Exposure method, article manufacturing method and program

Abstract

This technology provides advantages for exposing substrates via projection optics. [Solution] An exposure method for exposing a substrate via a projection optical system, comprising: a measurement step of illuminating a first pattern placed on the object surface of the projection optical system under first illumination conditions and measuring the imaging characteristics of the first pattern; an adjustment step of adjusting the projection optical system based on the imaging characteristics of the first pattern; and an exposure step of illuminating a second pattern of a master plate different from the first pattern under second illumination conditions different from the first illumination conditions, and exposing the substrate via the projection optical system adjusted in the adjustment step, wherein the measurement step includes selecting illumination conditions as the first illumination conditions such that the difference between the change in the imaging characteristics of the first pattern in response to a change in the wavefront aberration of the projection optical system and the change in the imaging characteristics of the second pattern in response to a change in the wavefront aberration of the projection optical system when the second pattern is illuminated under second illumination conditions falls within a target range.

Description

[Technical Field]

[0001] This invention relates to an exposure method, a method for manufacturing articles, and a program. [Background technology]

[0002] Semiconductor devices such as ultra-large-scale integrated circuits (ULSIs) and flat panel displays (FPDs) are manufactured through a photolithography process. The photolithography process includes an exposure process in which a pattern from a master plate called a mask or reticle is projected onto a substrate such as a glass plate or wafer on which a photosensitive material called a resist is placed (coated), and the substrate is exposed.

[0003] In recent years, there has been a growing demand for even finer pattern miniaturization in devices, and along with advancements in resist processes, the demand for miniaturization in exposure equipment is also increasing. In particular, for exposure equipment, improving the focusing accuracy to align the substrate surface with the imaging plane of the projection optical system, and improving the alignment accuracy to precisely superimpose each pattern across multiple processes are important themes.

[0004] On the other hand, exposure apparatuses have been proposed that can obtain better resolution for specific patterns by changing the lighting conditions, and one of the lighting conditions used for this purpose is called annular illumination.

[0005] Furthermore, techniques for measuring the focus position of an exposure apparatus (focus measurement) have been proposed conventionally (see Patent Documents 1 and 2). Patent Document 1 discloses a method in which a test substrate is exposed via a test pattern, and the focus position at which the line width of the test pattern takes its extreme value, or the focus position at the midpoint when sliced ​​with a certain line width value, is defined as the best focus position. Patent Document 2 discloses a method in which a slit and sensor provided on the image plane side of a projection optical system are used, and the position at which the measured value of the amount of exposure light passing through the slit takes its extreme value, or the focus position at the midpoint when sliced ​​with a certain amount of light, is defined as the best focus position.

[0006] In focus measurement, rough patterns or patterns without periodicity (e.g., isolated patterns) are generally used. This is because, when measuring focus using exposure, the line width of fine patterns is susceptible to variations due to the state of the photosensitive material on the substrate (variations in film thickness and degree of dryness), development conditions (variations in the concentration of each component in the developer), and measurement conditions (measurement reproducibility). Therefore, it is generally very difficult to measure changes in line width in response to focus changes with high accuracy. Furthermore, even when measuring focus with a sensor, using fine patterns makes it easy for variations in light intensity measurement to occur due to the effects of vibration, making it difficult to measure changes in light intensity in response to focus changes with high accuracy. For this reason, in focus measurement, it is generally necessary to use patterns with a certain degree of line width and periodicity. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 6-216004 [Patent Document 2] Japanese Patent Publication No. 2021-76721 [Overview of the project] [Problems that the invention aims to solve]

[0008] Projection optical systems generally have a certain amount of wavefront aberration due to design specifications and manufacturing tolerances. When wavefront aberration exists in a projection optical system, differences in the best focus position occur between patterns, depending on the amount and type (wavefront shape) of the aberration. In other words, differences in the best focus position occur depending on the differences in patterns, i.e., differences in line width and period. Therefore, even if focus measurements are performed using a rough pattern and the exposure equipment is adjusted so that the substrate position matches the best focus position, patterns with different line widths and periods may still be outside the best focus position.

[0009] Masks used in device manufacturing generally contain various patterns with different line widths and periods, and as mentioned above, the best focus positions for these patterns differ from one another. Therefore, it is impossible to expose the mask to the best focus for all patterns, but it is preferable to expose it to the best focus for the finest pattern. This is because the finer the pattern, the smaller the depth of field, making it more susceptible to focus shifts (the line width after exposure is more likely to change). On the other hand, rough patterns with large line widths and periods have a large depth of field, so even if the exposure is slightly off from the best focus position, they are less affected by focus shifts (the line width after exposure is less likely to change).

[0010] However, as mentioned above, it is difficult to accurately measure the best focus position for fine patterns. Furthermore, if exposure is set to the best focus position for a rough pattern, the exposure will be shifted from the best focus position for the fine pattern. As a result, the line width of the fine pattern will be affected by the focus shift, and there is a risk that the variation in line width within the image will exceed an acceptable range.

[0011] This invention has been made in view of the problems of the prior art, and its exemplary objective is to provide a technique advantageous for exposing a substrate via a projection optical system. [Means for solving the problem]

[0012] To achieve the above object, as one aspect of the present invention, an exposure method is an exposure method for exposing a substrate through a projection optical system, including: illuminating a first pattern arranged on the object plane of the projection optical system under a first illumination condition, and measuring the imaging characteristics of the first pattern; an adjustment step of adjusting the projection optical system based on the imaging characteristics of the first pattern measured in the measurement step; illuminating a second pattern of a reticle different from the first pattern under a second illumination condition different from the first illumination condition, and an exposure step of exposing the substrate through the projection optical system adjusted in the adjustment step. The measurement step includes selecting, as the first illumination condition, an illumination condition in which the difference between the change in the imaging characteristics of the first pattern with respect to the change in the wavefront aberration of the projection optical system and the change in the imaging characteristics of the second pattern with respect to the change in the wavefront aberration of the projection optical system when the second pattern is illuminated under the second illumination condition falls within a target range.

[0013] A further object or other aspect of the present invention will be clarified by the embodiments described below with reference to the accompanying drawings.

Advantages of the Invention

[0014] According to the present invention, for example, a technique advantageous for exposing a substrate through a projection optical system can be provided.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic diagram showing the configuration of an exposure apparatus. [Figure 2] It is a flowchart for explaining an exposure method as one aspect of the present invention. [Figure 3] It is a diagram for explaining a test pattern. [Figure 4] It is a diagram showing an example of an effective light source distribution. [Figure 5] It is a diagram showing an example of an effective light source distribution. [Figure 6] It is a diagram showing an example of a pattern of a reticle. [Figure 7]This is a diagram for explaining the focus difference between patterns. [Figure 8] This is a diagram showing diffracted light on the pupil plane of a projection optical system.

Embodiment for Implementing the Invention

[0016] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are given the same reference numerals, and duplicate explanations are omitted.

[0017] <First Embodiment> An example of an exposure method as one aspect of the present invention will be described. The present invention can be applied, for example, when determining the best focus position of a projection optical system mounted on an exposure apparatus. In this embodiment, a mask, a reticle, etc. are used as the original plate, and a glass plate, a semiconductor wafer, etc. are used as the substrate.

[0018] Hereinafter, a determination method for determining the best focus position of an optical system that forms an image of light from an object plane on an image plane will be described. In this embodiment, an application example for determining the best focus position of a projection optical system that projects a pattern of an original plate onto a substrate, which is used in an exposure apparatus, will be described. Here, the best focus position of the projection optical system is the position where the image of the pattern of the original plate is formed with the highest contrast.

[0019] Referring to FIG. 1, the exposure apparatus 100 will be described. FIG. 1 is a schematic diagram showing the configuration of the exposure apparatus 100. The exposure apparatus 100 is a lithography apparatus that is used in a photolithography process, which is a manufacturing process of devices such as semiconductor devices and flat panel displays (FPDs), and forms a pattern on a substrate. The exposure apparatus 100 exposes the substrate through the original plate and transfers the pattern of the original plate to the substrate.

[0020] As shown in Figure 1, the exposure apparatus 100 includes an illumination optical system 1, a projection optical system 7, a master plate stage 22, a substrate stage 62, and a control unit 80. In this embodiment, an XYZ coordinate system is defined in which the horizontal plane is the XY plane and the vertical direction is the Z axis direction.

[0021] The exposure apparatus 100 irradiates the master plate 21 with light from a light source (not shown) via the illumination optical system 1, and projects the light from the pattern on the master plate 21 onto the substrate 61 via the projection optical system 7. Since a photosensitive material such as resist is placed (coated) on the substrate 61, the pattern of the master plate 21 is transferred to the substrate 61 through a subsequent development process. In this embodiment, the average wavelength (λ) of the light from the light source (exposure light) is 400 nm, and the numerical aperture (NA) of the projection optical system 7 is 0.1.

[0022] An effective light source aperture 11 is inserted (placed) in the optical path of the illumination optical system 1. By replacing (changing) the effective light source aperture 11, it is possible to set the light intensity distribution (effective light source distribution) at the pupil position of the projection optical system 7 to any shape.

[0023] In this embodiment, the effective light source aperture 11 sets the lighting conditions (second lighting conditions) known as the effective light source distribution shown in Figure 4, or so-called ring illumination 401, and the inner diameter of the ring (σ in ) is 0.425, outer diameter (σ out ) is 0.85. The annular illumination 401 is a light intensity distribution (second light intensity distribution) that has the same distribution in the X direction (first direction) and the Y direction (second direction orthogonal to the first direction) at the pupil position of the projection optical system 7. σ represents the diameter when the radius of the pupil of the projection optical system 7 is normalized to 1.

[0024] Furthermore, by replacing the effective light source aperture 11 with another effective light source aperture, it is possible to set the effective light source distribution shown in Figures 5(a), 5(b), 5(c), and 5(d), which are the lighting conditions referred to as dual-pole illumination 501, 502, 503, and 504.

[0025] The double-pole illumination 501 (first illumination condition) shown in Figure 5(a) uses the annular illumination 401 shown in Figure 4 at a distance σ ofs The shape is obtained by cutting out the overlapping portion between the annular band shifted by ±X and the original annular band. The annular illumination 401 is a light intensity distribution (first light intensity distribution) that has different distributions in the X direction and the Y direction at the pupil position of the projection optical system 7. In this embodiment, the distance σ ofs This value is 1.333, which corresponds to the distance that ±1st order diffracted light travels when a 1.5 μm line-and-space exposure is performed, with a projection optical system NA of 0.1 and an exposure light wavelength λ of 400 nm.

[0026] The dipole illumination 502 (third illumination condition) shown in Figure 5(b) is the same shape as the dipole illumination 501 shown in Figure 5(a) rotated by 90 degrees. The dipole illumination 502 is the light intensity distribution (third light intensity distribution) obtained by rotating the dipole illumination 501 by 90 degrees around the optical axis (Z-axis) of the projection optical system 7 at the pupil position of the projection optical system 7.

[0027] The dipole illumination 503 (fourth illumination condition) shown in Figure 5(c) is the same shape as the dipole illumination 501 shown in Figure 5(a), rotated 45 degrees clockwise. The dipole illumination 503 has a light intensity distribution (fourth light intensity distribution) that differs in the direction that forms a 45-degree clockwise angle with respect to the X direction (third direction) and in the direction perpendicular to this direction (fourth direction) at the pupil position of the projection optical system 7. Furthermore, the dipole illumination 503 is also the light intensity distribution obtained by rotating the dipole illumination 501 45 degrees around the optical axis of the projection optical system 7 at the pupil position of the projection optical system 7.

[0028] The dipole illumination 504 (fifth illumination condition) shown in Figure 5(d) is the same shape as the dipole illumination 501 shown in Figure 5(a), rotated 45 degrees counterclockwise. The dipole illumination 504 has a light intensity distribution (fifth light intensity distribution) that differs in the direction that forms a 45-degree counterclockwise angle with respect to the X direction (fifth direction) and in the direction perpendicular to this direction (sixth direction) at the pupil position of the projection optical system 7. Furthermore, the dipole illumination 504 is also the light intensity distribution obtained by rotating the dipole illumination 503 90 degrees around the optical axis of the projection optical system 7 at the pupil position of the projection optical system 7.

[0029] When exposing the substrate 61, the original plate stage 22, which holds the original plate 21, and the substrate stage 62, which holds the substrate 61, are scanned synchronously in the ±Y direction (scanning direction) under the control of the control unit 80. This allows the substrate 61 to be exposed in an area larger than the projection area of ​​the projection optical system 7 (the pattern area of ​​the original plate 21). When scanning of the original plate stage 22 and the substrate stage 62 is completed, the substrate stage 62 is moved by a certain amount in the X direction and / or Y direction to expose another shot area of ​​the substrate 61. When exposure of all shot areas of the substrate 61 is completed, the substrate 61 is removed from the exposure apparatus 100, and a new substrate 61 is loaded into the exposure apparatus 100.

[0030] In this embodiment, the projection optical system 7 is a reflective optical system including a concave mirror 3, a trapezoidal mirror 4, and a convex mirror 5. The projection optical system 7 is telecentric on both the object plane side and the image plane side. Therefore, the principal rays of light incident on the substrate 61 from the projection optical system 7 are parallel to the Z-axis on both the object plane side and the image plane side.

[0031] The control unit 80 is composed of an information processing device (computer) including, for example, a CPU and memory. The control unit 80 comprehensively controls each part of the exposure device 100 according to a program stored in a storage unit such as memory, and operates the exposure device 100. By controlling the operation of each part of the exposure device 100, the control unit 80 performs an exposure process to expose the substrate 61 and transfer the pattern of the master plate 21 onto the substrate 61. In this embodiment, the control unit 80 also functions as a processing unit that performs a determination process to determine the best focus position of the projection optical system 7. However, such a determination process does not necessarily have to be performed by the control unit 80; it may be performed by an information processing device outside the exposure device 100, and the best focus position of the projection optical system 7 may be obtained from the external information processing device.

[0032] The master plate 21 has various patterns formed on it for manufacturing devices such as integrated circuits and displays, for example, patterns 601, 602, 603, and 604 shown in Figure 6. Patterns 601 to 604 are the finest patterns in terms of line width and period among the patterns formed on the master plate 21. In this embodiment, patterns 601 to 604 have a line width of 1.5 μm and a period of 3 μm. Pattern 601 (second pattern) has periodicity in the X direction, and pattern 602 (fourth pattern) has periodicity in the Y direction. Pattern 602 is a pattern obtained by rotating pattern 601 by 90 degrees within the plane of the master plate 21. Pattern 603 (sixth pattern) has periodicity in the direction obtained by rotating the X axis counterclockwise by 45 degrees, i.e., in the +45 degree direction. Pattern 603 is a pattern obtained by rotating pattern 601 by 45 degrees within the plane of the master plate 21. Pattern 604 (the eighth pattern) has periodicity in the direction of a 45-degree clockwise rotation of the X-axis, i.e., in the -45-degree direction. Pattern 604 is a pattern obtained by rotating Pattern 603 by 90 degrees within the plane of the original plate 21.

[0033] When projecting the pattern of the master plate 21 onto the substrate 61 via the projection optical system 7, it is necessary to precisely match the best focus position of the projection optical system 7 with the surface position of the substrate 61 (the surface on which the photosensitive material is placed). If the best focus position of the projection optical system 7 and the surface position of the substrate 61 do not match, the image of the pattern of the master plate 21 formed on the substrate via the projection optical system 7 will be blurred, making it impossible to form the desired pattern image on the substrate.

[0034] Therefore, in this embodiment, an adjustment step is performed to adjust the best focus position of the projection optical system 7 before exposing the substrate 61. The best focus position of the projection optical system 7 differs depending on the orientation of the pattern, but in this embodiment, the best focus positions corresponding to the patterns in the four orientations can be adjusted individually. As a specific adjustment method for adjusting the best focus position of the projection optical system 7, for example, techniques well known in the industry, including the technique disclosed in Japanese Patent Application Publication No. 2019-132907, can be applied.

[0035] Before the adjustment process, a measurement process (focus measurement) is required to measure the best focus position of the projection optical system 7. For example, the following method can be used to measure the best focus position: Expose the test substrate through a test pattern, measure the line width of the test pattern transferred to the test substrate, and define the best focus position as the focus position where the line width takes its extreme value, or the focus position of the midpoint when sliced ​​at a certain level (line width value).

[0036] In this type of focus measurement, rough patterns or patterns without periodicity (e.g., isolated patterns) are generally used. This is because, when measuring focus using exposure, the line width of fine patterns is susceptible to variations due to the state of the photosensitive material on the substrate (variations in film thickness and degree of dryness), development conditions (variations in the concentration of each component in the developer), and measurement conditions (measurement reproducibility). Therefore, it is generally very difficult to measure changes in line width in response to changes in focus with high precision. For this reason, in focus measurement, it is generally necessary to use patterns with a certain degree of line width and periodicity.

[0037] On the other hand, projection optical systems generally have a certain amount of wavefront aberration due to design values ​​and manufacturing tolerances. When wavefront aberration exists in a projection optical system, a difference in the best focus position occurs between patterns, depending on the amount and type (wavefront shape) of the aberration. In other words, a phenomenon occurs where the best focus position differs depending on the difference in patterns, i.e., the difference in line width and period. This phenomenon will be referred to as "inter-pattern focus difference" below.

[0038] Referring to Figures 7(a), 7(b), 7(c), and 7(d), we will explain the imaging characteristics, such as the difference in the best focus position, depending on the line width and period of the pattern, i.e., the difference in focus between patterns.

[0039] Figure 7(a) shows the region 721 on the pupil surface of the projection optical system 7 that contributes to imaging when the fine pattern 701 is exposed with the annular illumination 401 shown in Figure 4. Figure 7(b) shows the region 722 on the pupil surface of the projection optical system 7 that contributes to imaging when the rough pattern 702 is exposed with the annular illumination 401 shown in Figure 4. Figure 7(c) shows the region 723 on the pupil surface of the projection optical system 7 that contributes to imaging when the rough pattern 702 is exposed with the bipolar illumination 501 shown in Figure 5(a). In Figures 7(a) to 7(c), the darker the color of the regions 721 to 723 contributing to imaging in the pupil region of the projection optical system 7 (in the order of gray, diagonal lines, and dots), the higher the contribution to imaging.

[0040] Referring to Figures 8(a) and 8(b), we will explain how the region 721 shown in Figure 7(a) contributes to image formation.

[0041] Figure 8(a) shows the position of diffracted light on the pupil plane of the projection optical system 7 when a fine pattern 701 is exposed with an annular illumination 401. Figure 8(a) shows the distribution of 0th-order light 801, the distribution of +1st-order diffracted light (+1st-order light) 802, and the distribution of -1st-order diffracted light (-1st-order light) 803. Distributions 802 and 803 are, respectively, distributions 801 shifted in the X direction. The amount of shift σx (positional displacement) between distribution 801 and distribution 802, and between distribution 801 and distribution 803, is larger the finer the pattern and smaller the coarser the pattern. For example, if the fine pattern 701 is a line-and-space pattern with a line width of 1.5 μm and a period of 3.0 μm, the shift amount σx is 1.333. Parts of distributions 802 and 803 extend outside the pupil plane of the projection optical system 7. The diffracted light from the portion that extends beyond the pupil plane of the projection optical system 7 is blocked by an aperture (not shown) located near the pupil position of the projection optical system 7, or on the object side of such an aperture, and therefore does not reach the image plane of the projection optical system 7. The diffracted light of the second order or higher (as a whole) extends beyond the pupil plane of the projection optical system 7 and does not contribute to imaging at all, so it is ignored here. In order to form an image on the image plane of the projection optical system 7, the 0th order light and the ±1st order light must interfere with each other. In the case shown in Figure 8(a), the 0th order light and the +1st order light, or the 0th order light and the -1st order light, interfere (two-beam interference).

[0042] Figure 8(b) is a diagram illustrating the interference between the 0th-order light and the +1st-order light. Interference occurs when both the 0th-order and +1st-order light reach the image plane of the projection optical system 7, causing the pattern to be imaged. All of the 0th-order light reaches the image plane of the projection optical system 7, but of the 1st-order light, only the light from region 805 reaches the image plane of the projection optical system 7. Therefore, of the +1st-order light, only the light from region 805 contributes to imaging. Of the 0th-order light, only the light from region 804 is coherent (interferable) with the +1st-order light, i.e., it interferes with the +1st-order light and contributes to imaging.

[0043] Figure 8(c) is a diagram illustrating the interference between 0th-order light and -1st-order light. Similar to +1st-order light, only the light in region 807 contributes to imaging among the -1st-order light. Among the 0th-order light, only the light in region 806 is coherent (interferable) with the -1st-order light, i.e., it interferes with the -1st-order light and contributes to imaging.

[0044] Thus, of the 0th-order light (distribution 801), +1st-order light (distribution 802), and -1st-order light (distribution 803), only the light from regions 804, 805, 806, and 807 contributes to imaging. Therefore, within the pupil region of the projection optical system 7, the region that contributes to imaging is the region through which the light from regions 804 to 807 passes, i.e., region 721 shown in Figure 7(a). In region 721, the darker regions are the overlapping regions of regions 804 and 807, and the overlapping regions of 805 and 806, and these regions contribute relatively large to imaging.

[0045] Similarly, Figures 7(b) and 7(c) show the regions through which the 0th-order light and ±1st-order light pass under their respective conditions (combinations of effective light source and pattern). In the cases shown in Figures 7(b) and 7(c), since the pattern is a rough pattern, the shift amount σx between the 0th-order light and ±1st-order light is smaller than in the case shown in Figure 7(a), and it can be understood that regions 722 and 723 are regions that contribute to imaging. In the cases shown in Figures 7(b) and 7(c), diffracted light of the 2nd order and above also contributes to imaging, but it is small compared to the contribution of the 0th-order light and ±1st-order light to imaging, so it can be ignored.

[0046] Referring to Figures 7(a) and 7(b), although the illumination conditions for illuminating the patterns are the same annular illumination 401, the fineness of the patterns differs, resulting in a significant difference in the regions contributing to imaging at the pupil plane of the projection optical system 7 between region 721 and region 722. Specifically, the dotted region 710 shown in Figure 7(d) is included in region 722 shown in Figure 7(b), but not in region 721 shown in Figure 7(a). Therefore, the performance of the projection optical system 7 corresponding to the dotted region 710 shown in Figure 7(d) contributes to imaging in the case shown in Figure 7(b), but does not contribute to imaging in the case shown in Figure 7(a). Thus, depending on the performance of the projection optical system 7 corresponding to region 710, a difference in imaging characteristics arises between the case shown in Figure 7(a) and the case shown in Figure 7(b).

[0047] On the other hand, referring to Figures 7(a) and 7(c), although the illumination conditions and patterns are different, the regions contributing to image formation at the pupil plane of the projection optical system 7 are similar in region 721 and region 723. This can be understood, for example, from the fact that the dotted region 710 shown in Figure 7(d) is not included in either region 721 shown in Figure 7(a) or region 723 shown in Figure 7(c). Therefore, regardless of the performance of the projection optical system 7, there is little difference in imaging characteristics between the case shown in Figure 7(a) and the case shown in Figure 7(c).

[0048] We have explained the reasons why differences in focus occur between patterns. However, the imaging characteristics that result in differences between patterns are not limited to the best focus position, but also include, for example, the difference in line width between the left and right sides (the difference between the line width at the right edge and the line width at the left edge of a line and space pattern), distortion, etc.

[0049] Table 1 below shows the focus sensitivity calculated by optical software. Focus sensitivity is the degree to which each term component (the i-th component) of the Zernike polynomial, which in this embodiment expands the wavefront aberration of the projection optical system 7 into a polynomial, indicates the degree to which each term component (the i-th component) of the Zernike polynomial has an influence on the best focus position. The unit of focus sensitivity is μm / λ, that is, the quantity that represents the change in the best focus position [μm] per unit quantity (1λ) of each term (1λ) of the Zernike polynomial that represents the wavefront aberration.

[0050]

Table 1

[0051] The amount of focus difference between patterns depends on each term component of the Zernike polynomial representing the wavefront aberration of the projection optical system 7. Generally, in each term of the Zernike polynomial, the low-order terms (for example, terms from 4 to 18) have a relatively large generation amount, and the high-order terms (for example, terms from 19 to 36) have a relatively small generation amount. Note that for 37 or more terms of the Zernike polynomial, since the generation amount is even smaller, it can be ignored. Also, in the present embodiment, among the wavefront aberrations of the projection optical system 7, the wavefront aberration represented by terms 4 to 6 of the Zernike polynomial can be corrected by an adjustment mechanism (not shown) that adjusts the projection optical system 7.

[0052] Assume the absolute value Zn of the maximum generation amount of the n-th term of the Zernike polynomial representing the wavefront aberration of the projection optical system 7 as follows. Zn = 0.05λ (7 ≤ n ≤ 18) Zn = 0.01λ (19 ≤ n ≤ 36) Zn = 0 (n ≤ 6 or 37 ≤ n) In this case, the maximum generation amount ΔFab of the focus difference between patterns in the case shown in FIG. 7(a) and the case shown in FIG. 7(b), and the maximum generation amount ΔFac of the focus difference between patterns in the case shown in FIG. 7(a) and the case shown in FIG. 7(c) are represented by the following equations.

[0053]

Equation

[0054] In the above equation, (Z i ×(B i -A i )) and (Z i ×(C i -A[[ID=4!]] iThe terms )) represent the contribution of the i-th term of the Zernike polynomial, which represents wavefront aberration, to the inter-pattern focus difference when Zi occurs. Since each term of the Zernike polynomial can take both positive and negative values, the maximum occurrences ΔFab and ΔFac are given as absolute values.

[0055] When calculating the maximum generation amounts ΔFab and ΔFac for the focus sensitivity shown in Table 1, ΔFab = 9.1 μm and ΔFac = 4.9 μm. When the target value (target range) of the focus difference between patterns is set to 5 μm or less, the case shown in Figure 7(b) does not achieve the target value, while the case shown in Figure 7(c) does. Therefore, when adjusting the focus in the case shown in Figure 7(b), there is a possibility that the deviation from the best focus position when exposed in the case shown in Figure 7(a) will exceed 5 μm. On the other hand, when adjusting the focus in the case shown in Figure 7(c), there is no possibility that the deviation from the best focus position when exposed in the case shown in Figure 7(a) will exceed 5 μm.

[0056] Thus, in this embodiment, the target value is set so that the deviation from the best focus position (maximum occurrence amount ΔFac) is less than or equal to a predetermined value, specifically 5 μm or less. Note that the assumption and target value for the maximum occurrence amount of focus difference between patterns are not limited to the calculation formulas and numerical values ​​described above; other calculation formulas and numerical values ​​may also be used.

[0057] As described above, the master plate 21 has various patterns formed on it for manufacturing devices such as integrated circuits and displays, and these patterns have different best focus positions. Therefore, it is impossible to expose the master plate 21 to the best focus of all the patterns formed on it, but in this embodiment, the exposure is adjusted so that the best focus is on patterns 601 to 604, which are the finest patterns in terms of line width and period.

[0058] For example, even if focus measurement is performed using the case shown in Figure 7(b) (annular illumination + rough pattern) and the surface position of the substrate 61 is matched with the best focus position, in the case shown in Figure 7(a) (annular illumination + fine pattern), the image will be out of focus. Therefore, there is a possibility that the substrate 61 will be exposed with a focus misalignment exceeding the target value of 5 μm for the inter-pattern focus difference.

[0059] Therefore, in this embodiment, focus measurement is performed using the case shown in Figure 7(c) (dual-pole illumination + rough pattern) to match the surface position of the substrate 61 with the best focus position. This allows the exposure apparatus 100 to be adjusted so that, even though a rough pattern is used as the test pattern (measurement pattern), the substrate 61 is exposed in a state close to the best focus position in the case shown in Figure 7(a) (annular illumination + fine pattern). Here, a state close to the best focus position means a state in which the focus deviation is smaller than the target value of 5 μm.

[0060] Refer to Figure 3 to explain the test patterns used for focus measurement. Figure 3 is a diagram showing an example of a measurement pattern group 300 that includes multiple measurement patterns 301, 302, 303, and 304 as test patterns.

[0061] The measurement pattern group 300 may be provided on the master plate 21, or on a separate test master plate for focus measurement. The measurement pattern group 300 includes, for example, measurement patterns 301, 302, 303, and 304 (first pattern, third pattern, fifth pattern, and seventh pattern) whose directions of extension (longitudinal direction) are different from each other, as shown in Figure 3. The four measurement patterns 301 to 304 are each independent single line patterns and are referred to as isolated line (iso) patterns. In this embodiment, the measurement patterns 301 to 304 have a line width of 5 μm. The measurement patterns 301 to 304 can also be replaced with other patterns. For example, an isolated pattern with a line width of 5 μm and a periodic pattern with a line width of 5 μm and a period of 10 μm have approximately the same focus sensitivity. Therefore, a periodic pattern with a line width of 5 μm and a period of 10 μm may be used instead of the measurement patterns 301 to 304.

[0062] The measurement patterns 301 to 304 are designed so that the line width of their images is maximized when the surface position of the substrate 61 coincides with the best focus position of the projection optical system 7. Therefore, the best focus position of the projection optical system 7 can be determined by measuring the line width of the images of the measurement patterns 301 to 304 formed via the projection optical system 7 at each of several positions in the optical axis direction on the image plane side of the projection optical system 7, i.e., in the Z direction.

[0063] The line width of the images of measurement patterns 301 to 304 may be measured as the dimensions of the resist pattern by an external measuring device of the exposure apparatus 100, or by a measuring unit (not shown) provided in the exposure apparatus 100. Alternatively, instead of measuring the dimensions of the resist pattern formed on the substrate, the line width of the images of measurement patterns 301 to 304 may be measured by measuring the aerial image of the projection pattern by the projection optical system 7. In this case, for example, a detection unit (not shown) for detecting the intensity of light from the projection optical system 7 is provided in the exposure apparatus 100, and the aerial image (intensity of light) of the projection pattern by the projection optical system 7 is detected by the detection unit at each of several different positions in the Z direction. This allows the line width of the images of measurement patterns 301 to 304 to be measured.

[0064] In this embodiment, we will explain using as an example the case in which a test pattern (measurement patterns 301 to 304) is actually transferred to a test substrate via a projection optical system 7, and measurement data is obtained by measuring the line width (dimension) of the test pattern transferred to the test substrate. Specifically, for each of several states in which the position of the test substrate in the Z direction is different from each other, the test pattern is projected onto the test substrate via the projection optical system 7 to expose the test substrate. Then, by measuring the line width of the resist pattern formed on the test substrate after the development process, multiple measurement data corresponding to the multiple states are obtained.

[0065] Next, with reference to Figure 2, the exposure method in this embodiment will be described as the operation of the exposure apparatus 100. Figure 2 is a flowchart illustrating the exposure method as one aspect of the present invention.

[0066] Steps S201 to S207 are part of the process for measuring the best focus position of the projection optical system 7, and use a test substrate without a device pattern and a test master with a test pattern formed in place of the device pattern. In steps S201 to S207, the test patterns (measurement patterns 301 to 304) of the test master are transferred to the test substrate via the projection optical system 7 in each of several states in which the position of the test substrate in the Z direction is different from each other. Steps S201 to S207 are controlled by the control unit 80.

[0067] In S200, the test master is loaded into the exposure apparatus 100. The test master loaded into the exposure apparatus 100 is held by the master stage 22.

[0068] In S299, the test substrate is loaded into the exposure apparatus 100. The test substrate loaded into the exposure apparatus 100 is held by the substrate stage 62.

[0069] In S201, the effective light source aperture 11, which is positioned (inserted) at the pupil position of the illumination optical system 1, is replaced (switched) to change the effective light source distribution. In this embodiment, the effective light source distribution is changed from the annular illumination 401 shown in Figure 4 to the bipolar illumination 501 shown in Figure 5(a). In other words, bipolar illumination 501 is selected as the effective light source distribution. Bipolar illumination 501 is an illumination condition in which the difference between the change in the imaging characteristics of the test pattern using bipolar illumination and the change in the imaging characteristics of the pattern on the original plate 21 using annular illumination, in response to the change in wavefront aberration of the projection optical system 7, falls within the target range. Note that the effective light source distribution may be changed using another means instead of the effective light source aperture 11.

[0070] In S202, the test substrate is positioned in a predetermined location. Specifically, the substrate stage 62 holding the test substrate is driven so that the test substrate, on which the resist has been placed (coated), is positioned in a preset initial position. The initial position can be arbitrarily set by the user via a user interface provided in the exposure apparatus 100. The initial position can be set, for example, to the lower limit (negative limit in the Z direction) or upper limit (positive limit in the Z direction) of the range (movement range) in which the test substrate can be moved in the Z direction. In this embodiment, the initial position is set to the lower limit of the movement range of the test substrate.

[0071] In S203, the test pattern (or its image) is projected onto the test substrate via the projection optical system 7 to expose the test substrate. Specifically, the measurement patterns 301 to 304 (measurement pattern group 300) shown in Figure 3 are transferred (formed) onto the test substrate via the projection optical system 7 as the test pattern of the test master.

[0072] In S204, for each of several states in which the position of the test substrate in the Z direction differs from one another by a predetermined amount, it is determined whether the test pattern has been transferred to the test substrate, that is, whether the exposure of the test substrate has been completed. In this embodiment, since the initial position is set to the lower limit of the movement range of the test substrate, it is determined whether the position of the test substrate has reached the upper limit of the movement range. If the initial position is set to the upper limit of the movement range of the test substrate, it is sufficient to determine whether the position of the test substrate has reached the lower limit of the movement range. If the exposure of the test substrate is not completed (there is a state in which the test pattern has not been formed on the test substrate), the process proceeds to S205.

[0073] In step S205, the test board is moved in the Z direction. Specifically, the board stage 62 that holds the test board is driven in the Z direction by a predetermined amount (a predetermined step amount). In this embodiment, since the initial position is set to the lower limit of the movement range of the test board, the board stage 62 is driven in steps toward the positive side in the Z direction so that the test board rises. If the initial position is set to the upper limit of the movement range of the test board, the board stage 62 should be driven in steps toward the negative side in the Z direction so that the test board descends.

[0074] In S206, the test substrate is moved in the X and / or Y directions. Specifically, the substrate stage 62 that holds the test substrate is driven by a predetermined amount (a predetermined step amount) in the X and / or Y directions so that the unexposed area of ​​the test substrate is positioned below the projection optical system 7.

[0075] In this manner, steps S203 to S206 are repeated for each of the multiple states in which the position of the test substrate in the Z direction is different from each other, until the transfer of the test pattern to the test substrate is completed, that is, until the test substrate reaches the upper limit of the movement range. Then, in S204, if it is determined that the exposure of the test substrate is complete (there is no state in which the test substrate has not formed a test pattern), the process proceeds to S207.

[0076] In S207, it is determined whether exposure to all effective light source distributions (in this embodiment, the dual-pole illuminations 501, 502, 503, and 504 shown in Figures 5(a) to 5(d)) has been completed. If exposure to all effective light source distributions has not been completed, the process proceeds to S201, the effective light source aperture 11 is replaced, and the process is changed to the next effective light source distribution (for example, the dual-pole illumination 502). Then, S202 to S206 are performed in the same manner. Note that in S202, the predetermined position where the test substrate is placed is the initial position in the Z direction, and in the X and Y directions, it is an unexposed region that does not overlap with the test pattern transferred in the previous loop. In this embodiment, S201 to S206 are repeated sequentially until exposure to the dual-pole illuminations 503 and 504 is completed.

[0077] If it is determined in S207 that exposure to all effective light sources has been completed, the process proceeds to S208. S208 to S210 are steps for measuring the dimensions, specifically the line width, of the test pattern (resist pattern) transferred onto the test substrate.

[0078] In S208, the test substrate is removed from the exposure device 100. The test substrate removed from the exposure device 100 is transported to a developing device located outside the exposure device 100.

[0079] In step S209, the developing apparatus develops the test substrate onto which the test pattern has been transferred via steps S201 to S207. As a result, a resist pattern corresponding to the test pattern appears on the test substrate.

[0080] In S210, the line width of the test pattern is measured as the dimension of the test pattern on the test substrate developed in S209. Specifically, the line width of the test pattern formed on the test substrate is measured for each of several states in which the position of the test substrate in the Z direction is different from each other. The measurement of the line width of the test pattern may be performed by the user using a microscope, by an external measuring device of the exposure apparatus 100, or by a measuring unit (not shown) provided in the exposure apparatus 100.

[0081] Steps S211 and S212 are steps to determine the best focus position of the projection optical system 7. Steps S211 and S212 may be performed by the control unit 80 or by a computer (information processing device) located outside the exposure apparatus 100.

[0082] In S211, the best focus position of the projection optical system 7 is determined. Specifically, first, measurement data of the line width of the test pattern measured in S210 is acquired, that is, multiple measurement data showing the measured line width of the test pattern corresponding to each of multiple states in which the position of the test substrate in the Z direction is different from each other. In this embodiment, each measurement data Lij is the measured line width of the test pattern corresponding to the position of the test substrate in the Z direction (hereinafter referred to as "Z position Fi"). The subscript "i" is the measurement data number (i=0, 1, 2, ...), and the subscript "j" has the following meaning. j=1 is the measured line width of the measurement pattern 301 (test pattern) exposed with the dual-pole illumination 501 shown in Figure 5(a). j=2 is the measured line width of the measurement pattern 302 (test pattern) exposed with the dual-pole illumination 502 shown in Figure 5(b). j=3 is the measured line width of the measurement pattern 303 (test pattern) exposed with the dual-pole illumination 503 shown in Figure 5(c). j=4 is the measured line width of the measurement pattern 304 (test pattern) exposed with the dual-pole illumination 504 shown in Figure 5(d).

[0083] Next, the measurement data Lij is processed to calculate (determine) the best focus position of the projection optical system 7. Here, the measurement pattern 301 is used as an example test pattern. The value of the measurement data Li1 is plotted against the Z position, and an approximation function (for example, a quartic function) is fitted to determine the Z position where the measurement data Li1 takes an extremum, or the Z position that is the midpoint of the slice, as the best focus for measurement pattern 301. The same process can be applied to the measurement data Li2 to Li4 for measurement patterns 302 to 304. For the specific processing of the measurement data Lij, it is possible to apply well-known techniques in this industry, including, for example, the technique disclosed in Japanese Patent Application Publication No. 6-216004.

[0084] In S212, it is determined whether the deviation of the best focus position (deviation from the surface position of the substrate 61) determined in S211 is within the acceptable range. If the deviation of the best focus position is not within the acceptable range, the process proceeds to S213; if the deviation of the best focus position is within the acceptable range, the process proceeds to S214.

[0085] In S213, the projection optical system 7 is adjusted. Specifically, the best focus position of the projection optical system 7 is adjusted, and any deviation from the best focus position is adjusted to within an acceptable range. As described above, the projection optical system 7 can individually adjust the best focus position corresponding to the four measurement patterns 301 to 304. Although not shown in Figure 2, to confirm whether the projection optical system 7 has been properly adjusted, the process may proceed to S299 and repeat S201 to S212.

[0086] In S214, the effective light source aperture 11, which is positioned (inserted) at the pupil position of the illumination optical system 1, is replaced (switched) to change the effective light source distribution. In this embodiment, the effective light source distribution is changed from the bipolar illumination 501 shown in Figure 5(a) to the annular illumination 401 shown in Figure 4.

[0087] Steps S215 to S218 are steps in which an exposure treatment is performed on the substrate 61 using the master plate 21 in order to manufacture the device.

[0088] In step S215, the substrate 61 with the resist applied is loaded into the exposure apparatus 100. The substrate 61 loaded into the exposure apparatus 100 is held by the substrate stage 62.

[0089] In S216, the master plate 21 is loaded into the exposure apparatus 100. The master plate 21 loaded into the exposure apparatus 100 is held by the master plate stage 22. The test master plate can be removed from the exposure apparatus 100 at any time before the master plate 21 is loaded into the exposure apparatus 100.

[0090] In S217, the pattern of the master plate 21 held by the master plate stage 22 is projected onto the substrate 61 held by the substrate stage 62 via the projection optical system 7, which has been adjusted so that the shift in the best focus position is within an acceptable range, thereby exposing the substrate 61. At this time, the master plate stage 22 (master plate 21) and the substrate stage 62 (substrate 61) are scanned synchronously in the ±Y direction.

[0091] In S218, the substrate 61 exposed in S217 is unloaded from the exposure apparatus 100.

[0092] Thus, according to this embodiment, even if the pattern used to measure imaging characteristics such as focus is different from the pattern actually exposed, it is possible to measure imaging characteristics similar to those of the actually exposed pattern and adjust the projection optical system 7 accordingly. Therefore, in this embodiment, the substrate 61 can be exposed at a suitable focus position (best focus position).

[0093] <Second Embodiment> The method for manufacturing articles in this embodiment is suitable for manufacturing articles such as devices (semiconductor elements, magnetic storage media, liquid crystal display elements, etc.). This manufacturing method includes the steps of exposing a substrate coated with a photosensitive agent using the exposure method (exposure apparatus 100) shown in Figure 2, and developing the exposed substrate. This manufacturing method may also include other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing articles in this embodiment is advantageous compared to conventional methods in at least one of the performance, quality, productivity, and production cost of the articles.

[0094] <Third Embodiment> The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0095] The disclosures herein include the following exposure methods, methods for manufacturing articles, and programs.

[0096] (Item 1) An exposure method for exposing a substrate through a projection optical system, A measurement step of illuminating a first pattern placed on the object surface of the projection optical system under first illumination conditions and measuring the imaging characteristics of the first pattern, An adjustment step to adjust the projection optical system based on the imaging characteristics of the first pattern measured in the measurement step, An exposure step in which a second pattern of a master plate, different from the first pattern, is illuminated under second illumination conditions different from the first illumination conditions, and the substrate is exposed through the projection optical system adjusted in the adjustment step, It has, The measurement step includes selecting, as the first illumination condition, illumination conditions such that the difference between the change in the imaging characteristics of the first pattern in response to a change in the wavefront aberration of the projection optical system and the change in the imaging characteristics of the second pattern in response to a change in the wavefront aberration of the projection optical system when the second pattern is illuminated under the second illumination conditions falls within a target range. A method of exposure characterized by the following features.

[0097] (Item 2) The exposure method according to item 1, characterized in that the first illumination condition includes a first light intensity distribution having different distributions in a first direction and in a second direction orthogonal to the first direction at the pupil position of the projection optical system.

[0098] (Item 3) The exposure method according to item 1 or 2, characterized in that the second illumination condition includes a second light intensity distribution having the same distribution in the first direction and the second direction at the pupil position of the projection optical system.

[0099] (Item 4) The measurement step includes illuminating a third pattern, which is different from the first pattern and is placed on the object surface of the projection optical system, under third illumination conditions different from the first illumination conditions, and measuring the imaging characteristics of the third pattern. The adjustment step includes adjusting the projection optical system based on the imaging characteristics of the third pattern measured in the measurement step, The exposure step includes illuminating a fourth pattern different from the second pattern of the master plate under second illumination conditions, and exposing the substrate through the projection optical system adjusted in the adjustment step. The third illumination condition includes a third light intensity distribution having different distributions in the first direction and the second direction at the pupil position of the projection optical system, The fourth pattern is a pattern having periodicity in the second direction. An exposure method according to any one of items 1 to 3, characterized by the following:

[0100] (Item 5) The exposure method according to any one of items 1 to 4, characterized in that the second pattern is a pattern having periodicity in the first direction.

[0101] (Item 6) The exposure method according to any one of items 1 to 5, characterized in that the first pattern is a pattern that does not have periodicity.

[0102] (Item 7) The first pattern is a pattern having periodicity in the first direction, The period of the first pattern is greater than the period of the second pattern. An exposure method according to any one of items 1 to 5, characterized by the following:

[0103] (Item 8) The exposure method according to any one of items 1 to 7, characterized in that the third light intensity distribution is a light intensity distribution obtained by rotating the first light intensity distribution by 90 degrees around the optical axis of the projection optical system at the pupil position of the projection optical system.

[0104] (Item 9) The exposure method according to any one of items 1 to 8, characterized in that the fourth pattern is a pattern obtained by rotating the second pattern by 90 degrees within the plane of the original plate.

[0105] (Item 10) The exposure method according to any one of items 1 to 9, characterized in that the imaging characteristics include at least one of focus, linewidth difference, and distortion.

[0106] (Item 11) The absolute value of the i-th component obtained by expanding the wavefront aberration of the aforementioned projection optical system into a polynomial is Z. i C is the sensitivity of the change in the imaging characteristics of the first pattern measured in the measurement step to the i-th component. i A is the sensitivity of the i-th component to the change in the imaging characteristics of the second pattern exposed in the exposure step. i So, The aforementioned target range is,

[0107] TIFF2026100403000004.tif2862

[0108] The value represented is less than or equal to a predetermined value. An exposure method according to any one of items 1 to 10, characterized by the following:

[0109] (Item 12) The exposure method according to item 11, characterized in that the aforementioned polynomial is a Zernike polynomial.

[0110] (Item 13) The exposure method according to any one of items 1 to 12, characterized in that the measurement step includes changing the illumination conditions for illuminating the first pattern to the first illumination conditions before measuring the imaging characteristics of the first pattern.

[0111] (Item 14) The exposure method according to any one of items 1 to 13, characterized in that the exposure step includes changing the illumination conditions for illuminating the second pattern to the second illumination conditions before exposing the substrate.

[0112] (Item 15) The exposure method according to any one of items 1 to 14, characterized in that the illumination conditions for illuminating the first pattern and the second pattern are changed by changing the aperture positioned at the pupil position of the illumination optical system that illuminates the pattern arranged on the object surface.

[0113] (Item 16) The measurement step includes illuminating a fifth pattern, which is placed on the object surface of the projection optical system and is different from the first and third patterns, with a fourth illumination condition different from the first and third illumination conditions, and measuring the imaging characteristics of the fifth pattern. The adjustment step includes adjusting the projection optical system based on the imaging characteristics of the fifth pattern measured in the measurement step, The exposure step includes illuminating a sixth pattern different from the second and fourth patterns of the master plate under second illumination conditions, and exposing the substrate through the projection optical system adjusted in the adjustment step. The fourth illumination condition includes a fourth light intensity distribution having different distributions in a third direction that forms a 45-degree clockwise angle with respect to the first direction and in a fourth direction perpendicular to the third direction at the pupil position of the projection optical system. The sixth pattern is a pattern having periodicity in the third direction. An exposure method according to any one of items 4 to 15, characterized by the following:

[0114] (Item 17) The measurement step includes illuminating a seventh pattern, which is different from the first, third, and fifth patterns and is placed on the object surface of the projection optical system, with a fifth illumination condition different from the first, third, and fourth illumination conditions, and measuring the imaging characteristics of the seventh pattern. The adjustment step includes adjusting the projection optical system based on the imaging characteristics of the seventh pattern measured in the measurement step. The exposure step includes illuminating an eighth pattern different from the second, fourth, and sixth patterns of the master plate under second illumination conditions, and exposing the substrate through the projection optical system adjusted in the adjustment step. The fifth illumination condition includes a fifth light intensity distribution having different distributions in a fifth direction that forms a 45-degree counterclockwise angle with respect to the first direction and in a sixth direction perpendicular to the fifth direction at the pupil position of the projection optical system. The eighth pattern is a pattern having periodicity in the fifth direction. The exposure method described in item 16, characterized by the following:

[0115] (Item 18) The exposure method according to item 17, characterized in that the fifth light intensity distribution is a light intensity distribution obtained by rotating the fourth light intensity distribution by 90 degrees around the optical axis of the projection optical system at the pupil position of the projection optical system.

[0116] (Item 19) The exposure method according to item 17 or 18, characterized in that the eighth pattern is a pattern obtained by rotating the sixth pattern by 90 degrees within the plane of the original plate.

[0117] (Item 20) The exposure method according to any one of items 16 to 19, characterized in that the fourth light intensity distribution is a light intensity distribution obtained by rotating the first light intensity distribution by 45 degrees around the optical axis of the projection optical system at the pupil position of the projection optical system.

[0118] (Item 21) The exposure method according to any one of items 16 to 20, characterized in that the sixth pattern is a pattern obtained by rotating the second pattern by 45 degrees within the plane of the original plate.

[0119] (Item 22) An exposure method for exposing a substrate through a projection optical system, A measurement step involves illuminating a first pattern placed on the object surface of the projection optical system with bipolar illumination and measuring the imaging characteristics of the first pattern. An adjustment step to adjust the projection optical system based on the imaging characteristics of the first pattern measured in the measurement step, An exposure step in which a second pattern of the master plate, different from the first pattern, is illuminated with annular illumination, and the substrate is exposed through the projection optical system adjusted in the adjustment step, An exposure method characterized by having the following:

[0120] (Item 23) The exposure method according to item 22, characterized in that the dual pole illumination is an illumination condition in which the difference between the change in the imaging characteristics of the first pattern in response to a change in the wavefront aberration of the projection optical system and the change in the imaging characteristics of the second pattern in response to a change in the wavefront aberration of the projection optical system when the second pattern is illuminated with the annular illumination is within the target range.

[0121] (Item 24) A step of exposing a substrate using the exposure method described in any one of items 1 to 23, A step of developing the exposed substrate, A process for manufacturing an article from the developed substrate, A method for manufacturing an article, characterized by having the following:

[0122] (Item 25) A program for causing a computer to execute each step of the exposure method described in any one of items 1 through 23.

[0123] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0124] 100: Exposure apparatus 1: Illumination optics 7: Projection optics 11: Effective light source aperture 21: Master plate 22: Master plate stage 61: Substrate 62: Substrate stage 80: Control unit

Claims

1. An exposure method for exposing a substrate through a projection optical system, A measurement step of illuminating a first pattern placed on the object surface of the projection optical system under first illumination conditions and measuring the imaging characteristics of the first pattern, An adjustment step to adjust the projection optical system based on the imaging characteristics of the first pattern measured in the measurement step, An exposure step in which a second pattern of a master plate, different from the first pattern, is illuminated under second illumination conditions different from the first illumination conditions, and the substrate is exposed through the projection optical system adjusted in the adjustment step, It has, The measurement step includes selecting, as the first illumination condition, illumination conditions such that the difference between the change in the imaging characteristics of the first pattern in response to a change in the wavefront aberration of the projection optical system and the change in the imaging characteristics of the second pattern in response to a change in the wavefront aberration of the projection optical system when the second pattern is illuminated under the second illumination conditions falls within a target range. A method of exposure characterized by the following features.

2. The exposure method according to claim 1, characterized in that the first illumination condition includes a first light intensity distribution having different distributions in a first direction and in a second direction perpendicular to the first direction at the pupil position of the projection optical system.

3. The exposure method according to claim 2, characterized in that the second illumination condition includes a second light intensity distribution having the same distribution in the first direction and the second direction at the pupil position of the projection optical system.

4. The measurement step includes illuminating a third pattern, which is different from the first pattern and is placed on the object surface of the projection optical system, under third illumination conditions different from the first illumination conditions, and measuring the imaging characteristics of the third pattern. The adjustment step includes adjusting the projection optical system based on the imaging characteristics of the third pattern measured in the measurement step, The exposure step includes illuminating a fourth pattern different from the second pattern of the master plate under the second illumination conditions, and exposing the substrate through the projection optical system adjusted in the adjustment step. The third illumination condition includes a third light intensity distribution having different distributions in the first direction and the second direction at the pupil position of the projection optical system. The fourth pattern is a pattern having periodicity in the second direction. The exposure method according to feature 3.

5. The exposure method according to claim 4, characterized in that the second pattern is a pattern having periodicity in the first direction.

6. The exposure method according to claim 5, characterized in that the first pattern is a pattern that does not have periodicity.

7. The first pattern is a pattern having periodicity in the first direction, The period of the first pattern is greater than the period of the second pattern. The exposure method according to feature 5.

8. The exposure method according to claim 6 or 7, characterized in that the third light intensity distribution is a light intensity distribution obtained by rotating the first light intensity distribution by 90 degrees around the optical axis of the projection optical system at the pupil position of the projection optical system.

9. The exposure method according to claim 8, characterized in that the fourth pattern is a pattern obtained by rotating the second pattern by 90 degrees within the plane of the original plate.

10. The exposure method according to claim 1, characterized in that the imaging characteristics include at least one of focus, linewidth difference, and distortion.

11. The absolute value of the i-th component obtained by expanding the wavefront aberration of the aforementioned projection optical system into a polynomial is Z. ｉ C is the sensitivity of the change in the imaging characteristics of the first pattern measured in the measurement step to the i-th component. ｉ A is the sensitivity of the i-th component to the change in the imaging characteristics of the second pattern exposed in the exposure step. ｉ So, The aforementioned target range is, The value represented is less than or equal to a predetermined value. The exposure method according to feature 1.

12. The exposure method according to claim 11, characterized in that the aforementioned polynomial is a Zernike polynomial.

13. The exposure method according to claim 1, characterized in that the measurement step includes changing the illumination conditions for illuminating the first pattern to the first illumination conditions before measuring the imaging characteristics of the first pattern.

14. The exposure method according to claim 13, characterized in that the exposure step includes changing the illumination conditions for illuminating the second pattern to second illumination conditions before exposing the substrate.

15. The exposure method according to claim 14, characterized in that the illumination conditions for illuminating the first pattern and the second pattern are changed by changing the aperture positioned at the pupil position of the illumination optical system that illuminates the pattern arranged on the object surface.

16. The measurement step includes illuminating a fifth pattern, which is different from the first and third patterns and is placed on the object surface of the projection optical system, with a fourth illumination condition different from the first and third illumination conditions, and measuring the imaging characteristics of the fifth pattern. The adjustment step includes adjusting the projection optical system based on the fifth pattern imaging characteristics measured in the measurement step, The exposure step includes illuminating a sixth pattern different from the second and fourth patterns of the master plate under the second illumination conditions, and exposing the substrate through the projection optical system adjusted in the adjustment step. The fourth illumination condition includes a fourth light intensity distribution having different distributions in a third direction that forms a 45-degree clockwise angle with respect to the first direction and in a fourth direction perpendicular to the third direction at the pupil position of the projection optical system. The sixth pattern is a pattern having periodicity in the third direction. The exposure method according to feature 4.

17. The measurement step includes illuminating a seventh pattern, which is different from the first, third, and fifth patterns and is placed on the object surface of the projection optical system, with a fifth illumination condition different from the first, third, and fourth illumination conditions, and measuring the imaging characteristics of the seventh pattern. The adjustment step includes adjusting the projection optical system based on the imaging characteristics of the seventh pattern measured in the measurement step. The exposure step includes illuminating an eighth pattern different from the second, fourth, and sixth patterns of the master plate under second illumination conditions, and exposing the substrate through the projection optical system adjusted in the adjustment step. The fifth illumination condition includes a fifth light intensity distribution having different distributions in a fifth direction that forms a 45-degree counterclockwise angle with respect to the first direction and in a sixth direction perpendicular to the fifth direction at the pupil position of the projection optical system. The eighth pattern is a pattern having periodicity in the fifth direction. The exposure method according to feature 16.

18. The exposure method according to claim 17, characterized in that the fifth light intensity distribution is a light intensity distribution obtained by rotating the fourth light intensity distribution by 90 degrees around the optical axis of the projection optical system at the pupil position of the projection optical system.

19. The exposure method according to claim 18, characterized in that the eighth pattern is a pattern obtained by rotating the sixth pattern by 90 degrees within the plane of the original plate.

20. The exposure method according to claim 19, characterized in that the fourth light intensity distribution is a light intensity distribution obtained by rotating the first light intensity distribution by 45 degrees around the optical axis of the projection optical system at the pupil position of the projection optical system.

21. The exposure method according to claim 20, characterized in that the sixth pattern is a pattern obtained by rotating the second pattern by 45 degrees within the plane of the original plate.

22. An exposure method for exposing a substrate through a projection optical system, A measurement step involves illuminating a first pattern placed on the object surface of the projection optical system with bipolar illumination and measuring the imaging characteristics of the first pattern. An adjustment step to adjust the projection optical system based on the imaging characteristics of the first pattern measured in the measurement step, An exposure step in which a second pattern of the master plate, different from the first pattern, is illuminated with annular illumination, and the substrate is exposed through the projection optical system adjusted in the adjustment step, An exposure method characterized by having the following:

23. The exposure method according to claim 22, characterized in that the dual pole illumination is an illumination condition in which the difference between the change in the imaging characteristics of the first pattern in response to a change in the wavefront aberration of the projection optical system and the change in the imaging characteristics of the second pattern in response to a change in the wavefront aberration of the projection optical system when the second pattern is illuminated with the annular illumination is within the target range.

24. A step of exposing a substrate using the exposure method described in claim 1 or 22, A step of developing the exposed substrate, A process for manufacturing an article from the developed substrate, A method for manufacturing an article, characterized by having the following:

25. A program for causing a computer to perform each step of the exposure method described in claim 1 or 22.

Images