation device 32A that calculates the position of the spot image based on the image data collected by the imaging data collection device 31. , (D) a wavefront aberration calculation device 3 for calculating the wavefront aberration of the projection optical system PL based on the spot image position calculated by the position information calculation device 32A.
Includes 3 and 3. Here, the position information calculation device 32A
(I) An image data synthesizing device 3 that synthesizes a plurality of image data collected by the imaging data collecting device 31 to create position calculation data for calculating a spot image position.
4 and (ii) a position detection device 32 that calculates the position of the spot image based on the position calculation data.

Further, the storage device 40A includes (a) an image data storage area 41 for storing image data, (b) a spot image position storage area 42 for storing the calculated spot image position, and (c) a wavefront aberration. It has a wavefront aberration data storage area 43 for storing data and (d) a position calculation data storage area 44 for storing position calculation data.

In the present embodiment, the wavefront data processing device 80
Although A is configured by combining various devices as described above, the wavefront data processing device 80A is configured as a computer system and the main control device 30A is configured in the same manner as in the first embodiment. It is also possible to realize the function of each device by a program built in the wavefront data processing device 80A.

The exposure operation of the exposure apparatus 100A of this embodiment will be described below. The exposure apparatus 1 of this embodiment
The exposure operation by 00A differs from the exposure operation by the exposure apparatus 100 of the first embodiment described above only in the processing of the subroutine 101 in FIG. 6, that is, the wavefront aberration measurement processing of the projection optical system PL. Therefore, the following description will be made, focusing mainly on this difference.

As in the case of the above-described first embodiment, the wavefront sensor 90 is mounted on the wafer stage WST, and the wavefront data processing device 80 and the main control system 20 are presupposed for the following operations. Assume that and are connected.

Further, as in the case of the first embodiment, the indicating plate 91 of the wavefront sensor 90 mounted on the wafer stage.
The positional relationship between the opening 91a and the wafer stage WST is
It is assumed that the two-dimensional position mark 91b is accurately obtained by observing it with the alignment detection system AS.

In the present embodiment, first, in the subroutine 101 of FIG. 6, the wavefront aberration of the projection optical system PL is measured. In this subroutine 101, as shown in FIG. 12, first, in step 121, as shown in FIG.
A reticle set RA for measurement as generally shown in FIG. 13C is loaded on reticle stage RST by a reticle loader (not shown).

This measurement reticle set RA is shown in FIG.
As shown in (A), it comprises a measurement reticle RTA, a spacer SP, and a lemon skin plate DF. Here, the measurement reticle RTA and the lemon skin plate DF are fixedly connected via a spacer SP. The spacer SP has a hollow rectangular shape in plan view, and the illumination light IL passing through the lemon skin plate DF reaches the measurement reticle RTA through the hollow portion of the spacer SP. You can do it.

The measurement reticle RTA is shown in FIG.
As shown in FIG. 13B, a plurality (in FIG. 13B,
Nine) aperture pattern groups PHG _{1 to} PHG _N (FIG. 13)
In (B), N = 9) are formed in a matrix along the X and Y directions. The opening pattern group PH
G _{1 to} PHG _N are formed in a region having the size of a slit-shaped illumination region indicated by a dotted line in FIG.

Opening pattern group PHG_j(J = 1 to N)
Each of them is, for example, as shown in FIG.
13 (5 in FIG. 13C) opening patterns PH_j1~
PH _jM(M = 5 in FIG. 13B). Na
Opening pattern PH_jk(K = 1 to M) is the wavefront aberration
Opening pattern PH in measurement_jkAll of the same points
They are formed close enough to be considered.

Subsequently, reticle alignment using a reference mark plate (not shown) arranged on wafer stage WST, baseline measurement using alignment detection system AS, and the like are performed. Then, reticle stage RST is moved so that the first aperture pattern PH _{1 for} which aberration measurement is performed is located on optical axis AX of projection optical system PL. Such movement is performed by the main control system 20 controlling the reticle drive unit 23 via the stage control system 19 based on the position information (speed information) of the reticle stage RST detected by the reticle interferometer 16.

Returning to FIG. 12, next, at step 122, the opening 91a of the marking plate 91 of the wavefront sensor 90 is positioned at the conjugate position of the opening pattern PH ₁₁ with respect to the projection optical system PL.
That is, wafer stage WST is moved to the initial imaging position for opening pattern group PHG ₁ . Such movement is
The main control system 20 controls the wafer stage drive unit 24 via the stage control system 19 based on the position information (speed information) of the wafer stage WST detected by the wafer interferometer 18. At this time, the main control system 20
Based on the detection result of the multi-point focus position detection system (21, 22), the upper surface of the sign board 91 of the wavefront sensor 90 is made to coincide with the image surface on which the image of the aperture pattern PH ₁₁ is formed.
Wafer stage WS via wafer stage drive unit 24
Slightly drive T in the Z-axis direction.

As described above, the first opening pattern P
The arrangement of the optical devices for measuring the wavefront aberration of the projection optical system PL regarding the spherical wave from H ₁₁ is completed. Regarding such an optical arrangement, the optical axis AX1 of the wavefront sensor 90 is
FIG. 14 shows the projection optical system PL expanded along the optical axis.

In such an optical arrangement, the illumination system 10
When the illumination light IL is emitted from the
First opening pattern PH₁₁The light that reaches
Opening pattern PH₁₁Exit from. And projection optics
After passing through the system PL, the opening of the marking plate 91 of the wavefront sensor 90
It is focused on 91a. The first opening pattern PH ₁₁
Light that has passed through the opening patterns other than
It does not reach a. The light thus collected in the opening 91a
Is almost spherical, but the wavefront of the projection optical system PL is
It includes aberration.

The light that has passed through the opening 91a is converted into parallel light by the collimator lens 92 in the same manner as in the first embodiment, further passes through the relay lens system 93, and then enters the microlens array 94. . Here, the wavefront of the light incident on the microlens array 94 reflects the wavefront aberration of the projection optical system PL. That is, when the projection optical system PL has no wavefront aberration, FIG.
4, the wavefront WF is a plane orthogonal to the optical axis AX1, but when the projection optical system PL has a wavefront aberration, as shown by the chain double-dashed line in FIG. The wavefront WF 'is inclined at an angle according to the position.

The microlens array 94 forms an aperture pattern image in the aperture 91a on the conjugate plane of the marking plate 91, that is, the image pickup plane of the CCD 95, for each microlens 94a. When the wavefront of the light incident on the microlens 94a is orthogonal to the optical axis AX1, a spot image centered on the intersection of the optical axis of the microlens 94a and the image pickup surface is formed on the image pickup surface. Also, the micro lens 94a
When the wavefront of the light incident on the lens is tilted, a spot image centered on a point deviated from the intersection of the optical axis of the microlens 94a and the image pickup surface is formed on the image pickup surface by a distance corresponding to the tilt amount. To be imaged.

Returning to FIG. 12, next, at step 123, the CCD 95 captures the image formed on the imaging surface. The imaging data IMD obtained by this imaging is supplied to the wavefront data processing device 80. In the wavefront data processing device 80, the imaging data collection device 31 collects the imaging data IMD and stores the collected imaging data in the imaging data storage area 41.

Next, at step 124, it is judged if the imaging of all the aperture patterns PH _1k included in the aperture pattern group PHG ₁ is completed. At this stage, since the imaging of the opening pattern PH ₁₁ is only completed, a negative determination is made, and the process proceeds to step 125.
Move to.

At step 125, the opening pattern group PH
The wafer stage WST is moved so that the opening 91a of the marking plate 91 of the wavefront sensor 90 is located at the next imaging position related to G ₁ (the conjugate position of the opening pattern PH ₁₂ with respect to the projection optical system PL at this stage). . Such movement is
The main control system 20 controls the wafer stage drive unit 24 via the stage control system 19 based on the position information (speed information) of the wafer stage WST detected by the wafer interferometer 18. At this time also, the main control system 20 forms an image of the first aperture pattern PH ₂₁ in the aperture pattern group PHG ₂ based on the detection result of the multipoint focus position detection system (21, 22). If necessary, wafer stage WST is finely driven in the Z-axis direction via wafer stage drive unit 24 in order to match the upper surface of marking plate 91 of wavefront sensor 90 with the surface.

After that, the processing of steps 123 to 125 is repeated until a positive determination is made in step 124. Then, when the imaging of all the opening patterns PH _1k included in the opening pattern group PHG ₁ is completed and a positive determination is made in step 124, the process proceeds to step 126.

In step 126, the position information of each spot image is detected based on the image pickup result. In calculating such position information, first, the image data composition device 34 of the position information calculation device 32A causes the aperture pattern P included in the aperture pattern group PHG ₁ from the imaging data storage area 41.
The imaging result data for each H _1k is read. Then, the position calculation data for calculating the spot image position is obtained by adding together the data at the same pixel position in the image pickup result data for each aperture pattern PH _1k . In the position calculation data, the light that is wavefront-divided by the microlens array 94, that is, one of the aperture patterns PH _{11 to} PH _1M , the projection optical system P
L, the opening 91a of the marking plate 91, the collimator lens 92,
The non-uniformity of the light intensity distribution due to the uneven diffusion due to the lemon skin plate DF in the light sequentially passing through the relay optical system is reduced by the averaging effect on the uneven diffusion. As a result, a spot image is formed at a position that accurately reflects the wavefront shape. The image data composition device 34 stores the position calculation data thus obtained in the position calculation data storage area 44.

Next, the position calculation device 32 reads the position calculation data from the position calculation data storage area 44. Subsequently, the position calculation device 32 uses the microlens array 9
The center position of each spot image is calculated by calculating the center of gravity of the light intensity distribution of the composite image of each spot image formed on the image pickup surface of the CCD 95 by 4. Position calculation device 32
Stores the center position of each spot image thus obtained in the spot image position storage area 42 as position information of each spot image formed on the imaging surface of the CCD 95 by the microlens array 94.

Next, in step 127, the wavefront aberration calculating device 33 reads the detection result of the spot image position from the spot image position storage area 42, and passes the position of the first aperture pattern group PHG ₁ in the measurement reticle RT. The wavefront aberration of the projection optical system PL regarding light is calculated. The calculation of the wavefront aberration is performed by obtaining the coefficient of the Zernike polynomial from the difference between each spot image position expected when there is no wavefront aberration and the detected spot image position. The wavefront aberration thus calculated is stored in the wavefront aberration data storage area 43 together with the position of the aperture pattern group PHG ₁ .

Next, at step 128, it is judged if the wavefront aberration of the projection optical system PL has been calculated for all the aperture pattern groups. At this stage, since the wavefront aberration of the projection optical system PL is measured only for the first aperture pattern group PHG ₁ , a negative determination is made, and the processing shifts to step 129.

At step 129, the opening 91a of the marking plate 91 of the wavefront sensor 90 is moved to the next opening pattern group PHG ₂
Wafer stage WST is moved so as to reach the initial image pickup position of. In this movement, the main control system 20
This is performed by controlling the wafer stage drive unit 24 via the stage control system 19 based on the position information (speed information) of the wafer stage WST detected by the wafer interferometer 18. Even at this time, the main control system 20 also causes the image of the aperture pattern PH ₂₁ of the aperture pattern group PHG ₂ to be formed on the image plane based on the detection result of the multipoint focus position detection system (21, 22). In order to match the upper surfaces of the marking plates 91 of the wavefront sensor 90, the wafer stage WST is finely driven in the Z-axis direction via the wafer stage drive unit 24, if necessary.

Then, the wavefront aberration of the projection optical system PL is measured in the same manner as in the case of the aperture pattern group PHG ₁ . Then, the measurement result of the wavefront aberration is stored in the wavefront aberration data storage area 43 together with the position of the aperture pattern group PHG _2.
Stored in.

Thereafter, in the same manner as described above, the wavefront aberration of the projection optical system PL relating to the light passing through all the aperture pattern groups is sequentially measured, and the measurement result for each aperture pattern group is shown together with the position of the aperture pattern group. Data storage area 4
3 is stored. When the wavefront aberration of the projection optical system PL for all the aperture pattern groups is measured in this way, a positive determination is made in step 128. Then, the control device 39 reads the measurement result of the wavefront aberration from the wavefront aberration data storage area 43 and supplies it to the main control system 20 as the wavefront measurement result data WFA. After this, the processing shifts to step 102 in FIG.

Thereafter, similarly to the first embodiment, the loop processing of steps 102 → 103 → 101 is repeated until the wavefront aberration of the projection optical system PL becomes equal to or less than the allowable value. Then, when the wavefront aberration of the projection optical system PL becomes equal to or less than the allowable value, steps 104 to 107 are executed, and the pattern formed on the reticle R becomes the wafer W in each of the same manner as in the first embodiment. Transferred to the shot area.

As described above, in the second embodiment, although the passing positions on the lemon skin plate DF are different from each other, a plurality of aperture patterns which can be regarded as substantially the same point in the measurement of the wavefront aberration characteristic of the projection optical system PL are provided. Each of the passed light beams is sequentially passed through the projection optical system PL, the opening 91a, the collimator lens 92, and the relay optical system 93, and then wavefront split, and a spot image formed for each split wavefront is captured.
Then, the image pickup results obtained for each of the passed aperture patterns are added together for each same pixel position, and the position information of the spot image is detected from the combined result. As a result, it is possible to suppress the decrease in the accuracy of the detection result of the spot image position information due to the uneven light diffusion by the lemon skin plate DF, and it is possible to detect the position information of each spot image quickly and accurately.

Then, in this embodiment, the wavefront aberration of the projection optical system PL is obtained based on the detection result of the position information of each spot image detected with high accuracy. Therefore, according to the present embodiment, the wavefront aberration characteristic which is the optical characteristic of the projection optical system PL can be measured quickly and accurately.

Further, the projection optical system PL which is accurately obtained
The aberration of the projection optical system PL is adjusted based on the wavefront aberration of the projection optical system PL, and the predetermined pattern formed on the reticle R is projected onto the surface of the wafer W by the projection optical system PL having various aberrations sufficiently reduced. The pattern can be transferred onto the wafer W with high accuracy.

In the second embodiment, the wafer stage WST on which the wavefront aberration measuring apparatus 70A is mounted is moved for image pickup for each aperture pattern included in the same aperture pattern group, but the reticle stage RST is sufficient. When the two-dimensional drive can be performed with various strokes, the reticle stage RST can be moved.

When the reticle stage RST can be two-dimensionally driven with a stroke as large as the wafer stage WST, the measurement reticle RTA is replaced by the measurement reticle RT used in the first embodiment. It is also possible to fix the position of wafer stage WST and then sequentially move the opening patterns PH _{1 to} PH _N to the conjugate position of the opening 91 a of the marking plate 91 to capture a spot image.

Further, in the second embodiment, the spot image position is obtained by synthesizing the image pickup results for each of the plurality of aperture patterns in the same aperture pattern group, but for each of the plurality of image pickup results. It is also possible to calculate the spot image candidate positions and obtain the average of these spot image candidate positions as the spot image position.

Also in the second embodiment, as in the case of the above-described first embodiment, the modification using the measurement reticle on which the calibration pattern is further formed can be performed.

Although the number of aperture patterns in the measurement reticle RT is nine in each of the above embodiments, the number can be increased or decreased according to the desired measurement accuracy of the wavefront aberration. Further, the number and arrangement of the microlenses 94a in the microlens array 94 can be changed according to the desired measurement accuracy of the wavefront aberration.

Further, in each of the above embodiments, the target image for position detection is a spot image, but it may be an image of a pattern of another shape.

Further, in each of the above-described embodiments, the wavefront aberration measuring apparatus 70 is separated from the exposure apparatus main body 60 for exposure, but the wavefront aberration measuring apparatus 70 is separated from the exposure apparatus main body 60.
It goes without saying that the exposure may be carried out while being attached to the.

In each of the above embodiments, the case where the wavefront aberration of the projection optical system PL is measured and the wavefront aberration is adjusted at the time of regular maintenance after the exposure apparatus is assembled, and the wafer is prepared for the subsequent exposure. Although described, the wavefront aberration may be adjusted in the same manner as in the above embodiment when adjusting the projection optical system PL in manufacturing the exposure apparatus. When adjusting the projection optical system PL at the time of manufacturing the exposure apparatus, in addition to adjusting the positions of some of the lens elements forming the projection optical system PL performed in the above-described embodiment, adjusting the positions of other lens elements. It is possible to rework the lens element, replace the lens element, and so on.

Further, in each of the above-mentioned embodiments, the case of the scanning type exposure apparatus has been described, but the present invention is not limited to the step-and-repeat machine if the exposure apparatus is equipped with the projection optical system.
It can be applied regardless of the step-and-scan machine and the step-and-stitching machine.

Further, in each of the above-described embodiments, the present invention is applied to the measurement of the aberration of the projection optical system in the exposure apparatus, but it is not limited to the exposure apparatus and the measurement of various aberrations of the imaging optical system in other types of apparatus is also possible. The present invention can also be applied to.

Furthermore, the present invention can be applied to the measurement of the optical characteristics of various optical systems such as the shape of a reflecting mirror other than the aberration measurement of the optical system.

<< Manufacturing of Device >> Next, a device (semiconductor chip such as IC or LSI, liquid crystal panel, CCD, thin film magnetic head
Manufacturing of a micromachine etc. will be described.

First, in the design step, functional design of a device (for example, circuit design of a semiconductor device) is performed, and pattern design for realizing the function is performed. Subsequently, in a mask manufacturing step, a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in the wafer manufacturing step, a wafer is manufactured using a material such as silicon.

Next, in the wafer processing step, the mask and wafer prepared in the above steps are used to form an actual circuit or the like on the wafer by a lithography technique, as will be described later.

This wafer processing step is, for example, in manufacturing a semiconductor device, an oxidation step for oxidizing the surface of a wafer, and a CV for forming an insulating film on the surface of the wafer.
It has a pretreatment process of each stage of the wafer process such as a D step, an electrode formation step of forming electrodes on the wafer by vapor deposition, an ion implantation step of implanting ions into the wafer, and a post-treatment process described later. The pretreatment process is selected and executed according to the required treatment at each stage of the wafer process.

At each stage of the wafer process, when the pretreatment process is completed, the photoresist is applied to the wafer in the resist processing step, and subsequently, in the exposure step, the circuit pattern of the mask is printed on the wafer by the exposure apparatus 10 described above. Expose. Next, the exposed wafer is developed in the developing step, and subsequently, in the etching step, the exposed member other than the portion in which the resist remains is removed by etching. Then, in the resist removing step, the unnecessary resist after etching is removed.

As described above, by repeating the pretreatment process and the posttreatment process from the resist treatment step to the resist removal step, multiple circuit patterns are formed on the wafer.

When the wafer processing step is completed in this way, in the assembly step, the wafer processed in the wafer processing step is used to make chips. This assembly includes steps such as an assembly step (dicing and bonding) and a packaging step (chip encapsulation).

Finally, in the inspection step, inspections such as an operation confirmation test and a durability test of the device manufactured in the assembly step are performed. After these steps, the device is completed and shipped.

As described above, a device in which a fine pattern is formed accurately can be manufactured with high mass productivity.

[0157]

As described above in detail, according to the optical characteristic measuring method of the present invention, the optical characteristic of the optical system to be tested can be accurately measured.

Further, according to the optical characteristic measuring apparatus of the present invention, the optical characteristic of the optical system to be measured is measured by using the optical characteristic measuring method of the present invention. It can be measured with high accuracy.

Further, according to the optical system adjusting method of the present invention, the optical characteristic of the optical system is adjusted based on the optical measurement of the optical system accurately measured by the optical characteristic measuring method of the present invention. The optical characteristics of the system can be adjusted to desired characteristics quickly and accurately.

Further, according to the exposure apparatus of the present invention, since the optical characteristic measuring apparatus of the present invention for measuring the optical characteristic of the projection optical system is provided, the optical characteristic measuring apparatus of the present invention accurately measures the optical characteristic, A predetermined pattern can be transferred to the substrate by using a projection optical system whose optical characteristics are guaranteed to be well adjusted.

[Brief description of drawings]

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

FIG. 2 is a diagram schematically showing a configuration of the wavefront sensor of FIG.

FIG. 3 is a diagram for explaining a surface state of the sign board in FIG.

4 (A) and FIG. 4 (B) are diagrams showing a configuration of the microlens array of FIG.

5 is a block diagram showing a configuration of a main control system of FIG.

6 is a flow chart for explaining a process in an exposure operation by the apparatus of FIG.

FIG. 7 is a flowchart for explaining a process in the aberration measurement subroutine of FIG.

FIG. 8 is a diagram showing an example of a measurement pattern formed on the measurement reticle according to the first embodiment.

FIG. 9 is a diagram for explaining an optical arrangement when a spot image is captured in the first embodiment.

FIG. 10 is a diagram schematically showing a configuration of an exposure apparatus according to a second embodiment of the present invention.

11 is a block diagram showing a configuration of a main control system of FIG.

FIG. 12 is a flowchart for explaining processing in an aberration measurement subroutine in the second embodiment.

FIG. 13 is a diagram for explaining a configuration example of a measurement reticle set in the second embodiment.

FIG. 14 is a diagram for explaining an optical arrangement when a spot image is captured in the second embodiment.

[Explanation of symbols]

23 ... Reticle stage driving unit (driving device), 24 ... Wafer stage driving unit (driving device), 32 ... Position calculation device (position information calculation device), 33 ... Wavefront aberration calculation device (optical characteristic calculation device), 70 ... Wavefront Aberration measuring device, 90 ... Wavefront sensor (image information detecting device), 91a ... Aperture (light receiving aperture), 94 ... Microlens array (wavefront dividing member),
94a ... Microlens (lens element), 95 ... CCD
(Image detection device), 98 ... Microlens (lens element), 99 ... Mirror drive mechanism (part of wavefront division optical system exchange device), DF ... Lemon skin plate (light diffusion member), PL
... Projection optical system (test optical system), PT, PTA ... Measurement reticle (mask), W ... Wafer (substrate).

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Jun Kogo             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon (72) Inventor K. Mizuno             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon F term (reference) 2G086 HH06

Claims (13)

[Claims] 1. The optical characteristic of the optical system to be measured is measured based on the light that has passed through a light diffusing member, a mask on which a predetermined pattern is formed, and the optical system to be measured, and then reaches an aperture for receiving light. An optical characteristic measuring method, wherein at least one position of the light diffusing member, the mask, and the light receiving opening is changed with respect to the light reaching the light receiving opening, and the light is passed through the light receiving opening. A pattern image position detecting step of forming a plurality of pattern images by dividing light into wavefronts, and detecting position information of each of the plurality of pattern images; and a pattern image position detecting step of each of the plurality of pattern images detected in the pattern image position detecting step. Based on location information
An optical characteristic measuring method, comprising: an optical characteristic calculating step of calculating an optical characteristic of the test optical system. 2. In the relative position changing step, the mask and the light diffusing member are relatively moved while maintaining a conjugate positional relationship between the mask and the light receiving opening with respect to the optical system to be tested. The optical characteristic measuring method according to claim 1, which is characterized in that. 3. The optical characteristic measuring method according to claim 2, wherein the predetermined pattern is a circular opening, and the stroke of the relative movement is about the diameter of the circular opening. 4. The pattern image position detecting step comprises relatively moving the mask and the light receiving opening while maintaining the positional relationship between the light diffusing member and the mask. The optical characteristic measuring method described in. 5. The predetermined pattern is a plurality of openings, and the relative movement of the mask and the light receiving opening is such that the light receiving opening has a conjugate position with respect to the test optical system of each of the plurality of openings. 5. The optical characteristic measuring method according to claim 4, wherein the relative movement is sequentially performed. 6. The optical characteristic measuring method according to claim 1, wherein the pattern image is a spot image. 7. The optical characteristic measuring method according to claim 1, wherein the optical characteristic is a wavefront aberration. 8. An optical characteristic measuring device for measuring the optical characteristic of the optical system to be inspected, based on the light which has passed through a mask having a predetermined pattern and the optical system to be inspected, and then has reached the aperture for receiving light. A light diffusing member for diffusing incident light and emitting the light toward the mask; and having the light receiving opening, the light passing through the light receiving opening is wavefront-divided to form a plurality of pattern images. An image information detection device for forming and detecting information of the plurality of pattern images;
A drive device that changes at least one position of the light diffusing member, the mask, and the image information detection device with respect to the light reaching the light receiving opening; based on a detection result by the image information detection device, A position information calculation device for calculating position information of each of the plurality of pattern images; and an optical characteristic of the optical system to be tested based on position information of each of the plurality of pattern images calculated by the position information calculation device. An optical characteristic measuring device comprising: 9. The image information detection device includes a wavefront division member that forms a plurality of patterns by wavefront division of light that has passed through the light receiving opening; and an image detection device that detects the plurality of pattern images. The optical characteristic measuring device according to claim 8, further comprising: 10. The optical characteristic measuring device according to claim 9, wherein the wavefront dividing member is a microlens array in which a plurality of lens elements are arranged. 11. The optical characteristic measuring device according to claim 8, wherein the optical characteristic is a wavefront aberration. 12. An optical system adjusting method for adjusting an optical characteristic of an optical system, wherein the optical characteristic of the optical system is determined by using the optical characteristic measuring method according to claim 1. An optical system adjusting method comprising: an optical characteristic measuring step of measuring; and an optical characteristic adjusting step of adjusting an optical characteristic of the optical system based on a measurement result in the optical characteristic measuring step. 13. By irradiating the substrate with exposure light,
An exposure apparatus for transferring a predetermined pattern onto the substrate, comprising: a projection optical system arranged on an optical path of exposure light; and the projection optical system being a test optical system. An exposure apparatus comprising: