Automatic focusing device, exposure device, photolithography device and exposure method

Abstract

The present invention provides an automatic focusing device, an exposure device, a photolithography device, and an exposure method. The automatic focusing device includes a motion unit, a film stage, a displacement sensor detection device, and a control system. The film stage is disposed on the motion unit and is configured to carry a substrate. The motion unit is configured to drive the film stage to move up and down in a vertical direction and to rotate along the axial direction of the film stage. The displacement sensor detection device is disposed below the substrate on the film stage and is configured to detect the amount of warping of the substrate. The control system is configured to control the motion unit to drive the film stage to move up and down in a vertical direction based on the amount of warping of the substrate, thereby automatically focusing the substrate during the exposure process. The automatic focusing device provided by the present invention can ensure that the exposure surface of a large warped film is kept as closely aligned as possible with the focal plane of the projection objective lens during the exposure process, thereby achieving optimal exposure performance.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processing and manufacturing, and in particular to an automatic focusing device, an exposure device, a photolithography device and an exposure method. Background Art

[0002] The photolithography apparatus is a key component in integrated circuit manufacturing. Its function is to sequentially image different mask patterns onto a substrate (such as a semiconductor silicon wafer or LCD panel) at precisely aligned positions. However, this alignment varies due to the physical and chemical changes that successive patterns undergo. Therefore, an alignment system is required to ensure that the alignment of the corresponding mask on the silicon wafer is precisely achieved each time. As the number of electronic components per unit surface area of a substrate increases and their size becomes smaller and smaller, the precision requirements for integrated circuits are increasing. Therefore, the position of each mask image on the substrate must be increasingly accurately fixed, placing increasing demands on the alignment accuracy during photolithography.

[0003] In the existing technology, in a scanning lithography system, in order for the projection objective to clearly project the mask pattern onto the workpiece, it is necessary to measure whether the exposure surface of the workpiece coincides with the focal plane of the projection objective. Therefore, a focusing and leveling sensor system is usually used to measure the vertical position of the exposure surface of the workpiece, and a focusing and leveling device is used to support the stage for movement so that the exposure surface of the workpiece coincides with the focal plane of the projection objective, thereby achieving a focusing operation.

[0004] However, with the development of the semiconductor industry, the types of silicon wafers are increasing. In recent years, the emergence of warped wafers has put new demands on focusing devices. Warped wafers refer to substrates that are uneven, including situations where the cross-section of the entire wafer is bow-shaped, bowl-shaped, or uneven in various places. Because the edges of warped wafers, especially those with large warps, are not on the same horizontal plane, the optimal exposure surface at each edge of the large warped wafer is not fixed. If focusing is performed on a large warped wafer using conventional focusing and leveling methods in the prior art, the exposure surface of some parts of the surface may coincide with the focal plane of the projection objective lens, but the exposure surface of other parts to be exposed may deviate from the focal plane of the projection objective lens. Exposure in this manner cannot achieve optimal results, and the exposure performance of the substrate cannot be guaranteed.

[0005] Therefore, there is an urgent need for a focusing solution for large-warp films that can keep the exposure surface of the large-warp film as closely aligned with the focal plane of the projection objective lens as possible during the exposure process to achieve optimal exposure performance. Summary of the Invention

[0006] The purpose of the present invention is to provide an automatic focusing device, an exposure device, a photolithography device and an exposure method, which can solve the problem in the prior art that there is no suitable solution for exposing the edges of large warped silicon wafers so that the exposure surface of the large warped wafer can be kept as consistent as possible with the focal plane of the projection objective during the exposure process to achieve optimal exposure performance.

[0007] In order to solve the above technical problems, the present invention provides an automatic focusing device for automatically focusing the substrate during the exposure process, comprising a motion unit, a wafer stage, a displacement sensor detection device and a control system; the wafer stage is arranged on the motion unit, and the wafer stage is configured to carry the substrate; the motion unit is configured to drive the wafer stage to move up and down in the vertical direction, and to rotate along the axial direction of the wafer stage; the displacement sensor detection device is arranged below the substrate on the wafer stage, and is configured to collect the warping amount of the substrate; the control system is configured to control the motion unit to drive the wafer stage to move up and down in the vertical direction according to the warping amount of the substrate, so as to automatically focus the substrate during the exposure process.

[0008] Furthermore, the displacement sensor detection device is configured to measure the warping amount of each acquisition point of the substrate during the rotation process according to a set acquisition frequency; the control system is configured to generate a position-warping amount curve of the substrate based on the position coordinates of each acquisition point on the substrate and the warping amount corresponding to each acquisition point, and control the wafer stage to move up and down in the vertical direction according to the position-warping amount curve and the exposure position of the substrate, so as to automatically focus the substrate during the exposure process.

[0009] Furthermore, the automatic focusing device also includes a visual acquisition system and a transfer bracket; the motion unit is also configured to drive the wafer stage to perform horizontal movement in the horizontal direction; the visual acquisition system is arranged above the substrate on the wafer stage, and the visual acquisition system is configured to collect edge data of the substrate; the transfer bracket is configured to remove the substrate from the wafer stage or place the substrate on the wafer stage; the control system is also configured to obtain the eccentricity of the substrate based on the edge data of the substrate, and control the motion unit to drive the wafer stage to perform horizontal movement in the horizontal direction based on the eccentricity to center the substrate.

[0010] Furthermore, the motion unit includes an X-axis motion mechanism, a Y-axis motion mechanism, a Z-axis motion mechanism and a rotating table, the Y-axis motion mechanism is arranged on the X-axis motion mechanism, the Z-axis motion mechanism is arranged on the Y-axis motion mechanism, the rotating table is arranged on the Z-axis motion mechanism, and the wafer carrier is arranged on the rotating table; the X-axis motion mechanism is configured to drive the Y-axis motion mechanism to move horizontally along the X-axis; the Y-axis motion mechanism is configured to drive the Z-axis motion mechanism to move horizontally along the Y-axis; the Z-axis motion mechanism is configured to drive the rotating table to move up and down in the vertical direction; the rotating table is configured to drive the wafer carrier to rotate along the axial direction of the wafer carrier.

[0011] Furthermore, the wafer support table and / or the transfer bracket are vacuum suction cups.

[0012] In order to solve the above technical problems, the present invention also provides an exposure device, including the automatic focusing device as described above.

[0013] The present invention also provides a photolithography device, comprising the exposure device as described above.

[0014] The present invention also provides an exposure method, comprising the following steps:

[0015] S1: The motion unit drives the wafer stage to rotate so that the notch of the substrate on the wafer stage rotates to be directly above the displacement sensor detection device, and the control system establishes a substrate coordinate system according to the position of the notch of the substrate;

[0016] S2: The motion unit continues to drive the wafer stage to rotate, and the displacement sensor detection device measures the warping amount of each sampling point of the substrate during the rotation process according to a certain sampling frequency;

[0017] S3: The control system generates a position-warping amount curve of the substrate according to the position coordinates of each acquisition point on the substrate and the warping amount corresponding to each acquisition point;

[0018] S4: The motion unit drives the wafer stage to move so that the substrate on the wafer stage is located at an exposure station;

[0019] S5: The exposure assembly starts to expose the substrate, and at the same time, the control system controls the wafer stage to move up and down in the vertical direction according to the position-warping amount curve and the exposure position of the substrate, so as to automatically focus the substrate during the exposure process.

[0020] Furthermore, before S1, the substrate is further centered, specifically including:

[0021] S001: The wafer stage receives the wafer from the external device and carries the substrate, and the motion unit drives the wafer stage to move horizontally to the pre-alignment station;

[0022] S002: The motion unit drives the wafer stage to rotate one circle, and the visual acquisition system acquires edge data of the substrate;

[0023] S003: The control system obtains the eccentricity of the substrate according to the edge data of the substrate;

[0024] S004: The motion unit drives the wafer stage to move up and down in the vertical direction, so that the wafer stage moves to the handover station;

[0025] S005: At the handover station, the handover bracket removes the substrate from the wafer stage;

[0026] S006: The control system controls the motion unit to drive the wafer stage to move horizontally according to the eccentricity, so as to compensate for the eccentricity of the substrate;

[0027] S007: The transfer bracket places the substrate back onto the wafer stage;

[0028] S008: The motion unit drives the wafer stage to move up and down in the vertical direction, so that the wafer stage moves to the pre-alignment station to complete the centering of the substrate.

[0029] Furthermore, after S008, the process of centering the substrate further includes:

[0030] S009: The motion unit drives the wafer stage to rotate one circle, and the visual acquisition system acquires edge data of the substrate after centering;

[0031] S010: The control system obtains the residual eccentricity of the substrate after compensation based on the edge data of the substrate after centering, and determines whether the residual eccentricity is within a set error;

[0032] S011: If the residual eccentricity is within the set error, the centering of the substrate is completed; otherwise, S002-S010 are repeated.

[0033] Furthermore, before S4, the substrate is oriented, specifically including:

[0034] The motion unit drives the wafer stage to rotate, and the visual acquisition system collects data on the notch position of the substrate;

[0035] The control system obtains the notch direction of the notch of the substrate according to the notch position data;

[0036] The control system controls the motion unit to drive the wafer stage to rotate according to the notch direction of the notch of the substrate, so that the notch of the substrate rotates to a set angle, thereby completing the orientation of the substrate.

[0037] Furthermore, the step of the control system in S5 controlling the wafer stage to move up and down in the vertical direction according to the position-warping amount curve and the exposure position of the substrate specifically includes:

[0038] The control system obtains the position coordinates of the exposure position of the substrate in the substrate coordinate system;

[0039] The control system obtains the warping amount corresponding to the exposure position according to the position-warping amount curve, and obtains the warping change amount of the exposure position area;

[0040] The control system interpolates the warpage variation into a set point generator of the Z-direction motion mechanism of the motion unit to control the wafer stage to move up and down in the vertical direction.

[0041] Compared with the prior art, the automatic focusing device, exposure device, photolithography device and exposure method provided by the present invention have the following advantages:

[0042] By setting up a displacement sensor detection device specifically for detecting the warping amount of the substrate edge, the displacement sensor detection device can obtain the warping amount of the substrate edge when the substrate stage rotates one circle. In this way, during the exposure process, the vertical position of the substrate can be adjusted in real time according to the warping amount at the exposure position, so that the exposure surface is always kept coincident with the focal plane of the projection objective lens as much as possible, thereby achieving the best exposure performance.

[0043] Furthermore, by measuring the warpage of each acquisition point during the rotation of the substrate at a certain acquisition frequency through a displacement sensor detection device, a position-warpage curve can be fitted to generate the warpage at each position of the edge of the substrate, and when the substrate is exposed, the warpage at the edge exposure position can be known from the position-warpage curve, so that when exposing the exposure position, the control device controls the motion unit in real time according to the change in the warpage, so that the motion unit drives the wafer stage to move up and down in the vertical direction to compensate for the warpage, so that the exposure surface and the focal plane of the projection objective lens remain coincident, thereby achieving optimal exposure performance.

[0044] In addition, the present invention also optimizes the control strategy of the control system for controlling the motion unit. By introducing variables that are prone to position deviations through feedback control, the motion unit controls the movement of the film stage more accurately and smoothly, further ensuring that the exposure surface of the substrate and the focal plane of the projection objective remain coincident, thereby achieving optimal exposure performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the structure of an automatic focusing device in one embodiment of the present invention;

[0046] Figure 2a Schematic diagram of a substrate edge exposure method in one embodiment of the present invention;

[0047] Figure 2b Schematic diagram of a circular exposure method for a substrate in one embodiment of the present invention;

[0048] Figure 2c Schematic diagram of a substrate segmented exposure method in one embodiment of the present invention;

[0049] Figure 2d Schematic diagram of a linear exposure method for a substrate in one embodiment of the present invention;

[0050] Figure 3 1 is a schematic flow chart of an exposure method according to one embodiment of the present invention;

[0051] Figure 4 Schematic diagram of the process of centering a substrate in one embodiment of the present invention;

[0052] Figure 5 Schematic diagram of the process of exposing the edge of a substrate in one embodiment of the present invention;

[0053] Figure 6 Schematic diagram of an automatic focusing control strategy for synchronously controlling a rotating stage and a Z-axis motion mechanism in one embodiment of the present invention;

[0054] Figure 7 Schematic diagram of an S-wave-shaped warped silicon wafer in one embodiment of the present invention;

[0055] Figure 8a A position-warpage curve diagram of an S-shaped warped silicon wafer according to one embodiment of the present invention;

[0056] Figure 8b Graph showing the output of the Z-axis motion mechanism in one embodiment of the present invention.

[0057] The accompanying drawings are numerals as follows:

[0058] 100-Motion unit; 200-Film holding table; 300-Displacement sensor detection device; 400-Substrate; 500-Visual acquisition system; 600-Transfer bracket; 700-Exposure assembly; 800-Control system; 100X-X-axis motion mechanism; 100Y-Y-axis motion mechanism; 100Z-Z-axis motion mechanism; 100R-Rotary table. DETAILED DESCRIPTION

[0059] The following is a further detailed description of an automatic focusing device, exposure device, photolithography device and exposure method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description.

[0060] It should be noted that the drawings are in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0061] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0062] As used herein, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a . . . ," does not preclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element. The methods described herein comprise a series of steps, and the order in which the steps are presented herein is not necessarily the only order in which the steps may be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method.

[0063] The most common autofocus function currently on the market is primarily used in camera photography. This technology, based on image processing and utilizing computer hardware and image processing techniques, processes a series of digital images captured by the lens and CCD in real time, determining focus and image clarity. It then generates feedback signals to control lens movement until the captured image meets the desired performance, effectively completing autofocus. Currently, other manufacturers have yet to apply this image acquisition technology to edge exposure.

[0064] The core idea of the present invention is to provide an automatic focusing device, an exposure device, a photolithography device and an exposure method to solve the problem in the prior art that there is no suitable solution for exposing the edges of large warped sheets so that the exposure surface of the large warped sheet can be kept as consistent as possible with the focal plane of the projection objective during the exposure process to achieve optimal exposure performance.

[0065] In order to realize the above idea, the present invention provides an automatic focusing device for automatically focusing the substrate during the exposure process. Figure 1 As shown, it includes a motion unit 100, a wafer stage 200, a displacement sensor detection device 300 and a control system 800; the wafer stage 200 is arranged on the motion unit 100, and the wafer stage 200 is configured to carry the substrate 400; the motion unit 100 is configured to drive the wafer stage 200 to move up and down in the vertical direction, and to rotate along the axial direction of the wafer stage 200; the displacement sensor detection device 300 is arranged below the substrate 400 on the wafer stage 200, and is configured to collect the warping amount of the substrate 400; the control system 800 is configured to control the motion unit 100 to drive the wafer stage 200 to move up and down in the vertical direction according to the warping amount of the substrate 400, so as to automatically focus the substrate 400 during the exposure process. In the solution of this embodiment, a displacement sensor detection device 300 is provided specifically for detecting the warping amount of the edge of the substrate 400. The displacement sensor detection device 300 can obtain the change in the distance between the edge portion of the substrate 400 and the displacement sensor detection device 300 when the wafer stage 200 rotates one circle, thereby obtaining the warping amount of the edge of the substrate 400. In this way, during the exposure process, the vertical position of the substrate 400 can be adjusted in real time according to the warping amount at the exposure position, so that the exposure surface is kept as consistent as possible with the focal plane of the projection objective lens, thereby achieving optimal exposure performance.

[0066] As an implementation scheme of the present invention, the displacement sensor detection device 300 is configured to measure the warping amount of each collection point of the substrate 400 during the rotation process according to a set collection frequency; the control system 800 is configured to generate a position-warping amount curve of the substrate 400 according to the position coordinates of each collection point on the substrate 400 and the warping amount corresponding to each collection point, and control the wafer stage 200 to move up and down in the vertical direction according to the position-warping amount curve and the exposure position of the substrate 400, so as to automatically focus the substrate 400 during the exposure process. In the solution of this embodiment, the warpage at each position on the edge of the substrate 400 is determined by fitting and generating a position-warpage curve. When the substrate 400 is exposed, the warpage at each exposure position on the edge can be determined from the position-warpage curve. Therefore, when exposing the exposure position, the control device controls the motion unit 100 in real time based on the warpage variation, causing the motion unit 100 to move the substrate stage 200 vertically up and down to compensate for the warpage, thereby ensuring that the exposure surface and the focal plane of the projection lens coincide with each other and achieving optimal exposure performance. In this embodiment, the sampling frequency of the displacement sensor detection device 300 can be set based on the warpage variation of the edge of the substrate 400. When the edge warpage variation is large, the sampling frequency can be set shorter to obtain as much data as possible and improve the accuracy of the fitted position-warpage curve. When the edge warpage variation is small, the sampling frequency can be set longer to reduce the amount of data processing and improve efficiency without affecting the accuracy of the fitted position-warpage curve.

[0067] In addition, the setting position of the displacement sensor detection device 300 can be adjusted according to the size of the substrate 400 and the position to be exposed. The substrate in the present invention can be a semiconductor silicon wafer or an LCD panel. For example, when the substrate 400 is a semiconductor silicon wafer of various sizes such as 6 inches, 8 inches, and 12 inches, and the exposure is edge exposure, the displacement sensor detection device 300 can be set directly below the edge of the silicon wafer to collect the warping amount of the silicon wafer edge.

[0068] Furthermore, in order to realize the centering and orienting function of the substrate 400, the automatic focusing device of this embodiment also includes a visual acquisition system 500 and a transfer bracket 600; the motion unit 100 is also configured to drive the wafer stage 200 to perform horizontal movement in the horizontal direction; the visual acquisition system 500 is arranged above the substrate 400 on the wafer stage 200, and the visual acquisition system 500 is configured to collect edge data of the substrate 400; the transfer bracket 600 is configured to remove the substrate 400 from the wafer stage 200 or place the substrate 400 on the wafer stage 200; the control system 800 is also configured to obtain the eccentricity of the substrate 400 according to the edge data of the substrate 400, and control the motion unit 100 to drive the wafer stage 200 to perform horizontal movement in the horizontal direction according to the eccentricity to center the substrate 400. When the substrate is placed on the wafer table, its center does not necessarily coincide with the center of the wafer table. In this case, the substrate needs to be centered to ensure subsequent accurate exposure of the substrate. In this embodiment, the visual acquisition system 500 can collect edge data of the substrate 400, such as the edge shape and position of the substrate. The control system 800 can calculate the eccentricity between the substrate 400 and the center of the wafer table 200 based on the edge data, combined with information such as the size of the substrate, the position of the wafer table 200, and the position of the visual acquisition system 500. After knowing the eccentricity, the control system 800 can control the transfer bracket 600 to first remove the substrate 400 on the wafer table 200, and then control the motion unit 100 to drive the wafer table 200 to perform horizontal movement in the horizontal direction to compensate for the eccentricity, and then control the transfer bracket 600 to put the substrate 400 back on the wafer table 200. At this time, the center of the substrate 400 coincides with the center of the wafer table 200, completing the centering of the substrate 400.

[0069] Optionally, the motion unit 100 may include an X-axis motion mechanism 100X, a Y-axis motion mechanism 100Y, a Z-axis motion mechanism 100Z, and a rotating table 100R, wherein the Y-axis motion mechanism 100Y is arranged on the X-axis motion mechanism 100X, the Z-axis motion mechanism 100Z is arranged on the Y-axis motion mechanism 100Y, the rotating table 100R is arranged on the Z-axis motion mechanism 100Z, and the wafer stage 200 is arranged on the rotating table 100R; the X-axis motion mechanism 100Y is arranged on the X-axis motion mechanism 100X, the Z-axis motion mechanism 100Z is arranged on the Y-axis motion mechanism 100Y, the rotating table 100R is arranged on the Z-axis motion mechanism 100Z, and the wafer stage 200 is arranged on the rotating table 100R; The motion mechanism 100X is configured to drive the Y-axis motion mechanism 100Y to move horizontally in the X-axis; the Y-axis motion mechanism 100Y is configured to drive the Z-axis motion mechanism 100Z to move horizontally in the Y-axis; the Z-axis motion mechanism 100Z is configured to drive the rotary table 100R to move up and down in the vertical direction; and the rotary table 100R is configured to drive the wafer stage 200 to rotate along its axial direction, thereby driving the rotation of the substrate 400. The X-axis motion mechanism 100X, the Y-axis motion mechanism 100Y, and the Z-axis motion mechanism 100Z can all employ conventional power guide mechanisms in the prior art, such as stepper motors and other drive mechanisms, and the present invention does not impose any additional limitations thereto.

[0070] Preferably, the wafer stage 200 and / or the transfer bracket 600 in the embodiment of the present invention can be a vacuum suction cup. For example, the wafer stage 200 can be a large warp ceramic vacuum suction cup that matches the shape of the substrate 400. The vacuum suction cup can be used to realize the transfer function with an external manipulator, and the wafer can be received from an external device. The transfer method can be that the manipulator actively takes the wafer, that is, the manipulator lifts and lowers to take and place the substrate, and the vacuum suction cup only needs to switch the vacuum to complete the adsorption and release of the substrate. At the same time, the connection between the wafer stage 200 and the rotating table 100R can be a detachable connection, and the size of the vacuum suction cup of the wafer stage 200 can be replaced according to the size of the substrate 400 to adapt to substrates of various sizes. The transfer bracket 600 can be a C-shaped vacuum suction cup, which can adapt to the adsorption of substrates of different sizes.

[0071] The present invention also provides an exposure device, comprising the automatic focusing device as described above. In addition, the exposure device further comprises an exposure component 700, the exposure component 700 is used to expose the substrate 400, such as Figure 1 As shown, the exposure assembly 700 in the figure can realize edge exposure of the substrate 400, and the exposure mode can be edge exposure, ring exposure, segmented exposure, linear exposure, etc. Figure 2a-2d The automatic focusing device provided by the embodiment of the present invention can be applied to edge exposure, annular exposure, segmented exposure and linear exposure.

[0072] The present invention also provides a photolithography device, comprising the exposure device as described above.

[0073] Based on the above device, the present invention also provides an exposure method, such as Figure 3 As shown, the following steps are included:

[0074] S1: The motion unit 100 drives the wafer stage 200 to rotate, so that the notch of the substrate 400 on the wafer stage 200 rotates to be directly above the displacement sensor detection device 300, and the control system 800 establishes a substrate coordinate system according to the position of the notch of the substrate 400;

[0075] S2: The motion unit 100 continues to drive the wafer stage 200 to rotate, and the displacement sensor detection device 300 measures the warping amount of each sampling point of the substrate 400 during the rotation process according to a certain sampling frequency;

[0076] S3: The control system 800 generates a position-warping amount curve of the substrate 400 by fitting according to the position coordinates of each acquisition point on the substrate 400 and the warping amount corresponding to each acquisition point;

[0077] S4: The motion unit 100 drives the wafer stage 200 to move so that the substrate 400 on the wafer stage 200 is located at an exposure station;

[0078] S5: The exposure component 700 starts to expose the substrate 400. At the same time, the control system 800 controls the wafer stage 200 to move up and down in the vertical direction according to the position-warping amount curve and the exposure position of the substrate 400, so as to automatically focus the substrate 400 during the exposure process.

[0079] When the edge of the substrate 400 is exposed using the exposure method of this embodiment, the vertical position of the substrate 400 can be adjusted in real time according to the warping amount, so that the exposure surface of the substrate 400 and the focal plane of the projection objective lens are kept as consistent as possible to achieve optimal exposure performance.

[0080] During semiconductor device production, to ensure that the substrate can be exposed in a fixed posture, the substrate must be transferred to the workpiece stage with high centering and orientation accuracy. Because the position and orientation of the substrate are uncertain when placed in the substrate slot, a certain level of precision is required before the substrate is transferred to the workpiece stage. This involves measuring the substrate's center to determine its current position, and measuring the direction of the substrate's notch to determine its orientation.

[0081] Preferably, in the above exposure method, before S1, the substrate is further centered, such as Figure 4 As shown, specifically including:

[0082] S001: The wafer stage 200 receives a wafer from an external device and carries the substrate 400. The motion unit 100 drives the wafer stage 200 to move horizontally to a pre-alignment station.

[0083] S002: The motion unit 100 drives the wafer stage 200 to rotate one circle, and the visual acquisition system 500 acquires edge data of the substrate 400;

[0084] S003: The control system 800 obtains the eccentricity of the substrate 400 according to the edge data of the substrate 400;

[0085] S004: The motion unit 100 drives the wafer stage 200 to move up and down in the vertical direction, so that the wafer stage 200 moves to the handover station;

[0086] S005: At the handover station, the handover bracket 600 removes the substrate 400 from the wafer stage 200;

[0087] S006: The control system 800 controls the motion unit 100 to drive the wafer stage 200 to move horizontally according to the eccentricity, so as to compensate for the eccentricity of the base 400;

[0088] S007: The transfer bracket 600 places the substrate 400 back onto the wafer stage 200;

[0089] S008: The motion unit 100 drives the wafer stage 200 to move up and down in the vertical direction, so that the wafer stage 200 moves to the pre-alignment station to complete the centering of the substrate 400.

[0090] Furthermore, the centering result may be further verified to make the centering result more accurate. After S008, the process of centering the substrate 400 further includes:

[0091] S009: The motion unit 100 drives the wafer stage 200 to rotate one circle, and the visual acquisition system 500 acquires edge data of the centered substrate 400;

[0092] S010: The control system 800 obtains the residual eccentricity of the substrate 400 after compensation based on the edge data of the substrate 400 after centering, and determines whether the residual eccentricity is within a set error.

[0093] S011: If the residual eccentricity is within the set error, the centering of the substrate 400 is completed; otherwise, S002 to S010 are repeated.

[0094] Furthermore, the exposure method further includes, before S4, orienting the substrate 400 to ensure an accurate starting position for exposure. The orienting step specifically includes:

[0095] The motion unit 100 drives the wafer stage 200 to rotate, and the visual acquisition system 500 collects data on the notch position of the substrate 400;

[0096] The control system 800 obtains the notch direction of the notch of the substrate 400 according to the notch position data;

[0097] The control system 800 controls the motion unit 100 to drive the wafer stage 200 to rotate according to the notch direction of the notch of the substrate 400, so that the notch of the substrate 400 rotates to a set angle, thereby completing the orientation of the substrate.

[0098] Preferably, in step S5 of the exposure method, when the exposure component 700 starts to expose the substrate 400, taking edge exposure as an example, Figure 5 As shown, it may specifically include the following operations: the aperture of the exposure assembly 700 is switched to a specified field of view size, the control system 800 first determines whether the substrate 400 is in a pre-alignment completion state, and if so, the pre-exposure process is started, firstly the illumination optimization is performed, the actual illumination of the current light source is measured, and the control system 800 calculates the exposure parameters; then the X-axis motion mechanism 100X and the Y-axis motion mechanism 100Y of the motion unit 100 are moved to the specified exposure station, the light source is turned on, and the rotating table 100Z is rotated to the exposure start position to start uniform speed exposure.

[0099] The step of the control system 800 controlling the wafer stage 200 to move up and down in the vertical direction according to the position-warpage curve and the exposure position of the substrate 400 in S5 specifically includes:

[0100] The control system 800 obtains the position coordinates of the exposure position of the substrate 400 in the substrate coordinate system;

[0101] The control system 800 obtains the warping amount corresponding to the exposure position according to the position-warping amount curve, and obtains the warping change amount of the exposure position area;

[0102] The control system 800 interpolates the warping variation into the set point generator of the Z-axis motion mechanism 100Z of the motion unit 100 to control the wafer stage 200 to move up and down in the vertical direction, thereby achieving automatic adjustment of the vertical focal plane.

[0103] When the rotating stage 100Z rotates to the exposure end position, the light source is turned off, and the X-axis motion mechanism 100X and the Y-axis motion mechanism 100Y move the film with the film to the film unloading position, waiting for an external device to remove the exposed substrate. At this point, the edge exposure process with automatic focus adjustment is complete. Similar methods are used for circular exposure, segmented exposure, and linear exposure of the substrate 400, and will not be detailed here.

[0104] Furthermore, in the above solution, the control system 800 interpolates the warpage variation of the exposure position into the set point generator of the Z-direction motion mechanism 100Z of the motion unit 100 to control the vertical up-and-down movement of the wafer stage 200. The specific control strategy can be summarized as follows: Figure 6 As shown, when the rotating stage 100R starts the exposure movement with the sheet, the Z-axis motion mechanism 100Z generates a set point input for each motion position according to the interpolation setting of the warpage change amount and the trajectory planning strategy. The Z-axis motion mechanism 100Z and the rotating stage 100R itself can include a PID controller and a measurement system. The output value of the PID controller can control the actuator of the Z-axis motion mechanism 100Z. The measurement system is used to provide real-time feedback on the actual rising or falling distance of the Z-axis motion mechanism in the vertical position. The actual measurement value fed back by the measurement system in real time can be fed back to the input end of the PID controller. The PID controller adjusts the output value in real time according to the actual rising or falling distance of the feedback input and the set point input, so that the motion value of the Z-axis motion mechanism is more accurate. In this way, by feeding back real-time data to the PID controller through the measurement system, the tracking error can be reduced, thereby forming an accurate closed-loop feedback control.

[0105] In addition, if Figure 6 As shown, during the movement of the rotary table 100R and the Z-axis motion mechanism 100Z, especially in the acceleration and deceleration sections of the movement, large position errors will be generated. In order to eliminate these position errors, the acceleration trajectory planned by the set point generator can be introduced into the PID controller as feedforward compensation, thereby further reducing the position errors caused by acceleration or deceleration and making the adjustment process of the entire vertical focal plane smoother.

[0106] In order to verify the effect of the above control strategy, this embodiment uses the most typical S-wave warped silicon wafer as an example to perform actual exposure control using the above exposure method and control strategy. Figure 7 As shown in the figure, it is a schematic diagram of an S-wave warped silicon wafer. At this time, the warping curve of the silicon wafer is simulated as a sine wave, as shown in Figure 8a The performance curve of the synchronous focusing motion of the Z-direction motion mechanism 100Z during the exposure of the rotating table 100R with the film can be used to confirm the synchronous automatic control performance of the Z-direction motion mechanism 100Z, as shown in FIG. Figure 8bAs shown, the output curve of the Z-axis motion mechanism 100Z can fully track the changes of the input set point, with a maximum error value of 58 μm, which fully meets the control requirements of the vertical focal plane.

[0107] In summary, compared with the prior art, the automatic focusing device, exposure device, photolithography device, and exposure method provided by the present invention have the following advantages:

[0108] By setting up a displacement sensor detection device specifically for detecting the warping amount of the substrate edge, the displacement sensor detection device can obtain the warping amount of the substrate edge when the substrate stage rotates one circle. In this way, during the exposure process, the vertical position of the substrate can be adjusted in real time according to the warping amount at the exposure position, so that the exposure surface is always kept coincident with the focal plane of the projection objective lens as much as possible, thereby achieving the best exposure performance.

[0109] Furthermore, by measuring the warpage of each acquisition point during the rotation of the substrate at a certain acquisition frequency through a displacement sensor detection device, a position-warpage curve can be fitted to generate the warpage at each position of the edge of the substrate, and when the substrate is exposed, the warpage at the edge exposure position can be known from the position-warpage curve, so that when exposing the exposure position, the control device controls the motion unit in real time according to the change in the warpage, so that the motion unit drives the wafer stage to move up and down in the vertical direction to compensate for the warpage, so that the exposure surface and the focal plane of the projection objective lens remain coincident, thereby achieving optimal exposure performance.

[0110] In addition, the present invention also optimizes the control strategy of the control system for controlling the motion unit. By introducing variables that are prone to position deviations through feedback control, the motion unit controls the movement of the film stage more accurately and smoothly, further ensuring that the exposure surface of the substrate and the focal plane of the projection objective remain coincident, thereby achieving optimal exposure performance.

[0111] The above description is merely a description of preferred embodiments of the present invention and does not limit the scope of the invention. Any changes or modifications made by persons skilled in the art based on the above disclosure are intended to be protected by the claims. Obviously, various modifications and variations may be made by persons skilled in the art without departing from the spirit and scope of the present invention. Thus, to the extent such modifications and variations fall within the scope of the claims and their equivalents, the present invention is intended to encompass such modifications and variations.

Claims

1. An automatic focusing device for automatically focusing a substrate during exposure, characterized in that: It includes a motion unit, a wafer stage, a displacement sensor detection device and a control system; The wafer stage is disposed on the motion unit, and the wafer stage is configured to carry the substrate; The motion unit is configured to drive the wafer table to move up and down in the vertical direction, and to rotate along the axial direction of the wafer table; The displacement sensor detection device is arranged below the substrate on the wafer stage and is configured to collect the warping amount of the substrate; The control system is configured to control the motion unit to drive the wafer stage to move up and down in a vertical direction according to the warping amount of the substrate, so as to automatically focus the substrate during the exposure process; Wherein, the displacement sensor detection device is configured to measure the warping amount of each acquisition point of the substrate during the rotation process according to a set acquisition frequency; The control system is configured to fit a position-warping curve of the substrate based on the position coordinates of each acquisition point on the substrate and the warping amount corresponding to each acquisition point, obtain the warping amount corresponding to the exposure position based on the position-warping curve and the exposure position of the substrate, and obtain the warping change amount of the exposure position area, interpolate the warping change amount into a set point generator of the motion unit, and generate a set point input for each motion position of the motion unit according to a trajectory planning strategy to control the vertical up and down movement of the substrate stage to automatically focus the substrate during the exposure process; Furthermore, the motion unit further includes a PID controller and a measurement system. The measuring system is used to measure the actual rising or falling distance of the wafer stage in the vertical direction in real time, and input the actual rising or falling distance into the input end of the PID controller; The PID controller is used to adjust the set point input of the motion unit in real time according to the actual ascent or descent distance and acceleration trajectory fed back; wherein, the acceleration trajectory is obtained according to the planning of the set point generator.

2. The automatic focusing device according to claim 1, wherein: It also includes a visual acquisition system and a handover bracket; The motion unit is further configured to drive the wafer table to move horizontally; The visual acquisition system is disposed above the substrate on the wafer stage, and the visual acquisition system is configured to acquire edge data of the substrate; The transfer bracket is configured to remove the substrate from the wafer stage or place the substrate onto the wafer stage; The control system is further configured to obtain the eccentricity of the substrate according to the edge data of the substrate, and control the motion unit to drive the wafer stage to move horizontally according to the eccentricity to center the substrate.

3. The automatic focusing device according to claim 2, wherein: The motion unit includes an X-axis motion mechanism, a Y-axis motion mechanism, a Z-axis motion mechanism and a rotating table. The Y-direction motion mechanism is arranged on the X-direction motion mechanism, the Z-direction motion mechanism is arranged on the Y-direction motion mechanism, the rotating table is arranged on the Z-direction motion mechanism, and the wafer stage is arranged on the rotating table; The X-direction motion mechanism is configured to drive the Y-direction motion mechanism to move horizontally along the X-direction; The Y-direction motion mechanism is configured to drive the Z-direction motion mechanism to move horizontally along the Y direction; The Z-direction motion mechanism is configured to drive the rotary table to move up and down in the vertical direction; The rotating platform is configured to drive the wafer carrier to rotate along the axial direction of the wafer carrier.

4. The automatic focusing device according to claim 2, wherein: The wafer support table and / or the transfer bracket are vacuum suction cups.

5. An exposure device, characterized in that: The automatic focusing device comprises the automatic focusing device as described in any one of claims 1 to 4.

6. A photolithography apparatus, characterized in that: Comprising the exposure device according to claim 5.

7. An exposure method, characterized in that: The steps include: S1: The motion unit drives the wafer stage to rotate so that the notch of the substrate on the wafer stage rotates to just above the displacement sensor detection device, and the control system establishes a substrate coordinate system according to the position of the notch of the substrate; S2: The motion unit continues to drive the wafer stage to rotate, and the displacement sensor detection device measures the warping amount of each sampling point of the substrate during the rotation process according to a certain sampling frequency; S3: The control system generates a position-warping amount curve of the substrate according to the position coordinates of each acquisition point on the substrate and the warping amount corresponding to each acquisition point; S4: The motion unit drives the wafer stage to move so that the substrate on the wafer stage is located at an exposure station; S5: The exposure assembly starts exposing the substrate. At the same time, the control system obtains the warpage corresponding to the exposure position according to the position-warpage curve and the exposure position of the substrate, and obtains the warpage variation of the exposure position area. The warpage variation is interpolated into the set point generator of the motion unit. The trajectory planning strategy is used to generate the set point input of each motion position of the motion unit to control the vertical up and down movement of the wafer stage to automatically focus the substrate during the exposure process. S6: The measurement system of the motion unit measures the actual rising or falling distance of the wafer table in the vertical direction in real time, and inputs the actual rising or falling distance into the input end of the PID controller of the motion unit. The PID controller adjusts the set point input of the motion unit in real time according to the feedback of the actual rising or falling distance and the acceleration trajectory; wherein, the acceleration trajectory is obtained according to the planning of the set point generator.

8. An exposure method according to claim 7, characterized in that: Before S1, the substrate is further centered, specifically including: S001: The wafer stage receives the wafer from the external device and carries the substrate, and the motion unit drives the wafer stage to move horizontally to the pre-alignment station; S002: The motion unit drives the wafer stage to rotate one circle, and the visual acquisition system acquires edge data of the substrate; S003: The control system obtains the eccentricity of the substrate according to the edge data of the substrate; S004: The motion unit drives the wafer stage to move up and down in the vertical direction, so that the wafer stage moves to the handover station; S005: At the handover station, the handover bracket removes the substrate from the wafer stage; S006: The control system controls the motion unit to drive the wafer stage to move horizontally according to the eccentricity, so as to compensate for the eccentricity of the substrate; S007: The transfer bracket places the substrate back onto the wafer stage; S008: The motion unit drives the wafer stage to move up and down in the vertical direction, so that the wafer stage moves to the pre-alignment station to complete the centering of the substrate.

9. An exposure method according to claim 8, characterized in that: After S008, the process of centering the substrate further includes: S009: The motion unit drives the wafer stage to rotate one circle, and the visual acquisition system acquires edge data of the substrate after centering; S010: The control system obtains the residual eccentricity of the substrate after compensation based on the edge data of the substrate after centering, and determines whether the residual eccentricity is within a set error; S011: If the residual eccentricity is within the set error, the centering of the substrate is completed; otherwise, S002-S010 are repeated.

10. The exposure method according to claim 7, wherein: Before S4, the substrate is also oriented, specifically including: The motion unit drives the wafer stage to rotate, and the visual acquisition system collects data on the notch position of the substrate; The control system obtains the notch direction of the notch of the substrate according to the notch position data; The control system controls the motion unit to drive the wafer stage to rotate according to the notch direction of the notch of the substrate, so that the notch of the substrate rotates to a set angle, thereby completing the orientation of the substrate.

11. The exposure method according to claim 7, wherein: The step of the control system in S5 controlling the wafer stage to move up and down in the vertical direction according to the position-warping amount curve and the exposure position of the substrate specifically includes: The control system obtains the position coordinates of the exposure position of the substrate in the substrate coordinate system; The control system obtains the warping amount corresponding to the exposure position according to the position-warping amount curve, and obtains the warping change amount of the exposure position area; The control system interpolates the warpage variation into a set point generator of the Z-direction motion mechanism of the motion unit to control the wafer stage to move up and down in the vertical direction.

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