JP2012253163A - Wavefront aberration measuring device, wavefront aberration measuring method, exposure device, exposure method, and manufacturing method of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wavefront aberration measuring device which allows for high-precision measurement of the wavefront aberration of a tested optical system by suppressing the impact of interference pattern due to noise light.SOLUTION: The wavefront aberration measuring device which measures the wavefront aberration of a tested optical system comprises a first diffraction member having a first diffraction grating pattern and disposed on the object surface of the tested optical system, a second diffraction member having a second diffraction grating pattern and disposed on the object surface of the tested optical system, and a measurement part which measures the wavefront aberration of a tested optical system based on the light passed through the first diffraction grating pattern, the tested optical system, and the second diffraction grating pattern. When the magnification of the tested optical system is β, the pattern period of the first diffraction grating pattern is equal to 3β times that of the second diffraction grating pattern.

Description

  The present invention relates to a wavefront aberration measuring apparatus, a wavefront aberration measuring method, an exposure apparatus, an exposure method, and a device manufacturing method.

  In a photolithography process for manufacturing a semiconductor element or the like, exposure is performed by projecting and exposing a mask (or reticle) pattern onto a photosensitive substrate (a wafer coated with a photoresist, a glass plate, or the like) via a projection optical system. The device is used. In the exposure apparatus, as the degree of integration of semiconductor elements and the like is improved, the resolving power (resolution) required for the projection optical system is increasing. That is, as the pattern becomes finer, it is required to measure the aberration of the projection optical system with high accuracy and adjust the projection optical system so that the residual aberration is as small as possible.

  Conventionally, a shearing interferometer type wavefront aberration measuring apparatus is known (for example, see Patent Document 1). In this type of wavefront aberration measuring device, diffraction gratings are arranged on the object plane and image plane of the projection optical system as the test optical system, and formed through the object side diffraction grating, the projection optical system, and the image side diffraction grating. The wavefront aberration of the projection optical system is measured based on the interference fringes.

Special Table 2003-524175

  In a conventional shearing interferometer type wavefront aberration measuring apparatus, when the magnification of the optical system to be tested is β, the pattern period P1 of the object side diffraction grating is 1 / (2β) of the pattern period P2 of the image side diffraction grating. By doubling, the diffracted light that interferes through the image side diffraction grating is controlled. As a result, the generation of interference fringes due to noise light is relatively large with respect to the interference fringes due to measurement light, and as a result, it is difficult to measure the wavefront aberration of the optical system under test with high accuracy.

  The present invention has been made in view of the above-mentioned problems, and provides a wavefront aberration measuring apparatus capable of measuring the wavefront aberration of a test optical system with high accuracy while suppressing the influence of interference fringes caused by noise light. With the goal. In addition, the present invention accurately transfers a pattern to a photosensitive substrate through a projection optical system in which wavefront aberration is adjusted using a wavefront aberration measuring apparatus that measures wavefront aberration of a test optical system with high accuracy. An object of the present invention is to provide an exposure apparatus capable of performing the above.

In order to solve the above problem, in the first embodiment, in the wavefront aberration measuring apparatus for measuring the wavefront aberration of the optical system to be tested,
A first diffraction member having a first diffraction grating pattern and disposed on an object plane of the optical system to be tested;
A second diffraction member having a second diffraction grating pattern and disposed on the image plane of the test optical system;
A measurement unit that measures the wavefront aberration of the test optical system based on the light that has passed through the first diffraction grating pattern, the test optical system, and the second diffraction grating pattern;
Provided is a wavefront aberration measuring apparatus characterized in that when the magnification of the test optical system is β, the pattern period of the first diffraction grating pattern is 3β times the pattern period of the second diffraction grating pattern.

In the second embodiment, in the wavefront aberration measuring method for measuring the wavefront aberration of the test optical system,
Disposing a first diffraction grating pattern on an object plane of the test optical system;
When the magnification of the test optical system is β, a second diffraction grating pattern having a pattern period 1 / (3β) times the pattern period of the first diffraction grating pattern is formed on the image plane of the test optical system. Placing,
Measuring wavefront aberration of the test optical system based on the light having passed through the first diffraction grating pattern, the test optical system, and the second diffraction grating pattern. Provide a method.

In the third embodiment, the wavefront aberration measuring device of the first embodiment is provided,
An exposure apparatus is provided that exposes a predetermined pattern placed on the object plane of the test optical system onto a photosensitive substrate placed on the image plane of the test optical system.

In the fourth embodiment, the test optical system is adjusted using the wavefront aberration information obtained by the wavefront aberration measuring method of the second embodiment,
An exposure method is provided, wherein a predetermined pattern placed on the object plane of the test optical system is exposed to a photosensitive substrate placed on the image plane of the test optical system.

In the fifth embodiment, using the exposure apparatus of the third embodiment or the exposure method of the fourth embodiment, exposing the predetermined pattern to the photosensitive substrate;
Developing the photosensitive substrate having the predetermined pattern transferred thereon, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
And processing the surface of the photosensitive substrate through the mask layer. A device manufacturing method is provided.

  In the wavefront aberration measuring apparatus according to the embodiment, it is possible to measure the wavefront aberration of the optical system to be measured with high accuracy while suppressing the influence of interference fringes caused by noise light. In the exposure apparatus according to the embodiment, the pattern is accurately transferred to the photosensitive substrate via the projection optical system in which the wavefront aberration is adjusted by using the wavefront aberration measuring apparatus that measures the wavefront aberration of the optical system to be measured with high accuracy. can do.

It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment. It is a figure showing roughly the composition of the wave aberration measuring device of an embodiment. It is a figure which shows partially the diffraction grating pattern of the object side diffraction member in embodiment. It is a figure which shows partially the diffraction grating pattern of the image side diffraction member in embodiment. It is a figure which shows partially the diffraction grating pattern of the object side diffraction member in a 1st modification. It is a figure which shows unit pattern A1 in the diffraction grating pattern of FIG. It is a figure which shows the amplitude of the diffracted light in each pattern A1, C1, and S1 of FIG. It is a figure which shows partially the diffraction grating pattern of the two-dimensional structure in a 2nd modification. It is a figure which shows partially the diffraction grating pattern of the object side diffraction member in a 3rd modification. It is a figure which shows unit pattern A2 in the diffraction grating pattern of FIG. It is a figure which shows the amplitude of the diffracted light in each pattern A2, C2, S2 and F2 of FIG. It is a figure which shows unit pattern A2 'which comprises the diffraction grating pattern of the object side diffraction member in a 4th modification. It is a figure which shows unit pattern A3 which comprises the diffraction grating pattern of the object side diffraction member in a 5th modification. It is a figure which shows the amplitude of the diffracted light in each pattern A3, C3, S3, and F3 of FIG. It is a figure which shows unit pattern A4 which comprises the diffraction grating pattern of the object side diffraction member in a 6th modification. It is a figure which shows the amplitude of the diffracted light in each pattern A4, C4, S4, and F4 of FIG. It is a flowchart which shows the manufacturing process of a semiconductor device. It is a flowchart which shows the manufacturing process of liquid crystal devices, such as a liquid crystal display element.

  Hereinafter, embodiments will be described with reference to the accompanying drawings. FIG. 1 is a view schematically showing a configuration of an exposure apparatus according to the embodiment. In FIG. 1, the X axis and the Y axis are set in a direction parallel to a transfer surface (exposure surface) of a wafer W as a photosensitive substrate, and the Z axis is set in a direction orthogonal to the wafer W. . More specifically, the XY plane is set parallel to the horizontal plane, and the + Z axis is set upward along the vertical direction.

  Referring to FIG. 1, exposure light (illumination light) EL is supplied from a light source LS to the exposure apparatus of the present embodiment. As the light source LS, for example, an ArF excimer laser light source that supplies light with a wavelength of 193 nm can be used. The exposure apparatus according to the present embodiment includes an illumination optical system IL including an optical integrator (homogenizer), a field stop, a condenser lens, and the like. The exposure light EL composed of ultraviolet pulse light emitted from the light source LS passes through the illumination optical system IL and illuminates the mask (reticle) M.

  A pattern to be transferred is formed on the mask M, and a rectangular pattern region having a long side along the X direction and a short side along the Y direction is illuminated. The light that has passed through the mask M forms a mask pattern at a predetermined projection magnification on an exposure area (shot area) on a wafer (photosensitive substrate) W coated with a photoresist via the projection optical system PL. That is, a rectangular exposure region having a long side along the X direction and a short side along the Y direction on the wafer W so as to optically correspond to the rectangular illumination region on the mask M. A pattern image is formed in (or the static exposure region).

  The mask M is held parallel to the XY plane on the mask stage MS. The mask stage MS incorporates a mechanism for moving the mask M in the X direction, the Y direction, and the rotation direction. The mask stage MS is controlled and measured in real time by the mask laser interferometer (not shown) in the X direction, the Y direction, and the rotational direction. The wafer W is fixed in parallel to the XY plane on the wafer stage WS via a wafer holder (not shown).

  Specifically, the wafer stage WS includes a Z stage (not shown) that moves the wafer W in the Z direction, and an XY stage (not shown) that holds the Z stage and moves along the XY plane. The Z stage controls the focus position (position in the Z direction) and tilt angle of the wafer W. In the Z stage, the positions in the X direction, the Y direction and the rotation direction are measured and controlled in real time by a wafer laser interferometer (not shown). The XY stage controls the X direction, Y direction, and rotation direction of the wafer W.

  The main control system CR provided in the exposure apparatus of the present embodiment adjusts the position of the mask M in the X direction, the Y direction, and the rotation direction based on the measurement values measured by the mask laser interferometer. That is, the main control system CR adjusts the position of the mask M by transmitting a control signal to a mechanism incorporated in the mask stage MS and moving the mask stage MS. Further, the main control system CR adjusts the focus position (position in the Z direction) and the tilt angle of the wafer W in order to align the surface on the wafer W with the image plane of the projection optical system PL by the auto focus method and the auto leveling method. I do.

  That is, the main control system CR transmits a control signal to the drive system DR, and adjusts the focus position and the tilt angle of the wafer W by driving the Z stage by the drive system DR. Further, the main control system CR adjusts the positions of the wafer W in the X direction, the Y direction, and the rotation direction based on the measurement values measured by the wafer laser interferometer. That is, the main control system CR transmits a control signal to the drive system DR and drives the XY stage by the drive system DR to adjust the position of the wafer W in the X direction, the Y direction, and the rotation direction.

  At the time of exposure, the pattern image of the mask M is collectively projected and exposed within a predetermined shot area on the wafer W. Thereafter, the main control system CR transmits a control signal to the drive system DR, and drives the XY stage of the wafer stage WS along the XY plane by the drive system DR, thereby bringing another shot area on the wafer W to the exposure position. Move step. In this way, the operation of batch exposing the pattern image of the mask M on the wafer W by the step-and-repeat method is repeated.

  Alternatively, the main control system CR transmits a control signal to a mechanism incorporated in the mask stage MS and transmits a control signal to the drive system DR, and the mask stage at a speed ratio corresponding to the projection magnification of the projection optical system PL. The pattern image of the mask M is scanned and exposed in a predetermined shot area on the wafer W while driving the XY stage of the MS and the wafer stage WS. Thereafter, the main control system CR transmits a control signal to the drive system DR, and drives the XY stage of the wafer stage WS along the XY plane by the drive system DR, thereby bringing another shot area on the wafer W to the exposure position. Move step.

  Thus, the operation of scanning and exposing the pattern image of the mask M on the wafer W by the step-and-scan method is repeated. That is, while controlling the positions of the mask M and the wafer W using the drive system DR and the wafer laser interferometer, the mask stage MS and the wafer stage along the short side direction of the rectangular stationary exposure region and the illumination region, that is, the Y direction. By moving (scanning) the WS and the mask M and the wafer W synchronously, the wafer W has a width equal to the long side of the static exposure region and the scanning amount (movement amount) of the wafer W. A mask pattern is scanned and exposed to a region having a length corresponding to the above.

  Wafer stage WS is equipped with wavefront aberration measuring apparatus 1 for measuring the wavefront aberration of projection optical system PL. As shown in FIG. 2, the wavefront aberration measuring apparatus 1 includes a test mask TM disposed on a mask stage MS when measuring the wavefront aberration of the projection optical system PL that is a test optical system. For example, as partially shown in FIG. 3, the test mask TM is provided with a diffraction grating pattern 21 having a pattern period (pitch) P1. The diffraction grating pattern 21 has a plurality of strip-shaped light transmission portions 21 a and light shielding portions 21 b that are alternately arranged along the pitch direction (horizontal direction in FIG. 3: measurement direction).

  The width of the light transmission part 21a and the light-shielding part 21b along the pitch direction are equal to each other and P1 / 2. The test mask TM as the object side diffractive member is formed by providing a strip-shaped light shielding portion 21b made of a light shielding material such as chromium on a light transmissive substrate made of, for example, quartz or fluorite. Similarly to the exposure mask M, the test mask TM is arranged on the object plane (or the vicinity thereof) of the projection optical system PL. Hereinafter, in the drawings showing the patterns, black portions indicate light shielding portions, and white portions indicate light transmission portions.

  Further, the wavefront aberration measuring apparatus 1 includes a diffractive member MD disposed on the image plane (or the vicinity thereof) of the projection optical system PL when measuring the wavefront aberration of the projection optical system PL. The diffraction member MD is provided with a diffraction grating pattern 22 (22a, 22b) having a pattern form similar to the diffraction grating pattern 21 (21a, 21b), and a light shielding region 40 surrounding the diffraction grating pattern 22. That is, the diffraction member MD is provided with a diffraction grating pattern 22 having a pattern period (pitch) of P2, for example, as partially shown in FIG.

  The diffraction grating pattern 22 has a plurality of strip-shaped light transmission portions 22a and light shielding portions 22b arranged alternately along the pitch direction (horizontal direction in FIG. 4: measurement direction). The width of the light transmission part 22a along the pitch direction and the light shielding part 22b are equal to each other and are P2 / 2. Similar to the test mask TM, the diffractive member MD as the image-side diffractive member has a light-transmitting substrate made of, for example, quartz or fluorite, a strip-shaped light-blocking portion 22b made of a light-blocking material such as chromium, and a light-blocking member. It is formed by providing the region 40.

  Furthermore, the wavefront aberration measuring apparatus 1 includes a photodetector 11 that detects light that has passed through the diffractive member MD, and a measuring unit 12 that is supplied with an output signal of the photodetector 11. The photodetector 11 has, for example, a CCD type or CMOS type two-dimensional imaging device, and detects interference fringes formed through the diffraction member MD. The measurement unit 12 measures the wavefront aberration of the projection optical system PL based on the interference light (interference fringes) detected by the light detection unit 11. The output of the measuring unit 12, that is, the measurement result of the wavefront aberration measuring device 1, is supplied to the main control system CR.

  When measuring the wavefront aberration of the projection optical system PL, the main control system CR drives the wafer stage WS and positions the wavefront aberration measurement apparatus 1 with respect to the projection optical system PL. Specifically, the main control system CR positions the wavefront aberration measuring apparatus 1 so that the diffraction grating pattern 22 of the diffraction member MD is positioned at a required position directly below the projection optical system PL. Further, the main control system CR replaces the exposure mask M on the mask stage MS with the test mask TM, and the test mask TM with respect to the illumination area formed on the object plane of the projection optical system PL by the illumination optical system IL. The diffraction grating pattern 21 provided in is positioned.

  FIG. 2 shows, as an example, a state in which the diffraction grating pattern 22 of the diffractive member MD is positioned on the optical axis AX of the projection optical system PL. At this time, the test mask TM and the diffraction member MD are positioned so that the pitch direction of the diffraction grating patterns 21 and 22 matches the X direction (or Y direction). In this state, the illumination light EL from the illumination optical system IL is diffracted through the diffraction grating pattern 21 of the test mask TM, and enters the diffraction grating pattern 22 of the diffraction member MD through the projection optical system PL.

  Diffracted light generated through the diffraction grating pattern 22 forms interference fringes (Fourier images) of shearing interference on the light receiving surface 11 a of the light detection unit 11. Information on the intensity distribution of the interference fringes formed on the light receiving surface 11 a of the light detection unit 11 is supplied to the measurement unit 12. The measurement unit 12 obtains the phase distribution of the shearing wavefront (distortion of the fringes of the Fourier image) by Fourier transforming the intensity distribution, and obtains the wavefront aberration of the projection optical system PL from the phase distribution. Alternatively, a fringe scan for stepping the diffraction grating pattern 21 of the test mask TM or the diffraction grating pattern 22 of the diffraction member MD in a direction perpendicular to the optical axis is performed, and the shearing wavefront of the shearing wavefront is obtained from the information on the intensity distribution of the interference fringes obtained. The phase distribution may be obtained, and the wavefront aberration of the projection optical system PL may be obtained from the phase distribution.

  Further, if necessary, the diffraction member MD is moved stepwise along the X direction (or Y direction) by the action of the wafer stage WS, and the X direction (or Y direction) within the effective image formation region of the projection optical system PL. Wavefront aberrations for a plurality of points along the line are sequentially measured. Furthermore, if necessary, the test mask TM and the diffractive member MD are rotated 90 degrees around the Z axis, and then the diffractive member MD is moved stepwise along the Y direction (or the X direction) while the projection optical system PL Wavefront aberrations relating to a plurality of points along the Y direction (or X direction) in the effective imaging region are sequentially measured.

  As described above, in the conventional shearing interferometer type wavefront aberration measuring apparatus, when the magnification of the optical system to be tested is β, the pattern period P1 of the diffraction grating on the object side is changed to the pattern period of the diffraction grating on the image side. By setting 1 / (2β) times P2, that is, by setting P1 = P2 / (2β), the diffracted light that interferes through the diffraction grating on the image side is controlled. In this case, the signal forming the interference fringes is controlled by the combination of the coherence γ determined by the object side diffraction grating and the diffraction efficiency an of the nth order diffracted light and the diffraction efficiency am of the mth order diffracted light by the image side diffraction grating. .

  In the prior art, since it is set so as to satisfy the relationship P1 = P2 / (2β), only diffracted light components separated by the second order interfere with each other. Specifically, interference fringes between + 1st order light and primary light, interference fringes between + 1st order light and + 3rd order light, interference fringes between −1st order light and −3rd order light, + 3rd order light and + 5th order light. Interference fringes between the diffracted lights separated by the second order are formed, such as interference fringes between -3rd order light and -5th order light. A signal necessary for measuring the aberration of the test optical system is an interference fringe by ± first-order light (measurement light).

Other interference fringes, that is, interference fringes between primary light and + 3rd order light, interference fringes between −1st order light and −3rd order light, interference fringes between + 3rd order light and + 5th order light, and −3rd order light -Interference fringes due to higher-order light such as interference fringes with fifth-order light are noise. When the coherence of the light separated by the Nth order in the diffracted light by the image side diffraction grating is represented by γ _N , all the coherence by the diffracted light of the order separated by the second order is the same at γ ₂ . As a result, the generation of interference fringes due to high-order light as noise light is relatively large compared to interference fringes due to ± 1st-order light as measurement light, and as a result, the wavefront aberration of the optical system to be measured can be measured with high accuracy. Have difficulty.

In the present embodiment, when the magnification of the projection optical system PL is β, the pattern period (pitch) P1 of the diffraction grating pattern 21 of the test mask TM and the pattern period P2 of the diffraction grating pattern 22 of the diffraction member MD are expressed by the following equations: The relationship shown in (1) is satisfied. That is, the pattern period P 1 (for example, about several μm) of the diffraction grating pattern 21 is set to be 3β times the pattern period P 2 of the diffraction grating pattern 22.
P1 = P2 × 3β (1)

  In this case, the shearing interference fringes formed through the diffractive member MD are the interference fringes between the 0th order light and the + 1st order light, the interference fringes between the 0th order light and the −1st order light, and the 0th order light and the + 3rd order light. 0th order light and odd order like interference fringe, 0th order light and −3rd order interference fringe, 0th order light and + 5th order light interference fringe, 0th order light and −5th order light interference fringe. It is an interference fringe with the diffracted light. Among them, signals necessary for measuring the aberration of the projection optical system PL are interference fringes between 0th-order light and + 1st-order light and interference fringes between 0th-order light and + 1st-order light. Other interference fringes, that is, interference fringes between 0th order light and + 3rd order light, interference fringes between 0th order light and −3rd order light, interference fringes between 0th order light and + 5th order light, 0th order light and −5th Like the interference fringe with the next light, the interference fringe between the 0th order light and the higher order light is noise.

In the present embodiment, since the relationship expressed by the above formula (1) is satisfied, coherence γ ₃ between the 0th order light and the + _third order light that is noise light, and the 0th order light that is the noise light and −3 the coherence gamma ₃ of the next light, a measuring light 0 order light and coherence gamma ₁ with coherent gamma _1, and a measuring light 0 order light and -1 order light and the +1 order light One third of the above. Also, the coherence gamma ₅ with coherence gamma _5, and 0-order light and -5-order light as noise light 0 order light and +5 order light, 5 minutes coherent gamma ₁ of the measuring light 1 of

  Thus, the wavefront aberration measuring apparatus 1 according to the present embodiment can measure the wavefront aberration of the projection optical system PL with high accuracy based on the interference fringes with high contrast while suppressing the influence of the interference fringes due to the noise light. In the exposure apparatus of the present embodiment, the wavefront aberration measuring apparatus 1 is used to measure the wavefront aberration of the projection optical system PL with high accuracy as needed, and the projection optical system PL is optically adjusted as necessary to keep the wavefront aberration within an allowable range. Can be suppressed. As a result, the pattern of the mask M can be accurately transferred to the wafer W via the projection optical system PL in which the wavefront aberration is adjusted.

  In the above-described embodiment, the diffraction grating pattern 21 of the test mask TM is configured by one type of pattern including a plurality of strip-shaped light transmitting portions 21a and light shielding portions 21b arranged alternately along one direction. ing. However, without being limited thereto, for example, a test mask TM having a diffraction grating pattern 23 partially shown in FIG. 5 and a diffraction member MD having a diffraction grating pattern 22 partially shown in FIG. 4 are used. Variations are possible. The diffraction grating pattern 23 is configured by a combination of two types of patterns having different line widths or pitches.

  Specifically, the diffraction grating pattern 23 is formed by repeating a unit pattern A1 corresponding to one pattern period P1 along one direction (horizontal direction in FIG. 5). As shown in FIG. 6, the unit pattern A1 is a combination of a central pattern C1 having a single wide light transmission part at the center and a peripheral pattern S1 having a pair of narrow light transmission parts at the periphery. . Each pattern A1, C1, and S1 is line-symmetric with respect to a center line extending in the vertical direction in FIG. In the diffraction grating pattern 23, the patterns C1 and S1 are repeated along one direction according to the pattern period P1.

  FIG. 7 shows the amplitude of the diffracted light in each of the patterns A1, C1, and S1. In FIG. 7, the vertical axis represents the amplitude of the diffracted light, and the horizontal axis represents the diffraction order. Referring to FIG. 7, the amplitude of the third-order diffracted light in the central pattern C1 and the amplitude of the third-order diffracted light in the peripheral pattern S1 have the same sign, and the amplitude of the third-order diffracted light in the peripheral pattern S1 is greater than the amplitude of the first-order diffracted light. It is high. As a result, it can be seen that the amplitude of the third-order diffracted light in the unit pattern A1 is high. Further, it can be seen that the amplitude of the first-order diffracted light in the central pattern C1 and the amplitude of the first-order diffracted light in the peripheral pattern S1 are different from each other, and as a result, the amplitude of the first-order diffracted light in the unit pattern A1 is low.

  That is, the diffraction grating pattern 23 formed by repeating the unit pattern A1 is composed of a combination of two types of patterns that weaken the first-order diffracted light and strengthen the third-order diffracted light. In other words, the diffraction grating pattern 23 has a pattern structure in which the diffraction efficiency of the third-order diffracted light is higher than the diffraction efficiency of the first-order diffracted light.

  In the above embodiment and the modification of FIG. 5, the coherence due to the third-order diffracted light formed through the diffraction grating patterns 21 and 23 becomes the coherence of the measurement light. In the modification of FIG. 5, since the diffraction grating pattern 23 having higher diffraction efficiency of the third-order diffracted light than the diffraction grating pattern 21 is used, the coherence of the measurement light can be increased as compared with the above-described embodiment. That is, in the modification of FIG. 5, it is possible to measure the wavefront aberration of the projection optical system PL with higher accuracy while suppressing the influence of interference fringes due to noise light to be smaller than in the above-described embodiment.

  In the above-described embodiment and the modification of FIG. 5, the diffraction grating patterns 21 to 23 having a one-dimensional structure in which unit patterns are repeated along one direction are used. However, the present invention is not limited to this. For example, a diffraction grating pattern having a two-dimensional structure in which unit patterns are two-dimensionally repeated along two directions orthogonal to each other can be used. In the configuration using the diffraction grating pattern having the two-dimensional structure, the diffraction member MD is moved only stepwise along the XY plane without rotating around the Z axis, and the configuration using the diffraction grating pattern having the one-dimensional structure is faster. In addition, wavefront aberration can be measured.

  Specifically, for example, a test mask TM provided with a diffraction grating pattern 31 having a two-dimensional structure partially shown in FIG. 8, and a diffraction grating pattern having a two-dimensional structure similarly partially shown in FIG. The structure using the diffraction member MD provided with 32 is possible. The diffraction grating patterns 31 and 32 are obtained by making the diffraction grating patterns 21 and 22 in the above-described embodiment two-dimensional. That is, the diffraction grating patterns 31 and 32 have strip-shaped light-shielding portions arranged at intervals along two directions orthogonal to each other.

  Further, for example, a test mask TM provided with a diffraction grating pattern 33 having a two-dimensional structure partially shown in FIG. 9 and a diffraction member MD provided with a diffraction grating pattern 32 partially shown in FIG. It is also possible to use it. The diffraction grating pattern 33 is obtained by making the diffraction grating pattern 23 in the modification of FIG. 5 two-dimensional. The diffraction grating pattern 33 is formed by repeating unit patterns A2 corresponding to one pattern period P1 along two directions orthogonal to each other.

  As shown in FIG. 10, the unit pattern A2 includes a central pattern C2 having a single square light transmission part at the center, a peripheral pattern S2 having four rectangular light transmission parts at the periphery, and four at four corners. This is a combination with a four-corner pattern F2 having two square light transmission portions. Each pattern A2, C2, S2, and F2 is point-symmetric with respect to the center point. In the diffraction grating pattern 33, the patterns C2, S2, and F2 are repeated along two directions orthogonal to each other according to the pattern period P1.

  FIG. 11 shows the amplitude of the diffracted light in each of the patterns A2, C2, S2, and F2. In FIG. 11, the vertical axis represents the amplitude of the diffracted light, and the horizontal axis represents the diffraction order. Referring to FIG. 11, the amplitude of the third-order diffracted light in the central pattern C2, the amplitude of the third-order diffracted light in the peripheral pattern S2, and the amplitude of the third-order diffracted light in the four-corner pattern F2 have the same sign, and the peripheral pattern S2 and the four-corner pattern The amplitude of the third-order diffracted light in F2 is higher than the amplitude of the first-order diffracted light. As a result, it can be seen that the amplitude of the third-order diffracted light in the unit pattern A2 is high.

  The amplitude of the first-order diffracted light in the central pattern C2 and the amplitude of the first-order diffracted light in the peripheral pattern S2 and the amplitude of the first-order diffracted light in the four-corner pattern F2 are different from each other. As a result, the first-order diffracted light in the unit pattern A2 It can be seen that the amplitude is low. That is, the diffraction grating pattern 33 formed by repeating the unit pattern A2 has a pattern structure in which the diffraction efficiency of the third-order diffracted light is higher than the diffraction efficiency of the first-order diffracted light. As a result, also in the modified example of FIG. 9, the wavefront aberration of the projection optical system PL can be measured with higher accuracy as in the modified example of FIG.

  Note that a test mask TM having a diffraction grating pattern formed by repeating unit patterns A2 ′ as shown in FIG. 12 in two directions orthogonal to each other and a diffraction grating pattern 32 partially shown in FIG. 8 are provided. Using the diffractive member MD, the same effect as that of the modified example of FIG. 9 can be obtained. The unit pattern A2 'is a combination of a central pattern C2' having the same form as the central pattern C2 in FIG. 10 and a peripheral pattern S2 'having a light transmission portion that is elongated along a square side. Each pattern A2 ', C2' and S2 'is point-symmetric with respect to the center point.

  In the modification of FIG. 9, the unit pattern A2 is composed of a strip-shaped light-shielding portion arranged at intervals along two directions orthogonal to each other, and its transmittance is 25%. As a result, in the modified example of FIG. 9, high-speed measurement of wavefront aberration can be realized using a diffraction grating pattern having a two-dimensional structure. However, the loss of light quantity in the diffraction grating pattern is intended to improve the signal intensity of measurement light. As a result, it is disadvantageous for high-accuracy measurement of wavefront aberration.

  For example, by using a diffraction grating pattern formed of a unit pattern having two or two-dimensionally arranged rhombus-shaped or triangular light-transmitting portions, it is possible to achieve both ensuring of light quantity and ensuring coherence. In this case, the loss of light quantity can be suppressed even if a diffraction grating pattern having a two-dimensional structure is used, and as a result, high-speed measurement of wavefront aberration by securing the light quantity and high-precision measurement by improving the coherence of measurement light. It is possible to achieve both.

  Specifically, a test mask TM having a diffraction grating pattern formed by repeating unit patterns A3 as shown in FIG. 13 along two directions orthogonal to each other, and a diffraction grating pattern 32 partially shown in FIG. Using the diffractive member MD provided with can ensure both light quantity and coherence. The unit pattern A3 has a plurality of rhombus-shaped (including square) light transmissive portions arranged two-dimensionally and has a transmittance of 50%.

  The unit pattern A3 includes a central pattern C3 having a single square-shaped light transmitting portion at the center, a peripheral pattern S3 having four rhombus-shaped light transmitting portions at the periphery, and four square-shaped light transmitting portions at four corners. Is a combination with a four-corner pattern F3. Each pattern A3, C3, S3 and F3 is point-symmetric with respect to the center point.

  FIG. 14 shows the amplitude of the diffracted light in each pattern A3, C3, S3, and F3. In FIG. 14, the vertical axis represents the amplitude of the diffracted light, and the horizontal axis represents the diffraction order. Referring to FIG. 14, the amplitude of the third-order diffracted light in the central pattern C3, the amplitude of the third-order diffracted light in the peripheral pattern S3, and the amplitude of the third-order diffracted light in the four-corner pattern F3 have the same sign, and the third time in the peripheral pattern S3. The amplitude of the folded light is higher than the amplitude of the first-order diffracted light. As a result, it can be seen that the amplitude of the third-order diffracted light in the unit pattern A3 is high. That is, the diffraction grating pattern formed by repeating the unit pattern A3 has a pattern structure in which the diffraction efficiency of the third-order diffracted light is higher than the diffraction efficiency of the first-order diffracted light. Furthermore, since the pattern shown in FIG. 15 does not generate diffracted light in the 45 degree direction, noise in the 45 degree direction can also be eliminated.

  Similarly, a test mask TM having a diffraction grating pattern formed by repeating a unit pattern A4 as shown in FIG. 15 in two directions orthogonal to each other and a diffraction grating pattern 32 partially shown in FIG. 8 are provided. Using the diffractive member MD, it is possible to achieve both ensuring of light quantity and ensuring coherence. The unit pattern A4 has a plurality of triangular light transmission portions arranged two-dimensionally, and its transmittance is 50%.

  The unit pattern A4 includes a central pattern C4 having a single square light transmission portion at the center, a peripheral pattern S4 having four triangular light transmission portions at the periphery, and four triangular light transmission portions at four corners. Is a combination with a four-corner pattern F4. Each pattern A4, C4, S4 and F4 is point-symmetric with respect to the center point.

  FIG. 16 shows the amplitude of the diffracted light in each pattern A4, C4, S4 and F4. In FIG. 16, the vertical axis represents the amplitude of the diffracted light, and the horizontal axis represents the diffraction order. Referring to FIG. 16, the amplitude of the third-order diffracted light in the central pattern C4, the amplitude of the third-order diffracted light in the peripheral pattern S4, and the amplitude of the third-order diffracted light in the four corner pattern F4 have the same sign, and as a result, in the unit pattern A4 It can be seen that the amplitude of the third-order diffracted light is high. That is, the diffraction grating pattern formed by repeating the unit pattern A4 has a pattern structure in which the diffraction efficiency of the third-order diffracted light is higher than the diffraction efficiency of the first-order diffracted light.

  In the above description, in each figure showing the pattern, the black portion indicates the light shielding portion, and the white portion indicates the light transmitting portion. However, the present invention is not limited to this, and a diffraction grating pattern in which a black portion is a light transmission portion and a white portion is a light shielding portion, that is, a diffraction grating pattern in which the light shielding portion and the light transmission portion in each figure are replaced. Even if is used, the same effects as those of the above-described embodiment and each modification can be obtained.

  In the above-described embodiment, the wavefront aberration measuring apparatus 1 is mounted on the wafer stage WS. However, the present invention is not limited to this, and the entire wavefront aberration measuring apparatus 1 may be provided outside the wafer stage WS. Further, the wavefront aberration measuring apparatus 1 may be provided on a different stage from the wafer stage WS.

  In the above-described embodiment, the present invention is applied to the measurement of the wavefront aberration of the projection optical system mounted on the exposure apparatus. However, the present invention is not limited to this, for example, a single projection optical system before being mounted on the exposure apparatus, a single projection optical system removed from the exposure apparatus, and a general test optical whose application is not limited to the exposure apparatus The present invention can be similarly applied to systems (refractive optical systems, catadioptric optical systems, and reflective optical systems).

  In the above-described embodiment, a variable pattern forming apparatus that forms a predetermined pattern based on predetermined electronic data can be used instead of a mask. As the variable pattern forming apparatus, for example, a spatial light modulation element including a plurality of reflection elements driven based on predetermined electronic data can be used. An exposure apparatus using a spatial light modulator is disclosed, for example, in US Patent Publication No. 2007/0296936. In addition to the non-light-emitting reflective spatial light modulator as described above, a transmissive spatial light modulator may be used, or a self-luminous image display element may be used.

  The exposure apparatus of the above-described embodiment is manufactured by assembling various subsystems including the respective constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. Is done. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus may be manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  Next, a device manufacturing method using the exposure apparatus according to the above-described embodiment will be described. FIG. 17 is a flowchart showing a manufacturing process of a semiconductor device. As shown in FIG. 17, in the semiconductor device manufacturing process, a metal film is vapor-deposited on a wafer W to be a semiconductor device substrate (step S40), and a photoresist, which is a photosensitive material, is applied on the vapor-deposited metal film. (Step S42). Subsequently, using the projection exposure apparatus of the above-described embodiment, the pattern formed on the mask (reticle) M is transferred to each shot area on the wafer W (step S44: exposure process), and the wafer W after the transfer is completed. Development, that is, development of the photoresist to which the pattern has been transferred (step S46: development process).

  Thereafter, using the resist pattern generated on the surface of the wafer W in step S46 as a mask, processing such as etching is performed on the surface of the wafer W (step S48: processing step). Here, the resist pattern is a photoresist layer in which unevenness having a shape corresponding to the pattern transferred by the projection exposure apparatus of the above-described embodiment is generated, and the recess penetrates the photoresist layer. It is. In step S48, the surface of the wafer W is processed through this resist pattern. The processing performed in step S48 includes, for example, at least one of etching of the surface of the wafer W or film formation of a metal film or the like. In step S44, the projection exposure apparatus of the above-described embodiment performs pattern transfer using the wafer W coated with the photoresist as a photosensitive substrate.

  FIG. 18 is a flowchart showing a manufacturing process of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 18, in the liquid crystal device manufacturing process, a pattern forming process (step S50), a color filter forming process (step S52), a cell assembling process (step S54), and a module assembling process (step S56) are sequentially performed. In the pattern forming process of step S50, a predetermined pattern such as a circuit pattern and an electrode pattern is formed on the glass substrate coated with a photoresist as the plate P using the projection exposure apparatus of the above-described embodiment. The pattern forming step includes an exposure step of transferring the pattern to the photoresist layer using the projection exposure apparatus of the above-described embodiment, and development of the plate P on which the pattern is transferred, that is, development of the photoresist layer on the glass substrate. And a developing step for generating a photoresist layer having a shape corresponding to the pattern, and a processing step for processing the surface of the glass substrate through the developed photoresist layer.

  In the color filter forming process in step S52, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning direction. In the cell assembly process in step S54, a liquid crystal panel (liquid crystal cell) is assembled using the glass substrate on which the predetermined pattern is formed in step S50 and the color filter formed in step S52. Specifically, for example, a liquid crystal panel is formed by injecting liquid crystal between a glass substrate and a color filter. In the module assembling process in step S56, various components such as an electric circuit and a backlight for performing the display operation of the liquid crystal panel are attached to the liquid crystal panel assembled in step S54.

  In addition, the present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device, for example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, It can also be widely applied to an exposure apparatus for manufacturing various devices such as an image sensor (CCD or the like), a micromachine, a thin film magnetic head, and a DNA chip. Furthermore, the present invention can also be applied to an exposure process (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed using a photolithography process.

In the above-described embodiment, ArF excimer laser light (wavelength: 193 nm) is used as exposure light. However, the present invention is not limited to this, and other suitable laser light sources such as KrF excimer laser light (wavelength: 248 nm). The present invention can also be applied to an F ₂ laser light source that supplies laser light having a wavelength of 157 nm.

  In the above-described embodiment, a so-called immersion method is applied in which the optical path between the projection optical system and the photosensitive substrate is filled with a medium (typically liquid) having a refractive index larger than 1.1. You may do it. In this case, as a technique for filling the liquid in the optical path between the projection optical system and the photosensitive substrate, a technique for locally filling the liquid as disclosed in International Publication No. WO99 / 49504, a special technique, A method of moving a stage holding a substrate to be exposed as disclosed in Kaihei 6-124873 in a liquid bath, or a predetermined stage on a stage as disclosed in JP-A-10-303114. A method of forming a liquid tank having a depth and holding the substrate therein can be employed. Here, the teachings of International Publication No. WO99 / 49504, JP-A-6-124873 and JP-A-10-303114 are incorporated by reference.

DESCRIPTION OF SYMBOLS 1 Wavefront aberration measuring device 11 Light detection part 12 Measurement part LS Light source IL Illumination optical system MD Diffraction member M Mask TM Test mask MS Mask stage PL Projection optical system W Wafer WS Wafer stage CR Main control system

Claims (16)

In the wavefront aberration measuring apparatus for measuring the wavefront aberration of the test optical system,
A first diffraction member having a first diffraction grating pattern and disposed on an object plane of the optical system to be tested;
A second diffraction member having a second diffraction grating pattern and disposed on the image plane of the test optical system;
A measurement unit that measures the wavefront aberration of the test optical system based on the light that has passed through the first diffraction grating pattern, the test optical system, and the second diffraction grating pattern;
2. A wavefront aberration measuring apparatus according to claim 1, wherein when the magnification of the test optical system is β, the pattern period of the first diffraction grating pattern is 3β times the pattern period of the second diffraction grating pattern. The wavefront aberration measuring apparatus according to claim 1, wherein the first diffraction grating pattern is configured by a combination of two kinds of patterns that intensify third-order diffracted light. The wavefront aberration measuring apparatus according to claim 2, wherein the two types of patterns have different line widths or pitches. 4. The wavefront aberration according to claim 1, wherein the first diffraction grating pattern has a pattern structure in which a diffraction efficiency of the third-order diffracted light is higher than a diffraction efficiency of the first-order diffracted light. Measuring device. 5. The wavefront aberration measuring apparatus according to claim 1, wherein the first diffraction grating pattern and the second diffraction grating pattern have a two-dimensional structure. 6. 6. The wavefront aberration measuring apparatus according to claim 5, wherein the first diffraction grating pattern has a band-shaped light transmission part or light shielding part arranged at intervals along two directions orthogonal to each other. 6. The wavefront aberration measuring apparatus according to claim 5, wherein the first diffraction grating pattern has a rhombus-shaped or triangular light-transmitting part or light-shielding part arranged two-dimensionally. In a wavefront aberration measuring method for measuring wavefront aberration of a test optical system,
Disposing a first diffraction grating pattern on an object plane of the test optical system;
When the magnification of the test optical system is β, a second diffraction grating pattern having a pattern period 1 / (3β) times the pattern period of the first diffraction grating pattern is formed on the image plane of the test optical system. Placing,
Measuring wavefront aberration of the test optical system based on the light having passed through the first diffraction grating pattern, the test optical system, and the second diffraction grating pattern. Method. 9. The wavefront aberration measuring method according to claim 8, wherein a diffraction grating pattern configured by a combination of two types of patterns that intensify third-order diffracted light is used as the first diffraction grating pattern. 10. The wavefront aberration according to claim 8, wherein a diffraction grating pattern having a pattern structure in which the diffraction efficiency of the third-order diffracted light is higher than the diffraction efficiency of the first-order diffracted light is used as the first diffraction grating pattern. Measurement method. 11. The wavefront aberration measuring method according to claim 8, wherein a diffraction grating pattern having a two-dimensional structure is used as the first diffraction grating pattern and the second diffraction grating pattern. 11. 12. The wavefront according to claim 11, wherein the first diffraction grating pattern is a diffraction grating pattern having a band-shaped light transmitting portion or light shielding portion arranged at intervals along two directions orthogonal to each other. Aberration measurement method. 12. The wavefront aberration measuring method according to claim 11, wherein a diffraction grating pattern having a two-dimensionally arranged rhombus or triangular light transmitting part or light shielding part is used as the first diffraction grating pattern. A wavefront aberration measuring apparatus according to any one of claims 1 to 7,
An exposure apparatus that exposes a predetermined pattern placed on an object plane of the test optical system onto a photosensitive substrate placed on an image plane of the test optical system. Adjusting the optical system to be tested using wavefront aberration information obtained by the wavefront aberration measuring method according to any one of claims 8 to 13,
An exposure method comprising exposing a predetermined pattern placed on an object plane of the test optical system to a photosensitive substrate placed on an image plane of the test optical system. Using the exposure apparatus according to claim 14 or the exposure method according to claim 15, exposing the predetermined pattern to the photosensitive substrate;
Developing the photosensitive substrate having the predetermined pattern transferred thereon, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
Processing the surface of the photosensitive substrate through the mask layer. A device manufacturing method comprising:

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