Method and device for scanning surface shape of exit / entrance silicon wafer and photoetching machine

Abstract

The invention relates to the technical field of photoetching, in particular to an exit / entrance silicon wafer surface shape scanning method and device and a photoetching machine.The method comprises the steps that a silicon wafer is scanned according to a preset overall-situation surface shape scanning path, and height information of a light spot exit area is obtained; performing plane fitting on the height information of the light spot exit area to obtain height information of a next entrance intersection point adjacent to the light spot exit area; according to the height information of the entrance intersection point, determining the posture information of the silicon wafer stage before the light spot enters; before the light spot enters the field, the silicon wafer stage is controlled to move until the silicon wafer is in the effective measurement interval of the horizontal sensor according to the posture information of the silicon wafer stage, so that the silicon wafer accurately enters the measurement range of the horizontal sensor, and the situation that the silicon wafer needs to be captured before entering the field every time is avoided, thereby improving the global scanning efficiency.

Description

Technical Field

[0001] The present invention relates to the field of lithography technology, and in particular, to a method and device for scanning the surface shape of a silicon wafer during entry and exit, and a lithography machine. Background Art

[0002] The full-surface shape scanning of a silicon wafer is the measurement and evaluation of the surface topography of the silicon wafer by a lithography machine to ensure the transfer accuracy and quality of the lithography machine image. Before the silicon wafer is exposed, by globally scanning the upper surface of the silicon wafer, the surface shape characteristics of the silicon wafer surface are obtained to evaluate the quality and applicability of the silicon wafer.

[0003] With the development of lithography technology and the gradual improvement of lithography process requirements, its depth of focus range has also been sharply reduced. To avoid incorrect measurement data of the horizontal sensor, it is necessary to keep the distance between the horizontal sensor and the silicon wafer surface within the effective measurement range of the horizontal sensor at all times; currently, the measurement range of the horizontal sensor on the lithography machine is only a few micrometers. If no capture operation is performed at the global scan entry point, the change range of the silicon wafer surface shape may exceed the sensor range, resulting in inaccurate measurement data. And after deviating from the optimal measurement interval, it will lead to problems in height data calculation, and then reduce the scanning accuracy. Therefore, when globally scanning the silicon wafer plane, it is necessary to make the height of the edge of the silicon wafer scanning area within the measurement range of the horizontal sensor, so as to avoid the situation that during the global scan process, due to the change in the height of the silicon wafer edge, the horizontal sensor has a periodic jump during measurement, resulting in a deviation between the measurement result and the displacement of the moving stage. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for scanning the surface shape of a silicon wafer during entry and exit, and a lithography machine, so as to solve the problem of how to make the height of the edge of the silicon wafer scanning area within the measurement range of the horizontal sensor during the global scan process, and avoid the situation that due to the change in the height of the silicon wafer edge, the horizontal sensor has a periodic jump during measurement, resulting in a deviation between the measurement result and the displacement of the moving stage.

[0005] An embodiment of the present invention provides a method for scanning the surface shape of a silicon wafer during entry and exit. The method includes: scanning the silicon wafer according to a preset full-surface shape scanning path to obtain height information of a light spot exit area, where the light spot exit area is an intersection area between the preset full-surface shape scanning path and the inner edge of the silicon wafer edge safety area, and the inner edge of the edge safety area is at a preset distance from the silicon wafer edge; performing a plane fitting on the height information of the light spot exit area to obtain height information of the next entry intersection adjacent to the light spot exit area, where the entry intersection is the intersection point where the center of the light spot re-enters the inner edge of the edge safety area along the preset full-surface shape scanning path; determining the silicon wafer stage attitude information before the light spot enters according to the height information of the entry intersection; and before the light spot enters, controlling the silicon wafer stage to move according to the silicon wafer stage attitude information so that the silicon wafer is within the effective measurement range of the horizontal sensor.

[0006] Optionally, the performing a plane fitting on the height information of the light spot exit area to obtain height information of the next entry intersection adjacent to the light spot exit area includes: performing a first plane fitting according to the height of each scanning point in the light spot exit area; calculating the difference between the fitting height of the first plane fitting and the height of each scanning point in the light spot exit area; if the difference is greater than a preset value, replacing the height of the scanning point in the light spot exit area corresponding to the value greater than the preset value with the fitting height of the first plane fitting, and then performing a second plane fitting; and obtaining the height information of the next entry intersection adjacent to the light spot exit area according to the second plane fitting.

[0007] Optionally, the method further includes: determining the preset value according to the first plane fitting residual, and the preset value is three times the residual.

[0008] Optionally, the scanning the silicon wafer according to a preset full-surface shape scanning path to obtain height information of a light spot exit area includes: scanning the light spot exit area according to the light spot to obtain the height of each scanning point in the light spot exit area, where each scanning point is the intersection point of the light spot with the inner side of the inner edge of the edge safety area in the exit area, and the center point of the silicon wafer is located on the inner side of the inner edge of the edge safety area.

[0009] Optionally, the controlling the silicon wafer stage to move according to the silicon wafer stage attitude information so that the silicon wafer is within the effective measurement range of the horizontal sensor before the light spot enters includes: determining the entry point coordinates; and before the light spot enters the silicon wafer from the entry point, controlling the upper surface of the silicon wafer edge at the entry intersection to be at the same height as the zero plane of the horizontal sensor at the entry point according to the silicon wafer stage attitude information.

[0010] Optionally, determining the entry point coordinates includes: determining the first direction center coordinates of the preset global surface scanning path as the first direction position coordinates of the entry point, the first direction is parallel to the direction of travel of the light spot on the surface of the silicon wafer, and the first direction is parallel to the surface of the silicon wafer; determining the second direction coordinates of the initial contact point between the light spot and the edge of the silicon wafer as the second direction position coordinates of the entry point, the second direction is perpendicular to the first direction, and the second direction is parallel to the surface of the silicon wafer.

[0011] Optionally, before the step of scanning the silicon wafer according to the preset global surface scanning path, the step includes: moving the upper edge surface of the silicon wafer to the zero plane of the horizontal sensor by the silicon wafer stage to determine the scanning starting point.

[0012] Compared with the prior art, the in-and-out silicon wafer surface scanning method provided by the present invention has the following beneficial effects:

[0013] The embodiment of the present invention provides a method for scanning the surface of a silicon wafer entering and exiting the field. The method scans the silicon wafer according to a preset global surface scanning path to obtain height information of a spot exit area, where the spot exit area is an area where the preset global surface scanning path intersects with the edge of the silicon wafer. The height information of the spot exit area is plane-fitted to obtain height information of a next entry intersection point adjacent to the spot exit area, and the height of the next entry intersection point is predicted according to the edge height of the spot exit area. The entry intersection point is an intersection point where the center of the spot enters the edge of the silicon wafer again along the preset global surface scanning path. The wafer stage posture information before the spot enters the field is determined according to the height information of the entry intersection point. Before the spot enters the field, the wafer stage posture information is determined according to the wafer stage posture information. The wafer stage is controlled to move until the wafer is within the effective measurement range of the horizontal sensor, that is, the wafer surface scanning method for entry and exit provided by the present invention calculates the height information of the entry point by fitting according to the height information of the light spot exit area, and obtains the height information of the entry intersection, and then obtains the posture information of the wafer stage according to the height information of the entry intersection, so that the wafer is directly and accurately brought into the measurement range of the horizontal sensor for global scanning of the wafer according to the posture information of the wafer stage, thereby avoiding the deviation between the measurement result and the displacement of the moving stage caused by the periodic jump of the horizontal sensor during the measurement due to the change of the wafer edge height during the global scanning process, and also avoiding the need for capture operation before each entry, thereby improving the global scanning efficiency.

[0014] An embodiment of the present invention further provides a silicon wafer surface shape scanning device for entry and exit. The device includes: an acquisition module, configured to scan a silicon wafer according to a preset full-surface shape scanning path to obtain height information of a light spot exit area, where the light spot exit area is an intersection area between the preset full-surface shape scanning path and the inner edge of the silicon wafer edge safety area, and the inner edge of the edge safety area is at a preset distance from the silicon wafer edge; a fitting module, configured to perform plane fitting on the height information of the light spot exit area to obtain height information of the next entry intersection adjacent to the light spot exit area, where the entry intersection is the intersection where the center of the light spot re-enters the inner edge of the edge safety area along the preset full-surface shape scanning path; a determination module, configured to determine the silicon wafer stage attitude information before the light spot enters according to the height information of the entry intersection; a control module, configured to control the silicon wafer stage to move to an effective measurement range of a horizontal sensor according to the silicon wafer stage attitude information before the light spot enters, so that the silicon wafer is in the effective measurement range of the horizontal sensor.

[0015] The beneficial effect of the silicon wafer surface shape scanning device provided by the present invention is that it can achieve the same technical effect as the above-mentioned entry and exit silicon wafer surface shape scanning method. To avoid repetition, it will not be elaborated here.

[0016] An embodiment of the present invention further provides a lithography machine, which includes a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, the above method is implemented.

[0017] The beneficial effect of the lithography machine provided by the present invention is that it can achieve the same technical effect as the above-mentioned entry and exit silicon wafer surface shape scanning method. To avoid repetition, it will not be elaborated here.

[0018] An embodiment of the present invention further provides a computer-readable storage medium, which stores a computer program. When the computer program is read and run by a processor, the above method is implemented.

[0019] The beneficial effect of the computer-readable storage medium provided by the present invention is that it can achieve the same technical effect as the above-mentioned entry and exit silicon wafer surface shape scanning method. To avoid repetition, it will not be elaborated here. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0021] Figure 1Schematic diagram of the return signal of the horizontal sensor in the embodiment of the present invention;

[0022] Figure 2 Schematic diagram of the scanning trajectory of the silicon wafer entering and leaving the field in the embodiment of the present invention;

[0023] Figure 3 Schematic diagram of the fitting of the edge scan of the silicon wafer entering the field in the embodiment of the present invention;

[0024] Figure 4 Schematic flow chart of a method for scanning the surface shape of a silicon wafer entering and leaving the field provided by the embodiment of the present invention;

[0025] Figure 5 Schematic flow chart of another method for scanning the surface shape of a silicon wafer entering and leaving the field provided by the embodiment of the present invention;

[0026] Figure 6 Schematic structural diagram of a device for scanning the surface shape of a silicon wafer entering and leaving the field in the embodiment of the present invention.

[0027] Description of the drawings: A - Scanning starting point; B - Entrance intersection point; C - Entrance point; F - Edge safety area; H - Edge safety distance; L1 - Inner edge of the edge safety area; L2 - Preset full-surface shape scanning path; L3 - Edge of the silicon wafer; E1 - First sector; E2 - Second sector; E3 - Third sector; E4 - Fourth sector. Detailed implementation manners

[0028] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention is provided in conjunction with the accompanying drawings.

[0029] In order to be able to measure the height Z and the inclination angle Ry of the silicon wafer simultaneously, the horizontal sensor used in the embodiment of the present invention includes n measurement light spots, where n is an odd number. The central detection light spot is used to measure the height Z, and multiple light spots are combined for measurement and the inclination angle Ry is obtained by linearly fitting the measurement data. To avoid the height of the silicon wafer to be measured being outside the effective detection area, it is usually necessary to position the detection light spot within the detection window and use the measurement signal of the horizontal sensor as the height feedback for the closed-loop control of the measurement system, and control the silicon wafer to keep the surface of the silicon wafer at the zero height of the horizontal sensor during the step scanning process. At this time, the difference between the height change information of the silicon wafer stage recorded by the measurement system of the silicon wafer stage itself and the zero height information of the horizontal sensor represents the surface shape change of the silicon wafer.

[0030] Figure 1 Schematic diagram of the return signal of the horizontal sensor in the embodiment of the present invention. The two light intensity detection signals L l and L rWhen collecting signals, when the height of the measured surface moves in the Z direction, the collected signals change periodically. At present, the measurement range of the horizontal sensor on the lithography machine is only a few micrometers, while the change range of the silicon wafer surface shape may exceed the sensor range, resulting in inaccurate measurement data. In addition, the above-mentioned collected signals change periodically, which will cause problems in calculating the height data after leaving the optimal measurement range, and then reduce the scanning accuracy. Therefore, a method for scanning the silicon wafer surface shape during the entry and exit while performing a global scan of the silicon wafer is used to solve the problem that the horizontal sensor fails due to the protrusion, depression, burrs, etc. at the edge of the silicon wafer when entering the silicon wafer surface shape during the global scan.

[0031] Figure 2 This is a schematic diagram of the scanning trajectory of the silicon wafer during entry and exit in the embodiment of the present invention. Among them, the black square is the light spot exit area, and the "x" point is the entry point. When the horizontal sensor reaches the entry point, the silicon wafer stage is adjusted to obtain the entry adaptation height of the horizontal sensor. When performing a step scan of the silicon wafer surface shape, the detection light spot of the horizontal sensor will enter the silicon wafer at different positions. During the global scan of the silicon wafer, the first entry requires a capture operation, and the remaining entry postures are extrapolated through plane fitting.

[0032] Figure 3 This is a schematic diagram of the fitting entry of the silicon wafer edge scan in the embodiment of the present invention. Among them, the black square is the light spot exit area of column D, and the "x" point is the entry point C of column D+1. The inner edge L1 of the edge safety area is at a distance H from the silicon wafer edge L3. The area between the inner edge L1 of the edge safety area and the silicon wafer edge L3 forms the edge safety area F. According to the height information of each scan site in the exit area of column D, the height information of the entry intersection point B is fitted. When the measurement light spot of the horizontal sensor reaches the position of the entry point C, the height of the entry intersection point B is made to be at the same height as the zero plane of the horizontal sensor.

[0033] The embodiment of the present invention provides a method for scanning the silicon wafer surface shape during entry and exit. Refer to Figure 4 The schematic flow chart of a method for scanning the silicon wafer surface shape during entry and exit shown above. The above method includes:

[0034] S410, scanning the silicon wafer according to a preset global surface shape scanning path to obtain the height information of the light spot exit area.

[0035] Among them, the above-mentioned light spot exit area is the intersection area between the preset full-surface scanning path and the inner edge of the wafer edge safety area. The inner edge of the above-mentioned edge safety area is at a preset distance from the above-mentioned wafer edge. Among them, the above-mentioned preset distance is the wafer edge safety distance to ensure that the horizontal sensor has an adjustable error tolerance distance after entering the wafer, so that each detection light spot of the horizontal sensor focuses on the wafer surface, so that the horizontal sensor can work normally. The area between the inner edge of the above-mentioned edge safety area and the above-mentioned wafer edge is the edge safety area; preferably, the value of the above-mentioned preset distance is 3 mm; obtaining the height information of the above-mentioned light spot exit area can obtain the height information of the wafer edge in the exit area, so as to be able to predict the height information of other areas adjacent to the light spot exit area.

[0036] Optionally, scan the light spot exit area according to the light spot to obtain the height of each scan point in the above-mentioned light spot exit area. The height of each scan point is the height information of the light spot exit area; among them, each scan point is the intersection of the light spot and the inner side of the inner edge of the edge safety area in the exit area, and the center point of the wafer is located inside the inner edge of the above-mentioned edge safety area.

[0037] S420. Perform plane fitting on the height information of the above-mentioned light spot exit area to obtain the height information of the next entry intersection adjacent to the above-mentioned light spot exit area.

[0038] Among them, the above-mentioned entry intersection is the intersection where the center of the light spot re-enters the inner edge of the edge safety area along the preset full-surface scanning path. Obtaining the height information of the next entry intersection can obtain the height information of the wafer edge surface corresponding to this point, so as to adjust the wafer stage according to the above-mentioned height information of the wafer edge surface, so that the wafer is within the measurement range of the horizontal sensor when it enters.

[0039] Optionally, during the process of fitting points, only several edge information points are used for plane fitting. The point selection part is as Figure 2 shown, that is, each scan point in the light spot exit area. Since the sensor is horizontally distributed and vertically scanned, a set of measured data can be obtained. Perform plane fitting on the measured data and calculate the fitting residual. Plane fitting can formulate the scanned surface type, transform the scanned point data into a continuous and differentiable plane through formula fitting, and replace the fitting data at the mutation points beyond the fitting range to make the fitting plane smoother, and perform secondary fitting using the repaired data to obtain a fitting result that more conforms to the wafer edge data.

[0040] S430. Determine the attitude information of the wafer stage before the light spot enters according to the height information of the above-mentioned entry intersection.

[0041] Among them, the above wafer stage attitude information is the wafer stage height adjustment information determined according to the height information of the entry intersection point. After the height of the wafer stage is adjusted, the wafer stage reaches the target position, so that the wafer is within the measurement range of the horizontal sensor.

[0042] S440, before the light spot enters the field, control the movement of the wafer stage according to the above wafer stage attitude information so that the wafer is within the effective measurement range of the horizontal sensor.

[0043] Optionally, determine the entry point coordinates; before the light spot enters the wafer from the entry point, according to the wafer stage attitude information, control the upper surface of the edge of the wafer at the entry intersection point to be at the same height as the zero plane of the horizontal sensor at the entry point, so that the wafer is within the effective measurement range of the horizontal sensor after entry.

[0044] The method for scanning the wafer surface during entry and exit provided by the embodiment of the present invention scans the wafer according to a preset global surface profile scanning path to obtain the height information of the light spot exit area. The above light spot exit area is the area where the preset global surface profile scanning path intersects the wafer edge; perform plane fitting on the height information of the above light spot exit area to obtain the height information of the next entry intersection point adjacent to the above light spot exit area, and complete the prediction of the height of the next entry intersection point according to the edge height of the light spot exit area. The above entry intersection point is the intersection point where the center of the light spot enters the wafer edge again along the preset global surface profile scanning path; determine the wafer stage attitude information before the light spot enters according to the height information of the above entry intersection point; before the above light spot enters, control the movement of the wafer stage according to the above wafer stage attitude information so that the above wafer is within the effective measurement range of the horizontal sensor, that is, the method for scanning the wafer surface during entry and exit provided by the present invention calculates the height information of the entry point by fitting according to the height information of the light spot exit area, obtains the height information of the entry intersection point, and then obtains the pose information of the wafer stage according to the height information of the entry intersection point, so that the wafer can directly and accurately enter the measurement range of the horizontal sensor for global scanning of the wafer according to the pose information of the wafer stage, avoiding the situation that during the global scanning process, due to the change in the height of the wafer edge, the horizontal sensor has a periodic jump during measurement, resulting in a deviation between the measurement result and the displacement of the moving stage. In addition, it also avoids the need for a capture operation before each entry, thereby improving the global scanning efficiency.

[0045] In one embodiment, the embodiment of the present invention provides an implementation manner of performing plane fitting on the height information of the light spot exit area to obtain the height information of the next entry intersection point adjacent to the above light spot exit area.

[0046] Optionally, perform a first plane fitting according to the heights of each scanning point in the light spot exit area; calculate the difference between the fitting height of the first plane fitting and the heights of each scanning point in the light spot exit area; if the difference is greater than a preset value, replace the height of the scanning point in the light spot exit area corresponding to the value greater than the preset value with the fitting height of the first plane fitting, and then perform a second plane fitting; according to the second plane fitting, obtain the height information of the next entry intersection adjacent to the light spot exit area.

[0047] Optionally, determine the preset value according to the residual of the first plane fitting, and the preset value is three times the residual.

[0048] Exemplarily, as Figure 2 and Figure 3 shown, during the measurement of edge data, the data is extrapolated. After scanning the silicon wafer in the Y direction, several points inside the inner edge L1 of the safe area of the silicon wafer edge are used. The center point of the silicon wafer is located inside the inner edge L1 of the safe area of the silicon wafer edge; perform a plane fitting on the n measurement light spots arranged in the X direction and the XYZ information of each scanning point to obtain the entry and exit scanning fitting data representing the surface shape information of the silicon wafer edge in the D column of the Y-direction scan. Compare the fitting plane with the data acquisition plane of the silicon wafer, calculate the residual δ, and replace the data exceeding 3δ with the fitting data, and perform a secondary fitting on the replaced entry and exit scanning fitting data to more accurately determine the trend of the silicon wafer edge, so as to determine the entry coordinates (X scanin , Y scanin ) for accurately entering the (D + 1)th column during the global scan.

[0049] It should be noted that in plane fitting, different coordinate systems may lead to different fitting results. Therefore, different coordinate systems such as the Cartesian coordinate system and the polar coordinate system can be used in plane fitting, and their fitting results may be different. The fitting result with a smaller residual will be selected.

[0050] In one embodiment, the present invention provides an implementation manner for determining the entry point coordinates.

[0051] Optionally, determine the first direction position coordinate of the entry point as the central coordinate in the first direction of the preset global surface scan path. The first direction is parallel to the traveling direction of the light spot on the surface of the silicon wafer and parallel to the surface of the silicon wafer; determine the second direction coordinate of the initial contact point between the light spot and the silicon wafer edge as the second direction position coordinate of the entry point. The second direction is perpendicular to the first direction and parallel to the surface of the silicon wafer.

[0052] Exemplarily, the entry position of the (D + 1)th column (X scanin , Y scanin)Determined by the following information, such as Figure 2 As shown, the rectangular space divided by exposure fields will be formed on the silicon wafer to be measured; as Figure 3 shown, several measurement light spots of the horizontal sensor are distributed along the X direction. A Cartesian rectangular coordinate system is established at the center point of the silicon wafer. The four quadrants of the coordinate system divide the silicon wafer into 4 sectors, which are respectively denoted as the first sector E1, the second sector E2, the third sector E3, and the fourth sector E4, representing the four sectors in the first, second, third, and fourth quadrants respectively. According to the Y-direction scanning rule, if the entry position is in the E3 area during the scanning process, the exit position will be in the E2 area. During the scanning along the Y-axis, when the scanning D column enters the field, that is, when first entering the silicon wafer scanning area, an adjustment program needs to be executed to make the silicon wafer at the zero height of the horizontal sensor to complete the capture operation; after the D column scanning, the entry point C(X scanin ,Y scanin ) is located in the D + 1 column, the central detection light spot is at the central position of the D + 1 column, and the Y coordinate of the first scanning point where the right scanning light spot enters the edge safety area F is used as Y scanin , and the X coordinate of the central position of the D + 1 column is used as X scanin ; during the scanning process of the D + 1 column, scanning will be performed from the E3 area to the E2 area. Similarly, each scanning site in the silicon wafer exit area will be collected within the E2 area for plane fitting and quadratic fitting, so as to extrapolate and calculate the entry point of the D + 2 column (X scanin ,Y scanin ), X scanin is the X coordinate of the central position of the D + 2 column, and Y scanin is the Y coordinate of the first scanning point where the right scanning light spot enters the edge safety area F; in addition, when the scanning path crosses the Y axis of the coordinate system, X scanin is the X coordinate of the central position of the D + k column, and Y scanin becomes the Y coordinate of the first scanning point where the left scanning light spot enters the edge safety area F, where k is a positive integer.

[0053] In one embodiment, before step S410 of the embodiment of the present invention, the above method further includes an implementation manner of the wafer stage capturing the wafer.

[0054] Optionally, the upper surface of the edge of the wafer is moved to the zero plane of the horizontal sensor by the wafer stage to determine the scanning starting point.

[0055] As a feasible implementation manner, refer to Figure 5Schematic flowchart of another method for scanning the surface shape of a silicon wafer during entry and exit. The above method includes the following steps: S502 Capture the silicon wafer; S504 Obtain the height information of the light spot exit area; S506 Based on the height information of the light spot exit area, perform plane fitting; S508 Based on the plane fitting result, calculate the height of the entry intersection point; S510 Based on the height of the entry intersection point, make the silicon wafer accurately enter the zero plane of the horizontal sensor.

[0056] In step S502, by controlling the movement of the silicon wafer stage, the upper surface of the edge of the silicon wafer is moved to the zero plane of the horizontal sensor to complete the capture of the silicon wafer.

[0057] Exemplarily, as Figure 2 and Figure 3 shown, by controlling the movement of the silicon wafer stage, the upper surface of the edge of the silicon wafer is moved to the zero plane of the horizontal sensor to determine the scanning starting point A and complete the capture of the silicon wafer.

[0058] In step S504, when the light spot exits along the preset full surface shape scanning path, obtain the height information of the exit area.

[0059] Exemplarily, as Figure 2 shown, the black square in the figure is the light spot exit area, and several measuring light spots of the horizontal sensor are arranged in sequence along the X direction. When each measuring light spot exits along the inner edge L1 of the safety area, the height information measured by each of the above measuring light spots is the height information of each scanning site in the light spot exit area.

[0060] In step S506, perform plane fitting according to the height information of each scanning site in the light spot exit area, compare the fitted plane with the height information of each scanning site in the light spot exit area, calculate the residual δ. If there is data exceeding 3δ, use the fitted data for substitution, and perform secondary fitting on the substituted silicon wafer plane data to obtain the fitting result.

[0061] In step S508, extrapolate the height information of the entry intersection point according to the fitting result.

[0062] Exemplarily, as Figure 3 shown, determine the coordinates of the entry intersection point B through the intersection coordinates of the center line of the preset full surface shape scanning path and the inner edge of the safety distance and the light spot length information; according to the fitting function obtained by plane fitting and the coordinates of the entry intersection point B, determine the Z coordinate of the entry intersection point B, which is the height information of the entry intersection point B.

[0063] In step S510, the X coordinate of the center line of the Y-direction scanning segment of the preset full-surface shape scanning path is determined as the X coordinate of the entry point, and the Y coordinate of the initial contact point between the measurement light spot and the wafer edge is determined as the Y coordinate of the entry point, so as to determine the entry point coordinates; before the measurement light spot of the horizontal sensor reaches the entry point, according to the height of the entry intersection point, by controlling the wafer stage, the height corresponding to the entry intersection point is made to be at the same height as the zero plane of the horizontal sensor.

[0064] Exemplarily, as Figure 3 shown, the X coordinate of the center line of column D is determined as the X coordinate of the entry point C, and the Y coordinate of the initial contact point between the measurement light spot and the wafer edge L3 is determined as the Y coordinate of the entry point C, so as to realize the determination of the coordinates of the entry point C; when the measurement light spot of the horizontal sensor reaches the position of the entry point C, according to the height of the entry intersection point B, the posture adjustment information of the wafer stage is obtained, so that the height of the entry intersection point B is at the same height as the zero plane of the horizontal sensor.

[0065] The embodiment of the present invention provides a method for scanning the wafer surface shape during entry and exit. Under the scanning of this method, the scanning accuracy of the overall wafer surface shape can be improved, and the deviation of the global scanning result caused by the too large height difference of the horizontal sensor entering the wafer edge can be avoided. The wafer scanning method described by this method can ensure that the entry posture of the global scanning is within the best measurement range of the horizontal sensor. Since the measurement range of the horizontal sensor on the lithography machine is only a few micrometers, and the change range of the wafer surface shape may exceed the sensor range, resulting in inaccurate measurement data. The method for scanning the wafer surface shape during entry and exit provided by this embodiment can omit the global scanning process of the wafer edge surface shape, and calculate the height information of the entry point by fitting, so as to control the wafer to directly enter the measurement range for global scanning of the wafer.

[0066] The embodiment of the present invention also provides a device for scanning the wafer surface shape during entry and exit. Refer to Figure 6 the structural schematic diagram of a device for scanning the wafer surface shape during entry and exit shown. The above device includes:

[0067] An acquisition module 602, configured to scan the wafer according to a preset full-surface shape scanning path to obtain the height information of the light spot exit area, where the light spot exit area is the intersection area between the preset full-surface shape scanning path and the inner edge of the wafer edge safety area, and the inner edge of the edge safety area is at a preset distance from the wafer edge;

[0068] A fitting module 604, configured to perform plane fitting on the height information of the light spot exit area to obtain the height information of the next entry intersection point adjacent to the light spot exit area, where the entry intersection point is the intersection point where the center of the light spot re-enters the inner edge of the edge safety area along the preset full-surface shape scanning path;

[0069] A determination module 606, configured to determine the attitude information of the wafer stage before the light spot enters the field, according to the height information of the above-mentioned entry intersection point;

[0070] A control module 608, configured to control the wafer stage to move to a position where the wafer is within the effective measurement range of the horizontal sensor before the light spot enters the field, according to the above-mentioned attitude information of the wafer stage.

[0071] An embodiment of the present invention further provides a lithography machine, which includes a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, the steps of the above-mentioned wafer surface shape scanning method for entry and exit are implemented.

[0072] An embodiment of the present invention further provides a computer-readable storage medium, which stores a computer program. When the computer program is read and run by a processor, the above-mentioned wafer surface shape scanning method for entry and exit is implemented, and the same technical effects can be achieved. To avoid repetition, it will not be elaborated here. Among them, the computer-readable storage medium can be, for example, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc, etc.

[0073] Of course, those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by a computer program instructing a control device. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above-mentioned method embodiments. Among them, the storage medium can be a memory, a magnetic disk, an optical disc, etc.

[0074] Finally, it should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the element.

[0075] Each embodiment in this specification is described in a progressive manner. The key points of each embodiment are the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0076] Although the present invention has been disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for scanning the surface shape of a silicon wafer during entry and exit, characterized in that, The method includes: Scanning a silicon wafer according to a preset full-surface pattern scanning path to obtain height information of a light spot exit area, where the light spot exit area is an intersection area between the preset full-surface pattern scanning path and the inner edge of the silicon wafer edge safety area, and the inner edge of the edge safety area is at a preset distance from the silicon wafer edge; Performing a plane fitting on the height information of the light spot exit area to obtain height information of the next entry intersection adjacent to the light spot exit area, where the entry intersection is the intersection point where the center of the light spot re-enters the inner edge of the edge safety area along the preset full-surface pattern scanning path; Determining the silicon wafer stage attitude information before the light spot enters according to the height information of the entry intersection; Before the light spot enters, controlling the silicon wafer stage to move to a position where the silicon wafer is within the effective measurement range of the horizontal sensor according to the silicon wafer stage attitude information.

2. The method for scanning the silicon wafer surface shape for entry and exit according to claim 1, wherein The performing a plane fitting on the height information of the light spot exit area to obtain height information of the next entry intersection adjacent to the light spot exit area includes: Performing a first plane fitting according to the heights of each scanning point in the light spot exit area; Calculating the difference between the fitting height of the first plane fitting and the heights of each scanning point in the light spot exit area; If the difference is greater than a preset value, replacing the height of the scanning point in the light spot exit area corresponding to the value greater than the preset value with the fitting height of the first plane fitting, and then performing a second plane fitting; Obtaining the height information of the next entry intersection adjacent to the light spot exit area according to the second plane fitting.

3. The method for scanning the silicon wafer surface shape for entry and exit according to claim 2, wherein The method further includes: Determining the preset value according to the residual of the first plane fitting, where the preset value is three times the residual.

4. The method for scanning the surface shape of a silicon wafer for entry and exit according to claim 2, characterized in that, The scanning the silicon wafer according to a preset full-surface pattern scanning path to obtain height information of the light spot exit area includes: Scanning the light spot exit area according to the light spot to obtain the heights of each scanning point in the light spot exit area, where each scanning point is the intersection point of the light spot with the inner side of the inner edge of the edge safety area, and the center point of the silicon wafer is located on the inner side of the inner edge of the edge safety area.

5. The method for scanning the silicon wafer surface shape for entry and exit according to claim 1, characterized in that, The before the light spot enters, controlling the silicon wafer stage to move to a position where the silicon wafer is within the effective measurement range of the horizontal sensor according to the silicon wafer stage attitude information includes: Determining the entry point coordinates; Before the light spot enters the silicon wafer from the entry point, controlling the upper surface of the silicon wafer edge at the entry intersection to be at the same height as the zero plane of the horizontal sensor at the entry point according to the silicon wafer stage attitude information.

6. The method for scanning the silicon wafer surface shape for entry and exit according to claim 5, wherein The determining the entry point coordinates includes: Determining the first-direction position coordinate of the entry point as the center coordinate in the first direction of the preset full-surface pattern scanning path, where the first direction is parallel to the traveling direction of the light spot on the surface of the silicon wafer and the first direction is parallel to the surface of the silicon wafer; Determining the second-direction position coordinate of the entry point as the second-direction coordinate of the initial contact point between the light spot and the silicon wafer edge, where the second direction is perpendicular to the first direction and the second direction is parallel to the surface of the silicon wafer.

7. The method for scanning the silicon wafer surface shape for entry and exit according to claim 1, characterized in that, Before the step of scanning the silicon wafer according to the preset full-surface profile scanning path, it includes: Moving the upper surface of the edge of the silicon wafer to the zero plane of the horizontal sensor through the silicon wafer stage to determine the scanning starting point.

8. An in-out silicon wafer surface shape scanning device, characterized in that, The device includes: An acquisition module, configured to scan the silicon wafer according to a preset full-surface profile scanning path to obtain height information of a light spot exit area, where the light spot exit area is an intersection area between the preset full-surface profile scanning path and the inner edge of the edge safety area of the silicon wafer, and the inner edge of the edge safety area is at a preset distance from the edge of the silicon wafer; A fitting module, configured to perform plane fitting on the height information of the light spot exit area to obtain height information of the next entry intersection adjacent to the light spot exit area, where the entry intersection is the intersection where the center of the light spot re-enters the inner edge of the edge safety area along the preset full-surface profile scanning path; A determination module, configured to determine the attitude information of the silicon wafer stage before the light spot enters according to the height information of the entry intersection; A control module, configured to control the movement of the silicon wafer stage to make the silicon wafer within the effective measurement range of the horizontal sensor according to the attitude information of the silicon wafer stage before the light spot enters.

9. A lithography machine, the lithography machine comprising a memory and a processor, the memory storing a computer program that can run on the processor, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and when the computer program is read and run by the processor, it implements the method according to any one of claims 1-7.

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