Exposure apparatus, exposure method, and article manufacturing method

Abstract

Provided are an exposure apparatus, an exposure method, and an article manufacturing method. The exposure apparatus includes: a first mark having a longitudinal direction in a first direction; and a second mark having a longitudinal direction in a second direction different from the first direction, the first mark and the second mark being arranged on a surface on which a master is arranged; a third mark having a longitudinal direction in the first direction; and a fourth mark having a longitudinal direction in the second direction, the third mark and the fourth mark being arranged on a substrate stage configured to hold a substrate; and a detector configured to detect a first light amount of light that has passed through the first mark and the third mark and a second light amount of light that has passed through the second mark and the fourth mark to obtain light amount information.

Description

Technical Field

[0001] This disclosure relates to an exposure apparatus, an exposure method, and a method for manufacturing an article. Background Technology

[0002] In the manufacturing process of semiconductor devices formed from micropatterns, exposure apparatuses are used to reduce the pattern presented on a template (marker or mask) and project and transfer it onto a substrate (wafer) coated with a photosensitive material (photoresist). To meet the requirements for higher resolution, exposure apparatuses need to improve the consistency (overlap accuracy) between the pattern on the marker and the pattern on the substrate. Exposure apparatuses also need to increase productivity (throughput) while meeting these requirements.

[0003] To improve overlap accuracy, high-precision alignment of the original and the substrate is required. One known method for aligning the original and the substrate involves arranging marks on both the original and substrate sides. These marks consist of an opening (transmitting portion) for transmitting light and a light-blocking portion for blocking light. When the original-side mark is illuminated, light passing through the opening forms an image of the original-side mark on a reference mark (substrate-side mark) disposed on a substrate stage holding the substrate. When the opening of the reference mark changes relative to the image of the original-side mark in the horizontal and focusing directions, the intensity of the light passing through the reference mark changes. Based on information about this change, the relative position of the original and the substrate stage (substrate) can be obtained.

[0004] From a throughput perspective, the exposure apparatus needs to maximize performance, thus requiring the time spent obtaining the relative position of the master and substrate to be minimized. Even for a single section, the relative displacement between the master and substrate exists in two horizontal directions and one focusing direction, i.e., a total of three directions. Furthermore, measurements need to be taken at multiple image heights to determine the magnification component of the projection optics system, the rotational component of the master, etc., and to align the effective patterned area of ​​the master with the predetermined position on the substrate. To obtain the relative position of the master and substrate, multiple multi-axis drives of the substrate stage are unavoidable. In addition, acceleration / deceleration operations occur each time the drive mode is switched.

[0005] To minimize the impact on throughput, Japanese Patent Application Publication No. 2008-53618 and Japanese Patent No. 5457767 disclose techniques for marker arrangement and measurement sequences to efficiently complete measurements using a simple stage drive. For example, Japanese Patent Application Publication No. 2008-53618 discloses a technique for parallel processing of markers arranged at multiple image heights. More specifically, pairs of X-direction measurement markers and Y-direction measurement markers are arranged at the left and right ends of the original image, and the left and right image heights are measured simultaneously, allowing the relative position of the original image and the substrate to be obtained in a short time. According to this technique, the X-direction measurement markers and Y-direction measurement markers corresponding to the left and right image heights are arranged as reference markers serving as substrate-side markers. Japanese Patent No. 5457767 discloses a preprocessing technique for correcting imaging magnification and distortion of a projection optical system before measuring the relative position of the original image and the substrate.

[0006] However, even the technology disclosed in Japanese Patent Application Publication No. 2008-53618 requires two measurements in the horizontal and focusing directions, one in the X and one in the Y directions. If, due to magnification errors and distortions in the projection optics system, the distance between the left and right image heights on the substrate side differs from the design value or changes over time, it cannot be expected that the original side mark and the substrate side mark will completely overlap (have a conjugate imaging relationship). As a result, the contrast decreases due to the intensity change with the movement of the substrate stage, and a decrease in measurement accuracy (reliability) is inevitable.

[0007] Conversely, the technology disclosed in Japanese Patent No. 5457767 can stabilize measurement accuracy, but it further increases preprocessing when two measurements are required in the X and Y directions for each of the horizontal and focusing directions. This contradicts the requirement for higher throughput of the exposure device. Summary of the Invention

[0008] This disclosure provides a technique that facilitates the alignment of the original and the substrate.

[0009] According to a first aspect of this disclosure, an exposure apparatus is provided that projects a pattern of a master onto a substrate via a projection optics system and exposes the substrate. The exposure apparatus includes: a first mark and a second mark, the first mark having a longitudinal direction in a first direction, and the second mark having a longitudinal direction in a second direction different from the first direction, the first mark and the second mark being disposed on a surface on which the master is disposed; a third mark and a fourth mark, the third mark having a longitudinal direction in the first direction, and the fourth mark having a longitudinal direction in the second direction, the third mark and the fourth mark being disposed on a substrate stage configured to hold the substrate; and a detector, which is... The system is configured to detect a first amount of light that has passed through the first and third marks and a second amount of light that has passed through the second and fourth marks to obtain light quantity information; and a controller configured to move the substrate stage upward along the surface holding the substrate in a third direction that is obliquely intersecting the first and second directions, to include a state in which the image of the first mark overlaps with the third mark and a state in which the image of the second mark overlaps with the fourth mark, to obtain light quantity information from the detector regarding the first and second light quantities respectively, and to obtain the relative positions of the first and third marks and the second and fourth marks based on the light quantity information.

[0010] According to a second aspect of this disclosure, an exposure method is provided that projects a pattern of a master onto a substrate via a projection optics system and exposes the substrate. The exposure method includes: obtaining light quantity information by detecting a first light quantity of light that has passed through a first mark and a third mark, and a second light quantity of light that has passed through a second mark and a fourth mark, wherein the first mark is disposed on a surface on which the master is disposed and has a longitudinal direction in a first direction, the third mark is disposed on a substrate stage configured to hold the substrate and has a longitudinal direction in the first direction, the second mark is disposed on the surface and has a longitudinal direction in a second direction different from the first direction, and the fourth mark is disposed on the substrate stage and has a longitudinal direction in the second direction; and obtaining the relative positions of the first mark and the third mark and the second mark and the fourth mark based on the light quantity information, wherein, in obtaining the light quantity information, light quantity information is obtained respectively with respect to the first light quantity and the second light quantity by moving the substrate stage upward along a third direction obliquely intersecting the first and second directions on the surface holding the substrate, to include states in which the image of the first mark overlaps with the third mark and states in which the image of the second mark overlaps with the fourth mark.

[0011] According to a third aspect of this disclosure, a method for manufacturing an article is provided, the method comprising exposing a substrate using the aforementioned exposure apparatus, developing the exposed substrate, and manufacturing an article from the developed substrate.

[0012] Other aspects of this disclosure will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating the construction of an exposure apparatus according to one aspect of the present disclosure.

[0014] Figure 2 This is a diagram showing the structure of the base plate on the substrate side.

[0015] Figure 3 This diagram illustrates the alignment process between the original and the substrate in conventional techniques.

[0016] Figure 4 This diagram illustrates the alignment process between the original and the substrate in conventional techniques.

[0017] Figure 5 This diagram illustrates the alignment process between the original and the substrate in the comparative example.

[0018] Figure 6 This diagram illustrates the alignment process between the original and the substrate in the embodiments.

[0019] Figure 7 This diagram illustrates the alignment process between the original and the substrate in the embodiments.

[0020] Figure 8 This diagram illustrates the alignment process between the original and the substrate in the embodiments.

[0021] Figure 9 This diagram illustrates the alignment process between the original and the substrate in the comparative example.

[0022] Figure 10 This is a graph showing an example of the waveform representing the amount of light detected by the second original measurement system. Detailed Implementation

[0023] The embodiments will now be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the claims. Several features are described in the embodiments, but not all features are necessary, and multiple features can be combined arbitrarily. In the drawings, the same reference numerals denote the same or similar parts, and repeated descriptions thereof will be omitted.

[0024] Figure 1This is a schematic diagram illustrating the construction of an exposure apparatus EXA according to one aspect of the present disclosure. The exposure apparatus EXA is a photolithography apparatus used in the manufacturing process of devices such as semiconductor elements, and exposes a substrate via a master (marker or mask) to form a pattern on the substrate. The exposure apparatus EXA projects the pattern of the master onto the substrate via a projection optics system and transfers it onto the substrate.

[0025] The exposure apparatus EXA includes: a master stage 2 for holding the master image 1, a substrate stage 4 for holding the substrate 3, and an illumination optical system 5 for illuminating the master image 1 held by the master stage 2. The exposure apparatus EXA also includes a projection optical system 6 and a controller 17. The projection optical system 6 projects the pattern (image) of the master image 1 illuminated by the illumination optical system 5 onto the substrate 3 held by the substrate stage 4. The controller 17 provides overall control over the operation of the exposure apparatus EXA.

[0026] In this embodiment, the exposure device EXA is implemented as a scanning exposure device (scanner) that simultaneously scans the original 1 and the substrate 3 along the scanning direction (i.e., by a step-scanning method) to transfer the pattern of the original 1 onto the substrate 3. Note that the exposure device EXA can also be implemented as an exposure device (stepper) that fixes the original 1 (i.e., by a step-repeat method) and transfers the pattern of the original 1 onto the substrate 3.

[0027] In this specification and accompanying drawings, directions are represented in the XYZ coordinate system, where the direction parallel to the surface on which the substrate 3 is disposed is defined as the XY plane. Directions parallel to the X, Y, and Z axes of the XYZ coordinate system are defined as the X direction, Y direction, and Z direction, respectively. Rotations about the X-axis, Y-axis, and Z-axis are defined as θX, θY, and θZ, respectively. The Z direction is aligned with the optical axis of the projection optical system 6, the Y direction is the scanning direction for scanning the original 1 and the substrate 3, and the X direction is the non-scanning direction.

[0028] The illumination optics system 5 uses light with a uniform illuminance distribution to illuminate the predetermined illumination area of ​​the original image 1. The light illuminating the original image 1, i.e., the exposure light, includes, for example, i-rays generated from a mercury lamp, and short-wavelength ultraviolet light from a KrF excited excimer laser or an ArF excited excimer laser. The exposure light also includes extreme ultraviolet (EUV) rays with wavelengths ranging from a few nanometers (nm) to several hundred nanometers (nm) that can be used to fabricate finer semiconductor elements, etc.

[0029] The original stage 2 is a movable stage used to hold and position the original 1 and the original side reference plate 20. The original stage 2 is configured to be able to move in two dimensions in a plane (i.e., the XY plane) perpendicular to the optical axis of the projection optical system 6 via a drive mechanism including a linear motor, and to be able to rotate in the θZ direction.

[0030] A reflector 7 is mounted on the original plate stage 2. A laser interferometer 9 is mounted opposite the reflector 7 to measure the position of the original plate stage 2 via the reflector 7. The laser interferometer 9 measures the position of the original plate stage 2 (containing the original plate 1 and the original plate-side reference plate 20) in both two-dimensional and rotational directions in real time, and outputs the measurement results to the controller 17. Based on the measurement results of the laser interferometer 9, the controller 17 moves the original plate stage 2 via a drive mechanism, thereby positioning the original plate 1 and the original plate-side reference plate 20 held by the original plate stage 2.

[0031] The original-side reference plate 20 is a replacement component for the original plate 1, configured to enable EXA calibration of the exposure apparatus even when the original plate 1 is not held by the original plate stage 2. The original-side reference plate 20 includes at least one reference mark 201. The reference mark 201 is a mark detected by the second original plate measurement system 14. The reference mark 201 includes a first mark 201A and a second mark 201B. The longitudinal direction of the first mark 201A is a first direction (Y direction), and the longitudinal direction of the second mark 201B is a second direction (X direction) different from (perpendicular to) the first direction. The first mark 201A is typically formed by a plurality of mark groups periodically arranged in the second direction, consisting of an opening (transmitting portion) for transmitting light and a light-blocking portion for blocking light. The second mark 201B is typically formed by a plurality of mark groups periodically arranged in the first direction, consisting of an opening (transmitting portion) for transmitting light and a light-blocking portion for blocking light. In the reference mark 201 (first mark 201A and second mark 201B), the ratio between the width of the opening and the width of the light-shielding portion is, for example, 1:3. Note that the reference mark 201 may not be disposed on the original plate side reference plate 20, but on the original plate 1. In other words, the reference mark 201 is sufficient to be arranged on the surface (position) where the original plate 1 is disposed, that is, on the object plane of the projection optical system 6.

[0032] The projection optical system 6 is an optical system comprising multiple optical elements, and projects the pattern of the original plate 1 or the reference mark 201 of the original plate side reference plate 20 onto the substrate 3 at a predetermined projection magnification. In this embodiment, the projection optical system 6 is a reduction projection system with a projection magnification of less than 1.

[0033] The substrate stage 4 is a movable stage for holding and positioning the substrate 3. The substrate stage 4 includes an θZ tilting stage that holds the substrate 3 via a chuck, an XY stage that supports the θZ tilting stage, and a base that supports the XY stage. The substrate stage 4 is configured to be movable via a drive mechanism 18 including a linear motor or the like.

[0034] A target 8, including a mirror or a grating, is disposed on a substrate stage 4. Measurement units 10 and 12 are disposed opposite to the target 8, each including a laser interferometer or an encoder head, to measure the position of the substrate stage 4 via the target 8. Measurement unit 10 measures the position of the substrate stage 4 (the held substrate 3) in the X, Y, and θZ directions in real time and outputs the measurement results to the controller 17. Measurement unit 12 measures the position of the substrate stage 4 in the Z, θX, and θY directions in real time, and outputs the measurement results to the controller 17. Based on the measurement results of measurement units 10 and 12, the controller 17 moves the substrate stage 4 via a drive mechanism 18, thereby positioning the substrate 3 held by the substrate stage 4.

[0035] The substrate-side reference plate 11 is disposed on at least one corner of the substrate stage 4. The substrate-side reference plate 11 is disposed on the substrate stage 4 at the same height as the surface of the substrate 3. Figure 2 This is a diagram showing the structure of the substrate-side reference plate 11 disposed on the substrate stage 4.

[0036] The substrate-side reference plate 11 includes a reference mark 111 detected by the first original plate measurement system 13, a reference mark 112 detected by the substrate measurement system 16, and a reference mark 113 detected by the second original plate measurement system 14. Several reference marks 111, 112, and 113 can be disposed on the substrate-side reference plate 11, or can form a mark group consisting of several marks. The reference mark 113 includes a third mark 113A and a fourth mark 113B. The longitudinal direction of the third mark 113A is a first direction (Y direction), and the longitudinal direction of the fourth mark 113B is a second direction (X direction) different from the first direction (perpendicular to the first direction). The third mark 113A is typically formed by multiple mark groups periodically arranged in the second direction, consisting of an opening (transmitting portion) for transmitting light and a light-blocking portion for blocking light. The fourth mark 113B is typically formed by multiple mark groups periodically arranged in the first direction, consisting of an opening (transmitting portion) for transmitting light and a light-blocking portion for blocking light. In reference mark 113 (third mark 113A and fourth mark 113B), the distance between the opening and the light-shielding part is the same as the distance between the opening and the light-shielding part of reference mark 201, but the ratio between the width of the opening and the width of the light-shielding part is, for example, 1:4. In this embodiment, it is assumed that the positional relationship (X direction and Y direction) between reference mark 111 or reference mark 113 and reference mark 112 is known.

[0037] In the EXA exposure apparatus, when measurement units 10 and 12 measure the position of the substrate stage 4 via the target 8, higher measurement accuracy can be achieved at a shorter distance traveled by the measurement light from measurement units 10 and 12 through the air, considering the fluctuation of the air's refractive index. Therefore, in order to measure the reference marks 111, 112, and 113 disposed on the substrate-side reference plate 11 with high accuracy, it is preferable to use... Figure 2 The reference plate 11 on the lower left side of the substrate is shown.

[0038] A thermometer 114 is disposed near the substrate-side reference plate 11. In this embodiment, the thermometer 114 is disposed on the substrate stage 4 to measure the ambient temperature of the substrate stage 4.

[0039] The first original plate measuring system 13 is disposed near the original plate stage 2. The first original plate measuring system 13 illuminates the original plate side reference mark (not shown) with light from the same light source that emits exposure light to expose the substrate 3. The first original plate measuring system 13 also illuminates the substrate side reference mark 111 via the projection optics system 6. The first original plate measuring system 13 includes a photoelectric conversion element (e.g., a CCD camera) that accumulates (detects) the light (reflected light) from the original plate side reference mark and the substrate side reference mark 111, and performs photoelectric conversion on the light. Based on the signal from the photoelectric conversion element, the first original plate measuring system 13 measures the position of these reference marks. The position of the reference marks measured by the first original plate measuring system 13 is used to align the original plate 1 and the substrate 3. For example, the relative position (X, Y, and Z directions) of the original plate 1 and the substrate 3 can be aligned by aligning the position and focus of the original plate side reference mark and the substrate side reference mark 111.

[0040] In addition to the first original measurement system 13, at least one second original measurement system 14 is disposed below the substrate-side reference plate 11. The second original measurement system 14 is a transmission-type measurement system that includes a detector formed by a light intensity sensor or an image sensor, and detects light that has passed through the reference mark 113 (the openings of the third mark 113A and the fourth mark 113B) on the substrate-side reference plate 11. The second original measurement system 14 illuminates the original-side reference mark 201 with light from the same light source that emits exposure light to expose the substrate 3. The second original measurement system 14 also illuminates the substrate-side reference mark 113 via a projection optics system 6. The light passing through the original-side reference mark 201 forms an image on the substrate-side reference plate 11 via the projection optics system 6, and the light passing through the substrate-side reference mark 113 is detected by the second original measurement system 14. At this time, the substrate stage 4 moves in the X, Y, and Z directions. Based on the information obtained from the change in the amount of light that has passed through the substrate-side reference mark 113, the position and focus of the original side reference plate 20 (or the original 1) and the substrate-side reference plate 11 can be aligned.

[0041] In this way, in the EXA exposure apparatus, either the first master plate measurement system 13 or the second master plate measurement system 14 can be used to align the relative positions of the master plate stage 2 (master plate 1) and the substrate stage 4 (substrate 3). In this embodiment, the alignment using the second master plate measurement system 14, which is a transmission-type master plate measurement system, will be mainly described below.

[0042] The focus measurement system 15 includes an illumination system that illuminates the substrate 3 held by the substrate stage 4 with oblique incident light and a detection system that detects the light reflected from the substrate 3. The focus measurement system 15 measures the focus and outputs the measurement result to the controller 17. Based on the measurement result of the focus measurement system 15, the controller 17 controls the position (focus position) of the substrate 3 held by the substrate stage 4 in the Z direction and its tilt angle by moving the substrate stage 4 in the Z direction via the drive mechanism 18.

[0043] The substrate measurement system 16 includes an illumination system and a detection system. The illumination system illuminates the alignment mark 19 on the substrate 3 and the reference mark 112 on the substrate-side reference plate 11 with light. The detection system detects the light reflected by the alignment mark 19 or the reference mark 112. The substrate measurement system 16 measures the position of the alignment mark 19 or the reference mark 112 and outputs the measurement result to the controller 17. Based on the measurement result of the substrate measurement system 16, the controller 17 controls the position of the substrate 3 held by the substrate stage 4 in the X and Y directions by moving the substrate stage 4 in the X and Y directions via the drive mechanism 18.

[0044] The controller 17 is composed of a computer (information processing device) including a CPU, memory, etc., and comprehensively controls the various units of the exposure apparatus EXA according to the program stored in the memory, etc. The controller 17 controls the exposure process (exposure method) to project the pattern of the original plate 1 onto the substrate 3 via the projection optical system 6, and expose the substrate 3, that is, to transfer the pattern of the original plate 1 onto the substrate 3. The exposure process includes an alignment process for the original plate 1 and the substrate 3, which is a step of aligning the original plate 1 held by the original plate stage 2 and the substrate 3 held by the substrate stage 4.

[0045] The alignment process in the EXA exposure apparatus will be explained below. First, refer to... Figure 3 and Figure 4 Explain the alignment process in traditional techniques.

[0046] Figure 3 This diagram illustrates the state in which light that has passed through the reference mark 201 of the original side reference plate 20 during the alignment process forms an image on the reference mark 113 of the substrate side reference plate 11 (i.e., the state in which the image of the reference mark 201 is formed on the reference mark 113). Figure 3In the second original measurement system 14, the detector of the second original measurement system 14, more specifically, the detection surface of the light intensity sensor is represented by a square area, and the third mark 113A and the fourth mark 113B of the reference mark 113 are each represented by a white rectangular area. In other words, the white rectangular area represents the opening of the third mark 113A and the fourth mark 113B, while the black area represents the light-blocking part of the third mark 113A and the fourth mark 113B. As an image of the reference mark 201, the second mark image 201BI of the second mark 201B is represented by a shaded rectangular area.

[0047] Figure 3 Only the second mark image 201BI of the second mark 201B is shown. The longitudinal direction of the second mark 201B is the Y direction (first direction) perpendicular to the X direction (second direction) because only the second mark 201B in the reference mark 201 is illuminated. Typically, the illumination optics system 5 of the exposure apparatus EXA includes a mask mechanism (not shown) that restricts and guides the exposure light to a specific area of ​​the original plate 1 or the original-side reference plate 20 (i.e., only illuminating that specific area). By using the mask mechanism, it is possible to achieve... Figure 3 The state shown is where only the second marker image 201BI is formed on the reference marker 113 (fourth marker 113B).

[0048] exist Figure 3 In the shown state, the substrate stage 4 moves in the X direction indicated by the arrow. In this case, when the light-shielding portion of the second mark image 201BI of the second mark 201B overlaps with the light-shielding portion of the fourth mark 113B of the reference mark 113, the amount of light detected by the second original plate measurement system 14 becomes minimum. Conversely, when the openings of the second mark image 201BI and the fourth mark 113B overlap, the amount of light detected by the second original plate measurement system 14 becomes maximum. This is because the light detected by the second original plate measurement system 14 is light that passes through both the opening of the second mark 201B and the opening of the fourth mark 113B. In this embodiment, the position of the substrate stage 4 where the amount of light detected by the second original plate measurement system 14 becomes maximum is set as a reference in the X direction for the relative position (relative displacement) between the original plate stage 2 (original plate 1) and the substrate stage 4 (substrate 3). Note that the maximum relative displacement between the original stage 2 and the substrate stage 4 in the X direction is much smaller than half the product of the periodic alternating spacing of the openings and light-shielding portions of the second mark 201B on the original side and the fourth mark 113B on the substrate side and the projection magnification of the projection optical system 6.

[0049] and Figure 3 similar, Figure 4This illustrates the state in which light that has passed through the reference mark 201 of the original side reference plate 20 forms an image on the reference mark 113 of the substrate side reference plate 11, that is, the image of the reference mark 201 is formed on the reference mark 113. Figure 4 In this process, by using a mask mechanism, a first mark image 201AI of the first mark 201A is formed only on the reference mark 113 (third mark 113A).

[0050] exist Figure 4 In the shown state, the substrate stage 4 moves along the Y direction indicated by the arrow. In this case, when the light-shielding portion of the first mark image 201AI of the first mark 201A overlaps with the light-shielding portion of the third mark 113A of the reference mark 113, the amount of light detected by the second original plate measurement system 14 becomes minimum. Conversely, when the openings of the first mark image 201AI and the third mark 113A overlap, the amount of light detected by the second original plate measurement system 14 becomes maximum. This is because the light detected by the second original plate measurement system 14 is light that passes through both the opening of the first mark 201A and the opening of the third mark 113A. In this embodiment, the position of the substrate stage 4 where the amount of light detected by the second original plate measurement system 14 is maximum is set as a reference in the Y direction of the relative position (relative displacement) between the original plate stage 2 (original plate 1) and the substrate stage 4 (substrate 3). Note that the maximum relative displacement between the original stage 2 and the substrate stage 4 in the Y direction is much smaller than half the product of the periodic alternating spacing of the openings and light-shielding portions of the first mark 201A on the original side and the third mark 113A on the substrate side and the projection magnification of the projection optical system 6.

[0051] After obtaining the relative positions of the original stage 2 and the substrate stage 4 in the X and Y directions in this manner, the substrate stage 4 is moved so that the reference mark 201 and the reference mark 113 overlap each other, thereby aligning the original 1 and the substrate 3. In this state, the substrate stage 4 is moved in the Z direction, and the image of the original side reference mark 201 becomes the clearest when the substrate-side reference plate 11 is aligned with the focal plane of the projection optical system 6. In other words, the blurred portion of the image of the reference mark 201 is not blocked by the light-shielding portion of the substrate-side reference mark 113, but reaches the second original measurement system 14, and therefore, the amount of light detected by the second original measurement system 14 is the maximum. In this embodiment, the position of the substrate stage 4 where the amount of light detected by the second original measurement system 14 is the maximum is set as the reference for the relative position (relative displacement) of the original stage 2 (original 1) and the substrate stage 4 (substrate 3) in the Z direction.

[0052] Figure 3 and Figure 4Only one second original measurement system 14 is shown. However, as described above, multiple second original measurement systems 14 may be arranged below the substrate-side reference plate 11. For example, reference marks 201 may be arranged on the left and right sides of the original-side reference plate 20, and the second original measurement systems 14 may be arranged on the left and right sides respectively corresponding to them. In this case, as described in the conventional art, the substrate stage 4 moves once in the X direction to obtain a waveform representing the change in the left and right (two) light amounts, i.e., light amount information. Based on this light amount information, the error of the projection magnification of the projection optical system 6 can be obtained. If the relative deviation between the original stage 2 and the substrate stage 4 in the Z direction can be obtained for the left and right (two) image heights, information about the tilt of the substrate stage 4 relative to the image plane of the projection optical system 6 can be obtained, and thus the tilt of the substrate stage 4 can be corrected.

[0053] In conventional alignment processes, two movements of the substrate stage 4 in the X and Y directions (stage driving) and the switching of the mask mechanism are necessary in the horizontal direction. In actual exposure processes, sometimes only the average of the focus information obtained in the X direction and the focus information obtained in the Y direction (average focus information) is needed. Even in this case, the necessity of two stage drives in the Z direction significantly impacts the throughput of the exposure apparatus EXA. To further improve the throughput of the exposure apparatus EXA, it is necessary to improve the efficiency of the alignment process (parallelization of processing).

[0054] As a method to improve alignment processing efficiency, such as Figure 5 As shown, it is conceivable to move the substrate stage 4 in an inclined direction (third direction) that intersects the Y direction (first direction) and the X direction (second direction) by using two second original measurement systems 14A and 14B. With a single stage drive, light quantity information about the X direction and light quantity information about the Y direction can be obtained simultaneously. Note that the inclined direction in which the substrate stage 4 moves is, for example, a direction that intersects the X and Y directions at a 45° angle (hereinafter also referred to as the "45° direction"). Figure 5 This diagram illustrates the alignment process between the original 1 and the substrate 3 in the comparative example.

[0055] exist Figure 5 In the comparative example shown, the increased number of the second original measurement system 14 (i.e., the light quantity sensor) increases cost and complicates the wiring and processing system. Furthermore, calibration work is required to account for individual differences in the sensitivity of the light quantity sensors. The light quantity sensor has a minimum package size in addition to the size of the detection surface. When the light quantity sensors are arranged without interference between these dimensions, the X-marks in the X-direction and the Y-marks in the Y-direction are separated from each other in the reference marks, making them not approximately belonging to the same viewing angle (like height). Therefore, as... Figure 5 The comparison example shown using two second original measurement systems 14A and 14B (two light sensors) is impractical.

[0056] Therefore, this embodiment is based on the premise that there is a second original measurement system 14 (light sensor) for a certain viewpoint, and the control mask mechanism illuminates the reference marks that are arranged close to the X mark and Y mark, that is, illuminates the two marks.

[0057] The following will refer to Figure 6 , Figure 7 and Figure 8 To illustrate the alignment process in this embodiment. More specifically, as... Figure 6 As shown, in the first state, the substrate stage 4 is set to a position where it begins to move in the tilt direction (scan start position). The first state is as follows: the light that has passed through the opening of the first mark 201A (first mark image 201AI) is blocked by the light-shielding part of the third mark 113A, while the light that has passed through the opening of the second mark 201B (second mark image 201BI) passes through the opening of the fourth mark 113B.

[0058] Here, since the relative positions of the original stage 2 (original 1) and the substrate stage 4 (substrate 3) are unknown, alignment is performed. As described above, the ratio between the width of the opening in the reference mark 113 and the width of the light-shielding portion is 1:4, and the width of the opening in the reference mark 113 and the width of the light-shielding portion are on the order of 100 nm or larger. Considering the overlap accuracy required by the EXA exposure apparatus, the measurement accuracy and correction amount are at most about a few nm. In the EXA exposure apparatus, the measurement accuracy of the position of the substrate stage 4 measured by the measurement units 10 and 12 is at most equal to or less than about a few nm. Therefore, as Figure 6 As shown, the scanning start position of the substrate stage 4 can be set to the first state.

[0059] Note that it is conceivable that the substrate stage 4 expands due to the exposure energy, and the distance between the target 8 and the reference mark 113, detected by the measurement units 10 and 12, changes from the design value over time. In this case, the scanning start position of the substrate stage 4 is corrected by multiplying the measurement result of the change in the ambient temperature of the substrate stage 4 (measured by the thermometer 114) by the coefficient of thermal expansion and the distance between the target 8 and the reference mark 113.

[0060] like Figure 7 As shown, the substrate stage 4 is tilted from the direction indicated by the arrow. Figure 6The first state (scan start position) shown moves along the horizontal surface (the surface of the holding substrate 3) to the second state. The second state is as follows: light that has passed through the opening of the first mark 201A (first mark image 201AI) passes through the opening of the third mark 113A, while light that has passed through the opening of the second mark 201B (second mark image 201BI) is blocked by the light-shielding part of the fourth mark 113B. Figure 7 In this process, the number of lines (pattern number) of the light-shielding portions of the first mark image 201AI and the third mark 113A is set to be equal to the number of lines of the light-shielding portions of the second mark image 201BI and the fourth mark 113B. However, the number of lines of the light-shielding portions of the third mark 113A and the fourth mark 113B, as well as their length in the longitudinal direction, can be increased to suppress the influence on the total amount of light detected by the second original measurement system 14 during the period before the substrate stage 4 finishes moving in the tilt direction.

[0061] When the substrate stage 4 moves further along the tilting direction, it returns to its original position. Figure 6 The first state is shown. In this embodiment, during stage driving, the substrate stage 4 experiences a state where the first light intensity is maximized after passing through the first mark 201A and the third mark 113A, and a state where the second light intensity is maximized after passing through the second mark 201B and the fourth mark 113B. Note that the state where the first light intensity is maximized is the state where the second light intensity is minimized, and vice versa. In the exposure apparatus EXA, even during stage driving, the measurement units 10 and 12 measure the position of the substrate stage 4. By determining the position of the substrate stage 4 where the first and second light intensities are maximized, the relative positions of the original stage 2 (original 1) and the substrate stage 4 (substrate 3) in the X and Y directions can be obtained in one stage drive. In other words, the relative positions of the first mark 201A and the third mark 113A, and the relative positions of the second mark 201B and the fourth mark 113B, can be obtained based on the light intensity information about the first and second light intensities obtained by the second original measurement system 14, respectively.

[0062] In this embodiment, reference marks 201 can also be arranged on the left and right sides of the original side reference plate 20, and corresponding second original plate measurement systems 14 can be arranged on the left and right sides respectively. In this case, as described above, the substrate stage 4 can move simultaneously in the tilting direction of the left and right reference marks 201, so that the left and right second original plate measurement systems 14 can obtain light quantity information about the X and Y directions respectively through a single stage drive.

[0063] Regarding measurement accuracy, for example, it is preferable to perform preprocessing to correct imaging characteristics before alignment, such as predicting the magnification and distortion of the projection optical system 6 from information about the energy applied in the exposure process. More specifically, the projection optical system 6 is adjusted such that the positional relationship between the first mark 201A and the third mark 113A via the projection optical system 6 and the positional relationship between the second mark 201B and the fourth mark 113B via the projection optical system 6 satisfy a predetermined positional relationship.

[0064] In this embodiment, after obtaining the relative positions of the master stage 2 and the substrate stage 4 in the X and Y directions, the master 1 and the substrate 3 can be aligned by moving the substrate stage 4 so that the reference mark 201 and the reference mark 113 overlap. In this state, the substrate stage 4 moves in the Z direction to obtain average focus information. Therefore, in this embodiment, it is not necessary to perform stage driving twice in the X and Y directions, and the throughput of the exposure apparatus EXA can be further improved. In some cases, focus information about the X direction and focus information about the Y direction may be required separately. In this case, with the first mark image 201AI or the second mark image 201BI located in the light-shielding part of the reference mark 113, the substrate stage 4 moves in the Z direction. However, the amount of light detected by the second master measurement system 14 (light intensity sensor) becomes twice the amount of light measured in the X and Y directions. Therefore, as Figure 8 As shown, the substrate stage 4 can be moved so that half of the first mark image 201AI or the second mark image 201BI is located at the opening of the reference mark 113.

[0065] In this manner, according to this embodiment, during the alignment process, the substrate stage 4 is moved in an inclined direction to include states where the first marker image 201AI overlaps with the third marker 113A and states where the second marker image 201BI overlaps with the fourth marker 113B. The second master plate measurement system 14 can obtain light quantity information regarding the first amount of light that has passed through the first marker 201A and the third marker 113A, and light quantity information regarding the second amount of light that has passed through the second marker 201B and the fourth marker 113B. Based on this light quantity information, the relative positions of the first marker 201A and the third marker 113A, and the relative positions of the second marker 201B and the fourth marker 113B, can be obtained. According to this embodiment, while reducing the time spent on the alignment process (stage drive), the master plate 1 and the substrate 3 can be aligned with high precision, which helps to improve the overlap accuracy and throughput in the EXA exposure apparatus.

[0066] In this embodiment, during the alignment process, the scan start position where the substrate stage 4 begins to move in the tilt direction is set to a first state, but it is not limited to this. For example, the scan start position of the substrate stage 4 can be set to a second state, and the substrate stage 4 can move in the tilt direction to reach the first state. In this way, the scan start position of the substrate stage 4 is not limited, and the substrate stage 4 is sufficient to move in the tilt direction to include both the first and second states in the alignment process. An example of a stage drive that moves the substrate stage 4 in the tilt direction is a stage drive that starts the movement of the substrate stage 4 in the tilt direction from the first state and ends the movement of the substrate stage 4 in the tilt direction from the second state.

[0067] Figure 9 The stage drive shown can be conceived as another form of stage drive, provided that a second original measurement system 14 (light sensor) exists for a given viewing angle. For example... Figure 9 As shown, the stage driver includes a state from the first state ( Figure 6 The system performs a first stage drive to move the substrate stage 4 along the Y direction, and a second stage drive to move the substrate stage 4 along the X direction after the first stage drive has ended. This stage drive includes braking, in which the substrate stage 4 is accelerated in the X direction, decelerated after reaching a predetermined speed, and then accelerated in the Y direction, decelerated after reaching a predetermined speed. This is essentially equivalent to performing two stage drives. Note that even if the substrate stage 4 moves continuously while maintaining a predetermined speed to draw a circular track, it is necessary to increase the speed in the Y direction while decreasing the speed in the X direction. Therefore, the light quantity information obtained by the second original measurement system 14 cannot be sampled at equal intervals, and the light quantity information becomes either sparse or dense. This undesirably complicates both the stage drive and the light quantity information. Figure 9 This diagram illustrates the alignment process between the original 1 and the substrate 3, which serve as a comparative example.

[0068] The technique used for stabilizing the alignment process in this embodiment will be explained. This technique is primarily used to ensure the high reliability of measurements required for alignment processing in the EXA exposure apparatus.

[0069] For example, in the alignment process, the stage drive for moving the substrate stage 4 in the tilt direction is not limited to being performed once, but can be performed multiple times, as described above. Performing the stage drive multiple times can average out the unavoidable variations in the measurement reproducibility range during the alignment process.

[0070] In this embodiment, as an example of stage driving, it is preferable to achieve the first state or the second state with high precision at the scanning start position of the substrate stage 4 for the following two reasons.

[0071] First, if the scanning start position of the substrate stage 4 deviates significantly, both the light that has passed through the first mark 201A and the third mark 113A and the light that has passed through the second mark 201B and the fourth mark 113B will reach the second original measurement system 14. When the light quantity information obtained by the second original measurement system 14 is a waveform representing the light quantity, the waveforms corresponding to each beam are mixed, making it difficult to separate the position information in the X direction and the position information in the Y direction.

[0072] The second reason is to suppress the shift in light intensity peak caused by waveform proximity effect. Figure 10 It is a graph showing an example of waveforms, each waveform being obtained as light quantity information by the second original measurement system 14, and representing the light quantity detected by the second original measurement system 14. Figure 10 The composite waveform WV1 is shown as a waveform obtained by moving the substrate stage 4 in the tilt direction. Figure 10 The diagram also shows an X-waveform WV2 obtained by moving the substrate stage 4 in the X direction and a Y-waveform WV3 obtained by moving the substrate stage 4 in the Y direction. The composite waveform WV1 is obtained by combining the X-waveform WV2 and the Y-waveform WV3, and represents the relative positions of the original stage 2 (original 1) and the substrate stage 4 (substrate 3) in the X and Y directions. Due to the waveform proximity effect, the center of gravity of a portion of the composite waveform WV1 corresponding to the X-waveform WV2 is noticeably shifted to the right. When the X-waveform WV2 and the Y-waveform WV3 are added, although numerical calculations and theory suggest otherwise... Figure 10 This is evident, but the peak value of the portion corresponding to the X waveform WV2 also shifts to the right. This shift is caused by a large deviation in the scan start position of the substrate stage 4. If the X waveform WV2 is located at the center of the portion of the composite waveform WV1 corresponding to the Y waveform WV3, the left-right symmetry of the composite waveform WV1 is almost unaffected, and the peak position hardly shifts. Note that the imbalance in left-right symmetry caused by a shift of approximately a few nm in the measured target can be ignored. From these points of view, determining (correcting) the scan start position of the substrate stage 4 based on the measurement results of the thermometer 114 is very effective, as described above.

[0073] Through calculation, the synthesized waveform WV1 can also be divided into X waveform WV2 and Y waveform WV3. For example, as shown in the reference... Figure 9The aforementioned pre-execution of a stage drive including a first stage drive and a second stage drive obtains and stores a function f(x) representing the X waveform and a function g(x) representing the Y waveform, where x is a variable representing the moving distance (position) of the substrate stage 4. Note that functions f(x) and g(x) can be logically calculated using optical simulation with design values. If each of functions f(x) and g(x) is a unimodal function with peaks at positions a and b, then a and b can be obtained by fitting the sum of functions f(x) and g(x), as given in equation (1):

[0074] Synthetic waveform (x) = f(xa) + g(xb)...(1).

[0075] If we assume the x-symmetry of functions f(x) and g(x), then the odd-order components containing linear components when fitting the synthesized waveform (x) into a polynomial can be considered as errors caused by waveform proximity effects, and the peak can be obtained by removing the odd-order components. For example, let T(x) be near the peak in the direction of information extracted from the synthesized waveform (x), the peak can be obtained by fitting T(x) into the finite-dimensional polynomial given by equation (2) and removing the odd-order components:

[0076] T(x)=a(x-x0)4+b(x-x0)3+c(x-x0)2+d(x-x0)+e...(2).

[0077] In this way, the relative positions of the original stage 2 (original stage 1) and the substrate stage 4 (substrate 3) can be obtained based on the waveform obtained by removing asymmetric components from the synthetic waveform WV1, or by fitting the sum of a function representing the X waveform and a function representing the Y waveform.

[0078] The article manufacturing method according to embodiments of this disclosure is suitable for manufacturing articles such as semiconductor devices, liquid crystal display devices, flat panel displays, or MEMS. The manufacturing method includes a step of exposing a substrate to which a photosensitive material is applied using the aforementioned exposure apparatus EXA (exposure process), and a step of developing the exposed photosensitive material. Additionally, using the pattern of the developed photosensitive material as a mask, etching, ion implantation, and other processes are performed on the substrate to form a circuit pattern. By repeating exposure, development, etching, and other steps, a multilayered circuit pattern is formed on the substrate. In post-processing, the substrate carrying the circuit pattern is cut (processed), and chip mounting, bonding, and inspection steps are performed. The manufacturing method may also include other known steps (oxidation, deposition, vapor deposition, doping, planarization, photoresist removal, etc.). The article manufacturing method according to this embodiment is superior to conventional methods in at least one aspect of article performance, quality, productivity, and production cost.

[0079] Although this disclosure has been described with reference to exemplary embodiments, it should be understood that this disclosure is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such variations and equivalent structures and functions.

Claims

1. An exposure apparatus that projects a pattern of a master image onto a substrate via a projection optics system and exposes the substrate, the exposure apparatus comprising: A first mark and a second mark, the first mark having a longitudinal direction in a first direction, and the second mark having a longitudinal direction in a second direction different from the first direction, the first mark and the second mark being arranged on the surface on which the original is arranged; A third mark and a fourth mark, the third mark having a longitudinal direction in the first direction and the fourth mark having a longitudinal direction in the second direction, the third mark and the fourth mark being arranged on a substrate stage configured to hold the substrate; A detector is configured to detect a first amount of light that has passed through the first and third markers and a second amount of light that has passed through the second and fourth markers to obtain light quantity information; as well as The controller is configured to move the substrate stage upward along the surface holding the substrate via a third direction that intersects the first and second directions at an angle, to include a state in which the image of the first mark overlaps with the third mark and a state in which the image of the second mark overlaps with the fourth mark, by the detector to obtain light quantity information with respect to the first light quantity and the second light quantity, respectively, and to obtain the relative positions of the first mark and the third mark and the second mark and the fourth mark based on the light quantity information.

2. The exposure apparatus according to claim 1, wherein, The first mark and the third mark have a structure in which openings and light-blocking portions are periodically arranged in the second direction. The second mark and the fourth mark have a structure in which openings and light-blocking portions are periodically arranged in the first direction, and The controller causes the substrate stage to move upward on the third party, holding the surface of the substrate, to include a first state in which light that has passed through the opening of the first mark is blocked by the light-shielding part of the third mark, and light that has passed through the opening of the second mark passes through the opening of the fourth mark.

3. The exposure apparatus according to claim 2, wherein, The controller causes the substrate stage to move upward along the surface holding the substrate in the third party to include a second state in which light that has passed through the opening of the first mark passes through the opening of the third mark, and light that has passed through the opening of the second mark is blocked by the light-shielding part of the fourth mark.

4. The exposure apparatus according to claim 3, wherein, The controller starts the movement of the substrate stage in the third direction from the first state and ends the movement of the substrate stage in the third direction in the second state.

5. The exposure apparatus according to claim 1, wherein, The controller causes the substrate stage to move upward along the surface holding the substrate in the third party, including a state where the first light intensity becomes maximum and the second light intensity becomes minimum, and a state where the first light intensity becomes minimum and the second light intensity becomes maximum.

6. The exposure apparatus according to claim 1, wherein, The projection optics system is adjusted to set the positional relationship between the first mark and the third mark, and the positional relationship between the second mark and the fourth mark, to satisfy a predetermined positional relationship.

7. The exposure apparatus of claim 1, further comprising a measurement unit configured to measure the position of the substrate stage. in, The controller controls the movement of the substrate stage in the third direction based on the measurement results of the measuring unit.

8. The exposure apparatus of claim 7, further comprising a thermometer configured to measure the ambient temperature of the substrate stage. in, The controller corrects the position of the substrate stage based on the measurement results of the thermometer, and the substrate stage moves upward from the position on the third party.

9. The exposure apparatus according to claim 1, wherein, The detector obtains a synthesized waveform, obtained by synthesizing a waveform representing the first light quantity and a waveform representing the second light quantity, as the light quantity information. The controller obtains the relative positions of the first marker and the third marker, as well as the relative positions of the second marker and the fourth marker, based on the waveform obtained by removing asymmetric components from the synthesized waveform.

10. The exposure apparatus according to claim 1, wherein, The detector obtains a synthesized waveform as the light quantity information by synthesizing a first waveform representing the first light quantity and a second waveform representing the second light quantity. The controller obtains the relative positions of the first marker and the third marker, and the relative positions of the second marker and the fourth marker, based on the waveform obtained by fitting the synthesized waveform to the sum of a function representing the first waveform and a function representing the second waveform.

11. The exposure apparatus according to claim 1, wherein, The detector includes a light intensity sensor configured to detect the first light intensity and the second light intensity.

12. The exposure apparatus according to claim 1, wherein, The detector includes a light intensity sensor configured to detect the first light intensity and a light intensity sensor configured to detect the second light intensity.

13. An exposure method comprising projecting a pattern of an original onto a substrate via a projection optics system and exposing the substrate, the exposure method comprising: Light quantity information is obtained by detecting a first light quantity that has passed through a first mark and a third mark, and a second light quantity that has passed through a second mark and a fourth mark. The first mark is disposed on the surface on which the original is disposed and has a longitudinal direction in a first direction. The third mark is disposed on a substrate stage configured to hold the substrate and has a longitudinal direction in the first direction. The second mark is disposed on the surface and has a longitudinal direction in a second direction different from the first direction. The fourth mark is disposed on the substrate stage and has a longitudinal direction in the second direction. as well as Based on the light intensity information, the relative positions of the first marker and the third marker, as well as the relative positions of the second marker and the fourth marker, are obtained. In obtaining the light quantity information, the substrate stage is moved upward along a third direction that holds the surface of the substrate at an angle intersecting the first and second directions, to include states where the image of the first mark overlaps with the third mark and states where the image of the second mark overlaps with the fourth mark, thereby obtaining light quantity information about the first light quantity and the second light quantity, respectively.

14. A method for manufacturing an article, comprising: The substrate is exposed using the exposure apparatus as defined in claim 1; The exposed substrate is then developed; as well as Articles are manufactured from the developed substrate.

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