Exposure apparatus, exposure method, and article manufacturing method

Abstract

To reduce deterioration in productivity due to calibration operation.SOLUTION: An exposure device has a projection optical system for projecting a pattern of a mask onto a substrate, a detection optical system for detecting light quantity distribution of illumination light having passed through a first measurement mark arranged on an object surface of the projection optical system, the projection optical system and a second measurement mark arranged on an image surface of the projection optical system, and a control part for controlling a relative position between the mask and the substrate, in which the control part controls a relative position in an optical axis direction of the projection optical system and a relative position in a direction vertical to the optical axis direction at a third timing after a second timing after a first timing, based on first light quantity distribution of the illumination light having passed through the first measurement mark and the second measurement mark detected by the detection optical system at the first timing, and second light quantity distribution of illumination light having passed through each of the first measurement mark and the second measurement mark detected by the detection optical system at the second timing.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an exposure apparatus, an exposure method, and a method for manufacturing an article. [Background technology]

[0002] Exposure tools are used to transfer mask patterns onto substrates in the photolithography process used to manufacture semiconductor devices, flat panel displays (FPDs), and other devices. To accurately transfer the mask pattern onto the substrate, exposure tools must adjust alignment (the relative positioning of the mask and substrate in the direction perpendicular to the optical axis of the projection optical system) and focus (the focal point of the light irradiated onto the substrate) with high precision.

[0003] As one method of alignment and focus adjustment, calibration using a TTL (Through The Lens) method via a projection optical system has been proposed. Patent Document 1 discloses details of focus calibration using the TTL method. In focus calibration, generally, the amount of light obtained via the projection optical system and stage-side marks is detected while the substrate stage is driven in the optical axis direction of the projection optical system. The position of the substrate where optimal focus is obtained on the surface (resist layer) is determined from the change in light amount when the substrate stage is driven in the optical axis direction of the projection optical system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-348019 Summary of the Invention [Problem to be solved by the invention]

[0005] It is known that the optimal relative position between the mask and the substrate (best focus position) changes over time due to air fluctuations inside the projection optical system caused by the effects of heat during the exposure process and misalignment of components that make up the projection optical system. If the exposure process is performed while the best focus position is misaligned, there is a risk of exposure accuracy decreasing. Therefore, even if focus calibration has been performed once, if the best focus position changes, it is necessary to perform focus calibration again. However, because focus calibration takes time, productivity in substrate processing decreases.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an exposure apparatus that is advantageous in reducing the decrease in productivity caused by the calibration operation. [Means for solving the problem]

[0007] In order to achieve the above object, an exposure apparatus according to one aspect of the present invention includes: a projection optical system that projects a pattern of a mask onto the substrate; a detection optical system including a detection unit that detects a light intensity distribution of illumination light that has passed through a first measurement mark arranged on an object plane of the projection optical system, the projection optical system, and a second measurement mark arranged on an image plane of the projection optical system; and a control unit that controls a relative position between the mask and the substrate, wherein the detection optical system is an optical system that is arranged such that an image plane on which the illumination light is imaged is inclined with respect to a light receiving surface of the detection unit; and an optical system having a curvature of field, The control unit controls the relative position in the optical axis direction of the projection optical system based on the amount of change in the light quantity distribution detected by the detection unit. In order to achieve the above-mentioned object, an exposure apparatus as one aspect of the present invention comprises a projection optical system that projects a pattern of a mask onto a substrate, a detection optical system including a detection unit that detects the light intensity distribution of illumination light that has passed through the projection optical system and a second measurement mark that is located on the image plane of the projection optical system, and a control unit that controls the relative position of the mask and the substrate, wherein the detection optical system is an optical system that is arranged so that an image plane on which the illumination light is imaged is inclined with respect to the light receiving surface of the detection unit, and the control unit controls the relative position in the optical axis direction of the projection optical system based on the amount of change in the light intensity distribution detected by the detection unit, and the first measurement mark is located on a surface different from the surface on which the pattern of the mask is formed, and is illuminated by illumination light that is different from the illumination light used during the exposure process. In order to achieve the above-mentioned object, one aspect of the present invention provides an exposure apparatus comprising: a projection optical system that projects a mask pattern onto a substrate; a detection optical system including a detection unit that detects the light intensity distribution of illumination light that has passed through a first measurement mark arranged on an object plane of the projection optical system, the projection optical system, and a second measurement mark arranged on an image plane of the projection optical system; a control unit that controls the relative position of the mask and the substrate; and a substrate stage that holds the substrate, wherein the detection optical system is an optical system that is arranged so that an image plane on which the illumination light is imaged is inclined with respect to the light receiving surface of the detection unit, and the control unit controls the relative position in the optical axis direction of the projection optical system based on the amount of change in the light intensity distribution detected by the detection unit, and the second measurement mark is arranged on a surface different from the top surface of the substrate stage, and is illuminated by illumination light that is different from the illumination light used during exposure processing. In order to achieve the above-mentioned object, an exposure apparatus as one aspect of the present invention comprises a projection optical system that projects a pattern of a mask onto a substrate, a detection optical system including a detection unit that detects the light intensity distribution of illumination light that has passed through the projection optical system and a second measurement mark that is located on the image plane of the projection optical system, and a control unit that controls the relative position of the mask and the substrate, wherein the detection optical system is an optical system that is arranged so that an image plane on which the illumination light is imaged is inclined with respect to the light receiving surface of the detection unit, and the control unit controls the relative position in the optical axis direction of the projection optical system based on the amount of change in the light intensity distribution detected by the detection unit, and the detection optical system is arranged in the projection optical system. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an exposure apparatus that is advantageous in reducing the decrease in productivity due to the calibration operation. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus in a first embodiment. [Figure 2] FIG. 2 is a diagram showing an exposure apparatus during measurement processing. [Figure 3] FIG. 10 is a longitudinal aberration diagram showing field curvature. [Figure 4] FIG. 10 is a diagram showing a reference focus position. [Figure 5] FIG. 10 is a diagram showing a state where the focus position is shifted from the reference focus position. [Figure 6] 10 is a graph showing the correspondence between the light amount distribution and the focus position of the substrate stage. [Figure 7] FIG. 10 is a diagram illustrating a first method for calculating the best focus position. [Figure 8] FIG. 10 is a diagram illustrating a second method for calculating the best focus position. [Figure 9] FIG. 10 is a longitudinal aberration diagram showing field curvature when the envelope of the light quantity distribution does not have a maximum value. [Figure 10] FIG. 10 is a diagram showing the light intensity distribution at a reference alignment position. [Figure 11] FIG. 10 is a diagram showing a state where the alignment position is shifted from the reference alignment position. [Figure 12] FIG. 10 is a diagram showing the correspondence between field curvature and light quantity distribution. [Figure 13] FIG. 2 is a diagram showing the configurations of an alignment measurement system and a focus measurement system. [Figure 14] 10A and 10B are diagrams illustrating measurement marks and detected light quantity distributions in the second embodiment. [Figure 15] FIG. 10 is a schematic diagram showing the configuration of an exposure apparatus in a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same components, and redundant explanations will be omitted.

[0011] First Embodiment

[0012] (Configuration of exposure device) The configuration of an exposure apparatus in this embodiment will be described. The exposure apparatus in this embodiment is a lithography apparatus used in a photolithography process, which is a manufacturing process for devices such as semiconductor devices and FPDs. The exposure apparatus in this embodiment employs a step-and-scan method, and performs an exposure process in which a substrate is exposed through a mask having a surface on which a pattern is formed, and the mask pattern is transferred to the substrate. The exposure method in this embodiment is the step-and-scan method, but is not limited to this, and other exposure methods such as a step-and-repeat method may also be used to perform the exposure process.

[0013] Figure 1 is a diagram showing the configuration of an exposure apparatus 100 in this embodiment. Figure 1(a) is a schematic diagram showing the overall configuration of exposure apparatus 100. In this embodiment, a coordinate system is defined with the direction parallel to the optical axis of the projection optical system as the Z-axis direction, and an arbitrary plane perpendicular to this Z-axis direction as the XY plane.

[0014] Exposure apparatus 100 has an illumination optical system 1 that illuminates mask 2, a mask stage 3 that holds mask 2, a projection optical system 4 that projects the pattern of mask 2 onto substrate 5, and a substrate stage 6 that holds substrate 5. Exposure apparatus 100 also has a control unit 7 that controls each unit of exposure apparatus 100, an input unit 13, and a determination unit 14.

[0015] Furthermore, exposure apparatus 100 has a means for illuminating the first measurement mark with illumination light using illumination optical system 1, and detection optical system 20 for detecting the light intensity distribution of the illumination light that has passed through the illuminated mark portion including first measurement mark 115 and second measurement mark 109 and projection optical system 4. Detection optical system 20 has imaging system 21 and detection unit 22, which are configured with a system including lenses 23 and 24. The wavelength of the illumination light is the same as the wavelength of the exposure light that projects the pattern of mask 2 onto substrate 5.

[0016] The control unit 7 is made up of a computer including a CPU, memory, etc., and controls all parts of the exposure apparatus 100 to operate the exposure apparatus 100. For example, when performing exposure processing, the control unit 7 controls the relative position between the mask 2 and the substrate 5 in the optical axis direction (Z-axis direction) of the projection optical system 4, and the relative position between the mask 2 and the substrate 5 in directions perpendicular to the optical axis of the projection optical system 4 (X-axis direction and Y-axis direction which are orthogonal to each other).

[0017] The input unit 13 is operated by a user to input exposure conditions (exposure area, illumination mode, pattern of the mask 2, etc.) for exposure processing, i.e., when transferring the pattern of the mask 2 to the substrate 5. Based on the exposure conditions input to the input unit 13, the determination unit 14 determines measurement conditions (number of measurements, accumulation time of the detection unit, etc.) required for calibration, which will be described later.

[0018] The detection optical system 20 is provided on the substrate stage 6 and is configured so that illumination light that has passed through a second measurement mark 109 formed on the upper surface of the substrate stage 6 is incident on the detection unit 22. In FIG. 1(a), the detection optical system is illustrated enlarged below the substrate stage 6 for convenience, but in reality it is configured inside the substrate stage 6. The detection unit 22 is, for example, an imaging element such as a line sensor in which multiple pixels are arranged in a predetermined direction. Note that the detection unit 22 may detect light reflected by the first measurement mark 115 and the second measurement mark 109, rather than light that has passed through a mark portion including the first measurement mark 115 and the second measurement mark 109.

[0019] The imaging system 21 is disposed between the projection optical system 4 and the detection unit 22 and is an optical system that forms images of the first measurement mark 115 and the second measurement mark 109 on the detection unit 22 side. In this embodiment, the imaging system 21 has a predetermined imaging magnification and is an optical system that multiplies the images of the first measurement mark 115 and the second measurement mark 109 by this magnification to form images on the detection unit 22 side and guides illumination light. The magnification can be appropriately set according to the resolution of the detection unit 22. The detection unit 22 includes multiple pixels and detects (captures) the images of the first measurement mark 115 and the second measurement mark 109 formed by the imaging system 21. The imaging system 21 is a system that has an appropriate amount of aberration (field curvature), as described below. The imaging system 21 may also be configured to include three or more lenses or other optical elements.

[0020] Illumination light (exposure light) from the illumination optical 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 optical system 4. The pattern surface of the mask 2 and the surface (resist layer) of the substrate 5 are positioned in a conjugate positional relationship via the projection optical system 4. Therefore, the pattern of the mask 2 is transferred onto the substrate 5 via the projection optical system 4. In this embodiment, the step-and-scan method is adopted, and therefore the exposure process is performed while the mask stage 3 and substrate stage 6 are synchronously scanned in the Y-axis direction.

[0021] 1(b) is a plan view showing the configuration of the mask stage 3. A first measurement mark 115 may be formed on the mask 2 held by the mask stage 3, in addition to the pattern to be transferred to 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. While a single first measurement mark 115 may be provided on the mask 2, it is preferable to provide a plurality of first measurement marks 115 in order to measure the characteristics of the projection optical system 4 in detail. The characteristics of the projection optical system 4 include, for example, the focal position and distortion.

[0022] FIG. 1C shows the details of the first measurement mark 115. FIG. 1C is a plan view showing the first measurement mark 115. The first measurement mark 115 includes a light-shielding region 115a, a transparent region 115b, which is a pattern of multiple regions having a predetermined line width and pitch, and a transparent region 115c. The transparent regions 115b are arranged along the X-axis direction to form a line-and-space pattern. In this embodiment, it is assumed that the first measurement mark 115 is formed on the mask 2, but this is not limiting and it is sufficient that the first measurement mark 115 is provided at a position corresponding to the object plane of the projection optical system 4. For example, the first measurement mark 115 may be provided on the mask stage 3. In this case, calibration of the projection optical system 4 can be performed even when the mask 2 is not placed on the mask stage 3.

[0023] The line-and-space pattern of the transparent region 115b may be various patterns (or a group of patterns) having different line widths, pitches, directions, etc. The transparent region 115c is provided to illuminate the transparent region 109c of the second measurement mark 109, which will be described later. In this embodiment, an example in which the transparent region 115c is provided to illuminate the transparent region 109c will be described. However, instead of providing the transparent region 115c, the transparent region 109c may be illuminated by irradiating the illumination light to an area outside the light-shielding region 115a.

[0024] Next, details of the second measurement mark 109 are shown in FIG. 1(d). FIG. 1(d) is a plan view showing the second measurement mark 109. The second measurement mark 109 includes a light-shielding region 109a, a transmitting region 109b, and a transmitting region 109c. In the description of this embodiment, it is assumed that the second measurement mark 109 is formed on the substrate stage 6, but this is not limiting. The mark 109 may be formed in a location other than the stage 6 as long as the mark 109 can be positioned at a position corresponding to the image plane of the projection optical system 4. The transmitting region 109b is provided to transmit the irradiation light that has passed through the transmitting region 115b of the first measurement mark 115.

[0025] 2 is a schematic diagram showing exposure apparatus 100 in a state where first measurement mark 115 and second measurement mark 109 have been positioned at the measurement positions, i.e., during measurement processing for alignment and focus adjustment. Alignment refers to the relative positioning of the mask and substrate in a direction perpendicular to the optical axis of the projection optical system, and focus refers to the focal point of light irradiated onto the substrate (the focal point in the projection optical system). In the following explanation, measurement for alignment and correction based on the alignment will be referred to as alignment calibration, and measurement for focus adjustment and correction based on the alignment will be referred to as focus calibration.

[0026] In this embodiment, in the alignment and focus calibration operation, the measurement process is performed without further moving the mask stage 3 or substrate stage 6 positioned at the measurement position in the Z-axis direction. When performing the measurement process, the control unit 7 drives the mask stage 3 so that it is positioned at the measurement position of the first measurement mark 115 determined by the determination unit 14. Similarly, when performing the above calibration operation, the control unit 7 drives the substrate stage 6 so that it is positioned at the measurement position of the second measurement mark 109 determined by the determination unit 14.

[0027] (Aberrations in the imaging system 21) The relationship between the aberration and the imaging position of the detection optical system 20 in this embodiment will be described with reference to Fig. 3. An example in which the detection optical system 20 has a predetermined field curvature as an optical characteristic will be described below. Fig. 3 is a longitudinal aberration diagram showing the field curvature in the imaging system 21. The vertical axis of the graph is the image height (X coordinate) of the imaging system, the horizontal axis is the imaging position (Z coordinate) in the optical axis direction, and curve 211 is a curve showing the field curvature in the detection optical system 20 (i.e., a curve showing the imaging position for each image height).

[0028] A characteristic of curve 211 is that a slight change in image height causes a large change in the image position in the optical axis direction near point 211b compared to near point 211a. For example, if imaging system 21 is positioned so that the optical axis of imaging system 21 perpendicularly intersects the light-receiving surface of detection unit 22 near point 211b, the pattern on the object plane of imaging system 21 will not be in focus over the entire light-receiving surface of detection unit 22, but will be in focus only over a portion of the light-receiving surface. In this embodiment, point 211a corresponds to the position of the optical axis of imaging system 21 of detection optical system 20, and point 212b corresponds to the measurement image height at which first measurement mark 115 and second measurement mark 109 are measured.

[0029] In this embodiment, as described above, the imaging system 21 is configured to generate the field curvature shown in Fig. 3, for example, and the center of the light-receiving surface of the detection unit 22 is positioned offset from the optical axis of the imaging system 21. Then, focus measurement is performed by illuminating the first measurement mark 115 with illumination light from the illumination optical system 1, and detecting the light that passes through the transmission area 115b of the first measurement mark 115 via the projection optical system 4 and the transmission area 109b of the second measurement mark 109 with the detection unit 22. This allows focus calibration to be performed by a method described below, without moving the mask stage 3 or substrate stage 6 positioned at the measurement position in the Z-axis direction.

[0030] In this embodiment, the first measurement mark 115 is illuminated with light from the illumination optical system 1, and the light that passes through the transmission area 115c of the first measurement mark 115 is detected by the detection unit 22 via the transmission area 109c of the projection optical systems 4 and 109. This allows alignment calibration to be performed simultaneously with focus calibration, using a method that will be described later.

[0031] (Focus calibration) Next, the change amount measurement process for determining the amount of focus change in this embodiment will be described with reference to FIGS. 4 and 5. FIGS. 4(a) and 5(a) are explanatory diagrams showing the state of exposure apparatus 100 during the focus change amount measurement process, and show the mark image of first measurement mark 115 projected onto detection unit 22 after passing through projection optical system 4, second measurement mark 109, and imaging system 21. The state in FIG. 4(a) is the state at a first timing (a state in which the focus position determined by the projection optical system is at the reference focus position). The state in FIG. 5(a) is the state at a second timing after the exposure process performed after the first timing (a state in which the focus position determined by the projection optical system has shifted from the reference focus position).

[0032] The projection optical system 4 is an optical system whose purpose is to focus and project the pattern image of the mask 2 onto the surface of the substrate 5. Therefore, the first measurement mark 115 needs to be imaged on a plane where the projection optical system 4 that projects it is focused and where the surface of the substrate 5 should be located.

[0033] 4(a) (first timing), the image of first measurement mark 115 formed on the plane where the surface of substrate 5 should be located is defined as imaged pattern 115P. Furthermore, the pattern image formed on detection unit 22 after imaged pattern 115P passes through imaging system 21 is defined as imaged pattern 115S.

[0034] At this time, due to the curvature of field of imaging system 21, imaging pattern 115S is imaged on a plane perpendicular to the optical axis of imaging system 21 and tilted with respect to the light receiving surface of detection unit 22. Therefore, in this embodiment, the imaging plane (imaging pattern 115S) of first measurement mark 115 by imaging system 21 only partially overlaps with the light receiving surface of detection unit 22. The imaging plane of second measurement mark 109 by imaging system 21 also only partially overlaps with the light receiving surface of detection unit 22.

[0035] 4(b) is a diagram showing the light intensity distribution (first light intensity distribution) of illumination light that passes through first measurement mark 115 and second measurement mark 109 and is detected by detection unit 22 at a first timing. The vertical axis of the graph represents the light intensity obtained on the light receiving surface of detection unit 22, and the horizontal axis represents the position of the light receiving surface of detection unit 22 in the X-axis direction. The first light intensity distribution includes distributions M1 to M7 corresponding to transmission region 115b of first measurement mark 115, and distributions P1 and P2 corresponding to transmission region 109b of second measurement mark 109. It also includes distributions V1 to V10 corresponding to light-blocking region 115a of first measurement mark 115, and distributions V1, V2, V9, and V10 corresponding to light-blocking region 109a of second measurement mark 109.

[0036] Here, because the imaging system 21 in this embodiment has field curvature, a misalignment occurs between the image plane of the detection optical system 20 and the light receiving surface of the detection unit 22. In the light intensity distribution, the light intensity is greatest where there is no or smallest misalignment, and the light intensity decreases in areas where the misalignment is greater depending on the amount of misalignment. In the light intensity distribution of FIG. 4(b), it can be seen that among distributions M1 to M7, distribution M4 has the greatest light intensity. This indicates that the position on the light receiving surface of the detection unit 22 corresponding to distribution M4 is in focus. The reason why the light intensities of distributions P1 and P2 are large despite the misalignment is because the width of the transmission region 109c of the second measurement mark 109 is wide and the sensitivity of the light intensity to changes in light intensity due to defocus is low.

[0037] A method for determining the in-focus position on the light receiving surface of the detection unit 22 from the light intensity distribution in FIG. 4(b) will be described. In this determination, attention is focused only on distributions M1 to M7 corresponding to the transmission region 115b of the first measurement mark. First, distributions M1, M2, and M3 indicate that the imaging position is shifted in the -Z direction (or +Z direction) with respect to the detection unit 22. Furthermore, distributions M5, M6, and M7 indicate that the imaging position is shifted in the +Z direction (or -Z direction) with respect to the detection unit 22. Therefore, if the position on the light receiving surface of the detection unit 22 corresponding to distribution M4 can be determined, it is possible to determine the in-focus position A on the light receiving surface of the detection unit 22 from the following equation (1). A=P×PixelSize×tanθ / Mag...(1)

[0038] In equation (1), P indicates the position on the light receiving surface of the detection unit 22 where the light intensity is greatest, and PixelSize indicates the size of a pixel of the detection unit 22. Furthermore, θ indicates the angle between the imaging surface of the imaging system 21 having field curvature and the light receiving surface of the detection unit 22, and Mag indicates the magnification of the imaging system 21.

[0039] Furthermore, the method for determining the in-focus position on the light receiving surface of the detection unit 22 is not limited to the method of determining the position on the light receiving surface using Equation (1). For example, it is also possible to obtain an envelope 26 consisting of distribution M4, which has the greatest light intensity, and the other distributions M1 to M3 and M5 to M7, and then more accurately determine the in-focus position from envelope 26. In this case, even if there is an in-focus position on the light receiving surface of the detection unit 22 near distribution M4 (for example, an intermediate position between distributions M4 and M3), it is possible to determine the in-focus position on the light receiving surface of the detection unit 22 from envelope 26. In FIG. 4(b), the position on the light receiving surface of the detection unit 22 corresponding to maximum value 27 (peak position) of envelope 26 obtained from distributions M1 to M7 is shown as position MI1.

[0040] Figure 5(a) shows a state in which the position of the substrate stage 6 has shifted in the Z-axis direction from the state shown in Figure 4(a) (a state at a second timing after the first timing). Due to the influence of heat during the exposure process, air fluctuations inside the projection optical system 4 and positional shifts of components that make up the projection optical system 4 may cause the image of the first measurement mark to shift in the Z-axis direction from 115P to 115Q, as shown in Figure 5(a). At this time, the image of the first measurement mark also shifts in the Z-axis direction near the detection unit 22 from 115S to 115T.

[0041] FIG. 5B shows the light intensity distribution (second light intensity distribution) of illumination light that passes through first measurement mark 115 and second measurement mark 109 and is detected by detection unit 22 at a second timing that follows the first timing. The vertical axis of the graph represents the light intensity obtained on the light receiving surface of detection unit 22, and the horizontal axis represents the position on the light receiving surface of detection unit 22 in the X-axis direction. In the second light intensity distribution, distribution M3 has the maximum light intensity among distributions M1 to M7, and the position corresponding to distribution M3 (or a position nearby) is the in-focus position on the light receiving surface of detection unit 22. In addition, position MI2 is the position on the light receiving surface of detection unit 22 that corresponds to maximum value 31 of envelope 30 obtained from distributions M1 to M7. Similar to position MI1 in the first light intensity distribution, position MI2 in the second light intensity distribution may also be the in-focus position.

[0042] By determining positions MI1 and MI2, a change amount measurement process can be performed to determine the amount of change in focus. That is, the position on the light receiving surface of detection unit 22 that is in focus at a first timing is compared with the position on the light receiving surface of detection unit 22 that is in focus at a second timing after the first timing (for example, after a predetermined time has elapsed or after the substrate has been exposed a predetermined number of times). As a result, the amount of change in focus can be determined.

[0043] 6 is a diagram showing the relationship between positions MI1 and MI2, which indicate positions in the X-axis direction on the light-receiving surface of the detection unit 22, and the best focus position of the projection optical system 4. It can be seen from Fig. 6 that when the position corresponding to the maximum value of the envelope changes from position MI1 to position MI2, the best focus position of the projection optical system 4 also changes from Z1 to Z2 accordingly.

[0044] Furthermore, if the influence of aberrations or other disturbances is significant, multiple measurement points may be prepared in advance for the best focus position determined by the projection optical system 4 and the positions on the light-receiving surface of the detector 22 corresponding to the maximum values ​​of the envelope. For example, the results of fitting the measurement points with an approximation formula may be stored in the controller 7 as table data. The controller 7 can determine the best focus position using table data indicating the correspondence between the light intensity distribution detected by the detector 22 and the relative positions of the mask 2 and substrate 5 in the optical axis direction (Z-axis direction). Therefore, it is possible to determine the best focus positions (e.g., Z1, Z2) at different times and the amount of change in the best focus position (e.g., Z1-Z2). This concludes the description of the change amount measurement process for determining the amount of focus change in this embodiment.

[0045] Here, two methods for determining the best focus position will be described. Both methods involve calculation from the change in the light intensity of the first measurement mark 15 in the detection unit 22 when the substrate stage 6 is driven in the Z-axis direction. In this embodiment, by setting the reference focus position to the best focus position determined at the first timing, it is no longer necessary to drive the substrate stage 6 positioned at the measurement position in the Z-axis direction in the second and subsequent calibrations. This makes it possible to suppress a decrease in productivity due to calibration.

[0046] The first method is to specify a pattern in the first measurement mark 115, and determine the position of the substrate stage 6 that will be the best focus position from the amount of change in light intensity in a distribution corresponding to the specified pattern (for example, one of the distributions M1 to M7 in FIG. 7). FIG. 7 is a diagram for explaining the first method for determining the best focus position. FIG. 7(a) shows the light intensity distribution of the pattern of the first measurement mark 115 detected by the detection unit 22 when the substrate stage 6 is at a certain position in the Z axis direction. FIG. 7(b) shows the light intensity distribution of the pattern of the first measurement mark 115 detected by the detection unit 22 when the substrate stage 6 is at a different position in the Z axis direction from that shown in FIG. 7(a). Here, for example, when focusing on the pattern of distribution M4, the light intensity in distribution M4 changes depending on the position of the substrate stage in the Z axis direction.

[0047] 7(c) is a graph showing changes in the amount of light detected by the detection unit 22 when focusing on distribution M4. The vertical axis of the graph represents the amount of light in distribution M4 in FIGS. 7(a) and 7(b), and the horizontal axis represents the position of the substrate stage in the Z-axis direction. As shown in FIG. 7(c), the amount of light changes depending on the position of the substrate stage in the Z-axis direction. At the best focus position of the substrate stage 6, the amount of light detected by the detection unit 22 is at its maximum, so the reference focus position can be determined by finding the position of the substrate stage 6 where the amount of light reaches its maximum value Z0 in FIG. 7(c).

[0048] Furthermore, when focusing on a distribution other than distribution M4, the reference focus position can be determined by taking into consideration the image plane shift amount that has been previously determined as the image plane shift amount at the image height corresponding to distribution M4.

[0049] The second method is to obtain the light intensity distribution of illumination light that has passed through the first measurement mark 115 at an image height where the field curvature of the imaging system 21 is minute, for example, near point 211(a) in the longitudinal aberration diagram of Fig. 3, and determine the best focus position from the amount of change in the light intensity of this illumination light. A minute field curvature means that the aberration (defocus amount) is less than ¼ of the focus calculation accuracy (for example, 3σ), and does not affect measurement.

[0050] 8A and 8B are diagrams illustrating a second method for determining the best focus position. FIG. 8A shows a light intensity distribution (illumination light intensity distribution) resulting from detection of the pattern image of the first measurement mark 115 by the detection unit 22 when the substrate stage 6 is at a certain position in the Z axis direction. FIG. 8B shows a light intensity distribution resulting from detection of the pattern image of the first measurement mark 115 by the detection unit 22 when the substrate stage 6 is at a different position in the Z axis direction from that shown in FIG. 8A. In FIGS. 8A and 8B, the detection unit 22 measures the light intensity at a position where the field curvature is minimal, and therefore, unlike in FIGS. 7A and 7B, there is little variation in the light intensity among the distributions M1 to M7.

[0051] Here, when focusing on the patterns M1 to M7, the amount of light detected by the detection unit 22 changes depending on the position of the substrate stage in the Z-axis direction. Figure 8(c) is a graph showing the change in the amount of light detected by the detection unit 22 when focusing on the distributions M1 to M7. The vertical axis of the graph represents the average value of the amount of light in the distributions M1 to M7 in Figures 8(a) and 8(b), and the horizontal axis represents the position of the substrate stage in the Z-axis direction. As shown in Figure 8(c), the amount of light changes depending on the position of the substrate stage in the Z-axis direction. At the best focus position of the substrate stage 6, the amount of light detected by the detection unit 22 is at its maximum, so the reference focus position can be determined by finding the position of the substrate stage 6 where the amount of light reaches its maximum value Z0 in Figure 8(c).

[0052] After calculating the reference focus position using the above method, the detection unit 22 is moved in the X-axis direction to an image height where the field curvature is sufficiently large (for example, near point 211b in FIG. 3), and the light intensity distribution corresponding to the first measurement mark 115 is obtained. This allows focus calibration.

[0053] Depending on the shape of the field curvature, the envelope may not have an extreme value when the substrate stage 6 is moved in the X direction from an image height where the field curvature is small to a sufficiently large image height. Fig. 9 is a longitudinal aberration diagram showing the field curvature when the envelope of the light quantity distribution detected by the detection unit 22 does not have an extreme value. The vertical axis of the graph is the image height (X coordinate) of the imaging system, the horizontal axis is the imaging position in the optical axis direction (Z coordinate), and curve 231 is a curve that shows the field curvature in the detection optical system 20 (i.e., a curve that shows the imaging position for each image height).

[0054] In curve 231, the light-receiving surface of detector 22 and the imaging position deviate significantly from the vicinity of point 231a. As a result, the pattern with the maximum light amount becomes distribution M1, and the envelope may not have a maximum value. In such a case, the substrate stage 6 is moved in the Z-axis direction so that the envelope has a maximum value, and the focus value is managed on the assumption that there is a difference from the best focus by the amount of movement, thereby making it possible to find the amount of change in the best focus position.

[0055] As described above, by setting the reference focus position to an appropriate focus position, it becomes unnecessary to drive the substrate stage 6 positioned at the measurement position in the Z-axis direction in the second and subsequent focus calibrations, which makes it possible to suppress a decrease in productivity due to calibration.

[0056] (Alignment calibration) Next, the change amount measurement process for determining the amount of change in alignment in this embodiment will be described with reference to FIGS. 10 and 11. This figure shows the light intensity distribution of illumination light that passes through first measurement mark 115 and second measurement mark 109 and is detected by detection unit 22 in the state of exposure apparatus 100 in FIG. 4(a). The vertical axis of the graph represents the light intensity obtained by detection unit 22, and the horizontal axis represents the position in the X-axis direction on the light-receiving surface of detection unit 22. The light intensity distribution in FIG. 10 includes distributions M1 to M7 corresponding to transmission region 115b of first measurement mark 115, and distributions P1 and P2 corresponding to transmission region 109b of second measurement mark 109. It also includes distributions V1 to V10 corresponding to light-shielded region 115b of first measurement mark 115, and distributions V1, V2, V9, and V10 corresponding to light-shielded region 109b of second measurement mark 109.

[0057] A method for determining an appropriate relative position (reference alignment position) between the mask 2 and the substrate stage 6 on the XY plane from the illumination light intensity distribution shown in FIG. 10 will be described. First, the position of the light receiving surface of the detection unit 22 of each pattern of distributions M1 to M7 corresponding to the first measurement mark 115 is calculated (for example, by calculating the center of gravity). Position 92 obtained by averaging the positions of each pattern is defined as MA1. Next, the position of the light receiving surface of the detection unit 22 of each pattern of distributions P1 and P2 is calculated (for example, by calculating the center of gravity). Position 93 obtained by averaging the positions of each pattern is defined as PA1. The difference between MA1 and PA1 represents the relative position between the first measurement mark 115 and the second measurement mark 109, i.e., the relative position between the mask 2 and the substrate stage 6.

[0058] FIG. 11(a) shows a state in which the alignment position (the relative position between the mask 2 and the substrate stage 6 in a direction parallel to the XY plane) has shifted from the state shown in FIG. 4(a). Heat and other factors generated during the exposure process may cause air fluctuations inside the projection optical system 4 or misalignment of the components that make up the projection optical system 4. This may cause the image of the first measurement mark 115 to shift in the X-axis direction from imaged pattern 115P to imaged pattern 115O, as shown in FIGS. 4(a) and 11(a). In such a case, the light intensity distribution shown in FIG. 10 changes to the light intensity distribution shown in FIG. 11(b).

[0059] 11(b), as in FIG. 10, position 95 obtained by averaging the positions of M1 to M7 is defined as MA2, and position 96 obtained by averaging the positions of P1 and P2 is defined as PA2. At this time, the position of MA2 has changed compared to MA1. PA1 and PA2 correspond to second measurement mark 109 after it has passed through projection optical system 4, and are therefore not affected by air fluctuations in projection optical system 4 or misalignment of components constituting projection optical system 4. Therefore, the position of transmission region 109b of second measurement mark 109 does not change due to the air fluctuations or misalignment of components, and the position of distribution PA2 corresponding to 109b does not change from the position of PA1. Here, when difference AA1 between MA1 and PA1 is defined as the alignment reference and difference AA2 is defined as the difference between MA2 and PA2, the amount of change between AA1 and AA2 is calculated as the amount of alignment change in this embodiment.

[0060] As described above, in this embodiment, the amount of change in alignment can be calculated. Furthermore, in this embodiment, the detection results by the detection unit 22 used in focus calibration can also be used in alignment calibration.

[0061] (Specific method of calibration operation) The above describes specific methods for calculating the amount of change in focus and alignment. However, unless it is determined whether the changes in the graphs in Figures 4(b) and 5(b) or Figures 10 and 11(b) are caused by the influence of the focus or alignment of the projection optical system 4, it may not be possible to correctly calculate the amount of change in focus and alignment. Below, a specific processing method for determining the amount of change in focus and alignment will be described.

[0062] In this embodiment, if the position of the image plane on which the first measurement mark 115 is formed in the XY plane changes due to the influence of air fluctuations in the projection optical system 4 or misalignment of components that make up the projection optical system 4, the measurement image height in the imaging system 21 will also change. Because the imaging system 21 in this embodiment has field curvature, the focal position of the imaging system 21 also changes in response to changes in the image height. As a result, even though only the imaging position of the first measurement mark 115 in the XY plane has changed, the light intensity distribution will appear as if the focus has also changed.

[0063] Therefore, in order to separate the amount of change that is affected by changes in the state of the projection optical system due to heat or the like (to calculate only the amount of change in focus), information regarding the amount of 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. Then, by subtracting the amount of change in focus from the information indicating the focus change of the feature corresponding to the position on the light-receiving surface of the detection unit 22, the amount of change in focus in the projection optical system 4 can be measured correctly.

[0064] When the position of the image plane on the XY plane where the first measurement mark 115 is focused changes due to the influence of air fluctuations in the projection optical system 4 or misalignment of the components that make up the projection optical system 4, the maximum value of the envelope of the light quantity distribution detected on the light receiving surface of the detection unit 22 also shifts. In other words, even though only the alignment position has changed, the position of the maximum value of the envelope shifts, resulting in a light quantity distribution that appears as if the focus has changed.

[0065] Therefore, in order to separate the amount of change affected by changes in the state of the projection optical system due to heat, etc. (to calculate only the amount of change in alignment), the difference between MA1 and PA1 is defined as ΔA, and the difference between MA2 and PA2 as ΔB, and the amount of change in MI1-ΔA and MI2-ΔB is calculated. The amount of change in alignment position is calculated from the difference between MA1-PA1 and MA2-PA2, and the amount of change in focus position is calculated from the difference between MI1-ΔA and MI2-ΔB. This makes it possible to correctly separate the positional deviations of focus and alignment.

[0066] Next, the amount of field curvature in this embodiment will be described with reference to FIG.

[0067] When the amount of field curvature is large within the range in which the detection unit 22 can detect the light quantity distribution, the light quantity distribution becomes steeper with changes in image height (the light quantity changes abruptly). Also, the amount of deviation of the envelope of the light quantity distribution increases when the focus changes. On the other hand, when the amount of field curvature is small, these characteristics are reversed.

[0068] 12(a) shows the light intensity distribution of illumination light when the amount of field curvature is large, with light intensity distribution 191 shown by the dashed line and light intensity distribution 193 shown by the solid line each showing light intensity distributions at different focus positions. The position of the center of gravity of envelope 192 of light intensity distribution 191 shown by the dashed line is designated MI191, and the position of the center of gravity of envelope 194 of light intensity distribution 193 shown by the solid line is designated MI193.

[0069] 12(b) shows the light intensity distribution of illumination light when the amount of field curvature is smaller than that in FIG. 12(a), where light intensity distribution 195 shown by the dashed line and light intensity distribution 197 shown by the solid line show light intensity distributions at different focus positions. The position of the center of gravity of envelope 196 of light intensity distribution 195 shown by the dashed line is designated MI195, and the position of the center of gravity of envelope 198 of light intensity distribution 197 shown by the solid line is designated MI197.

[0070] The light intensity distributions in Figures 12(a) and 12(b) are plotted assuming that only the amount of field curvature of the imaging system 21 of the detection optical system 20 differs, and the focus change amount and other conditions indicated by the two light intensity distributions shown by the solid and dashed lines are the same. Comparing Figures 12(a) and 12(b) reveals differences in the amount of change in the center of gravity of the two envelopes shown by the solid and dashed lines. Specifically, when comparing the difference between the two center of gravity positions MI191 and MI193 in Figure 12(a) with the difference between the two center of gravity positions MI195 and MI197 in Figure 12(b), the difference between MI191 and MI193 in Figure 11(a), where the field curvature is large, is smaller. Therefore, when the field curvature is large, the amount of focus change at the envelope extremes in the detector 22 becomes smaller, allowing for a wider measurement range. However, the detector becomes less sensitive to the focus change amount, resulting in reduced measurement accuracy.

[0071] The measurement range and measurement accuracy can be adjusted according to the required accuracy of the measurement system. There are trade-offs among the optical conditions of the imaging system 21 (design wavelength, numerical aperture, magnification, etc.), the line width and pitch of the line-and-space of the first measurement mark, and the specifications of the detection unit 22 (S / N ratio, pixel size), etc.

[0072] One guide to the amount of field curvature is the amount of field curvature where the pattern intensity at best focus (for example, distribution M4 in Figure 4(b)) is 1 and the surrounding pattern intensity of the same line width (for example, distributions M1 and M7 at the very edge in Figure 4(b)) is 0.2 or more. The reason for this is that if the pattern intensity is 0.2 or more, it is possible to obtain a contrast that is sufficiently measurable.

[0073] Next, a specific exposure method will be described. As described above, focus and alignment calibration operations can be performed based on the light intensity distribution detected by the detection unit 22. Furthermore, by knowing the relative positional relationship between the mask 2 and the substrate stage 6, the relative positions of the mask 2 and the substrate stage 6 can be controlled at a third timing, which is after the second timing, using an alignment measurement system and a focus measurement system, as will be described later. In other words, the control unit 7 can expose the pattern of the mask 2 onto the substrate 5 while appropriately managing the relative positional relationship between the mask 2 and the substrate 5.

[0074] FIG. 13 shows an alignment measurement system and a focus measurement system. The alignment measurement system 50 (also called an off-axis alignment scope) shown in FIG. 13(a) includes a light source 51 such as an LED, lenses 52, 53, 54, and 55, a half mirror 56, and an imaging unit 57. Light emitted from the light source 51 passes through lenses 52 and 53, is reflected by half mirror 56, passes through lens 54, and perpendicularly strikes the substrate 5. The light incident on the substrate 5 is reflected and scattered by an alignment mark or the like in a shot area of ​​the substrate 5. The reflected and scattered light passes through lens 54, half mirror 56, and lens 55, and forms an image of the alignment mark on the imaging unit 57, whereby 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.

[0075] 13(b) includes a light source 61 such as an LED, lenses 62, 63, and 64, and an imaging unit 65. Light emitted from the light source 61 passes through the lens 62 and is incident obliquely on the substrate 5. The incident light is reflected by the substrate 5, passes through the lenses 63 and 64, and is imaged by the imaging unit 65. The focus measurement system 60 measures the position of the second measurement mark 109 formed on the substrate stage 6 and the substrate stage 6 in the Z-axis direction (measures the surface height in the Z-axis direction). The positional relationship between the mask 2 and the substrate 5 can be determined from the measurement results in the X-axis, Y-axis directions, and Z-axis direction, and information related to the focus and alignment calibration.

[0076] The frequency with which the above calibration is performed may be set appropriately depending on the stability of the projection optical system 4 and the accuracy required of the exposure apparatus. In this embodiment, the calibration can be performed without driving the substrate stage 6, so even if the calibration is performed frequently, the impact on productivity is small. Therefore, by increasing the calibration frequency, it is possible to calibrate the relative positions of the mask 2 and the substrate 5 with high accuracy.

[0077] In this way, in the change amount measurement process in this embodiment, there is no need to drive the substrate stage 6 in the Z axis direction when determining the focus change amount. Therefore, in this embodiment, the time required for the operation of moving the substrate stage 6 in the Z axis direction (focus calibration operation) in calibration is reduced, and a decrease in productivity of the exposure apparatus 100 can be suppressed.

[0078] In this embodiment, the control unit 7 drives the substrate stage 6 to control the relative position of the mask 2 and the substrate 5 at the third timing. However, this is not limiting, and the mask stage 6 may be driven instead. Alternatively, both the mask stage 3 and the substrate stage 6 may be driven. In this embodiment, the multiple patterns (transmission areas) of the first measurement mark 115 and the second measurement mark 109 are aligned in the X direction. However, the first measurement mark and the second measurement mark may each have the same multiple patterns aligned in the Y direction. In this case, multiple detection units 22 are provided, serving as a first detection unit that detects images of the multiple patterns aligned in the X direction and a second detection unit that detects images of the multiple patterns aligned in the Y direction.

[0079] Second Embodiment In the first embodiment, an example was described in which the light intensity distribution of illumination light that has passed through the first measurement mark 115 and the second measurement mark 109, whose patterns are arranged in one direction (X-axis direction), is measured, and calibration is performed. In this embodiment, an example is described in which the light intensity distribution of the first measurement mark 115 and the second measurement mark 109, whose patterns are arranged in multiple directions (X-axis direction and Y-axis direction), is measured, and calibration is performed. The basic configuration of the exposure apparatus 100 is the same as in the first embodiment, and therefore a description thereof will be omitted. Furthermore, matters not mentioned in this embodiment follow the first embodiment.

[0080] FIG. 14A shows the first measurement mark 115 in this embodiment. The first measurement mark 115 in this embodiment includes a light-shielding region 115d, and transparent regions 115e, 115f, and transparent regions 115g, 115h, and 115i, which are multiple patterns having a predetermined line width and pitch. The transparent region 115e is arranged along the X-axis direction to form a line-and-space pattern. The transparent region 115f is arranged along the Y-axis direction to form a line-and-space pattern. In the description of this embodiment, it is assumed that the first measurement mark 115 is formed on the mask 2. However, this is not a limitation, and the first measurement mark 115 may be provided at a position corresponding to the object plane of the projection optical system 4. For example, the first measurement mark 115 may be provided on the mask stage 3. In this case, the projection optical system 4 can be calibrated even when the mask 2 is not placed on the mask stage 3.

[0081] Similarly to the first embodiment, the line and space patterns of the transparent regions 115e and 115f may be various patterns (or patterns) with different line widths, pitches, directions, etc. The transparent regions 115g, 115h, and 115i are provided to illuminate the transparent regions 109e, 109f, and 109g of the second measurement mark 109, which will be described later.

[0082] 14(b) is a diagram showing second measurement mark 109 in this embodiment. Second measurement mark 109 in this embodiment includes light-shielding region 109d, transparent regions 109e, 109f, and 109g, and transparent regions 109h and 109i. Transparent regions 109e and 109f are formed as a pattern in the X-axis direction, and transparent regions 109f and 109g are formed as a pattern in the Y-axis direction.

[0083] In the description of this embodiment, the second measurement mark 109 is provided on the substrate stage 6, but this is not limiting, and the mark 109 may be positioned at a position corresponding to the image plane of the projection optical system 4 and at a location where the pattern of the measurement mark 115 is projected. For example, the mark 109 may be provided on a unit or element different from the substrate stage 6.

[0084] Moreover, the transparent regions 109h and 109i are provided to transmit the pattern images of the transparent regions 115e and 115f of the first measurement mark 115.

[0085] 14(c) shows the light intensity distribution detected by the detection unit 22. Note that area 322 shows the illumination light reaching the light receiving surface of the detection unit 22. Areas 322a to 322e are illumination light that has passed through the first measurement mark 115 and the second measurement mark 109, and are images of the patterns of each mark.

[0086] Additionally, intersection line 322h represents the line where the light receiving surface and the imaging surface of detection unit 22 coincide. Because imaging system 21 has field curvature in both the X-axis and Y-axis directions, the light receiving surface and the imaging surface of detection unit 22 do not coincide completely with each other in both directions, but only partially, resulting in intersection line 322h.

[0087] Light quantity distribution 323 is the distribution of the amount of light received on the light-receiving surface of detection unit 22 in region 322f extending in the X-axis direction of detection unit 22. As shown in Figure 14(c), the light quantity in region 322a is distribution 323a in light quantity distribution 323, the light quantity in region 322b is distribution 323b in light quantity distribution 323, and the light quantity in region 322d is distribution 323d in light quantity distribution 323.

[0088] Light intensity distribution 324 is the distribution of the light intensity of illumination light received on the light-receiving surface of detection unit 22 in region 322g extending in the Y-axis direction of detection unit 22. As shown in Fig. 14(c) , the light intensity in region 322a is distribution 324a in light intensity distribution 324, the light intensity in region 322c is distribution 324c in light intensity distribution 324, and the light intensity in region 322e is distribution 324e in light intensity distribution 323.

[0089] In this embodiment, the light intensity distribution of the illumination light that has passed through the first and second measurement marks can be obtained in each of the X-axis and Y-axis directions, and alignment calibration can be performed in each of the X-axis and Y-axis directions based on the light intensity distribution in each direction. Also, focus calibration can be performed as in the first embodiment.

[0090] In this embodiment, a two-dimensional detection unit 22 such as an area sensor is used, and measurements can be performed in the X-axis and Y-axis directions with one detection unit 22, which makes it possible to save space and reduce costs compared to providing a detection unit 22 for each of the X-axis and Y-axis directions.

[0091] In the change amount measurement process in this embodiment, too, there is no need to drive the substrate stage 6 in the Z-axis direction when determining the focus change amount. Therefore, in this embodiment as well, the time required for the operation of moving the substrate stage 6 in the Z-axis direction (focus calibration operation) during calibration is reduced, and a decrease in productivity of the exposure apparatus 100 can be suppressed.

[0092] Third Embodiment In the first embodiment, an example was described in which the first measurement mark 115 is formed on the mask 2, the second measurement mark 109 is formed on the substrate stage 6, and the detection unit 22 is arranged on the substrate stage 6. In the present embodiment, an example will be described in which the first measurement mark 115 is arranged on a location other than the mask 2, the second measurement mark 109 is arranged on a location other than the substrate stage 6, or the detection unit 22 is arranged on a location other than the substrate stage 6.

[0093] Similar to the first embodiment, the first measurement mark 115 is arranged on the object plane of the projection optical system 4, and the second measurement mark 109 is arranged on the image plane of the projection optical system 4. The basic configuration of the exposure apparatus 100 is also similar to that of the first embodiment, and therefore a description thereof will be omitted. Matters not mentioned in this embodiment follow the first embodiment.

[0094] In the first embodiment, two methods for determining the best focus position were described. However, in this embodiment, the light intensity distribution obtained by the detection unit 22 does not change even when the substrate stage 6 is driven in the Z-axis direction. Therefore, the best focus position cannot be determined by the method described in the first embodiment. To determine the best focus position in this embodiment, when the detection unit 22 is installed, it is necessary to determine the best focus position based on the light intensity distribution that changes when the detection unit 22 is driven in the optical axis direction. Therefore, the detection unit 22 must have a mechanism for driving it in the optical axis direction. Alternatively, the best focus position may be determined by simultaneously using a detection optical system installed below the substrate stage 6, as in the first embodiment.

[0095] An exposure apparatus 100 of this embodiment will be described with reference to Figure 15. Figure 15(a) is a diagram showing the detection optical system 20 fixed to the side (the side surface of the lens barrel) of the projection optical system 4. As in Figure 1(a), the detection optical system 20 includes a detector 22 and an imaging system 21 including lenses 23 and 24, as well as mirrors 32 and 33 for guiding illumination light to the imaging system 21. Furthermore, the second measurement mark 109 is not formed on the substrate stage 6, but is instead positioned within the optical system 20, between the mirrors 32 and 33, at a position corresponding to the image plane of the projection optical system 4.

[0096] As described in the first embodiment, the detection unit 22 can measure the amount of change in focus and alignment without driving the substrate stage 6. In this embodiment, the detection optical system 20 including the detection unit 20 can measure the amount of change in focus and alignment without moving it in the optical axis direction while it is fixed to the projection optical system 4. By utilizing this feature, illumination light having an optical path slightly outside the illumination light (exposure light) that irradiates the substrate 5 during exposure processing is guided to the detection unit 22 of the detection optical system 20, the amount of change in focus and alignment of the projection optical system 4 can be constantly measured during exposure. This allows the calibration operation to be performed without waiting for measurements, thereby minimizing the decline in productivity.

[0097] 15(b) shows that the first measurement mark 115 is placed not on the mask 2 or mask stage 3, but in an optical system 40 above the projection optical system 4. In order to illuminate the first measurement mark 115, the optical system 40 includes elements such as a light source 41, a lens 42, and a mirror 43, and supplies illumination light that is separate from the illumination light used for the exposure process.

[0098] An advantage of this embodiment is that it is possible to calibrate by separating each part. For example, in comparison with the first embodiment, in the exposure apparatus 100 with the configuration shown in FIG. 15(b), it is possible to determine the imaging performance and deformation of only the projection optical system 4. Also, in comparison with the first embodiment, in the exposure apparatus 100 with the configuration shown in FIG. 15(a), it is possible to determine the drive performance and deformation of the substrate stage 6 by evaluating the difference in measurement values. In this way, it is advantageous compared to the first embodiment in that it is possible to grasp performance by separating each part.

[0099] Furthermore, in the change amount measurement process in this embodiment, there is no need to drive the substrate stage 6 in the Z-axis direction when determining the focus change amount. Furthermore, the optical system 20 including the detection unit 22 does not move in the optical axis direction. Therefore, in this embodiment as well, the time required for operations such as moving the substrate stage 6 in the Z-axis direction (focus calibration operation) during calibration is reduced, and a decrease in productivity of the exposure apparatus 100 can be suppressed.

[0100] <Embodiments of manufacturing methods of articles> The method for manufacturing an article according to an embodiment of the present invention is suitable for manufacturing, for example, flat panel displays (FPDs). The method for manufacturing an article according to this embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate using the above-described exposure apparatus (a step of exposing the substrate), and a step of developing the substrate on which the latent image pattern has been formed in this step. Furthermore, this manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing an article according to this embodiment is advantageous over conventional methods in at least one of the performance, quality, productivity, and production costs of the article.

[0101] Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0102] 2. Mask 4 Projection optical system 5. Substrate 7 Control Unit 22 Detection unit 100 Exposure device 109 Second Measurement Mark 115 First Timing Mark

Claims

1. a projection optical system that projects a mask pattern onto a substrate; a detection optical system including a detection unit that detects a light intensity distribution of illumination light that has passed through a first measurement mark arranged on an object plane of the projection optical system, the projection optical system, and a second measurement mark arranged on an image plane of the projection optical system; a control unit for controlling a relative position between the mask and the substrate, the detection optical system is an optical system that is arranged so that an image forming surface on which the illumination light is imaged is inclined with respect to a light receiving surface of the detection unit, and that has a curvature of field; The exposure apparatus is characterized in that the control unit controls the relative position in the optical axis direction of the projection optical system based on the amount of change in the light quantity distribution detected by the detection unit.

2. 2. The exposure apparatus according to claim 1, wherein the control unit controls the relative position in a direction perpendicular to the optical axis direction based on the light amount distribution.

3. 3. The exposure apparatus according to claim 1, wherein the control unit controls the relative position based on a change in a peak position of an envelope of the light quantity distribution.

4. 4. An exposure apparatus according to claim 1, wherein the control unit determines a best focus position based on a light intensity distribution detected by the detection optical system while moving the second measurement mark in the optical axis direction.

5. 5. An exposure apparatus according to claim 1, wherein the first measurement marks include at least two measurement marks.

6. 6. An exposure apparatus according to claim 1, wherein the object plane is a plane on which a pattern of the mask is formed.

7. 7. An exposure apparatus according to claim 1, wherein the first measurement mark is formed on the mask.

8. a mask stage for holding the mask; 7. An exposure apparatus according to claim 1, wherein the first measurement mark is formed on the mask stage.

9. 6. An exposure apparatus according to claim 1, wherein the first measurement mark is arranged on a surface different from the surface on which the pattern of the mask is formed, and is illuminated by illumination light different from the illumination light used during the exposure process.

10. 10. The exposure apparatus according to claim 1, wherein the image plane is a surface on the substrate when the substrate is placed thereon.

11. a substrate stage for holding the substrate; 10. An exposure apparatus according to claim 1, wherein the second measurement mark is formed on the substrate stage.

12. a substrate stage for holding the substrate; 10. An exposure apparatus according to claim 1, wherein the second measurement mark is arranged on a surface different from the upper surface of the substrate stage and is illuminated by illumination light different from the illumination light used during the exposure process.

13. An exposure apparatus according to any one of claims 1 to 12, characterized in that the control unit stores table data indicating a correspondence between the light quantity distribution detected by the detection unit and the relative position in the optical axis direction, and corrects the relative position in the optical axis direction using the table data.

14. 14. The exposure apparatus according to claim 1, wherein the detection optical system is arranged on a substrate stage that holds the substrate.

15. 14. The exposure apparatus according to claim 1, wherein the detection optical system is arranged in the projection optical system.

16. 16. An exposure apparatus according to claim 1, wherein the detection optical system has a line sensor that receives the illumination light.

17. A projection optical system for projecting a mask pattern onto a substrate; a detection optical system including a detection unit that detects a light intensity distribution of illumination light that has passed through a first measurement mark arranged on an object plane of the projection optical system, the projection optical system, and a second measurement mark arranged on an image plane of the projection optical system; a control unit for controlling a relative position between the mask and the substrate, the detection optical system is an optical system that is arranged such that an image forming surface on which the illumination light is imaged is inclined with respect to a light receiving surface of the detection unit, the control unit controls the relative position in the optical axis direction of the projection optical system based on the change in the light quantity distribution detected by the detection unit; an exposure apparatus, characterized in that the first measurement mark is arranged on a surface different from the surface on which the pattern of the mask is formed, and is illuminated by illumination light different from illumination light used during exposure processing;

18. A projection optical system for projecting a mask pattern onto a substrate; a detection optical system including a detection unit that detects a light intensity distribution of illumination light that has passed through a first measurement mark arranged on an object plane of the projection optical system, the projection optical system, and a second measurement mark arranged on an image plane of the projection optical system; a control unit for controlling the relative position of the mask and the substrate; a substrate stage for holding the substrate, the detection optical system is an optical system that is arranged such that an image forming surface on which the illumination light is imaged is inclined with respect to a light receiving surface of the detection unit, the control unit controls the relative position in the optical axis direction of the projection optical system based on the change in the light quantity distribution detected by the detection unit; an exposure apparatus, wherein the second measurement mark is arranged on a surface different from the upper surface of the substrate stage and is illuminated by illumination light different from illumination light used during exposure processing;

19. A projection optical system for projecting a mask pattern onto a substrate; a detection optical system including a detection unit that detects a light intensity distribution of illumination light that has passed through a first measurement mark arranged on an object plane of the projection optical system, the projection optical system, and a second measurement mark arranged on an image plane of the projection optical system; a control unit for controlling a relative position between the mask and the substrate, the detection optical system is an optical system that is arranged such that an image forming surface on which the illumination light is imaged is inclined with respect to a light receiving surface of the detection unit, the control unit controls the relative position in the optical axis direction of the projection optical system based on the change in the light quantity distribution detected by the detection unit; An exposure apparatus, wherein the detection optical system is disposed in the projection optical system.

20. An exposure method for performing an exposure process to transfer a mask pattern onto a substrate, comprising: a detection step of detecting, by a detection optical system including a detection unit, illumination light passing through a first measurement mark arranged on an object plane of a projection optical system that projects the pattern of the mask onto the substrate and a second measurement mark arranged on an image plane of the projection optical system; a control step of controlling the relative position of the mask and the substrate; an exposure step of performing the exposure process, the detection optical system is an optical system that is arranged so that an image forming surface on which the illumination light is imaged is inclined with respect to a light receiving surface of the detection unit, and that has a curvature of field; The exposure method is characterized in that the control step controls the relative position in the optical axis direction of the projection optical system based on the amount of change in the light quantity distribution detected in the detection step.

21. exposing a substrate using an exposure apparatus according to any one of claims 1 to 19; developing the exposed substrate; and producing an article from the developed substrate.

Images