JP2014022628A - Method for evaluating pupil luminance distribution, illumination optical system and method for adjusting the same, exposure apparatus, and method for manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating pupil luminance distribution for extracting even local difference between measured actual pupil luminance distribution and target pupil luminance distribution by using an easily interpretable physical index.SOLUTION: There is provided a method for evaluating pupil luminance distribution to be formed in an illumination pupil of an illumination optical system for supplying illumination light to an image-forming optical system for forming an image of a pattern arranged on a first plane, on a second plane. The method comprises: a first process of calculating two-dimensional data on difference distribution which is distribution representing difference between the measured pupil luminance distribution and target pupil luminance distribution, and in which a plurality of unit pupil areas to be obtained by virtually dividing the illumination pupil as a unit; and a second process of performing wavelet analysis to the two-dimensional data on the difference distribution to calculate distribution of wavelet coefficients of the two-dimensional data on the difference distribution.

Description

  The present invention relates to a pupil luminance distribution evaluation method, an illumination optical system and its adjustment method, an exposure apparatus, and a device manufacturing method.

  In an exposure apparatus used for manufacturing a device such as a semiconductor element, a light source emitted from a light source is a secondary light source (generally a surface light source consisting of a number of light sources via a fly-eye lens as an optical integrator). Form a predetermined light intensity distribution in the illumination pupil. Hereinafter, the light intensity distribution in the illumination pupil is referred to as “pupil luminance distribution”. The illumination pupil is defined as a position where the illumination surface becomes the Fourier transform plane of the illumination pupil by the action of the optical system between the illumination pupil and the illumination surface (a mask or a wafer in the case of an exposure apparatus). The

  The light from the secondary light source is collected by the condenser optical system and then illuminates the mask on which a predetermined pattern is formed in a superimposed manner. The light transmitted through the mask forms an image on the wafer via the projection optical system, and the mask pattern is projected and exposed (transferred) onto the wafer. The pattern formed on the mask is miniaturized, and it is indispensable to obtain a uniform illuminance distribution on the wafer in order to accurately transfer the fine pattern onto the wafer.

  Conventionally, there has been known an illumination optical system that realizes a desired pupil luminance distribution by using a movable multi-mirror configured by a large number of minute mirror elements arranged in an array and whose tilt angle and tilt direction are individually driven and controlled. It has been. In this illumination optical system, a movable multi-mirror as a spatial light modulator is used, so the degree of freedom in changing the external shape and distribution of the pupil luminance distribution is high, and it is determined appropriately according to the characteristics of the pattern to be transferred. A pupil luminance distribution having a complicated outer shape and distribution can be realized with high accuracy.

  The movable multi-mirror as a spatial light modulator has the ability to form a highly arbitrary pupil luminance distribution with high accuracy in the illumination pupil. However, the pupil luminance distribution actually formed on the illumination pupil (that is, the measured actual pupil luminance distribution) and the target pupil luminance distribution due to the mirror control error and various causes caused by other optical systems There is a considerable discrepancy between the two. At that time, a physical index with good visibility is required for evaluating whether or not the difference (deviation) between the actual pupil luminance distribution and the target pupil luminance distribution is acceptable. Here, a physical index with a good line-of-sight refers to a physical index that has a simple relationship with imaging characteristics and is easy to interpret qualitatively.

  Conventionally, there has been proposed a method for evaluating a pupil luminance distribution by utilizing a group of parameters representing a plurality of modulation actions including a Zernike polynomial therein (see Patent Document 1).

International Publication No. 2011/102109 Pamphlet

  In the evaluation method of the pupil luminance distribution described in Patent Document 1, a function expression that is continuously distributed over the entire pupil surface, such as a Zernike polynomial, is used. For this reason, for example, a local divergence such as a part in the pupil plane, that is, a local difference between the measured actual pupil luminance distribution and the target designed pupil luminance distribution is generally extracted. They are not good at it and tend to be difficult to express unless they use even higher-order components.

  The present invention has been made in view of the above-described problems, and also extracts a local difference between a measured actual pupil luminance distribution and a target pupil luminance distribution, using a physical index with good visibility. An object of the present invention is to provide a method for evaluating a pupil luminance distribution that can be used. In addition, the present invention uses a pupil luminance distribution evaluation method that also extracts a local difference between a measured actual pupil luminance distribution and a target pupil luminance distribution, and uses a target imaging performance as an actual target. An object of the present invention is to provide an illumination optical system capable of appropriately adjusting the pupil luminance distribution. Another object of the present invention is to provide an exposure apparatus that can perform good exposure under appropriate illumination conditions using an illumination optical system that appropriately adjusts the actual pupil luminance distribution.

In order to solve the above-described problem, in the first embodiment, an illumination pupil of an illumination optical system that supplies illumination light to an imaging optical system that forms an image of a pattern arranged on the first surface on the second surface is formed. A method for evaluating the pupil luminance distribution,
Two-dimensional data representing a difference between a measured pupil luminance distribution and a target pupil luminance distribution, the difference distribution using a plurality of unit pupil regions obtained by virtually dividing the illumination pupil. A first step for obtaining
A second step of performing wavelet analysis on the two-dimensional data of the difference distribution and calculating a distribution of wavelet coefficients of the two-dimensional data of the difference distribution is provided.

In the second embodiment, in the adjustment method of the illumination optical system that illuminates the illuminated surface with light from the light source,
Measuring the pupil luminance distribution formed in the illumination pupil of the illumination optical system;
Using the evaluation method of the first form to evaluate the pupil luminance distribution;
And adjusting a pupil luminance distribution formed on the illumination pupil based on the result of the evaluation.

  In the third embodiment, an illumination optical system characterized by being adjusted by the adjustment method of the second embodiment is provided.

In the fourth embodiment, in the illumination optical system that illuminates the illuminated surface with light from the light source,
A pupil distribution measuring device for measuring a pupil luminance distribution formed on the illumination pupil of the illumination optical system;
A pupil adjustment device for adjusting a pupil luminance distribution formed in the illumination pupil;
A control unit that evaluates the pupil luminance distribution using the pupil luminance distribution measured by the pupil distribution measuring device and the evaluation method of the first form, and controls the pupil adjustment device based on a result of the evaluation; An illumination optical system is provided.

In the fifth embodiment, in the illumination optical system that illuminates the illuminated surface with light from the light source,
A pupil distribution measuring device for measuring a pupil luminance distribution formed on the illumination pupil of the illumination optical system;
A pupil adjustment device for adjusting a pupil luminance distribution formed in the illumination pupil;
A control unit that evaluates the pupil luminance distribution using the pupil luminance distribution measured by the pupil distribution measuring device and the evaluation method of the first form, and controls the pupil adjustment device based on a result of the evaluation; With
The control unit is a distribution representing a difference between the measured pupil luminance distribution and a target pupil luminance distribution, and a plurality of unit pupil regions obtained by virtually dividing the illumination pupil are used as a unit. A difference calculation unit for obtaining two-dimensional data of a difference distribution;
There is provided an illumination optical system including a wavelet coefficient distribution calculation unit that performs wavelet analysis on the two-dimensional data of the difference distribution and calculates a distribution of wavelet coefficients of the two-dimensional data of the difference distribution.

  According to a sixth aspect, there is provided an exposure apparatus comprising the illumination optical system according to the third, fourth or fifth aspect for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. provide.

In the seventh embodiment, using the exposure apparatus of the sixth 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 pupil luminance distribution evaluation method according to the embodiment, a local difference between the measured actual pupil luminance distribution and the target pupil luminance distribution is also extracted using a physical index with good visibility, and as a result imaging performance The pupil luminance distribution can be satisfactorily evaluated by paying attention to. In the illumination optical system according to the embodiment, a desired imaging performance is targeted by using a pupil luminance distribution evaluation method that also extracts a local difference between a measured actual pupil luminance distribution and a target pupil luminance distribution. The pupil luminance distribution can be adjusted appropriately. In the exposure apparatus of the embodiment, it is possible to perform good exposure under appropriate illumination conditions by using an illumination optical system that appropriately adjusts the pupil luminance distribution, and as a result, it is possible to manufacture a good device.

It is a figure which shows the one-dimensional typical mode of the difference distribution of target pupil luminance distribution and actual pupil luminance distribution. It is a 1st figure explaining multi-resolution analysis. It is a 2nd figure explaining multi-resolution analysis. It is a figure which shows roughly the image of the grid data of each hierarchy obtained by performing multiresolution analysis with respect to the image of the sample data of pupil luminance distribution. For typical free-form pupil luminance distribution, the grid data of each layer obtained by performing multi-resolution analysis on the two-dimensional image of the difference distribution between the actual pupil luminance distribution and the target pupil luminance distribution It is a figure which shows an image roughly. It is a figure which shows a mode that each next grid data is obtained by multi-resolution analysis. It is a figure which shows a low-order wavelet and a high-order wavelet. It is a figure which shows base distribution Vn of the wavelet for every hierarchy. It is a figure which shows base distribution Hn of the wavelet for every hierarchy. It is a figure which shows base distribution Ln of the wavelet for every hierarchy. It is a figure which shows a mode that the distribution of a wavelet coefficient is calculated from two-dimensional data. It is a figure which shows a mode that a wavelet analysis is calculated with respect to the two-dimensional data of the difference distribution shown to Fig.5 (a), and the distribution of a wavelet coefficient is calculated. It is a figure which shows a mode that it converts into the image of the expression by a polar coordinate system from the image of the expression by an orthogonal coordinate system. It is a figure which shows the circular arc-shaped area | region expressed with a rectangular coordinate system. It is a figure which shows that the area of an area | region changes when converting the circular arc-shaped area | region of FIG. 14 into a rectangular-shaped area | region using the expression by a polar coordinate system. It is a figure which shows base distribution Rn of the wavelet for every hierarchy corresponding to the expression by a polar coordinate system. It is a figure which shows base distribution (theta) n of the wavelet for every hierarchy corresponding to the expression by a polar coordinate system. It is a figure which shows base distribution Ln of the wavelet for every hierarchy corresponding to the expression by a polar coordinate system. It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment. It is a figure which shows roughly the structure and effect | action of a spatial light modulation unit. It is a fragmentary perspective view of the spatial light modulator in a spatial light modulation unit. It is a figure which shows roughly the internal structure of a pupil distribution measuring apparatus. It is a flowchart of the adjustment method of the illumination optical system concerning embodiment. 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.

  Prior to specific description of the embodiment, the basic concept of the method for evaluating the pupil luminance distribution according to the present embodiment will be described. In the exposure apparatus, the actual pupil luminance distribution formed on the illumination pupil using the movable multi-mirror is slightly different from the pupil luminance distribution intended to be formed on the illumination pupil, that is, the target pupil luminance distribution. In addition, the imaging performance obtained by the actual pupil luminance distribution is slightly different from the desired imaging performance according to the target pupil luminance distribution. Hereinafter, in order to facilitate understanding of the description, it is assumed that the target pupil luminance distribution is a designed pupil luminance distribution.

  The target design pupil luminance distribution is appropriately determined according to the characteristics of the pattern to be transferred, and may have a complicated outer shape and distribution. Specifically, a free-form light intensity distribution with a relatively low pupil filling factor may be employed as the designed pupil luminance distribution. In this case, for example, in order to adjust the actual pupil luminance distribution with the desired imaging performance corresponding to the designed pupil luminance distribution as a target, the measured actual pupil luminance distribution and the target designed pupil luminance distribution are used. It is necessary to evaluate the difference with respect to the image formation performance.

In Patent Literature 1, the relationship between the measured actual pupil luminance distribution I _M (x, y) and the target designed pupil luminance distribution I _T (x, y) is shown in the following equation (a). It is modeled as follows. In Expression (a), T (x, y) is a net transmittance distribution function, and D _x and D _y are distortion functions. PSF is a function representing a blur effect (for example, a Gaussian function), C is an illumination flare component that acts uniformly over the entire pupil plane, and “*” represents convolution.
I _M (x, y) ≈T (x, y) [I _T (x, y) {x + D _x (x, y),
y + D _y (x, y)} * PSF] + C (a)

  As described above, in Patent Document 1, as shown in Expression (a), the pupil luminance distribution is evaluated by utilizing a plurality of parameter groups representing a plurality of modulation actions including a Zernike polynomial therein. That is, a function expression that is continuously distributed over the entire pupil surface, such as a Zernike polynomial, is used. For this reason, for example, a local divergence such as a part in the pupil plane, that is, a local difference between the measured actual pupil luminance distribution and the target designed pupil luminance distribution is generally extracted. They are not good at it and tend to be difficult to express unless they use even higher-order components.

  This means, for example, that it is difficult to express local phase defects when the wavefront aberration is expressed by a Zernike polynomial. In addition, since the means for extracting each parameter by analyzing an image of the measured actual pupil luminance distribution, that is, an actual measurement image, is a nonlinear least square method, there is a problem that a load is excessively applied to calculation accuracy, calculation time, and the like. Further, there is a problem that the orthogonality between the modulation parameters is deteriorated due to the feature (characteristic) of the pupil luminance distribution. Therefore, this embodiment proposes a method for evaluating the pupil luminance distribution using a new physical index that can solve these problems.

  First, as shown in FIGS. 1A and 1B, a region where a pupil luminance distribution is to be formed on the pupil plane is considered in one dimension for simplicity. When the actual pupil luminance distribution 102 indicated by the broken line is displaced in the horizontal direction with respect to the target pupil luminance distribution 101 indicated by the solid line in the left diagram of FIG. The difference distribution 103 with respect to the pupil luminance distribution 102 is a rectangular solitary wave distribution as shown on the right side of FIG.

  On the other hand, when the actual pupil luminance distribution 102 indicated by the broken line is shifted in the vertical direction with respect to the target pupil luminance distribution 101 indicated by the solid line in the left diagram of FIG. A difference distribution 103 between the actual pupil luminance distribution 102 and a rectangular isolated wave shape as shown in the right diagram of FIG. Specifically, in the left diagram of FIG. 1B, the actual pupil luminance distribution 102 is larger in the left half region than the target flat pupil luminance distribution 101. Here, in consideration of the condition that the total amount of light in the pupil plane is equal between the target pupil luminance distribution 101 and the actual pupil luminance distribution 102, the actual pupil luminance distribution 102 is more in the right half region. It becomes smaller automatically.

  That is, when the pupil luminance distribution is formed, such as the lateral displacement of the pupil luminance distribution on the pupil plane shown in FIG. 1A and the vertical displacement of the pupil luminance distribution on the pupil plane shown in FIG. The most typical and extreme errors that occur are the difference between the target pupil luminance distribution and the actual pupil luminance distribution. It turns out that there is a tendency to be expressed easily.

Next, multi-resolution analysis known in the field of image processing will be described. In the lowermost diagram of FIG. 2, the actual pupil luminance distribution on the illumination pupil 104 virtually divided into 2 ^N × 2 ^N rectangular unit pupil regions (grids) along two directions orthogonal to each other. A state in which 102 is formed is shown. The first processing target in the multi-resolution analysis is 2 ^N × 2 ^N grid data (two-dimensional data) related to the actual pupil luminance distribution 102.

Data of 2 ^N-1 × 2 ^N-1 sizes are obtained by sequentially taking the average value of luminance for every 2 × 2 pixels adjacent to this 2 ^N × 2 ^N grid data. Is the grid data of the next higher hierarchy. As it repeated each layer the same process, as shown in the uppermost drawing of FIG. 2, the value of the luminance of the 2 ⁰ i.e. one pixel 105, the original 2 ^N × 2 ^N pieces of grid data This corresponds to the average luminance. That is, the luminance value of the pixel 105 is represented by (A + B + C + D) / 4, which is the average value of the four pixel values A, B, C, and D in the next lower layer.

On the other hand, in FIG. 3, starting from one pixel 105 finally obtained by the ascending order processing in FIG. 2, a distribution obtained by taking a difference from the average value of the hierarchy one level higher is sequentially obtained as data. Hierarchical data (eg, N hierarchical levels) is obtained. Specifically, among the four pixels in the layer one level lower than the pixel 105, for example, the pixel having the luminance value B in the process of FIG. 2 is the average value (A + B + C + D) of the pixel 105 in the upper layer. Difference from / 4, that is, a value represented by B ′ = B− (A + B + C + D) / 4. The descending order process shown in FIG. 3 is repeated up to, for example, 2 ^N × 2 ^N grid data layers.

  Such a method of analyzing with changing resolution is called multi-resolution analysis in the field of image processing. By the multi-resolution analysis, it is possible to cleanly divide the information on the distribution to be analyzed into information on the global distribution and information on the distribution of fine structures.

  FIG. 4 is a diagram schematically showing an image of grid data in each layer obtained by performing multi-resolution analysis on an image of sample data having an appropriate pupil luminance distribution. FIG. 4A shows an image of sample data of the pupil luminance distribution to be analyzed. 4 (b), (c), (d), (e), (f), (g), and (h) show the third, fourth, fifth, and sixth orders obtained by multiresolution analysis. , 7th, 8th, and 9th order grid data images are shown.

The image shown in FIG. 4A is 2 ⁸ × 2 ⁸ (256 × 256) pieces of grid data of the pupil luminance distribution, and corresponds to the lowermost two-dimensional data in FIG. The images of the nth order (third order to ninth order) grid data shown in FIGS. 4B to 4H are 2 ⁿ⁻¹ × 2 ⁿ⁻¹ pieces of grid data, and are the uppermost in FIG. This corresponds to the two-dimensional data obtained in the (n−1) th hierarchy below the hierarchy of the pixel 105.

  In the 7th and 8th order grid data images, it is interpreted that the contour portion of the evaluation image shown in FIG. In the images of the 4th and 5th order grid data, it is interpreted that the structure of the global distribution of the evaluation image shown in FIG. 4A is expressed. In the present embodiment, the illumination pupil is virtually divided by the distribution representing the difference between the measured actual pupil luminance distribution and the target pupil luminance distribution, not the two-dimensional data of the pupil luminance distribution itself. A multi-resolution analysis process is performed on the two-dimensional data of the difference distribution obtained by using a plurality of unit pupil regions as an analysis target.

  FIG. 5 shows each layer obtained by performing multi-resolution analysis on a two-dimensional data image of a difference distribution between an actual pupil luminance distribution and a target pupil luminance distribution for a typical free-form pupil luminance distribution. It is a figure which shows schematically the image of grid data. FIG. 5A shows an image of two-dimensional data of the difference distribution to be analyzed. 5 (b), (c), (d), (e), (f), (g), and (h) show the second, third, fourth, and fifth orders obtained by multiresolution analysis. , 6th order, 7th order, 8th order grid data images are shown.

The image shown in FIG. 5A is 2 ⁸ × 2 ⁸ (256 × 256) pieces of grid data of the difference distribution, and corresponds to the lowermost two-dimensional data in FIG. The images of the ^nth- order (third-order to ninth-order) grid data shown in FIGS. 5B to 5H are 2 ^n-1 × 2 ^n-1 pieces of grid data, and are the uppermost in FIG. This corresponds to the two-dimensional data obtained in the (n−1) th hierarchy below the hierarchy of the pixel 105. The error (deviation) has the largest error in the 7th-order grid data, and there is a tendency that the error is relatively large in the 4th to 7th-order grid data.

  As shown in FIG. 5, by performing multi-resolution analysis on the image of the two-dimensional data of the difference distribution between the actual pupil luminance distribution and the target pupil luminance distribution, the difference distribution is divided into grid data for each layer. For example, by dividing into a global distribution error and a fine structure error, it can be understood which layer has the largest error. However, even if the divergence (error) at a predetermined level is a certain value, the influence on the imaging characteristics is generally different even with the same divergence amount depending on how the error is distributed.

Here, for example, as shown in FIG. 6, when considering the type of error distribution in a third-order 4 × 4 grid 106 obtained by multi-resolution analysis, each pixel has only a binary value. Even if it is the minimum requirement, it will be a huge number of combinations of 2 ¹⁶ . This is related to grasping the correlation between the pupil luminance distribution and the imaging characteristics.

  Next, a basic guideline for accurately knowing the relationship between the pupil luminance distribution and the imaging characteristics will be described. Unless how the error in the pupil luminance distribution affects the imaging performance is quantified using a physical quantity (physical index) with good visibility, it is impossible to determine how much error is allowed. If the imaging system is linear and the pupil luminance distribution error can be expressed by parameters orthogonal to each other, the output responses (for example, index values of imaging characteristics such as OPE values described later) are also orthogonal, This is ideal because it is only necessary to know the response characteristic of each parameter alone, and it is not necessary to perform the Monte Carlo calculation of the enormous number of combinations described with reference to FIG.

  However, in reality, since the response characteristic of the projection system of the exposure apparatus is a non-linear system, when the error of the pupil luminance distribution is expressed using parameters that are not orthogonal, the output responses are not orthogonal. However, it is possible to make the response characteristic on the output side approximately close to orthogonal by expressing the error of the pupil luminance distribution using physical quantities that are substantially orthogonal to each other. For example, the approximate linear combination management related to the imaging performance obtained by expressing the distribution of wavefront aberration using the Zernike coefficient is regarded as utilizing this property.

  Further, the degree of nonlinearity of the system may differ depending on how to select parameters on the input side, that is, parameters expressing an error in pupil luminance distribution. Therefore, as a result, it is necessary to select parameters that take into consideration the compatibility with the system as well as the orthogonality between the input parameters. Therefore, by further decomposing the distribution features (distribution characteristics) of each layer obtained by multi-resolution analysis into mutually orthogonal parameters, output responses almost orthogonal to each other are obtained from the parameters on the input side and nonlinear system that are approximately orthogonal to each other A method for realizing such a configuration will be described.

  Distribution characteristics in each layer obtained by multiresolution analysis are generally obtained by linear combination of solitary waves (wavelets) having a width corresponding to each layer as shown in FIG. 7 using a method called (discrete) wavelet transform. It is possible to express parameters that are orthogonal to each other. In FIG. 7, reference numeral 107 represents one low-order wavelet, and reference numeral 108 represents one high-order wavelet. In this embodiment, since the distribution of each layer that is the target of wavelet transformation is a two-dimensional image, as will be described later with reference to FIG. It becomes. The obtained parameters are not only orthogonal to each other within each layer, but also orthogonal between different layers.

  Unlike the Fourier transform, the wavelet transform can express both frequency information and position information, and has a high degree of freedom of expression. For this reason, the wavelet transform is suitable for evaluating the pupil luminance distribution as in the present embodiment. In addition, since the wavelet analysis process to be actually performed is publicly known, redundant description is omitted here. The distribution of wavelet coefficients of two-dimensional data can be calculated relatively easily by a less complicated linear calculation process that includes the process of multi-resolution analysis, and the calculation load is very small, unique and reversible. It is.

  8, FIG. 9 and FIG. 10 are diagrams showing the basis distribution of wavelets for each layer. Specifically, the uppermost diagram in FIG. 8 shows a base distribution V1 having a vertical component in the primary hierarchy. The primary hierarchy has a single basis distribution V1 as a wavelet, the value of the upper half area of the basis distribution V1 is +1, and the value of the lower half area is -1. The square circumscribing the base distribution V1 corresponds to the square circumscribing the largest pupil region. The point that the square of the outer frame corresponds to the square circumscribing the largest pupil region is the same in other base distributions.

There are 4 (= 2 ¹ × 2 ¹ ) types of basis distributions V2 in the secondary hierarchy. That is, in the four types of base distributions V2, the wavelets of the distribution corresponding to the base distribution V1 occupy each area obtained by dividing the square circumscribing the largest pupil area into four equal parts. In the tertiary hierarchy, there are 16 (= 2 ² × 2 ² ) types of basis distributions V3. That is, in the 16 types of base distributions V3, the wavelets of the distribution corresponding to the base distribution V1 occupy each area obtained by dividing the square circumscribing the largest pupil area into 16 equal parts. Illustration of the basis distribution having the vertical component in the fourth and subsequent layers is omitted.

  In the uppermost diagram in FIG. 9, a base distribution H <b> 1 having a horizontal component in the primary hierarchy is shown. The primary hierarchy has a single basis distribution H1 as a wavelet. The value of the left half region of the basis distribution H1 is +1 and the value of the right half region is -1. As described above, the square circumscribing the base distribution H1 corresponds to the square circumscribing the largest pupil region. There are four types of basis distributions H2 in the secondary hierarchy. That is, in the four types of base distributions H2, the wavelet of the distribution corresponding to the base distribution H1 occupies each region obtained by dividing the square circumscribing the largest pupil region into four equal parts. Illustration of the basis distribution having the horizontal component in the third and subsequent layers is omitted.

  The uppermost diagram in FIG. 10 shows a base distribution L1 having a diagonal component in the primary hierarchy. The primary hierarchy has a single basis distribution L1 as a wavelet, and the values of the upper left quadrant and lower right quadrant of the base distribution L1 are +1, the upper right quadrant and the lower left quadrant. The value of the region is -1. As described above, the square circumscribing the base distribution L1 corresponds to the square circumscribing the largest pupil region. There are four types of basis distributions L2 in the secondary hierarchy. That is, in the four types of base distributions L2, the wavelets of the distribution corresponding to the base distribution L1 occupy each region obtained by dividing the square circumscribing the largest pupil region into four equal parts. The basis distribution having diagonal components in the third and subsequent layers is not shown.

  Referring to FIGS. 8 to 10, it can be seen that the higher the hierarchy, the narrower the wavelet and, at the same time, the variation of the difference in the wavelet position increases two-dimensionally. By taking a projection (inner product) with a specific basis distribution, an expansion coefficient (similar to the Zernike coefficient), that is, a wavelet coefficient, indicating how much the component is present is obtained.

  As an example of calculating the distribution of wavelet coefficients from two-dimensional data, for example, in the case of an ultra low resolution distribution 109 of 8 × 8 pixels as shown in the upper diagram of FIG. 11, an ultra low resolution of 8 × 8 pixels is considered. The image distribution 109 is converted by wavelet analysis into an 8 × 8 wavelet coefficient distribution 110 as shown in the lower diagram of FIG. In this embodiment, since the two-dimensional data of the difference distribution between the measured actual pupil luminance distribution and the target pupil luminance distribution is set as the evaluation target, the average intensity is always zero. Taking this into account, the coefficient (scalar value) of the DC component 111 at the upper left in the wavelet coefficient distribution 110 is always zero.

  Further, the coefficients belonging to the respective base distributions V1, H1, L1, V2, H2, L2, V3, H3, and L3 are stored in an array as shown in the lower diagram of FIG. Therefore, the direction component to be noted and the coefficient of the hierarchy can be extracted from the coefficient distribution 110 as necessary. As in the case of the Fourier transform, the inverse transformation from the lower diagram of FIG. 11 to the upper diagram is also possible, so that all components up to the highest order can be calculated very quickly and accurately. is there.

Actually, wavelet analysis was performed on the two-dimensional data of the difference distribution shown in FIG. 5A, and the distribution of the wavelet coefficients of the two-dimensional data of the difference distribution was calculated. The image shown on the left side of FIG. 12 corresponds to the two-dimensional data of the difference distribution to be analyzed, and the image shown on the right side of FIG. 12 corresponds to the distribution of wavelet coefficients obtained by wavelet analysis. As described with reference to FIG. 5A, the two-dimensional data of the difference distribution to be analyzed shown on the left side of FIG. 12 includes the actual pupil luminance distribution, the target, and the typical freeform pupil luminance distribution. 2 ⁸ × 2 ⁸ (256 × 256) grid data of the difference distribution with respect to the pupil luminance distribution.

  In the image of the wavelet coefficient distribution shown on the right side of FIG. 12, as described with reference to the lower diagram of FIG. Further, the right half region and the lower half region of the wavelet coefficient distribution image occupy three-quarters of the entire image as the highest-order divergence information that varies in units of one pixel. Basically, as described above, since there is a tendency that the deviation is large in the low-order to middle-order components, there is a high possibility that all the order coefficients need not be evaluated.

  Wavelet analysis is a well-known technique in the field of general image processing. However, an image to be evaluated in this embodiment, that is, an image of two-dimensional data of a difference in pupil luminance distribution is basically an outer frame. Only a region in a circular pupil inscribed in the square is a target, and the distribution is often highly symmetrical about the center of the image. Also, taking into account the relationship with the imaging performance, rather than using the square area (square unit pupil area obtained by virtually dividing the illumination pupil) belonging to the grid data as the basic unit, Image forming performance is based on a structure such as a circular shape or a part of a sector shape (hereinafter referred to as an arc shape) in an orthogonal coordinate system (ξ, η) as shown in the left diagram of FIG. It can be expected that the correlation with

  Therefore, prior to wavelet analysis, a polar coordinate system (shown on the right side of FIG. 13) is obtained from an image (two-dimensional data) represented by an orthogonal coordinate system (ξ, η) as shown on the left side of FIG. By converting to an image represented by (r, θ), it can be expected that the image information is compatible with wavelet analysis, and as a result, it leads to a better physical index of the pupil luminance distribution. In the right side of FIG. 13, the horizontal axis indicates the direction of the azimuth angle θ, and the vertical axis indicates the direction of the radius vector r.

  The circular area 121 and the pair of arc-shaped areas 122 and 123 in the left diagram of FIG. 13 correspond to the rectangular area 121a and the pair of rectangular areas 122a and 123a in the right diagram of FIG. Yes. In this way, the circular area 121 and the arc-shaped areas 122 and 123 expressed by the orthogonal coordinate system (ξ, η) in the left diagram of FIG. 13 are represented by the polar coordinate system (r, In the expression by θ), it is converted into rectangular areas 121a, 122a, 123a.

In other words, the square-shaped region expressed by the polar coordinate system in the right diagram of FIG. 13 becomes an arc-shaped region when the representation by the orthogonal coordinate system is used in the left diagram of FIG. Therefore, even if the squares have the same size in the polar coordinate system, the area of the corresponding region in the orthogonal coordinate system increases as the distance from the origin increases. Specifically, as shown in FIG. 14, the area S of the arc-shaped region 131 expressed by the orthogonal coordinate system (ξ, η) is expressed by S = (r2 ² −r1 ² ) (θ2−θ1). The

  On the other hand, as shown in FIG. 15, when the arc-shaped region 131 of FIG. 14 is converted into a rectangular region 131 a using the representation in the polar coordinate system (r, θ), the area of the converted rectangular region 131 a is obtained. S ′ is represented by S ′ = (r2−r1) (θ2−θ1). That is, when the arc-shaped region 131 expressed by the orthogonal coordinate system (ξ, η) is converted into the rectangular region 131a using the expression by the polar coordinate system (r, θ), the area of the region is changed from S to S ′. To change.

  Therefore, in order to absorb the change in the area due to the conversion, the area ratio S / S ′ = (r2 + r1) / 2 is preliminarily multiplied when the expression based on the orthogonal coordinate system is converted to the expression based on the polar coordinate system. As a result, the effect of energy conservation is taken into consideration, and an appropriate relative comparison between the target pupil luminance distribution and the measured actual pupil luminance distribution is possible even in the polar coordinate system.

  Once the wavelet analysis is performed after converting into the two-dimensional data expressed in the polar coordinate system, the expansion coefficient in the base distribution as shown in FIGS. 16, 17 and 18 is calculated in the normal orthogonal coordinate system. It corresponds to that. Specifically, the uppermost diagram in FIG. 16 shows a base distribution R1 having a radial direction component in the primary hierarchy. The primary hierarchy has a single basis distribution R1 as a wavelet, the value of the annular zone outside the basis distribution R1 is +1, and the value of the inner circular zone is -1. The square circumscribing the base distribution R1 corresponds to the square circumscribing the largest pupil region.

There are 4 (= 2 ¹ × 2 ¹ ) types of base distributions R2 in the secondary hierarchy. That is, in the four types of base distributions R2, the upper half area of the outer ring-shaped area of the base distribution R1, the lower half area of the outer ring-shaped area, the upper half area of the inner circular area, the inner circle A wavelet having a distribution as shown in the figure occupies the lower half of the shape area. The basis distribution having the radial direction component in the third and subsequent layers is not shown.

  In the uppermost diagram of FIG. 17, a base distribution θ <b> 1 having an azimuth direction component in the primary layer is shown. The primary hierarchy has a single basis distribution θ1 as a wavelet, the value of the upper semicircular region of the basis distribution θ1 is +1, and the value of the lower semicircular region is −1. is there. The square circumscribing the base distribution θ1 corresponds to the square circumscribing the largest pupil region.

  There are four types of basis distributions θ2 in the secondary hierarchy. That is, in the four types of base distributions θ2, the upper half area of the outer ring-shaped area of the base distribution R1 in FIG. 16, the lower half area of the outer ring-shaped area, the upper half area of the inner circular area, The wavelets having the distribution as shown in the figure occupy the respective areas corresponding to the lower half of the inner circular area. The basis distribution having the azimuth direction component in the third and subsequent layers is not shown.

  The uppermost diagram in FIG. 18 shows a base distribution LL1 having a diagonal component in the primary hierarchy. The primary hierarchy has a single basis distribution LL1 as a wavelet, and the values of the upper half area and the upper half circle area of the outer ring-shaped area of the base distribution LL1 are +1, The value of the lower half region and the lower semicircular region is -1. The square circumscribing the base distribution LL1 corresponds to the square circumscribing the largest pupil region.

  There are four types of base distributions LL2 in the secondary hierarchy. That is, in the four types of base distributions LL2, the upper half region of the outer ring-shaped region of the base distribution R1 in FIG. 16, the lower half region of the outer ring-shaped region, the upper half region of the inner circular region, The wavelets having the distribution as shown in the figure occupy the respective areas corresponding to the lower half of the inner circular area. The basis distribution having diagonal components in the third and subsequent layers is not shown.

  Referring to FIGS. 16 to 18, since the area ratio between the +1 value region and the −1 value region changes as the order becomes lower, the area ratio weight described with reference to FIGS. 14 and 15 ( It can be seen that the orthogonality is improved by taking S / S ′) into account.

  In the present embodiment, first, the order (hierarchy) for which the spec value is to be calculated is fixed. Then, the minute modulation of the base distribution alone of each wavelet of the order is given as a disturbance to the target pupil luminance distribution, and an index value (for example, an OPE value) of imaging characteristics with respect to the pupil luminance distribution minutely modulated by the disturbance ) Is calculated. That is, the index value of the imaging characteristic corresponding to the pupil luminance distribution obtained by minutely modulating the target pupil luminance distribution with each wavelet basis distribution is obtained for each wavelet basis distribution.

  The task of obtaining the index value of the imaging characteristics corresponding to the minutely modulated pupil luminance distribution for each wavelet basis distribution can be performed in advance if the target pupil luminance distribution is known, and the calculation load is compared. Small. In this way, the modulation amount given to the target pupil luminance distribution and the difference between the index value of the imaging characteristic corresponding to the modulated pupil luminance distribution and the desired index value (for example, the RMS value of the error of the OPE value) Is the sensitivity for the basis distribution of each wavelet of that order. Further, the same operation is performed for the basis distributions of wavelets of other orders.

  In this way, if the target pupil luminance distribution is known, the sensitivity with respect to the imaging characteristics can be obtained in advance for each basis distribution of each order wavelet, and the database can be created as necessary. In the present embodiment, two-dimensional data of the difference distribution between the measured actual pupil luminance distribution and the target pupil luminance distribution is obtained, wavelet analysis is performed on the two-dimensional data of the difference distribution, and the difference distribution is calculated. Calculate the distribution of wavelet coefficients of two-dimensional data.

  Sensitivity for imaging characteristics is determined for each wavelet basis distribution, so if any wavelet coefficient is kept to a small extent, the imaging characteristics obtained from the measured actual pupil luminance distribution are targeted. It can be easily determined whether the desired imaging characteristics to be achieved with the pupil luminance distribution are sufficiently close. In other words, each wavelet coefficient obtained by wavelet analysis is a physical index with good visibility that is excellent in orthogonality, and using this physical index with good visibility, the measured actual pupil luminance distribution and the target pupil luminance distribution Thus, the pupil luminance distribution can be satisfactorily evaluated by focusing on the imaging performance.

  Hereinafter, embodiments will be described with reference to the accompanying drawings. FIG. 19 is a drawing schematically showing a configuration of an exposure apparatus according to the embodiment. In FIG. 19, the Z axis is along the normal direction of the transfer surface (exposure surface) of the wafer W, which is a photosensitive substrate, and the X axis is along the direction parallel to the paper surface of FIG. In the transfer surface of the wafer W, the Y axis is set along the direction perpendicular to the paper surface of FIG.

  Referring to FIG. 19, exposure light (illumination light) is supplied from the light source 1 to the exposure apparatus of the present embodiment. As the light source 1, for example, an ArF excimer laser light source that supplies light with a wavelength of 193 nm, a KrF excimer laser light source that supplies light with a wavelength of 248 nm, or the like can be used. The exposure apparatus of this embodiment supports an illumination optical system IL including a spatial light modulation unit 3, a mask stage MS that supports a mask M, a projection optical system PL, and a wafer W along the optical axis AX of the apparatus. Wafer stage WS.

  The light from the light source 1 illuminates the mask M through the illumination optical system IL. The light transmitted through the mask M forms an image of the pattern of the mask M on the wafer W via the projection optical system PL. The illumination optical system IL that illuminates the pattern surface (illuminated surface) of the mask M based on the light from the light source 1 is a multipolar illumination (bipolar illumination, quadrupole illumination, etc.) due to the action of the spatial light modulation unit 3. Deformation illumination such as annular illumination, normal circular illumination, etc. are performed. Further, modified illumination based on a free-form pupil luminance distribution having a complicated outer shape and distribution is performed according to the pattern characteristics of the mask M.

  The illumination optical system IL includes, in order from the light source 1 side along the optical axis AX, a beam transmission unit 2, a spatial light modulation unit 3, a relay optical system 4, and a micro fly's eye lens (or fly eye lens) 5. A condenser optical system 6, an illumination field stop (mask blind) 7, and an imaging optical system 8. The spatial light modulation unit 3 forms a desired light intensity distribution (pupil luminance distribution) in the far field region (Fraunhofer diffraction region) based on the light from the light source 1 via the beam transmitter 2. The internal configuration and operation of the spatial light modulation unit 3 will be described later.

  The beam transmitter 2 guides the incident light beam from the light source 1 to the spatial light modulation unit 3 while converting the incident light beam into a light beam having an appropriate size and shape, and changes the position of the light beam incident on the spatial light modulation unit 3. And a function of actively correcting the angular variation. The relay optical system 4 condenses the light from the spatial light modulation unit 3 and guides it to the micro fly's eye lens 5. The micro fly's eye lens 5 is, for example, an optical element composed of a large number of micro lenses having positive refractive power arranged vertically and horizontally and densely. The micro fly's eye lens 5 is formed by etching a parallel plane plate to form a micro lens group. Has been.

  In a micro fly's eye lens, unlike a fly eye lens composed of lens elements isolated from each other, a large number of micro lenses (micro refractive surfaces) are integrally formed without being isolated from each other. However, the micro fly's eye lens is the same wavefront division type optical integrator as the fly's eye lens in that the lens elements are arranged vertically and horizontally. A rectangular minute refracting surface as a unit wavefront dividing surface in the micro fly's eye lens 5 is a rectangular shape similar to the shape of the illumination field to be formed on the mask M (and the shape of the exposure region to be formed on the wafer W). It is.

  The micro fly's eye lens 5 divides the incident light beam into a wavefront to form a secondary light source (substantial surface light source; pupil luminance distribution) composed of a large number of small light sources at the illumination pupil at or near the rear focal position. . The incident surface of the micro fly's eye lens 5 is disposed at or near the rear focal position of the relay optical system 4. For example, a cylindrical micro fly's eye lens can be used as the micro fly's eye lens 5. The configuration and operation of the cylindrical micro fly's eye lens are disclosed in, for example, US Pat. No. 6,913,373.

  In this embodiment, the secondary light source formed by the micro fly's eye lens 5 is used as a light source, and the mask M arranged on the irradiated surface of the illumination optical system IL is Koehler illuminated. For this reason, the position where the secondary light source is formed is optically conjugate with the position of the aperture stop AS of the projection optical system PL, and the formation surface of the secondary light source can be called the illumination pupil plane of the illumination optical system IL. . Typically, the irradiated surface (the surface on which the mask M is disposed or the surface on which the wafer W is disposed when the illumination optical system including the projection optical system PL is considered) is optical with respect to the illumination pupil plane. A Fourier transform plane.

  The pupil luminance distribution is a light intensity distribution on the illumination pupil plane of the illumination optical system IL or a plane optically conjugate with the illumination pupil plane. When the number of wavefront divisions by the micro fly's eye lens 5 is relatively large, the overall light intensity distribution formed on the incident surface of the micro fly's eye lens 5 and the overall light intensity distribution (pupil luminance distribution) of the entire secondary light source. ) And a high correlation. For this reason, the light intensity distribution on the incident surface of the micro fly's eye lens 5 and the surface optically conjugate with the incident surface can also be referred to as a pupil luminance distribution.

  The condenser optical system 6 condenses the light emitted from the micro fly's eye lens 5 and illuminates the illumination field stop 7 in a superimposed manner. The light that has passed through the illumination field stop 7 forms an illumination region that is an image of the opening of the illumination field stop 7 in at least a part of the pattern formation region of the mask M via the imaging optical system 8. In FIG. 19, the installation of the optical path bending mirror for bending the optical axis (and thus the optical path) is omitted, but the optical path bending mirror can be appropriately disposed in the illumination optical path as necessary. .

  A mask M is placed on the mask stage MS along the XY plane (for example, a horizontal plane), and a wafer W is placed on the wafer stage WS along the XY plane. The projection optical system PL forms an image of the pattern of the mask M on the transfer surface (exposure surface) of the wafer W based on the light from the illumination area formed on the pattern surface of the mask M by the illumination optical system IL. . In this way, batch exposure or scan exposure is performed while the wafer stage WS is two-dimensionally driven and controlled in a plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL, and thus the wafer W is two-dimensionally driven and controlled. As a result, the pattern of the mask M is sequentially exposed in each exposure region of the wafer W.

  The internal configuration and operation of the spatial light modulation unit 3 will be described with reference to FIGS. As shown in FIG. 20, the spatial light modulation unit 3 includes a prism 32 and a spatial light modulator 30 disposed close to a side surface 32 a parallel to the YZ plane of the prism 32. The prism 32 is made of an optical material such as fluorite or quartz.

  The spatial light modulator 30 includes, for example, a plurality of mirror elements 30a that are two-dimensionally arranged along the YZ plane, a base 30b that holds the plurality of mirror elements 30a, and a cable (not shown) connected to the base 30b. And a drive unit 30c for individually controlling and driving the postures of the plurality of mirror elements 30a. In the spatial light modulator 30, the attitude of the plurality of mirror elements 30a is changed by the action of the drive unit 30c that operates based on the control signal from the control unit CR, and each mirror element 30a is set in a predetermined direction. The

  The prism 32 is obtained by replacing one side surface of the rectangular parallelepiped (the side surface facing the side surface 32a where the plurality of mirror elements 30a of the spatial light modulator 30 are arranged close to each other) with side surfaces 32b and 32c that are recessed in a V shape. It has an obtained form and is also called a K prism because of its cross-sectional shape along the XZ plane. Side surfaces 32b and 32c of the prism 32 that are recessed in a V shape are defined by two planes P1 and P2 that intersect to form an obtuse angle. The two planes P1 and P2 are both orthogonal to the XZ plane and have a V shape along the XZ plane.

  The inner surfaces of the two side surfaces 32b and 32c that are in contact with a tangent line (straight line extending in the Y direction) P3 between the two planes P1 and P2 function as the reflection surfaces R1 and R2. That is, the reflective surface R1 is located on the plane P1, the reflective surface R2 is located on the plane P2, and the angle formed by the reflective surfaces R1 and R2 is an obtuse angle. As an example, the angle between the reflection surfaces R1 and R2 is 120 degrees, the angle between the incident surface IP of the prism 32 perpendicular to the optical axis AX and the reflection surface R1 is 60 degrees, and the prism 32 perpendicular to the optical axis AX. The angle formed by the exit surface OP and the reflective surface R2 can be 60 degrees.

  In the prism 32, the side surface 32a on which the plurality of mirror elements 30a of the spatial light modulator 30 are arranged close to each other and the optical axis AX are parallel, and the reflection surface R1 is on the light source 1 side (upstream side of the exposure apparatus: FIG. 20 on the left side), the reflecting surface R2 is located on the micro fly's eye lens 5 side (downstream side of the exposure apparatus: right side in FIG. 20). More specifically, the reflecting surface R1 is obliquely arranged with respect to the optical axis AX, and the reflecting surface R2 is obliquely inclined with respect to the optical axis AX symmetrically with respect to the reflecting surface R1 with respect to a plane passing through the tangent line P3 and parallel to the XY plane. It is installed.

  The reflecting surface R1 of the prism 32 reflects the light incident through the incident surface IP toward the spatial light modulator 30. The plurality of mirror elements 30a of the spatial light modulator 30 are arranged in the optical path between the reflecting surface R1 and the reflecting surface R2, and reflect the light incident through the reflecting surface R1. The reflecting surface R2 of the prism 32 reflects the light incident through the spatial light modulator 30 and guides it to the relay optical system 4 through the exit surface OP.

  The spatial light modulator 30 applies the spatial modulation according to the incident position to the light incident through the reflecting surface R1 and emits the light. As shown in FIG. 21, the spatial light modulator 30 includes a plurality of minute mirror elements (optical elements) 30a arranged two-dimensionally within a predetermined plane. For ease of explanation and illustration, FIG. 20 and FIG. 21 show a configuration example in which the spatial light modulator 30 includes 4 × 4 = 16 mirror elements 30a. Are provided with a number of mirror elements 30a.

  Referring to FIG. 20, among the light beams incident on the spatial light modulation unit 3 along the direction parallel to the optical axis AX, the light beam L1 is the mirror element SEa of the plurality of mirror elements 30a, and the light beam L2 is the mirror element. The light is incident on a mirror element SEb different from SEa. Similarly, the light beam L3 is incident on a mirror element SEc different from the mirror elements SEa and SEb, and the light beam L4 is incident on a mirror element SEd different from the mirror elements SEa to SEc. The mirror elements SEa to SEd give spatial modulations set according to their positions to the lights L1 to L4.

  The array surface of the plurality of mirror elements 30 a of the spatial light modulator 30 is disposed at or near the front focal position of the relay optical system 4. The light reflected by the plurality of mirror elements 30a of the spatial light modulator 30 and given a predetermined angular distribution forms predetermined light intensity distributions SP1 to SP4 on the rear focal plane 4a of the relay optical system 4. That is, the relay optical system 4 determines the angle that the plurality of mirror elements 30a of the spatial light modulator 30 gives to the emitted light on the surface 4a that is the far field region (Fraunhofer diffraction region) of the spatial light modulator 30. Has been converted.

  Referring to FIG. 20 again, the incident surface of the micro fly's eye lens 5 is positioned at the rear focal plane 4a of the relay optical system 4. Therefore, the pupil luminance distribution formed in the illumination pupil immediately after the micro fly's eye lens 5 is the light intensity distributions SP1 to SP4 formed on the incident surface of the micro fly's eye lens 5 by the spatial light modulator 30 and the relay optical system 4. Corresponding distribution. As shown in FIG. 21, the spatial light modulator 30 includes a large number of minute mirror elements 30a regularly and two-dimensionally arranged along one plane, for example, with a planar reflecting surface as an upper surface. Is a movable multi-mirror.

  Each mirror element 30a is movable, and the tilt of the reflecting surface (that is, the tilt angle and tilt direction of the reflecting surface) is independently controlled by the action of the drive unit 30c that operates according to a command from the control unit CR. Each mirror element 30a can rotate continuously or discretely by a desired rotation angle with two directions (Y direction and Z direction) parallel to the arrangement plane and orthogonal to each other as rotation axes. That is, it is possible to two-dimensionally control the inclination of the reflecting surface of each mirror element 30a.

  When the reflection surface of each mirror element 30a is discretely rotated, the rotation angle is set in a plurality of states (for example,..., -2.5 degrees, -2.0 degrees, ... 0 degrees, +0.5 degrees). ... +2.5 degrees,. Although FIG. 21 shows a mirror element 30a having a square outer shape, the outer shape of the mirror element 30a is not limited to a square. However, from the viewpoint of light utilization efficiency, a shape that can be arranged so as to reduce the gap between the mirror elements 30a (a shape that can be closely packed) is preferable. From the viewpoint of light utilization efficiency, it is preferable to minimize the interval between two adjacent mirror elements 30a.

  In the spatial light modulator 30, the posture of the plurality of mirror elements 30a is changed by the action of the drive unit 30c that operates according to the control signal from the control unit CR, and each mirror element 30a is set in a predetermined direction. The The light reflected by the plurality of mirror elements 30a of the spatial light modulator 30 at a predetermined angle is applied to the illumination pupil immediately after the micro fly's eye lens 5 via the relay optical system 4 in a plurality of poles (bipolar). Light intensity distribution (pupil luminance distribution) such as a ring shape or a circular shape. Further, a pupil luminance distribution having a complicated outer shape and distribution is formed on the illumination pupil immediately after the micro fly's eye lens 5 in accordance with the pattern characteristics of the mask M.

  That is, the relay optical system 4 and the micro fly's eye lens 5 form a predetermined light intensity distribution in the illumination pupil of the illumination optical system IL based on the light that has passed through the spatial light modulator 30 in the spatial light modulation unit 3. A distribution forming optical system is configured. Another illumination pupil position optically conjugate with the rear focal position of the micro fly's eye lens 5 or in the vicinity thereof, that is, the pupil position of the imaging optical system 8 and the pupil position of the projection optical system PL (of the aperture stop AS) At the position), a pupil luminance distribution corresponding to the light intensity distribution in the illumination pupil immediately after the micro fly's eye lens 5 is also formed.

  The exposure apparatus of this embodiment includes a pupil distribution measurement device DT that is attached to, for example, a mask stage MS and measures a pupil luminance distribution formed on the illumination pupil of the illumination optical system IL. As shown in FIG. 22, the pupil distribution measuring device DT includes a pinhole member 10, a condenser lens 11, and a photodetector 12 such as a two-dimensional CCD image sensor. The pinhole member 10 is disposed on the irradiated surface of the illumination optical system IL (that is, the height position at which the pattern surface Pm of the mask M is to be positioned during exposure) during measurement. Further, the pinhole member 10 is disposed at the front focal position of the condenser lens 11, and the detection surface of the photodetector 12 is disposed at the rear focal position of the condenser lens 11.

  Therefore, the detection surface of the photodetector 12 is disposed at a position optically conjugate with the illumination pupil of the illumination optical system IL, that is, at a position optically conjugate with the pupil plane of the imaging optical system 8. In the pupil distribution measurement device DT, the light that has passed through the illumination optical system IL passes through the pinhole of the pinhole member 10, receives the condensing action of the condenser lens 11, and then reaches the detection surface of the photodetector 12. A light intensity distribution corresponding to the light intensity distribution (pupil luminance distribution) on the pupil plane of the imaging optical system 8 is formed on the detection surface of the photodetector 12.

  Thus, the pupil distribution measuring device DT is on a surface optically conjugate with the illumination pupil of the illumination optical system IL (the pupil plane of the imaging optical system 8) based on the light that has passed through the illuminated surface of the illumination optical system IL. Measure the light intensity distribution. Specifically, the pupil distribution measuring device DT monitors the pupil luminance distribution (pupil luminance distribution formed at the exit pupil position of the illumination optical system by the light incident on each point) for each point on the illuminated surface by the illumination optical system. To do.

  The control unit CR that comprehensively controls the operation of the exposure apparatus refers to the measurement result of the pupil distribution measurement device DT, so that a desired pupil luminance distribution is formed in the illumination pupil, so that the spatial light modulator 30 The plurality of mirror elements 30a are controlled. For a more detailed configuration and operation of the pupil distribution measuring device DT, reference can be made to, for example, Japanese Patent Laid-Open No. 2000-19012. Further, as the pupil distribution measuring device DT, for example, a device that detects the pupil luminance distribution through a pinhole disclosed in US Pat. No. 5,925,887 can be used.

  Further, instead of or in addition to the pupil distribution measurement device DT, based on light that has passed through the projection optical system PL (that is, based on light that has passed through the image plane of the projection optical system PL), A pupil distribution measurement device DTw (not shown) that measures the pupil luminance distribution on the pupil plane of the projection optical system PL (the exit pupil plane of the projection optical system PL) may be provided. Specifically, the pupil distribution measurement device DTw includes, for example, an imaging unit having a photoelectric conversion surface arranged at a position optically conjugate with the pupil position of the projection optical system PL, and each point on the image plane of the projection optical system PL. The pupil luminance distribution (pupil luminance distribution formed at the pupil position of the projection optical system PL by the light incident on each point) is monitored. As for the detailed configuration and operation of these pupil distribution measuring apparatuses, reference can be made to, for example, US Patent Publication No. 2008/0030707. Further, as a pupil distribution measuring device, the disclosure of US Patent Publication No. 2010/0020302 can be referred to.

  In the exposure apparatus, in order to transfer the pattern of the mask M onto the wafer W with high accuracy and faithfulness, it is important to perform exposure under appropriate illumination conditions according to the pattern characteristics of the mask M, for example. In the present embodiment, the pupil luminance distribution formed by the action of the spatial light modulator 30 is calculated using the spatial light modulation unit 3 including the spatial light modulator 30 in which the postures of the plurality of mirror elements 30a individually change. It can be freely and quickly changed, and thus various illumination conditions can be realized. That is, since the illumination optical system IL uses the spatial light modulator 30 having a large number of mirror elements 30a whose postures are individually controlled, the external shape of the pupil luminance distribution formed on the illumination pupil and the change of the distribution are related. The degree of freedom is high.

  However, as described above, the pupil luminance distribution formed on the illumination pupil using the spatial light modulation unit 3 is slightly different from the designed pupil luminance distribution, and the desired pupil luminance distribution corresponding to the designed pupil luminance distribution is obtained. Achieving imaging performance is difficult. In the exposure apparatus of the present embodiment, the pupil luminance distribution evaluation method according to the present embodiment is used to obtain a target pupil luminance distribution so that an imaging performance sufficiently close to the desired imaging performance can be obtained. The pupil luminance distribution formed on the illumination pupil is adjusted with the desired imaging performance to be achieved as a target, and consequently the illumination optical system IL is adjusted.

  FIG. 23 is a flowchart of the adjustment method of the illumination optical system according to the present embodiment. In the adjustment method of the illumination optical system IL according to the present embodiment, as shown in FIG. 23, a result corresponding to the pupil luminance distribution obtained by minutely modulating the target designed pupil luminance distribution with the basis distribution of each wavelet. An index value of image characteristics is obtained for each wavelet basis distribution (S11). In step S11, as described above, the minute modulation for each wavelet basis distribution in each order is given as a disturbance to the target designed pupil luminance distribution, and the result corresponding to the pupil luminance distribution minutely modulated by this disturbance is applied. For example, an OPE (Optical proximity effect) value is calculated as an index value for image characteristics.

  Specifically, the OPE value in the exposure apparatus is, for example, the line width of a resist pattern formed on a photosensitive substrate. In this case, the OPE value is a distribution dependent on the position of the image plane of the projection optical system, that is, a two-dimensional distribution. However, since the line width of the resist pattern in two directions orthogonal to each other on the image plane of the projection optical system tends to have an important meaning, the one-dimensional distribution of the OPE value along one direction (H direction) and the other A one-dimensional distribution of OPE values along the direction (V direction) can be handled as OPE value information.

  Since the target design pupil luminance distribution is known, the operation of step S11 for obtaining the OPE value corresponding to the minutely modulated pupil luminance distribution for each wavelet base distribution can be performed in advance. Thus, the difference between the modulation amount given to the target designed pupil luminance distribution and the OPE value corresponding to the modulated pupil luminance distribution and the desired OPE value to be achieved by the target designed pupil luminance distribution. The ratio to (the error of the OPE value) becomes the sensitivity regarding the base distribution of each wavelet of the order. Sensitivity to the OPE value obtained for each basis wavelet distribution of each order is made into a database as necessary.

Next, in the adjustment method of the illumination optical system IL according to the present embodiment, a distribution representing a difference between a measured actual pupil luminance distribution and a target designed pupil luminance distribution, and the illumination pupil is virtually Two-dimensional data of a difference distribution with a plurality of unit pupil regions obtained by division as a unit is obtained (S12). Specifically, in step S12, the pupil plane is virtually divided along two directions orthogonal to each other on the illumination pupil plane, whereby a plurality of rectangular unit pupil regions, for example, 2 ^N × 2 ^N square shapes are formed. Get the grid. Various forms of virtual division of the pupil plane are possible.

In step S12, the difference calculation unit 21 (see FIG. 19) provided in the control system CR uses, for example, 2 ^N × 2 ^N square unit pupil regions as units, and the pupil distribution measurement device DT. 2D data of the difference distribution between the actual pupil luminance distribution measured by the above and the target designed pupil luminance distribution is obtained. As described above, as the two-dimensional data of the difference distribution, the two-dimensional data of the polar coordinate expression obtained by the conversion from the expression by the orthogonal coordinate system to the expression by the polar coordinate system can be used.

  Next, in the adjustment method of the illumination optical system IL according to the present embodiment, wavelet analysis is performed on the two-dimensional data of the difference distribution, and the distribution of the wavelet coefficients of the two-dimensional data of the difference distribution is calculated (S13). Specifically, in step S13, the wavelet coefficient distribution calculation unit 22 (see FIG. 19) provided in the control system CR performs wavelet analysis on the two-dimensional data of the difference distribution obtained in step S12. Then, the distribution of wavelet coefficients of the two-dimensional data of the difference distribution is calculated.

  Thus, steps S11 to S13 constitute a method for evaluating the pupil luminance distribution formed on the illumination pupil of the illumination optical system that supplies illumination light to the projection optical system that forms the image of the pattern provided on the mask on the wafer. doing. In the evaluation method comprising steps S11 to S13, the measured actual pupil luminance distribution and the target designed pupil luminance are obtained by using each wavelet coefficient obtained by the wavelet analysis and having a good orthogonality and having a good visibility. A local difference from the distribution is also extracted, and as a result, the pupil luminance distribution can be satisfactorily evaluated by focusing on the imaging performance.

  Specifically, in step S11 constituting the evaluation method of the pupil luminance distribution according to the present embodiment, the sensitivity with respect to the imaging characteristics such as the OPE value is obtained for each basis distribution of the wavelet of each order. In step S12, two-dimensional data of a difference distribution between the measured actual pupil luminance distribution and the target designed pupil luminance distribution is obtained. In step S13, the wavelet analysis is performed on the two-dimensional data of the difference distribution obtained in step S12, thereby calculating the distribution of the wavelet coefficients of the two-dimensional data of the difference distribution.

  That is, in the pupil luminance distribution evaluation method (S11 to S13) according to this embodiment, the sensitivity to the OPE value is obtained for each base distribution of each wavelet. It is possible to easily determine whether the OPE value obtained from the measured actual pupil luminance distribution is sufficiently close to the desired OPE value. In the exposure apparatus of the present embodiment, for example, according to a predetermined program, the control unit CR as the information processing apparatus may execute a pupil luminance distribution evaluation method including steps S11 to S13.

  Finally, in the adjustment method of the illumination optical system IL according to the present embodiment, the pupil luminance distribution formed on the illumination pupil is adjusted based on the evaluation result of the pupil luminance distribution obtained in steps S11 to S13 (S14). . That is, in step S14, attention is paid to the sensitivity with respect to the imaging characteristics obtained for each basis distribution of wavelets of each order and the distribution of wavelet coefficients, and the spatial light modulator is referred to while referring to the measurement result of the pupil distribution measurement device DT. By controlling the postures of the plurality of 30 mirror elements 30a, an OPE value sufficiently close to a desired OPE value to be achieved in the target designed pupil luminance distribution can be obtained, that is, the error of the OPE value is reduced. The pupil luminance distribution formed on the illumination pupil of the illumination optical system IL is adjusted so as to be within the allowable range.

  As described above, in the adjustment method of the illumination optical system IL according to the present embodiment, the pupil luminance distribution that also extracts the local difference between the measured actual pupil luminance distribution and the target designed pupil luminance distribution is extracted. Using the evaluation method, the actual pupil luminance distribution can be appropriately adjusted with the desired imaging performance as a target. As a result, the exposure apparatus (IL, MS, PL, WS) of the present embodiment uses the illumination optical system IL that appropriately adjusts the actual pupil luminance distribution with the desired imaging performance as a target, and appropriate illumination conditions. A device with good performance can be manufactured by performing good exposure under the conditions.

  In the above-described embodiment, the pupil distribution measurement device DT uses the illumination pupil (imaging optical system) of the illumination optical system IL based on the light that has passed through the illuminated surface (position of the pattern surface of the mask M) of the illumination optical system IL. The light intensity distribution on a plane optically conjugate with the (8 pupil plane) is measured. However, the present invention is not limited to this, and the light intensity distribution on the surface optically conjugate with the illumination pupil can be measured based on the light traveling toward the irradiated surface of the illumination optical system IL. As an example, a part of the illumination light is extracted from the optical path between the micro fly's eye lens 5 and the condenser optical system 6, and the extracted light is optically conjugate with the illumination pupil immediately after the micro fly's eye lens 5. By detecting, the light intensity distribution corresponding to the pupil luminance distribution in the illumination pupil immediately after the micro fly's eye lens 5 is measured.

  Further, in the above-described embodiment, the K prism 32 integrally formed with one optical block is used as the prism member having the optical surface facing the arrangement surface of the plurality of mirror elements 30a of the spatial light modulator 30. Yes. However, the prism member having the same function as that of the K prism 32 can be configured by a pair of prisms without being limited thereto. In addition, a prism member having the same function as the K prism 32 can be configured by one plane-parallel plate and a pair of triangular prisms. Further, an assembly optical member having the same function as that of the K prism 32 can be constituted by one parallel plane plate and a pair of plane mirrors.

  In the present embodiment, as the spatial light modulator 30, for example, a spatial light modulator that continuously changes the directions of a plurality of mirror elements 30a arranged two-dimensionally is used. As such a spatial light modulator, for example, European Patent Publication No. 779530, US Pat. No. 5,867,302, US Pat. No. 6,480,320, US Pat. No. 6,600,591 U.S. Patent No. 6,733,144, U.S. Patent No. 6,900,915, U.S. Patent No. 7,095,546, U.S. Patent No. 7,295,726, U.S. Patent No. 7, No. 424,330, U.S. Patent No. 7,567,375, U.S. Patent Publication No. 2008/0309901, U.S. Patent Publication No. 2011/0181852, U.S. Patent Publication No. 2011/188017, and JP-A-2006. The spatial light modulator disclosed in Japanese Patent Application No. 113437 can be used. Note that the orientations of the plurality of mirror elements 5a arranged two-dimensionally may be controlled so as to have a plurality of discrete stages.

  In the above-described embodiment, as the spatial light modulator having a plurality of mirror elements that are two-dimensionally arranged and individually controlled, the directions (angle: inclination) of the plurality of two-dimensionally arranged reflecting surfaces are individually set. A controllable spatial light modulator is used. However, the present invention is not limited to this. For example, a spatial light modulator that can individually control the height (position) of a plurality of two-dimensionally arranged reflecting surfaces can be used. As such a spatial light modulator, for example, the spatial light modulator disclosed in FIG. 1d of US Pat. No. 5,312,513 and US Pat. No. 6,885,493 can be used. In these spatial light modulators, by forming a two-dimensional height distribution, an action similar to that of the diffractive surface can be given to incident light. The spatial light modulator having a plurality of reflection surfaces arranged two-dimensionally as described above is modified in accordance with the disclosure of, for example, US Pat. No. 6,891,655 and US Patent Publication No. 2005/0095749. May be.

  Further, in the above-described embodiment, as a pupil adjustment device that adjusts the pupil luminance distribution formed on the illumination pupil of the illumination optical system IL, a reflection having a plurality of mirror elements 30a arranged in a predetermined plane and individually controllable. A type of spatial light modulator 30 is used. However, the present invention is not limited to this, and a transmissive spatial light modulator including a plurality of transmissive optical elements arranged in a predetermined plane and individually controlled can also be used.

  In the above-described embodiment, the present invention is applied to a method for adjusting an illumination optical system mounted on an exposure apparatus, that is, an adjustment method for a single exposure apparatus. In this case, the target pupil luminance distribution in the evaluation method is the designed pupil luminance distribution, and the target OPE value is the OPE value to be achieved by the designed pupil luminance distribution.

  However, the present invention is not limited to this, and an adjustment method for matching with another exposure apparatus (mother machine), that is, for suppressing variations in resolution line width generated between two different exposure apparatuses. The present invention can be applied to the adjustment method. In this case, the target pupil luminance distribution in the evaluation method is the pupil luminance distribution used in the mother machine, and the target OPE value is the OPE value obtained from the pupil luminance distribution used in the mother machine.

  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. By using such a variable pattern forming apparatus, the influence on the synchronization accuracy can be minimized even if the pattern surface is placed vertically. As the variable pattern forming apparatus, for example, a DMD (digital micromirror device) including a plurality of reflecting elements driven based on predetermined electronic data can be used. An exposure apparatus using DMD is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-304135, International Patent Publication No. 2006/080285 pamphlet and US Patent Publication No. 2007/0296936 corresponding thereto. In addition to a non-light-emitting reflective spatial light modulator such as DMD, a transmissive spatial light modulator may be used, or a self-luminous image display element may be used. Here, the teachings of US Patent Publication No. 2007/0296936 are incorporated by reference.

  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. 24 is a flowchart showing a manufacturing process of a semiconductor device. As shown in FIG. 24, 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. 25 is a flowchart showing manufacturing steps of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 25, in the manufacturing process of the liquid crystal device, a pattern formation process (step S50), a color filter formation process (step S52), a cell assembly process (step S54), and a module assembly 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) or KrF excimer laser light (wavelength: 248 nm) is used as the exposure light. However, the present invention is not limited to this, and other suitable pulse lasers are used. A light source, for example, an F ₂ laser light source that supplies laser light with a wavelength of 157 nm, a Kr ₂ laser light source that supplies laser light with a wavelength of 146 nm, an Ar ₂ laser light source that supplies laser light with a wavelength of 126 nm, or the like can be used. It is also possible to use a CW (Continuous Wave) light source such as an ultrahigh pressure mercury lamp that emits bright lines such as g-line (wavelength 436 nm) and i-line (wavelength 365 nm). A harmonic generator of a YAG laser or the like can also be used. In addition, as disclosed in, for example, US Pat. No. 7,023,610, a single wavelength laser beam in an infrared region or a visible region oscillated from a DFB semiconductor laser or a fiber laser is used as vacuum ultraviolet light. For example, a harmonic that is amplified by a fiber amplifier doped with erbium (or both erbium and ytterbium) and wavelength-converted into ultraviolet light using a nonlinear optical crystal may be used.

  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.

  In the above-described embodiment, a so-called polarization illumination method disclosed in US Publication Nos. 2006/0170901 and 2007/0146676 can be applied. Here, the teachings of US Patent Publication No. 2006/0170901 and US Patent Publication No. 2007/0146676 are incorporated by reference.

  In the above-described embodiment, the present invention is applied to the illumination optical system that illuminates the mask in the exposure apparatus. However, the present invention is not limited to this, and the present invention generally relates to an illumination optical system for supplying illumination light to an imaging optical system that forms an image of an object disposed on the first surface on the second surface. Can be applied.

DESCRIPTION OF SYMBOLS 1 Light source 2 Beam transmission part 3 Spatial light modulation unit 30 Spatial light modulator 30a Mirror element 30c Drive part 4 Relay optical system 5 Micro fly eye lens 6 Condenser optical system 7 Illumination field stop (mask blind)
8 Imaging optical system IL Illumination optical system CR Control unit DT Pupil distribution measuring device M Mask PL Projection optical system W Wafer

Claims (21)

A method for evaluating a pupil luminance distribution formed on an illumination pupil of an illumination optical system that supplies illumination light to an imaging optical system that forms an image of a pattern arranged on a first surface on a second surface,
Two-dimensional data representing a difference between a measured pupil luminance distribution and a target pupil luminance distribution, the difference distribution using a plurality of unit pupil regions obtained by virtually dividing the illumination pupil. A first step for obtaining
A second step of performing wavelet analysis on the two-dimensional data of the difference distribution and calculating a distribution of wavelet coefficients of the two-dimensional data of the difference distribution. Including a third step of obtaining, for each wavelet base distribution, an index value of an imaging characteristic corresponding to the pupil luminance distribution obtained by minutely modulating the target pupil luminance distribution with the base distribution of each wavelet. The evaluation method according to claim 1. In the first step, as the two-dimensional data of the difference distribution, two-dimensional data of a polar coordinate expression obtained by conversion from an expression by an orthogonal coordinate system to an expression by a polar coordinate system is used. The evaluation method described. 4. The plurality of rectangular unit pupil regions are obtained in the first step by virtually dividing the illumination pupil along two directions orthogonal to each other in the illumination pupil. 5. The evaluation method according to any one of the above. 5. The evaluation method according to claim 2, wherein, in the third step, an OPE value corresponding to a pupil luminance distribution obtained by the minute modulation is obtained as the index value. 6. In the adjustment method of the illumination optical system that illuminates the illuminated surface with light from the light source,
Measuring the pupil luminance distribution formed in the illumination pupil of the illumination optical system;
Using the evaluation method according to any one of claims 1 to 5 to evaluate the pupil luminance distribution;
Adjusting the pupil luminance distribution formed in the illumination pupil based on the result of the evaluation. The adjustment method according to claim 6, wherein when measuring the pupil luminance distribution, a light intensity distribution on a surface optically conjugate with the illumination pupil is measured based on light passing through the irradiated surface. 8. The adjustment method according to claim 6, wherein when measuring the pupil luminance distribution, a light intensity distribution on a surface optically conjugate with the illumination pupil is measured based on light traveling toward the irradiated surface. . Adjusting a pupil luminance distribution formed in the illumination pupil by controlling a spatial light modulator provided in the illumination optical system and forming a pupil luminance distribution in the illumination pupil. The adjustment method according to any one of claims 6 to 8. An illumination optical system adjusted by the adjustment method according to claim 6. In the illumination optical system that illuminates the illuminated surface with light from the light source,
A pupil distribution measuring device for measuring a pupil luminance distribution formed on the illumination pupil of the illumination optical system;
A pupil adjustment device for adjusting a pupil luminance distribution formed in the illumination pupil;
The pupil luminance distribution is measured using the pupil luminance distribution measured by the pupil distribution measuring apparatus and the evaluation method according to any one of claims 1 to 5, and the pupil luminance distribution is evaluated based on a result of the evaluation. An illumination optical system comprising: a control unit that controls the pupil adjustment device. In the illumination optical system that illuminates the illuminated surface with light from the light source,
A pupil distribution measuring device for measuring a pupil luminance distribution formed on the illumination pupil of the illumination optical system;
A pupil adjustment device for adjusting a pupil luminance distribution formed in the illumination pupil;
The pupil luminance distribution is measured using the pupil luminance distribution measured by the pupil distribution measuring apparatus and the evaluation method according to any one of claims 1 to 5, and the pupil luminance distribution is evaluated based on a result of the evaluation. A control unit for controlling the pupil adjustment device,
The control unit is a distribution representing a difference between the measured pupil luminance distribution and a target pupil luminance distribution, and a plurality of unit pupil regions obtained by virtually dividing the illumination pupil are used as a unit. A difference calculation unit for obtaining two-dimensional data of a difference distribution;
An illumination optical system, comprising: a wavelet coefficient distribution calculation unit that performs wavelet analysis on the two-dimensional data of the difference distribution and calculates a distribution of wavelet coefficients of the two-dimensional data of the difference distribution. The illumination optics according to claim 11 or 12, wherein the pupil distribution measuring device measures a light intensity distribution on a surface optically conjugate with the illumination pupil based on light passing through the irradiated surface. system. The said pupil distribution measuring apparatus measures the light intensity distribution in the surface optically conjugate with the said illumination pupil based on the light which goes to the said to-be-irradiated surface, The any one of Claim 11 thru | or 13 characterized by the above-mentioned. The illumination optical system described. The pupil adjustment device includes a plurality of optical elements that are arranged on a predetermined plane and individually controlled, and includes a spatial light modulator that variably forms a pupil luminance distribution on the illumination pupil,
The illumination optical system according to claim 11, wherein the control unit controls the plurality of optical elements of the spatial light modulator. The spatial light modulator includes a plurality of mirror elements arranged two-dimensionally within the predetermined plane, and a drive unit that individually controls and drives the postures of the plurality of mirror elements. 15. The illumination optical system according to 15. 17. An exposure apparatus comprising the illumination optical system according to claim 10 for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. 18. A projection optical system that forms an image of the predetermined pattern on the photosensitive substrate, wherein the illumination pupil is at a position optically conjugate with an aperture stop of the projection optical system. The exposure apparatus described. 19. The exposure apparatus according to claim 18, wherein the target pupil luminance distribution is a designed pupil luminance distribution. 19. The exposure apparatus according to claim 18, wherein the target pupil luminance distribution is a pupil luminance distribution used in another exposure apparatus. Using the exposure apparatus according to any one of claims 17 to 20, 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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