Exposure apparatus, exposure method, and article manufacturing method

Abstract

This invention discloses an exposure apparatus, an exposure method, and a method for manufacturing an article. The control unit controls the relative position of the illumination light in the direction of the optical axis of the projection system and the relative position in the direction perpendicular to the optical axis, based on a first distribution of illumination light detected by the detection system at a first timing, a second distribution of illumination light detected by the detection system at a second timing after the first timing, and a third timing after the second timing, provided that the illumination light detected at the first and second timings has passed through the first and second marks.

Description

Technical Field

[0001] The embodiments relate to an exposure apparatus, an exposure method, and a method for manufacturing an article. Background Technology

[0002] In the photolithography process for manufacturing devices such as semiconductor devices or flat panel displays (FPDs), an exposure apparatus is used to transfer the pattern of a mask onto a substrate. Such an exposure apparatus requires precise adjustment of alignment (the relative position between the mask and the substrate in a direction perpendicular to the optical axis of the projection optics system) and focus (the focal point of the light illuminating the substrate) in order to accurately transfer the mask pattern onto the substrate.

[0003] Calibration using a telephoto lens (TTL) method with a projection optical system has been proposed as one of the alignment and focus adjustment methods. Japanese Patent Application Publication No. 4-348019 discusses a focus calibration technique using the TTL method. Generally, in focus calibration, while the substrate stage is driven in the optical axis direction of the projection optical system, the amount of light obtained through the projection optical system, marks on the stage, etc., is detected. Based on the change in the amount of light when the substrate stage is driven in the optical axis direction of the projection optical system, the position of the substrate on the surface (resist layer) where the optimal focus can be obtained is determined.

[0004] The optimal relative position (optimal focal position) of the mask and substrate changes over time due to air fluctuations within the projection optics system and positional deviations of its components caused by factors such as heat during exposure. If exposure is performed when the optimal focal position has deviated, exposure accuracy may decrease. Therefore, even if a focal calibration is performed once when the optimal focal position has changed, a second focal calibration is performed. However, since performing focal calibration takes time, the productivity of processing the substrate decreases. Summary of the Invention

[0005] According to one aspect of an embodiment, an exposure apparatus performs an exposure process to transfer a pattern of a mask onto a substrate. The exposure apparatus includes a projection system configured to project the pattern of the mask onto the substrate; a detection system configured to detect the light distribution of illumination light that has passed through a first mark, the projection system, and a second mark, the first mark being deployed on an object surface of the projection system and the second mark being deployed on an image plane of the projection system; and a control unit configured to control the relative position of the mask and the substrate. The control unit controls the relative position in the optical axis direction and in a direction perpendicular to the optical axis direction of the projection system based on a first distribution of illumination light detected by the detection system at a first timing, a second distribution of illumination light detected by the detection system at a second timing after the first timing, and a third timing after the second timing, where the illumination light detected at the first timing has passed through the first mark and the second mark, and the illumination light detected at the third timing has passed through the first mark and the second mark.

[0006] Further features of this disclosure will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0007] Figures 1A to 1D Each illustration is a schematic diagram of the configuration of the exposure apparatus according to the first exemplary embodiment.

[0008] Figure 2 This is a schematic diagram of the exposure apparatus during the measurement process.

[0009] Figure 3 It is a longitudinal aberration map of the image field curvature.

[0010] Figure 4A This is an explanatory diagram illustrating the state of the exposure apparatus at the reference focal point position, and Figure 4B This is a diagram illustrating the distribution of illumination light.

[0011] Figure 5A This is an explanatory diagram illustrating the state of the exposure apparatus at a position offset from the reference focal point. Figure 5B The diagram illustrates the distribution of illumination light.

[0012] Figure 6 This is a diagram illustrating the correspondence between the light distribution and the focal position on the substrate stage.

[0013] Figures 7A to 7C This is a diagram illustrating the first method for calculating the optimal focal position using individual diagrams.

[0014] Figures 8A to 8C This is a diagram illustrating the second method for calculating the optimal focal position using individual diagrams.

[0015] Figure 9 It is a longitudinal aberration map of the image field curvature when the envelope of the light distribution does not have a local maximum.

[0016] Figure 10 This is a diagram showing the light distribution at the reference alignment position.

[0017] Figure 11A This is an explanatory diagram illustrating the state of the exposure apparatus at a position deviating from the reference alignment position, and Figure 11B The diagram illustrates the distribution of illumination light.

[0018] Figure 12A and 12B These are diagrams illustrating the correspondence between image field curvature and light intensity distribution.

[0019] Figure 13A The configuration of the alignment measurement system is illustrated, and Figure 13B The diagram illustrates the configuration of the focal measurement system.

[0020] Figure 14A and 14B The illustration shows a measurement mark according to a second exemplary embodiment, and Figure 14C The diagram illustrates the light distribution detected by the detection unit.

[0021] Figure 15A and 15B Each illustration is a schematic diagram of the configuration of the exposure apparatus according to the third exemplary embodiment. Detailed Implementation

[0022] Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. In the drawings, the same components are indicated by the same reference numerals, and repeated descriptions thereof are omitted.

[0023] (Configuration of the exposure device)

[0024] A first exemplary embodiment of the present disclosure will now be described. The configuration of an exposure apparatus according to this exemplary embodiment will be described. The exposure apparatus according to this exemplary embodiment is a photolithography apparatus used in the photolithography process for manufacturing devices such as semiconductor devices or flat panel displays (FPDs). The exposure apparatus according to this exemplary embodiment employs a step-scan method to perform an exposure process that exposes a substrate through a mask having a surface patterned thereon and transfers the pattern of the mask onto the substrate. Although a step-scan method is used as the exposure method in this exemplary embodiment, the exposure method is not limited to the step-scan method. The exposure process can be performed by any other exposure method, such as a step-repetition method.

[0025] Figures 1A to 1D Each illustration shows the configuration of the exposure apparatus 100 according to this exemplary embodiment. Figure 1A This is a schematic diagram illustrating the overall configuration of the entire exposure apparatus 100. In this exemplary embodiment, it is assumed that the direction parallel to the optical axis of the projection optical system is set as the Z-axis direction and any plane perpendicular to the Z-axis direction is set as the XY plane to define the coordinate system.

[0026] The exposure apparatus 100 includes an optical illumination system 1 for illuminating the mask 2, a mask stage 3 for holding the mask 2, a projection optical system 4 for projecting the pattern of the mask 2 onto a substrate 5, and a substrate stage 6 for holding the substrate 5. The exposure apparatus 100 also includes a control unit 7, an input unit 13, and a determination unit 14 for controlling each unit of the exposure apparatus 100.

[0027] The exposure apparatus 100 further includes components for illuminating the first measurement mark using illumination light from the optical illumination system 1, and a detection optical system 20 for detecting the light intensity distribution of the illumination light that has passed through the projection optical system 4 and includes the marked portion of the illuminated first measurement mark 115 and second measurement mark 109. The detection optical system 20 includes an image forming system 21 and a detection unit 22. The image forming system 21 includes a system comprising lenses 23 and 24. The wavelength of the illumination light is the same as the wavelength of the exposure light used to project the pattern of the mask 2 onto the substrate 5.

[0028] The control unit 7 includes a computer comprising a central processing unit (CPU) and memory, and controls each unit of the exposure apparatus 100 in an integrated manner to operate the exposure apparatus 100. For example, when performing an exposure process, the control unit 7 controls the relative positions of the mask 2 and the substrate 5 in the optical axis direction (Z-axis direction) of the projection optical system 4, and in the directions perpendicular to the optical axis of the projection optical system 4 (the X-axis and Y-axis directions that are orthogonal to each other).

[0029] Exposure conditions for the exposure process (i.e., the process of transferring the pattern of mask 2 onto substrate 5) (examples of such conditions include exposure area, illumination mode, and pattern of mask 2) are input to input unit 13 via user operation. Determination unit 14 determines the measurement conditions for calibration, which will be described below, based on the exposure conditions input to input unit 13 (examples of such conditions include the number of measurements and storage time of detection unit 22).

[0030] The detection optical system 20 is provided on the substrate stage 6 and is configured such that illumination light that has passed through the second measurement mark 109 formed on the upper surface of the substrate stage 6 is incident on the detection unit 22. For ease of explanation, Figure 1A The detection optical system 20 shown is magnified below the substrate stage 6. However, in practice, the detection optical system 20 is formed inside the substrate stage 6. The detection unit 22 is, for example, an image sensor, such as a line sensor, in which multiple pixels are arranged in a predetermined direction. The detection unit 22 can detect light reflected by the first measurement mark 115 or the second measurement mark 109, rather than detecting light that has passed through the mark portion including the first measurement mark 115 and the second measurement mark 109.

[0031] Image forming system 21 is an optical system deployed between projection optical system 4 and detection unit 22, and forms images of first measurement mark 115 and second measurement mark 109 on detection unit 22. In this exemplary embodiment, image forming system 21 is an optical system having a predetermined image forming magnification, forming an image on detection unit 22 by multiplying the first measurement mark 115 and second measurement mark 109 by the predetermined image forming magnification, and guiding illumination light. The aforementioned magnification can be appropriately set according to the resolution of detection unit 22. Detection unit 22 includes multiple pixels and detects (captures) the images of first measurement mark 115 and second measurement mark 109 formed by image forming system 21. As described below, image forming system 21 is a system with appropriate aberration (field curvature). Image forming system 21 can be configured to include three or more lenses and other optical elements.

[0032] Illumination light (exposure light) from the optical illumination system 1 passes through the mask 2 held on the mask stage 3 and reaches the substrate 5 held on the substrate stage 6 via the projection optics system 4. The patterned surface of the mask 2 and the surface (resist layer) of the substrate 5 are deployed in a conjugate position relationship via the projection optics system 4. Therefore, the pattern of the mask 2 is transferred onto the substrate 5 via the projection optics system 4. Since a step-scan method is used in this exemplary embodiment, the exposure process is performed simultaneously by scanning the mask stage 3 and the substrate stage 6 in the Y-axis direction.

[0033] Figure 1BThis is a plan view illustrating an example configuration of the mask register 3. On the mask 2 held on the mask register 3, first measurement marks 115 can be formed separately from the pattern to be transferred onto the substrate 5. A plurality of first measurement marks 115 are provided at intervals in the X-axis and Y-axis directions of the mask 2. A single first measurement mark 115 can be provided on the mask 2. However, in one embodiment, a plurality of first measurement marks 115 are provided to measure the characteristics of the projection optics system 4 in detail. Examples of the characteristics of the projection optics system 4 include focal position and distortion.

[0034] Figure 1C The illustration shows the details of the first measurement mark 115. Figure 1C This is a plan view illustrating the first measurement mark 115. The first measurement mark 115 includes a light-shielding area 115a, a transmission area 115b including a plurality of patterns having predetermined line widths and spacings, and a transmission area 115c. The transmission area 115b is arranged along the X-axis and forms line and spatial patterns. Although this exemplary embodiment assumes that the first measurement mark 115 is formed on the mask 2, this disclosure is not limited to this case. The first measurement mark 115 may be provided at a location corresponding to the object surface of the projection optical system 4. For example, the first measurement mark 115 may be formed on the mask pedestal 3. In this case, calibration of the projection optical system 4 can be performed even if the mask 2 is not placed on the mask pedestal 3.

[0035] Various patterns (or groups of patterns) with different line widths, spacings, orientations, etc., can be used as line and space patterns for the transmission area 115b. The transmission area 115c is provided to illuminate the transmission area 109c of the second measuring mark 109, which will be described below. This exemplary embodiment illustrates an example where the transmission area 115c is provided to illuminate the transmission area 109c. However, instead of providing the transmission area 115c, the transmission area 109c can be illuminated by applying illumination light outside the range of the shading area 115a.

[0036] Next, Figure 1D The details of the second measurement mark 109 are illustrated. Figure 1D This is a plan view illustrating the second measurement mark 109. The second measurement mark 109 includes a light-shielding area 109a, a transmission area 109b, and a transmission area 109c. Although this exemplary embodiment assumes that the second measurement mark 109 is formed on the substrate stage 6, this disclosure is not limited to this case. The second measurement mark 109 can be formed at a location other than the substrate stage 6, as long as the second measurement mark 109 can be positioned at a location corresponding to the image plane of the projection optical system 4. The transmission area 109b is provided to allow illumination light that has passed through the transmission area 115b of the first measurement mark 115 to pass through.

[0037] Figure 2 This is a schematic diagram of the exposure apparatus 100 with the first measurement mark 115 and the second measurement mark 109 set at the measurement positions (i.e., during the alignment and focus adjustment measurement process). The term "alignment" refers to the relative positional alignment between the mask 2 and the substrate 5 in a direction perpendicular to the optical axis of the projection optical system 4. The term "focus" refers to the focal point of the light illuminating the substrate 5 (the focal point in the projection optical system 4). The measurement used for alignment and the correction based on that measurement are hereinafter referred to as "alignment calibration," and the measurement used for focus adjustment and the correction based on that measurement are hereinafter referred to as "focus calibration."

[0038] According to this exemplary embodiment, in the alignment and focus calibration operation, the measurement process is performed without further moving the mask stage 3 and substrate stage 6, which are already positioned at the measurement location, in the Z-axis direction. During the measurement process, the control unit 7 drives the mask stage 3 such that it is positioned at the measurement location of the first measurement mark 115 determined by the determination unit 14. Similarly, in performing the calibration operation described above, the control unit 7 drives the substrate stage 6 such that it is positioned at the measurement location of the second measurement mark 109 determined by the determination unit 14.

[0039] (Aberrations in image forming system 21)

[0040] Reference Figure 3 The relationship between aberrations and image formation position in the detection optical system 20 according to this exemplary embodiment is described below. The detection optical system 20 will be described as an example with optical properties having a predetermined image field curvature. Figure 3 This is a longitudinal aberration map of the image field curvature in the image forming system 21. The vertical axis in the figure represents the image height (X coordinate) of the image forming system 21, and the horizontal axis represents the image forming position (Z coordinate) in the optical axis direction. Curve 211 is a curve indicating the image field curvature in the detection optical system 20 (i.e., a curve indicating the image forming position at each image height).

[0041] Curve 211 is characterized in that, unlike near point 211a, near point 211b, even a slight change in image height significantly alters the image formation position along the optical axis. For example, when the optical axis of the image forming system 21 is deployed perpendicular to the light-receiving surface of the detection unit 22 near point 211b, the pattern on the object surface of the image forming system 21 is not focused on the entire light-receiving surface of the detection unit 22, but only partially. In this exemplary embodiment, point 211a corresponds to the position of the optical axis of the image forming system 21 of the detection optical system 20, and point 212b corresponds to the measured image height measured by the first measurement mark 115 and the second measurement mark 109.

[0042] In this exemplary embodiment, as described above, for example, the image forming system 21 is configured to generate Figure 3 The image field shown is curved, and the center of the light-receiving surface of the detection unit 22 is positioned offset from the optical axis of the image forming system 21. The first measurement mark 115 is then illuminated by illumination light from the optical illumination system 1, and the light that has passed through the transmission area 115b of the first measurement mark 115 is detected by the detection unit 22 through the projection optics system 4 and the transmission area 109b of the second measurement mark 109, thereby performing a focus measurement. This configuration allows focus calibration to be performed by the method described below without moving the mask stage 3 and substrate stage 6 already positioned at the measurement location.

[0043] In this exemplary embodiment, the first measurement mark 115 is illuminated by light from the optical illumination system 1, and the light that has passed through the transmission area 115c of the first measurement mark 115 is detected by the detection unit 22 through the projection optical system 4 and the transmission area 109c of the second measurement mark 109. Therefore, the alignment calibration operation can be performed simultaneously with the focus calibration operation by the method described below.

[0044] (Focus calibration)

[0045] Next, we will refer to Figure 4A and 4B as well as Figure 5A and 5B This describes the measurement process for the change in the amount of change of the measurement focus according to this exemplary embodiment. Figure 4A and Figure 5A These are illustrations of the state of the exposure device 100 during the processing of the change in the measurement focus, and an explanatory diagram illustrating the marked image projected onto the detection unit 22 after the image of the first measurement mark 115 has passed through the projection optical system 4, the second measurement mark 109, and the image forming system 21.

[0046] Figure 4AThe diagram illustrates the state at the first timing (the state corresponding to the focal position set by the projection optical system 4 and the reference focal position). Figure 5A The illustration shows the state of the second timing after the exposure process performed after the first timing (the state where the focus position set by the projection optics system 4 has deviated from the reference focus position).

[0047] The projection optics system 4 simultaneously focuses the pattern image of the projection mask 2 onto the surface of the substrate 5. Therefore, the image of the first measurement mark 115 is to be formed on the surface of the substrate 5, and the projection optics system 4 for projecting the image is positioned on the plane in a focused state.

[0048] This article assumes that Figure 4A In the state shown (i.e., at the first timing), the image of the first measurement mark 115 formed on the plane to be positioned on the surface of the substrate 5 is called the image forming pattern 115P. The pattern image obtained when the image forming pattern 115P passes through the image forming system 21 and the image of the image forming pattern 115P is formed on the detection unit 22 is called the image forming pattern 115S.

[0049] In this case, due to the image field curvature of the image forming system 21, the image forming pattern 115S is formed on a plane perpendicular to the optical axis of the image forming system 21 and inclined relative to the light receiving surface of the detection unit 22. Therefore, in this exemplary embodiment, the image forming plane (image forming pattern 115S) of the first measurement mark 115 provided by the image forming system 21 only partially overlaps with the light receiving surface of the detection unit 22. The image forming plane of the second measurement mark 109 provided by the image forming system 21 also partially overlaps with the light receiving surface of the detection unit 22.

[0050] Figure 4B This is a diagram illustrating the light quantity distribution (first light quantity distribution) of the illumination light that has passed through the first measurement mark 115 and the second measurement mark 109 and is detected by the detection unit 22 at a first timing. The vertical axis in the diagram represents the amount of light obtained on the light-receiving surface of the detection unit 22, and the horizontal axis represents the position on the light-receiving surface of the detection unit 22 in the X-axis direction. The first light quantity distribution includes distributions M1 to M7 corresponding to the transmission area 115b of the first measurement mark 115 and distributions P1 and P2 corresponding to the transmission area 109b of the second measurement mark 109. The first light quantity distribution also includes distributions V1 to V10 corresponding to the light-blocking area 115a of the first measurement mark 115 and distributions V1, V2, V9, and V10 corresponding to the light-blocking area 109a of the second measurement mark 109.

[0051] Here, because the image forming system 21 according to this exemplary embodiment has image field curvature, a deviation occurs between the image plane of the detection optical system 20 and the light receiving surface of the detection unit 22. In the light distribution, the light intensity increases in the portion where there is no deviation or the deviation is minimal, and decreases according to the amount of deviation in another portion where the deviation is greater than that portion. For example, from... Figure 4B As shown in the light intensity distribution, the light intensity in distribution M4 is the highest among distributions M1 to M7. This indicates that a focal point is obtained at the position corresponding to distribution M4 on the light receiving surface of detection unit 22. Each of distributions P1 and P2 has a large light intensity, but no focal point is obtained there. This is because the transmission region 109c of the second measurement mark 109 is wide and has low sensitivity to changes in the light intensity in a defocused state.

[0052] The description is based on Figure 4B The method shown describes the light distribution used to determine the position of the focal point (hereinafter also referred to as the focus position) on the light-receiving surface of the detection unit 22. In this determination method, only distributions M1 to M7 corresponding to the transmission area 115b of the first measurement mark 115 are considered. Initially, distributions M1, M2, and M3 indicate that the image forming position has deviated from the detection unit 22 in the -Z direction (or +Z direction). Distributions M5, M6, and M7 indicate that the image forming position has deviated from the detection unit 22 in the +Z direction (or -Z direction). Therefore, if the position on the light-receiving surface of the detection unit 22 corresponding to distribution M4 can be obtained, the focus position A on the light-receiving surface of the detection unit 22 can be determined by using the following expression (1).

[0053] A=P×PixelSize×tanθ / Mag…(1)

[0054] In expression (1), P represents the position where the maximum amount of light is presented on the light receiving surface of the detection unit 22, PixelSize represents the size of each pixel of the detection unit 22, θ represents the angle formed between the image forming plane of the image forming system 21 with image field curvature and the light receiving surface of the detection unit 22, and Mag represents the magnification of the image forming system 21.

[0055] The method for obtaining the focus position on the light-receiving surface of the detection unit 22 is not limited to the method of obtaining the position on the light-receiving surface using expression (1). For example, an envelope 26 is obtained, including the distribution M4 with the maximum light quantity, and other distributions M1 to M3 and M5 to M7, so that the position on the light-receiving surface can be accurately obtained based on the envelope 26. In such a case, even if the focus position on the light-receiving surface of the detection unit 22 is located near the distribution M4 (e.g., at the midpoint between distribution M4 and distribution M3), the focus position on the light-receiving surface of the detection unit 22 can be obtained based on the envelope 26. Figure 4B In the above, such a position on the light receiving surface of the detection unit 22 corresponding to the local maximum value 27 (peak position) of the envelope 26 obtained from distributions M1 to M7 is represented by position MI1.

[0056] Figure 5A The diagram shows the position of substrate platform 6 has changed from Figure 4A The state shown is a deviation in the Z direction (the state after the first timing). For example... Figure 5A As shown, due to air fluctuations inside the projection optics system 4 caused by heat and other factors during the exposure process, as well as positional deviations of the components of the projection optics system 4, the image of the first measurement mark 115 can deviate from 115P to 115Q in the Z-axis direction. In such a case, the image of the first measurement mark 115 also deviates from 115S to 115T in the Z-axis direction near the detection unit 22.

[0057] Figure 5B This is a diagram illustrating the light quantity distribution (second light quantity distribution) of the illumination light that has passed through the first measurement mark 115 and the second measurement mark 109 and been detected by the detection unit 22 at a second timing after the first timing. The vertical axis in the diagram represents the light quantity obtained on the light-receiving surface of the detection unit 22, and the horizontal axis represents the position on the light-receiving surface of the detection unit 22 in the X-axis direction. In the second light quantity distribution, the light quantity in distribution M3 is the largest among distributions M1 to M7, and the position corresponding to distribution M3 (or a position near that position) corresponds to the focus position on the light-receiving surface of the detection unit 22. The position on the light-receiving surface of the detection unit 22 corresponding to the local maximum value 31 of the envelope 30 obtained from distributions M1 to M7 is represented by position MI2. Similar to position MI1 in the first light quantity distribution, position MI2 in the second light quantity distribution can be the focus position.

[0058] The change in focus can be measured by obtaining positions MI1 and MI2. Specifically, the focus position on the light-receiving surface of the detection unit 22 at the first timing is compared with the focus position on the light-receiving surface of the detection unit 22 at the second timing (e.g., after a predetermined elapsed time or after a predetermined number of exposures to the substrate 5). As a result, the change in focus can be obtained.

[0059] Figure 6 This is a diagram illustrating the relationship between the optimal focal position of the projection optical system 4 and the positions MI1 and MI2 on the light-receiving surface of each indicator detection unit 22 in the X-axis direction. (See diagram from...) Figure 6 As can be seen, when the position corresponding to the local maximum value of the envelope changes from position MI1 to position MI2, the optimal focal position provided by the projection optical system 4 also changes from Z1 to Z2 according to the change in the position corresponding to the local maximum value of the envelope.

[0060] In cases where aberrations and other interferences are significant, multiple optimal focal positions to be provided by the projection optics system 4 and multiple measurement points for measuring the position on the light-receiving surface of the detection unit 22 corresponding to the local maximum value of the envelope can be prepared in advance. For example, the result of fitting the measurement points by approximation can be stored as tabular data in the control unit 7. The control unit 7 can obtain the optimal focal position using tabular data indicating the correspondence between the light quantity distribution detected by the detection unit 22 and the relative positions of the mask 2 and the substrate 5 in the optical axis direction (Z-axis direction). Thus, optimal focal positions at different timings (examples of such optimal focal positions include Z1, Z2) can be obtained, and the amount of change of the optimal focal position (examples of such amount of change include Z1-Z2) can be obtained. The process of measuring the amount of change of focal position according to this exemplary embodiment has been described above.

[0061] Two methods for determining the optimal focal position will now be described. In both methods, the optimal focal position is calculated based on the change in the amount of light from the first measurement mark 115 in the detection unit 22 when the substrate stage 6 is driven in the Z-axis direction. In this exemplary embodiment, the optimal focal position determined in the first timing is set as the reference focal position, thereby eliminating the need to drive the substrate stage 6, which is already positioned at the measurement location, in the Z-axis direction during the second and subsequent calibrations. Therefore, a decrease in productivity due to calibration can be prevented.

[0062] In the first method, a pattern is specified in the first measurement mark 115 and based on the distribution corresponding to the specified pattern (e.g., Figure 7A and 7BThe change in light intensity in any one of the distributions M1 to M7 shown determines the position of the substrate stage 6 corresponding to the optimal focal position. Figures 7A to 7C This is a diagram used to explain the first method for determining the optimal focal position. Figure 7A The illustration shows the light distribution of the pattern of the first measurement mark 115 detected by the detection unit 22 when the substrate stage 6 is located at a certain position in the Z-axis direction. Figure 7B The diagram illustrates the situation when the substrate stage 6 is located in the Z-axis direction and... Figure 7A At a different location, the light distribution of the pattern of the first measurement mark 115 is detected by the detection unit 22. In this case, for example, when focusing on the pattern of distribution M4, the light amount in distribution M4 changes according to the position of the substrate stage 6 in the Z-axis direction.

[0063] Figure 7C This is a graph illustrating the change in the amount of light detected by detection unit 22 when the focus distribution is M4. The vertical axis in the graph represents... Figure 7A and 7B The diagram shows the amount of light distributed in M4, and the horizontal axis in the diagram represents the position of the substrate stage 6 along the Z-axis. Figure 7C As shown, the amount of light changes correspondingly to the position of the substrate stage 6 along the Z-axis. Since the amount of light detected by the detection unit 22 is maximum at the optimal focal position of the substrate stage 6, it can be obtained by changing the amount of light... Figure 7C The position of the substrate stage 6, where the local maximum value Z0 is shown, is used to determine the reference focus position.

[0064] If we are interested in distributions other than M4, the reference focus position can be determined by considering the amount of image plane shift (where the amount of image plane shift at the image height corresponding to distribution M4 is pre-identified).

[0065] In the second method, an image height is obtained at a small inflection point in the image field curvature of the image forming system 21 (e.g., at...). Figure 3 The distribution of illumination light that has passed through the first measurement mark 115 is determined near point 211a in the longitudinal aberration map, and the optimal focal position is determined based on the amount of change in the amount of illumination light. Minor field curvature indicates that the aberration (defocus) is less than or equal to 1 / 4 of the focal calculation accuracy (e.g., 3σ) and is at a level where the measurement is not affected.

[0066] Figures 8A to 8C This is a diagram used to explain the second method for determining the optimal focal position. Figure 8A The illustration shows the light distribution (light distribution of illumination light) obtained as a result of the detection unit 22 detecting the pattern image of the first measurement mark 115 when the substrate stage 6 is located at a certain position in the Z-axis direction. Figure 8BThe diagram illustrates the situation when the substrate stage 6 is located in the Z-axis direction and... Figure 8A The light distribution is obtained as a result of the detection unit 22 detecting the pattern image of the first measurement mark 115 at another position different from the position in the image. Figure 8A and 8B In the process, the light intensity is measured by the detection unit 22 at locations where the image field curvature becomes minimal, therefore the change in light intensity in distributions M1 to M7 is less than that in the distribution M7. Figure 7A and 7B Changes in.

[0067] In this case, when focusing on the pattern distributed M1 to M7, the amount of light detected by the detection unit 22 changes according to the position of the substrate stage 6 in the Z-axis direction. Figure 8C This is a diagram illustrating the changes in the amount of light detected by detection unit 22 when the distributions of interest are M1 to M7. The vertical axis in the diagram represents... Figure 8A and 8B The figure shows the average light intensity in distributions M1 to M7, and the horizontal axis in the figure represents the position on the substrate stage 6 in the Z-axis direction. Figure 8C As shown, the light intensity changes according to the position on the substrate stage 6 along the Z-axis. Since the light intensity detected by the detection unit 22 becomes maximum at the optimal focal position of the substrate stage 6, a light intensity indication can be obtained. Figure 8C The position of the substrate stage 6, where the local maximum value Z0 is shown, is used to determine the reference focus position.

[0068] After calculating the reference focal position using the method described above, the detection unit 22 is located at an image height where the image field curvature is sufficiently large (e.g., at...). Figure 3 The point (near point 211b shown) is moved in the X-axis direction, and the light distribution corresponding to the first measurement mark 115 is obtained. Focus calibration can then be performed.

[0069] Depending on the shape of the field curvature, the envelope may not have an extreme value if the substrate stage 6 moves in the X direction from an image height with a small field curvature to an image height with a sufficiently large field curvature. Figure 9 This is a longitudinal aberration diagram showing the field curvature when the envelope of the light distribution detected by the detection unit 22 does not have an extreme value. Figure 9 In the diagram, the vertical axis represents the image height (X coordinate) of the image forming system, and the horizontal axis represents the image forming position (Z coordinate) along the optical axis. Curve 231 is a curve indicating the image field curvature in the detection optical system 20 (i.e., a curve indicating the image forming position at each image height).

[0070] In curve 231, the light-receiving surface of detection unit 22 and the image-forming position are significantly deviated from the position near point 231a. Therefore, distribution M1 can indicate the pattern in which the light intensity is maximum and the envelope may not have a local maximum. In this case, the substrate stage 6 is moved in the Z-axis direction to make the envelope have a local maximum, and the focal value is managed under the premise that there is a difference corresponding to the amount of movement of the substrate stage 6 from the optimal focal point, thereby obtaining the amount of change in the optimal focal position.

[0071] As described above, the appropriate focal position is set as the reference focal position, thereby eliminating the need to drive the substrate stage 6, which is already positioned at the measurement location, in the Z-axis direction during the second and subsequent focal calibrations. Therefore, a decrease in productivity due to calibration can be prevented.

[0072] (Alignment and calibration)

[0073] Next, we will refer to Figure 10 as well as Figure 11A and 11B This describes the change measurement process for obtaining the change in alignment according to this exemplary embodiment. Figure 10 and 11A The respective illustrations are in Figure 4A The diagram shows the light intensity distribution of the illumination light that has passed through the first measurement mark 115 and the second measurement mark 109 and been detected by the detection unit 22 in the state of the exposure apparatus 100 shown. The vertical axis in the diagram represents the light intensity obtained by the detection unit 22, and the horizontal axis in the diagram represents the position of the detection unit 22 on the light receiving surface in the X-axis direction. Figure 10 The light distribution shown includes distributions M1 to M7 corresponding to the transmission area 115b of the first measurement mark 115, and distributions P1 and P2 corresponding to the transmission area 109b of the second measurement mark 109. The light distribution also includes distributions V1 to V10 corresponding to the light-blocking area 115a of the first measurement mark 115, and distributions V1, V2, V9, and V10 corresponding to the light-blocking area 109a of the second measurement mark 109.

[0074] The description is based on Figure 10The method for determining the appropriate relative position (reference alignment position) between the mask 2 and the substrate stage 6 on the XY plane, as shown in the illumination light distribution diagram, involves first calculating (e.g., by centroid calculation) the position on the light-receiving surface of the detection unit 22 in each of the patterns M1 to M7 corresponding to the first measurement mark 115. The position 92, obtained by averaging the positions of the individual patterns, is represented by MA1. The positions on the light-receiving surfaces of the detection units 22 corresponding to the individual patterns P1 and P2 are then calculated (using, for example, centroid calculation). The position 93, obtained by averaging the positions of the individual patterns, is represented by PA1. The difference between MA1 and PA1 represents the relative position of the first measurement mark 115 and the second measurement mark 109, i.e., the relative position of the mask 2 and the substrate stage 6.

[0075] Figure 11A The diagram illustrates that the alignment position (the relative position of mask 2 and substrate stage 6 in a direction parallel to the XY plane) has deviated. Figure 4A The state shown is as described. Due to the influence of heat generated during the exposure process, air fluctuations inside the projection optical system 4 and positional deviations of the components of the projection optical system 4 may occur. Therefore, as... Figure 4A and 11A As shown, the image of the first measurement mark 115 can be offset from the image forming pattern 115P to the image forming pattern 115O in the X-axis direction. In this case, Figure 10 The light distribution shown changes to Figure 11B The light distribution shown is illustrated.

[0076] exist Figure 11B In the diagram, position 95, obtained by averaging the positions of distributions M1 to M7, is denoted by MA2, and position 96, obtained by averaging the positions of distributions P1 and P2, is denoted by PA2, as follows. Figure 10 As in the example above. In this case, position MA2 changes from position MA1. Positions PA1 and PA2 correspond to the second measurement mark 109 that has passed through the projection optical system 4, therefore positions PA1 and PA2 are not affected by air fluctuations inside the projection optical system 4 or by positional deviations of the components of the projection optical system 4. For this reason, the position of the transmission area 109b of the second measurement mark 109 does not change due to air fluctuations and positional deviations of the components, and the distribution position PA2 corresponding to the transmission area 109b does not change from the distribution position PA1. When the difference AA1 between MA1 and PA1 is set as a reference for alignment and the difference between MA2 and PA2 is represented by AA2, the changes in difference AA1 and difference AA2 are calculated as a change in alignment according to this exemplary embodiment.

[0077] As described above, in this exemplary embodiment, the amount of alignment change can be calculated. In this exemplary embodiment, the detection results from the detection unit 22 used in focus calibration can also be used in alignment calibration.

[0078] (Specific methods for calibration)

[0079] The methods for calculating changes in focus and alignment have been described in detail above. However, there are cases where... Figure 4B , 5B If the causes of the changes in the diagrams shown in 10 and 11B are separated into the effects of either the focus or the alignment of the projection optical system 4, then it is impossible to accurately calculate the changes in focus and alignment. The specific processing method for obtaining the changes in focus and alignment separately will be described below.

[0080] In this exemplary embodiment, when the position of the image plane forming the image of the first measurement mark 115 on the XY plane changes due to air fluctuations inside the projection optics system 4 and positional deviations of the components of the projection optics system 4, the measurement image height in the image forming system 21 also changes. The image forming system 21 according to this exemplary embodiment has field curvature, therefore the focal position of the image forming system 21 also changes according to the change in image height. Therefore, a light distribution indicating that the focal point has also changed, but only the image forming position of the first measurement mark 115 on the XY plane has actually changed, is obtained.

[0081] Therefore, in order to separate the changes that occur when the state of the projection optical system 4 changes due to heat or other factors (i.e., to calculate only the change in focus), information about the change in focus corresponding to the position on the light-receiving surface of the detection unit 22 is stored in advance in the control unit 7. Furthermore, the change in focus corresponding to the position on the light-receiving surface of the detection unit 22 is subtracted from the information indicating the characteristic focus change corresponding to the position on the light-receiving surface of the detection unit 22, thereby enabling accurate measurement of the change in focus in the projection optical system 4.

[0082] If the position of the image plane forming the image of the first measurement mark 115 on the XY plane changes due to air fluctuations inside the projection optical system 4 and positional deviations of the components of the projection optical system 4, then the local maximum value of the envelope of the light quantity distribution detected on the light receiving surface of the detection unit 22 also changes. In other words, the position indicating the change of the local maximum value of the envelope and the change of the focus are obtained, but only the light quantity distribution whose position has actually changed is aligned.

[0083] Therefore, in order to separate the changes affected by the alteration of the state of the projection optical system 4 due to heat, etc. (or to calculate only the changes in alignment), the changes MI1-ΔA and MI2-ΔB are calculated, where the difference between MA1 and PA1 is represented by ΔA, and the difference between MA2 and PA2 is represented by ΔB. The change in alignment position is calculated using the difference between MA1-PA1 and MA2-PA2, and the change in focal position is calculated using the difference between MI1-ΔA and MI2-ΔB. Thus, the positional deviation of the focal point and the positional deviation of the alignment can be accurately separated.

[0084] Next, we will refer to Figure 12A and 12B Describes the amount of image field curvature according to this exemplary embodiment.

[0085] When the field curvature is large within the range that the detection unit 22 can detect, the change in the light distribution relative to the image height is abrupt (the light intensity changes rapidly). The deviation in the envelope of the light distribution increases when the focus has changed. On the other hand, when the field curvature is small, the opposite characteristic is obtained.

[0086] Figure 12A The diagram illustrates the light intensity distribution of the illumination light when the image field curvature is large. Light intensity distribution 191, indicated by the dashed line, and light intensity distribution 193, indicated by the solid line, each indicate the light intensity distribution at different focal positions. The centroid of the envelope 192 in light intensity distribution 191 (indicated by the dashed line) is denoted by MI191, and the centroid of the envelope 194 in light intensity distribution 193 (indicated by the solid line) is denoted by MI193.

[0087] Figure 12B The diagram illustrates when the image field curvature is less than Figure 12A The light intensity distribution of the illumination light when the field curvature is measured. The light intensity distribution 195, indicated by the dashed line, and the light intensity distribution 197, indicated by the solid line, each indicate the light intensity distribution at different focal positions. The centroid position of the envelope 196 in the light intensity distribution 195, indicated by the dashed line, is represented by MI195, and the centroid position of the envelope 198 in the light intensity distribution 197, indicated by the solid line, is represented by MI197.

[0088] exist Figure 12A and 12B In the light quantity distributions shown, only the image field curvature in the image forming system 21 of the detection optical system 20 differs, and the changes in focus indicated by the two light quantity distributions, as shown by the solid and dashed lines, are the same as other conditions. In comparison... Figure 12A and 12B In this case, the changes in the centroid positions of the two envelopes indicated by the solid and dashed lines are different. Specifically, when... Figure 12AThe difference between the two center of gravity positions MI191 and MI193 shown is... Figure 12B In the case of comparing the differences between the two centroid positions MI195 and MI197 shown, where the image field curvature is large... Figure 12A The difference between MI191 and MI193 shown is less than Figure 12B The difference between MI195 and MI197 is shown in the diagram. Therefore, in cases of large image field curvature, the change in the focal point with the extremum of the envelope in the detection unit 22 decreases, thus increasing the measurement range by the amount corresponding to the reduced focal point change. On the other hand, the sensitivity to the change in focal point decreases, leading to a decrease in measurement accuracy.

[0089] The aforementioned measurement range and accuracy can be adjusted according to the required accuracy of the measurement system. The optical conditions of the image forming system 21 (e.g., design wavelength, numerical aperture, and magnification), the line width and spacing of the lines and spatial patterns of the first measurement mark 115, and the specifications of the detection unit 22 (e.g., signal-to-noise ratio (S / N) and pixel size) are subject to trade-offs.

[0090] As a criterion for image field curvature, when the pattern intensity at the optimal focal point (e.g., ...) Figure 4B When the distribution M4 shown is one, the pattern intensity can be set (e.g., with...). Figure 4B The distributions M1 and M7 at the ends of the image field become 0.2 or greater at the same linewidth in the surrounding region. This is because sufficient measurable contrast can be obtained at a pattern intensity of 0.2 or greater.

[0091] Next, the specific exposure method will be described. As described above, focus and alignment calibration operations can be performed based on the light distribution detected by the detection unit 22. If the relative positional relationship between the mask 2 and the substrate stage 6 is identified in advance, the relative position of the mask 2 and the substrate stage 6 can be controlled at a third time after the second time by using the alignment measurement system and focus measurement system described below. Specifically, the control unit 7 can expose the substrate 5 using the pattern of the mask 2 while properly managing the relative positional relationship between the mask 2 and the substrate 5.

[0092] Figure 13A The alignment measurement system is illustrated, and Figure 13B The diagram illustrates the focal point measurement system. Figure 13AThe alignment measurement system 50 shown (also referred to as an off-axis alignment mirror) includes a light source 51 (such as a light-emitting diode (LED)), lenses 52, 53, 54, and 55, a semi-reflective mirror 56, and an image capture unit 57. Light emanating from the light source 51 passes through lenses 52 and 53 and is reflected by the semi-reflective mirror 56. The reflected light passes through lens 54 and is incident perpendicularly on the substrate 5. The light incident on the substrate 5 is reflected and scattered by alignment marks on the projection area of ​​the substrate 5, and the reflected and scattered light passes through lenses 54, the semi-reflective mirror 56, and lens 55, such that an image of the alignment marks is formed on the image capture unit 57 and the alignment mark image is captured. The alignment measurement system 50 measures the position of the substrate 5 in the X-axis and Y-axis directions parallel to the XY plane.

[0093] Figure 13B The focal measurement system 60 shown (also known as a surface position measurement system) includes a light source 61 (such as an LED), lenses 62, 63, and 64, and an image capture unit 65. Light emanating from the light source 61 passes through lens 62 and is obliquely incident on the substrate 5. The incident light is reflected on the substrate 5, passes through lenses 63 and 64, and the image is captured by the image capture unit 65. The focal measurement system 60 performs a position measurement (measurement of surface height in the Z-axis direction) of the substrate pedestal 6 on a second measurement mark 109 formed on the substrate pedestal 6. The positional relationship between the mask 2 and the substrate 5 can be identified based on the measurement results in the X-axis, Y-axis, and Z-axis directions, as well as information regarding the aforementioned focal point and alignment calibration.

[0094] The frequency of performing the above calibration can be appropriately set according to the stability of the projection optics system 4 and the accuracy required for the exposure apparatus 100. Since the calibration according to this exemplary embodiment can be performed without driving the substrate stage 6, the adverse impact on productivity is small even when calibration is performed frequently. Therefore, the relative position of the mask 2 and the substrate 5 can be accurately calibrated by increasing the frequency of calibration.

[0095] Therefore, in the change measurement process according to this exemplary embodiment, it is not necessary to drive the substrate stage 6 in the Z-axis direction to obtain the change in focus. Therefore, according to this exemplary embodiment, during calibration, the time required for the operation of moving the substrate stage 6 in the Z-axis direction (focus calibration operation) can be reduced, thereby preventing a decrease in the productivity of the exposure apparatus 100.

[0096] Although this exemplary embodiment illustrates an example in which the third timing substrate stage 6 is driven for the control unit 7 to control the relative position of the mask 2 and the substrate 5, this disclosure is not limited to this example. For example, the mask stage 3 may be driven, or both the mask stage 3 and the substrate stage 6 may be driven. In this exemplary embodiment, multiple patterns (transparent areas) of the first measurement mark 115 and the second measurement mark 109 are arranged side by side in the X direction; however, alternatively, multiple patterns of the first measurement mark 115 and the second measurement mark 109, in which similar patterns are also arranged side by side in the Y direction, may be used. In such a case, multiple detection units 22 are prepared and provided as a first detection unit for detecting an image of the multiple patterns arranged in the X direction and a second detection unit for detecting an image of the multiple patterns arranged in the Y direction.

[0097] The second exemplary embodiment of this disclosure will now be described. The first exemplary embodiment described above illustrates an example where the light intensity distribution of illumination light passing through a first measuring mark 115 and a second measuring mark 109, in which patterns are arranged in one direction (X-axis direction), is measured to perform calibration. This exemplary embodiment illustrates an example where the light intensity distribution of illumination light passing through a first measuring mark 115 and a second measuring mark 109, in which patterns are arranged in multiple directions (X-axis direction and Y-axis direction), is measured to perform calibration. The basic configuration of the exposure apparatus 100 is similar to that of the first exemplary embodiment, and therefore its description is omitted. Matters not described in the second exemplary embodiment are similar to those described in the first exemplary embodiment.

[0098] Figure 14A The illustration shows a first measurement mark 115 according to this exemplary embodiment. The first measurement mark 115 according to this exemplary embodiment includes a light-shielding region 115d, transmission regions 115e and 115f (each of which is a plurality of patterns having a predetermined line width and spacing), and transmission regions 115g, 115h, and 115i. The transmission region 115e is arranged along the X-axis direction and forms a line and space pattern. The transmission region 115f is arranged along the Y-axis direction and forms a line and space pattern. Although this exemplary embodiment is described assuming that the first measurement mark 115 is formed on the mask 2, this disclosure is not limited to this example. The first measurement mark 115 may be provided at a location corresponding to the object surface of the projection optical system 4. For example, the first measurement mark 115 may be provided on the mask pedestal 3. In such a case, calibration of the projection optical system 4 can be performed even if the mask 2 is not placed on the mask pedestal 3.

[0099] As in the first exemplary embodiment, various patterns (or groups of patterns) with different line widths, spacings, orientations, etc., can be used as line and space patterns for the transmission regions 115e and 115f. Transmission regions 115g, 115h, and 115i are provided to illuminate the transmission regions 109e, 109f, and 109g of the second measuring mark 109, which will be described below.

[0100] Figure 14B The illustration shows a second measurement mark 109 according to this exemplary embodiment. The second measurement mark 109 according to this exemplary embodiment includes a light-blocking region 109d, light-transmitting regions 109e, 109f, and 109g, and light-transmitting regions 109h and 109i. Light-transmitting regions 109e and 109f are formed as patterns in the X-axis direction, and light-transmitting regions 109f and 109g are formed as patterns in the Y-axis direction.

[0101] While this exemplary embodiment illustrates an example of the second measurement mark 109 being provided on the substrate stage 6, this disclosure is not limited to this example. The second measurement mark 109 is disposed at a location corresponding to the image plane of the projection optics system 4 and where the pattern of the first measurement mark 115 is projected. For example, the second measurement mark 109 may be provided in a different unit or element than the substrate stage 6.

[0102] Transmission areas 109h and 109i are provided to allow the patterned image formed on the transmission areas 115e and 115f of the first measurement mark 115 to pass through.

[0103] Figure 14C The illustration shows the light distribution detected by detection unit 22. Region 322 represents the state of illumination light reaching the light-receiving surface of detection unit 22. Regions 322a to 322e represent patterned images.

[0104] Intersection line 322h represents the line where the light-receiving surface of the detection unit 22 matches the image forming plane. The image forming system 21 has image field curvature in each of the X-axis and Y-axis directions. Therefore, in each of the X-axis and Y-axis directions, the light-receiving surface of the detection unit 22 is not perfectly matched with the image forming plane and only partially overlaps with it. Thus, intersection line 322h is formed.

[0105] Light quantity distribution 323 is the distribution of light quantity received on the light receiving surface of the detection unit 22 within a region 322f extending in the X-axis direction of the detection unit 22. For example... Figure 14C As shown, the amount of light in region 322a corresponds to distribution 323a in light distribution 323, the amount of light in region 322b corresponds to distribution 323b in light distribution 323, and the amount of light in region 322d corresponds to distribution 323d in light distribution 323.

[0106] Light quantity distribution 324 is the distribution of the amount of illumination light received on the light-receiving surface of the detection unit 22 within a region 322g extending in the Y-axis direction of the detection unit 22. For example... Figure 14C As shown, the amount of light in region 322a corresponds to distribution 324a in light distribution 324, the amount of light in region 322c corresponds to distribution 324c in light distribution 324, and the amount of light in region 322e corresponds to distribution 324e in light distribution 323.

[0107] In this exemplary embodiment, the light intensity distribution of the illumination light that has passed through the first measurement mark 115 and the second measurement mark 109 can be obtained in each of the X-axis and Y-axis directions, and alignment calibration in each of the X-axis and Y-axis directions can be performed based on the light intensity distribution in each of the X-axis and Y-axis directions. Focus calibration can also be performed in a manner similar to that in the first exemplary embodiment.

[0108] In this exemplary embodiment, a two-dimensional detection unit 22 (such as a region sensor) can be used, and the position in the X-axis and Y-axis directions can be measured by a single detection unit 22. Therefore, unlike the case where detection units 22 are prepared in each of the X-axis and Y-axis directions, space and cost savings can be achieved.

[0109] In the change measurement process according to this exemplary embodiment, it is not necessary to drive the substrate stage 6 in the Z-axis direction to obtain the change in focus. Therefore, according to this exemplary embodiment, during calibration, the time for the operation (focus calibration operation) of moving the substrate stage 6 in the Z-axis direction can be reduced, thereby preventing a decrease in the productivity of the exposure apparatus 100.

[0110] The third exemplary embodiment of this disclosure will now be described. The first exemplary embodiment described above illustrates an example where a first measurement mark 115 is formed on a mask 2, a second measurement mark 109 is formed on a substrate stand 6, and a detection unit 22 is deployed on the substrate stand 6. This exemplary embodiment illustrates an example where the first measurement mark 115 is deployed at a location other than the mask 2, an example where the second measurement mark 109 is deployed at a location other than the substrate stand 6, and an example where the detection unit 22 is deployed at a location other than the substrate stand 6.

[0111] The third exemplary embodiment is similar to the first exemplary embodiment in that the first measurement mark 115 is deployed on the object surface of the projection optical system 4 and the second measurement mark 109 is deployed on the image plane of the projection optical system 4. The basic configuration of the exposure apparatus 100 is similar to that of the first exemplary embodiment, and therefore its description is omitted. Matters not described in this exemplary embodiment are similar to those in the first exemplary embodiment.

[0112] While the first exemplary embodiment described above illustrates two methods for obtaining the optimal focal position, this exemplary embodiment illustrates an example where no change is observed in the light distribution obtained by the detection unit 22 even when the substrate stage 6 is driven in the Z-axis direction. Therefore, it is difficult to determine the optimal focal position using the methods described in the first exemplary embodiment. To determine the optimal focal position according to this exemplary embodiment, the optimal focal position is determined based on the light distribution changed by the driving of the detection unit 22 in the optical axis direction when the detection unit 22 is placed. Therefore, the detection unit 22 must include a mechanism for driving the detection unit 22 in the optical axis direction. Alternatively, a detection optical system 20 placed below the substrate stage 6 as in the first exemplary embodiment can be used in combination to determine the optimal focal position.

[0113] Reference Figure 15A and 15B Description of the exposure apparatus 100 according to this exemplary embodiment. Figure 15A The illustration shows the detection optical system 20 fixed and deployed on the side (on the side surface of the lens barrel) of the projection optical system 4. Figure 1A As shown in the configuration, in the detection optical system 20, not only is an image forming system 21, including a system comprising a detection unit 22, a lens 23, and a lens 24, deployed, but also mirrors 32 and 33 are deployed to guide illumination light to the image forming system 21. The second measurement mark 109 is not formed on the substrate stage 6, but is deployed between mirrors 32 and 33 in the optical system 20 at a position corresponding to the image plane of the projection optical system 4.

[0114] As described above in the first exemplary embodiment, the detection unit 22 can measure the changes in focus and alignment without driving the substrate stage 6. In this exemplary embodiment, the detection optical system 20, including the detection unit 22, can measure the changes in focus and alignment while the projection optical system 4 is fixed, without needing to move the projection optical system 4 in the optical axis direction. By utilizing this feature, illumination light having an optical path slightly outside the illumination light (exposure light) to be irradiated onto the substrate 5 during the exposure process is guided to the detection unit 22 of the detection optical system 20, thereby enabling continuous measurement of the changes in focus and alignment of the projection optical system 4 while performing the exposure process. Therefore, calibration operations can be performed without measurement waiting time, thereby reducing productivity loss.

[0115] Figure 15B The illustration shows the first measurement mark 115 not deployed on the mask 2 or mask stand 3, but deployed in an optical system 40 above the projection optical system 4. The optical system 40 includes elements such as a light source 41, a lens 42, and a mirror 43 to illuminate the first measurement mark 115 and to supply illumination light different from the illumination light used for exposure processing.

[0116] The advantage of this exemplary embodiment is that, for example, calibration can be performed separately for each part. For example, compared to the first exemplary embodiment, in having Figure 15B In the exposure apparatus 100 configured as shown, only the image forming performance, distortion, etc., of the projection optical system 4 can be identified. Furthermore, compared to the first exemplary embodiment, in the case of… Figure 15A In the exposure apparatus 100 configured as shown, the driving performance, deformation, etc. of the substrate stage 6 can be identified by evaluating the differences between measured values. Therefore, compared with the first exemplary embodiment, the advantage of this exemplary embodiment is that the performance of each part can be identified separately.

[0117] Furthermore, in the change measurement process according to this exemplary embodiment, there is no need for operations to drive the substrate stage 6 in the Z-axis direction to obtain the change in focus. The optical system 20, including the detection unit 22, also does not move in the optical axis direction. Therefore, according to this exemplary embodiment, during calibration, the time spent on operations such as moving the substrate stage 6 in the Z-axis direction (focus calibration operation) can be reduced, thereby preventing a decrease in the productivity of the exposure apparatus 100.

[0118] <Exemplary Example of Article Manufacturing Method>

[0119] The article manufacturing method according to exemplary embodiments of the present disclosure is suitable for manufacturing, for example, FPDs. The article manufacturing method according to exemplary embodiments includes a process for forming a latent image pattern on a photosensitive agent coated on a substrate 5 using the aforementioned exposure apparatus 100 (substrate exposure process), and a process for developing the substrate 5 with the latent image pattern formed. The article manufacturing method also includes other known processes (such as oxidation, film formation, deposition, doping, planarization, etching, resist removal, dicing, bonding, and encapsulation). Compared with related art methods, the article manufacturing method according to exemplary embodiments is advantageous in at least one of the following aspects: article performance, quality, productivity, and production cost.

[0120] Exemplary embodiments of this disclosure have been described above. However, this disclosure is not limited to the exemplary embodiments described above and can be modified or changed in various ways without departing from the spirit of this disclosure.

[0121] According to one aspect of this disclosure, an exposure apparatus can be provided that has the advantage of reducing productivity loss due to calibration operations.

[0122] While this disclosure has been described with reference to exemplary embodiments, it is to be understood that this disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be given the broadest interpretation in order to cover all such modifications and equivalent structures and functions.

Claims

1. An exposure apparatus, comprising: A projection system configured to project a pattern of a mask onto a substrate; A detection system, comprising a detection unit configured to detect the light quantity distribution of illumination light that has passed through a first marker, the projection system, and a second marker, wherein the first marker is deployed on an object surface of the projection system, and the second marker is deployed on an image plane of the projection system; as well as A control unit configured to control the relative position of the mask and the substrate. The detection system detects a light distribution through the detection unit at a first timing interval as a first light distribution, and at a second timing interval as a second light distribution. The first timing interval occurs before the exposure process of exposing the pattern on the substrate, and the second timing interval occurs after the exposure process. The control unit controls the relative positions of the mask and the substrate in the optical axis direction of the projection system and in the direction perpendicular to the optical axis direction, based on the first light distribution and the second light distribution.

2. The exposure apparatus according to claim 1, wherein, The control unit controls the relative position of the mask and the substrate based on the change in light intensity from the first light distribution to the second light distribution.

3. The exposure apparatus according to claim 1, wherein, The control unit controls the relative position of the mask and the substrate based on the difference between the peak position of the envelope of the first light quantity distribution and the peak position of the envelope of the second light quantity distribution.

4. The exposure apparatus according to claim 1, wherein, The second light distribution is the light distribution detected by the detection unit after the first light distribution has been detected by the detection unit, and then the exposure device has performed an exposure process for a predetermined number of times or for a predetermined period of time.

5. The exposure apparatus according to claim 1, wherein, When the first light distribution is detected by the detection unit, the relative position in the direction of the optical axis is the optimal focal position of the projection system.

6. The exposure apparatus according to claim 5, wherein, The control unit determines the optimal focal position based on the light distribution detected by the detection system while moving the second mark in the direction of the optical axis.

7. The exposure apparatus according to claim 1, wherein, The first marker includes at least two markers.

8. The exposure apparatus according to claim 1, wherein, The object surface is a surface on which the pattern of the mask is formed.

9. The exposure apparatus according to claim 1, wherein, The first mark is formed on the mask.

10. The exposure apparatus of claim 1, further comprising a mask stand for holding the mask. in, The first mark is formed on the mask stand.

11. The exposure apparatus according to claim 1, wherein, The first mark is deployed on a surface different from the surface on which the pattern of the mask is formed, and is illuminated by a different illumination light than the illumination light used by the exposure apparatus to perform the exposure process.

12. The exposure apparatus according to claim 1, wherein, The image plane is a surface on the substrate when the substrate is deployed.

13. The exposure apparatus of claim 1, further comprising a substrate stage for holding the substrate. in, The second mark is formed on the substrate stand.

14. The exposure apparatus according to claim 1, wherein, The second mark is deployed on a surface different from the upper surface of the substrate stand that holds the substrate, and is illuminated by a different illumination light than the illumination light used by the exposure apparatus to perform the exposure process.

15. The exposure apparatus according to claim 1, wherein, The control unit stores tabular data and uses the tabular data to correct the relative positions of the mask and the substrate in the optical axis direction. The tabular data indicates the correspondence between the light distribution detected by the detection unit and the relative positions of the mask and the substrate in the optical axis direction.

16. The exposure apparatus according to claim 1, wherein, The detection system is deployed on a substrate stand that holds the substrate.

17. The exposure apparatus according to claim 1, wherein, The detection system is deployed on the projection system.

18. The exposure apparatus according to claim 1, wherein, The detection system is deployed such that the image forming plane of the illumination light being formed into an image does not perfectly match the light receiving surface of the detection unit and partially overlaps with the light receiving surface.

19. The exposure apparatus according to claim 18, wherein, The detection system is a system with image field curvature.

20. An exposure method for performing an exposure process to transfer a pattern of a mask onto a substrate, the exposure method comprising: The light distribution of illumination light that has passed through a first marker, a projection system, and a second marker is detected. The first marker is deployed on the object surface of the projection system, and the second marker is deployed on the image plane of the projection system. as well as Controlling the relative position of the mask and the substrate, Wherein, the detection uses a first light distribution detected at a first timing as a first light distribution, and a second light distribution detected at a second timing as a second light distribution. The first timing occurs before the exposure process that exposes the pattern on the substrate, and the second timing occurs after the exposure process. In the control, based on the first light distribution and the second light distribution, the relative positions of the mask and the substrate in the optical axis direction of the projection system and in the direction perpendicular to the optical axis direction are controlled.

21. A method for manufacturing an article, comprising: The substrate is exposed using the exposure apparatus according to any one of claims 1 to 19; To develop the exposed substrate; as well as Articles are manufactured using developed substrates.

Images