Film thickness measurement calibration method and film thickness measurement calibration system

Abstract

The invention relates to a film thickness measurement calibration method and a film thickness measurement calibration system, which are used for calibrating a measurement position when an optical film thickness measurement device is used for measuring the film thickness on a wafer, a cutting channel area of the wafer is provided with a target liner, and a film to be measured covers the surface of the target liner, comparing the current test area photo with an ideal measurement area pattern taking the target liner as a central point, judging whether the pattern offset of the target liner in the current test area photo is smaller than a set threshold, if so, judging that the current test area photo is valid, and if not, judging that the current test area photo is not valid. The optical film thickness measuring equipment takes the central point of the current test area photo as the measuring position, if not, the current test area photo is judged to be invalid, and the corresponding correction suggestion is fed back, so that the risk that the measuring result is abnormal due to the fact that the position of the gasket to be measured in the measuring area photo deviates is reduced.

Description

Technical Field

[0001] The present invention relates to the field of film thickness measurement, and in particular to a film thickness measurement calibration method and a film thickness measurement calibration system. Background Art

[0002] In the semiconductor manufacturing process, it is usually necessary to monitor the thickness of the film. Using the principle of reflection interference, the film thickness is measured optically. It has the advantages of non-contact, high measurement accuracy and high speed, and has been widely used.

[0003] When measuring the thickness of a thin film formed on a wafer during a semiconductor manufacturing process by optical means, the die region is usually not suitable for film thickness measurement because of its complex graphic structure and uneven surface height. The commonly used method is to set a pad with a flat top surface in the cutting path area, and optically measure the thickness of the thin film covering the surface of the pad to infer the thickness of the same thin film in the die region.

[0004] Usually, more than one pad is set in the scribe line area, and each pad is small in size (about tens of microns in length). Existing optical film thickness measurement equipment (such as KLA's SpectraFilm TM When locating the target pad, the F1 thin film measurement system usually first determines the center of the wafer and the chip area range, then moves the wafer and performs at least one alignment to locate a measurement area where the target pad is located. The equipment takes a photo of the measurement area and then obtains the center point of the photo as the measurement position. Figure 1 The target pad 10 in the measurement area photo and the center point of the photo as the measurement position 11 are shown in an ideal situation. Figure 1 As shown, the measurement area photo is a rectangle, and the intersection point of the diagonal lines of the rectangle is the center point of the photo, that is, the measurement position 11.

[0005] However, in the process of locating the measurement area where the target pad 10 is located, the position of the target pad 10 may be offset in the obtained measurement area photo due to problems such as large alignment errors or pattern recognition errors. Figure 2 , which shows the target pad 10 when the pad position in the measurement area photo is offset and the center point of the photo as the measurement position 11. It can be seen that due to the offset of the position of the target pad 10 in the measurement area photo, the target pad 10 does not fall in the center area of ​​the photo. At this time, if the center point of the photo is used as the measurement position 11, the measurement spot may not irradiate the target pad 10, which will cause an abnormal measurement spectrum and then an abnormal film thickness measurement result. Summary of the invention

[0006] In order to obtain accurate film thickness measurement results, the present invention provides a film thickness measurement calibration method and a film thickness measurement calibration system.

[0007] In one aspect, the present invention provides a film thickness measurement calibration method, which is used to calibrate a measurement position when measuring the thickness of a film to be measured on a wafer using an optical film thickness measurement device, wherein a cutting path area of ​​the wafer has a target pad at a target measurement position, and the film to be measured covers a surface of the target pad, and the film thickness measurement calibration method comprises:

[0008] Acquire the length and width data of the target pad and the length and width data of the test area photograph collected by the optical film thickness measurement device;

[0009] Constructing an ideal measurement area pattern, wherein the outer peripheral contour of the ideal measurement area pattern is the same as the measurement area photograph and the target pad is used as the center point;

[0010] Acquire a current test area photo, wherein the current test area photo includes a pattern of the target pad;

[0011] Determine whether the graphic offset of the target pad in the current test area photo is less than a set threshold value compared to the ideal measurement area pattern. If so, determine that the current test area photo is valid, and make the optical film thickness measurement device use the center point of the current test area photo as the measurement position. If not, determine that the current test area photo is invalid, and feedback correction advice to make the graphic offset less than the set threshold value.

[0012] Optionally, the film thickness measurement and calibration method further includes:

[0013] After adjusting the relative positions of the camera used by the optical film thickness measurement device to take the test area photo and the wafer according to the correction opinion, an updated current test area photo is obtained, and it is determined whether the graphic offset of the target pad in the updated current test area photo is greater than the set threshold compared with the ideal measurement area pattern, and information on whether the updated current test area photo is valid or invalid and corresponding correction opinions are given based on the judgment result.

[0014] Optionally, the pattern of the target pad has a first length side, a second length side, a first width side and a second width side; the outer contour of the ideal measurement area pattern has a first extended length side formed by translating a straight line covering the first length side in a direction away from the second length side by a first extension amount, a second extended length side formed by translating a straight line covering the second length side in a direction away from the first length side by a second extension amount, a first extended width side formed by translating a straight line covering the first width side in a direction away from the second width side by a third extension amount, and a second extended width side formed by translating a straight line covering the second width side in a direction away from the first width side by a fourth extension amount.

[0015] Optionally, an absolute value of a difference between the first extension amount and the second extension amount is smaller than a length setting error, and an absolute value of a difference between the third extension amount and the fourth extension amount is smaller than a width setting error.

[0016] Optionally, the outer contour of the current test area photo has a first photo length edge in the same direction as the first extended length edge, a second photo length edge in the same direction as the second extended length edge, a first photo width edge in the same direction as the first extended width edge, and a second photo width edge in the same direction as the second extended width edge.

[0017] Optionally, judging whether the graphic offset of the target pad in the current test area photo is greater than a set threshold compared with the ideal measurement area pattern includes:

[0018] Measuring the current measurement area photo to obtain, in the current test area photo, a first spacing between the length side of the first photo and the target pad, a second spacing between the length side of the second photo and the target pad, a third spacing between the width side of the first photo and the target pad, and a fourth spacing between the width side of the second photo and the target pad;

[0019] Determine whether the absolute value of the difference between the first spacing and the first expansion amount, the absolute value of the difference between the second spacing and the second expansion amount, the absolute value of the difference between the third spacing and the third expansion amount, and the absolute value of the difference between the fourth spacing and the fourth expansion amount are all less than the set threshold; if so, determine that the current test area photograph is valid, and make the optical film thickness measurement device use the center point of the current test area photograph as the measurement position; if not, determine that the current test area photograph is invalid and feedback the correction advice.

[0020] Optionally, the correction advice is obtained based on at least one of a difference between the first spacing and the first expansion amount, a difference between the second spacing and the second expansion amount, a difference between the third spacing and the third expansion amount, and a difference between the fourth spacing and the fourth expansion amount.

[0021] In one aspect, the present invention provides a film thickness measurement calibration system, which is used to calibrate a measurement position when measuring the thickness of a film to be measured on a wafer using an optical film thickness measurement device, wherein a cutting road area of ​​the wafer has a target pad at a target measurement position, and the film to be measured covers a surface of the target pad, and the film thickness measurement calibration system comprises:

[0022] A data acquisition module configured to acquire the length and width data of the target pad and the length and width data of the test area photograph collected by the optical film thickness measurement device;

[0023] A pattern construction module configured to construct an ideal measurement area pattern, wherein the outer peripheral contour of the ideal measurement area pattern is the same as the measurement area photo and takes the target pad as a center point;

[0024] a photo calling module, configured to obtain a photo of a current test area, wherein the photo of the current test area includes a graphic of the target pad; and

[0025] The analysis module is configured to determine whether the graphic offset of the target pad in the current test area photo is less than a set threshold value compared to the ideal measurement area pattern. If so, the current test area photo is determined to be valid, and the optical film thickness measurement device uses the center point of the current test area photo as the measurement position. If not, the current test area photo is determined to be invalid and feedback is given to correct the graphic offset to be less than the set threshold value.

[0026] Optionally, the pattern of the target pad has a first length side, a second length side, a first width side and a second width side; the outer contour of the ideal measurement area pattern has a first extended length side formed by translating a straight line covering the first length side in a direction away from the second length side by a first extension amount, a second extended length side formed by translating a straight line covering the second length side in a direction away from the first length side by a second extension amount, a third extended width side formed by translating a straight line covering the first width side in a direction away from the second width side by a third extension amount, and a second extended width side formed by translating a straight line covering the second width side in a direction away from the first width side by a fourth extension amount; and the absolute value of the difference between the first extension amount and the second extension amount is less than the length setting error, and the absolute value of the difference between the third extension amount and the fourth extension amount is less than the width setting error.

[0027] Optionally, the analysis module includes:

[0028] a measuring unit configured to measure the current measurement area photo to obtain a first spacing of a target pad in the current test area photo from a length edge of the first photo, a second spacing from a length edge of the second photo, a third spacing from a width edge of the first photo, and a fourth spacing from a width edge of the second photo;

[0029] The data processing unit is configured to determine whether the absolute value of the difference between the first spacing and the first expansion amount, the absolute value of the difference between the second spacing and the second expansion amount, the absolute value of the difference between the third spacing and the third expansion amount, and the absolute value of the difference between the fourth spacing and the fourth expansion amount are all less than the set threshold value; if so, the current test area photo is valid, so that the optical film thickness measuring device uses the center point of the current test area photo as the measurement position; if not, the current test area photo is invalid.

[0030] The film thickness measurement calibration method and film thickness measurement calibration system provided by the present invention can calibrate the measurement position when measuring the thickness of the film to be measured on the wafer using an optical film thickness measurement device, wherein a current test area photo is compared with an ideal measurement area pattern with the target pad as the center point, and it is determined whether the graphic offset of the target pad in the current test area photo is less than a set threshold compared with the ideal measurement area pattern. If so, it is determined that the current test area photo is valid, and the optical film thickness measurement device uses the center point of the current test area photo as the measurement position. If not, it is determined that the current test area photo is invalid and corresponding correction opinions are fed back. It can be seen that by comparing the current test area photograph with the ideal measurement area pattern, information on whether the target pad in the current test area photograph is basically at the center point of the photograph can be obtained, and adjustments can be made according to the correction opinions to calibrate the target pad in the direction of the center point of the photograph. This helps to reduce the risk of abnormal measurement results due to the offset of the pad position to be measured in the measurement area photograph. When the center point of the corrected current test area photograph is used as the measurement position, since the target pad is basically at the center point of the photograph, it can be ensured that the measurement spot falls within the target pad range, thereby helping to obtain accurate optical film thickness measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the target pad in the measurement area photo and the center point of the photo under ideal conditions.

[0032] Figure 2 It is a schematic diagram of the target pad and the center point of the photo when the pad position in the measurement area photo is offset.

[0033] Figure 3 4 is a flow chart of a film thickness measurement and calibration method according to an embodiment of the present invention.

[0034] Figure 4 Schematic diagram of an ideal measurement area pattern in one embodiment of the present invention.

[0035] Figure 5 Schematic diagram of a photo of the current test area in one embodiment of the present invention.

[0036] Figure 6 Schematic diagram of a film thickness measurement and calibration system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following is a further detailed description of the film thickness measurement calibration method and film thickness measurement calibration system of the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be understood that the drawings in the specification are all 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.

[0038] Currently, when using optical measurement to measure the film thickness on the pad surface in the cutting area, the optical film thickness measurement equipment first determines the center of the wafer and the chip area (die) range in order to obtain the measurement position as the incident point of the light spot. Then, the wafer must be moved and aligned at least once to locate the measurement area where the target pad is located and reduce the movement error. TM Taking the F1 thin film measurement system as an example, its search for the target pad includes the following process: first, the wafer center is determined by identifying the edge arc of the wafer; the wafer is moved and aligned through the characteristic pattern to obtain the cutting path range outside the chip area, and a first characteristic point with a first distance (R1) from the wafer center is defined in the cutting path range; when the distance between the target pad to be found and the first characteristic point is still far, in order to reduce the movement error, the wafer is moved again and aligned through the characteristic pattern, and a second characteristic point is defined at a position closer to the target pad in the cutting path range, and the second characteristic point is a second distance (R2) from the first characteristic point, and the target pad is a third distance (R3) from the second characteristic point; then a photo of the test area containing the target pad is taken; the center point of the photo of the test area is used as the measurement position. However, referring to Figure 2 When locating the measurement area where the target pad is located, the position of the target pad may be offset in the measurement area photo due to problems such as large alignment errors or graphic recognition errors, thereby causing abnormal measurement results.

[0039] An embodiment of the present invention relates to a film thickness measurement calibration method and a film thickness measurement calibration system, which can calibrate the measurement position when measuring the thickness of a thin film to be measured on a wafer using an optical film thickness measurement device, thereby helping to reduce the risk of abnormal measurement results due to the offset of the position of the pad to be measured in a measurement area photo.

[0040] The wafer has a target pad at a target measurement position in the scribe line area, and the film to be measured covers the surface of the target pad. Optionally, the wafer has multiple pads in the scribe line area. When measuring the film thickness, the film thickness on the target pads in different areas can be measured in multiple areas on the wafer and then the average value can be taken to improve the film thickness measurement accuracy.

[0041] Reference Figure 3 According to the film thickness measurement calibration method of an embodiment of the present invention, first, step S1 is executed to obtain the length and width data of the target pad at the target measurement position and the length and width data of the test area photo collected by the optical film thickness measurement equipment.

[0042] The length and width data of the target pad are data that need to be determined when designing the layout of the target pad, and are known data that can be obtained from wafer design data. Figure 1 As shown, other pads may be formed around the target pad, and the distance between two adjacent pads may also be obtained from the wafer design data, and the sizes of the pads may be the same, for example. The target pad is, for example, rectangular. As an example, the length of each pad is about 50 microns to 60 microns. The length and width data of the test area photo collected by the optical film thickness measurement device may be obtained according to the instruction manual, parameter settings or historical test area photos of the optical film thickness measurement device.

[0043] Reference Figure 3 , then, executing step S2, constructing an ideal measurement area pattern, the outer contour of the ideal measurement area pattern is the same as the measurement area photo and takes the target pad as the center point.

[0044] Since the optical film thickness measuring device can use the center point of the photo of the designated test area as the measurement position, ideally, when the center point of the photo is the target pad, the measurement position is within the target pad range, which can ensure the accuracy of the measurement position. In this embodiment, step S2 is used to construct a test area photo template under the ideal condition for comparison. As an example, according to the size of the test area picture, the outer contour of the ideal measurement area pattern is a rectangle with a length of 22 cm and a width of 17 cm.

[0045] In the ideal measurement area pattern, the target pad is located at the center of the pattern, that is, the target pad is located at the symmetric center of the rectangle of the ideal measurement area pattern. When constructing the ideal measurement area pattern, the center of the pattern can be determined by the target pad first, and then the graphics of each pad in the ideal measurement area pattern are obtained according to the length and width data of the target pad and the distance data between the target pad and the surrounding pads, and then the target pad is symmetrically expanded in the length direction and width direction respectively, until the distance between the two boundary lines formed along the length direction of the target pad is substantially equal to the length of the test area photo, and the distance between the two boundary lines formed along the width direction of the target pad is substantially equal to the width of the test area photo.

[0046] Reference Figure 4 The graphic of the target pad 10 has a first length side L1, a second length side L2, a first width side W1 and a second width side W2; the outer peripheral contour of the ideal measurement area pattern has a first extended length side L1a formed by translating a straight line covering the first length side W1 in a direction away from the second length side L2 by a first extension amount TR1, a second extended length side L2a formed by translating a straight line covering the second length side L2 in a direction away from the first length side L1 by a second extension amount TR2, a first extended width side W1a formed by translating a straight line covering the first width side W1 in a direction away from the second width side W2 by a third extension amount TR3, and a second extended width side W2a formed by translating a straight line covering the second width side W2 in a direction away from the first width side W1 by a fourth extension amount TR4.

[0047] The absolute value of the difference between the first extension amount TR1 and the second extension amount TR2 is, for example, less than a length setting error, and the absolute value of the difference between the third extension amount TR3 and the fourth extension amount TR4 is, for example, less than a width setting error. Optionally, the first extension amount TR1 is equal to the second extension amount TR2, and the third extension amount TR3 is equal to the fourth extension amount TR4.

[0048] Reference Figure 3 Then, step S3 is executed to obtain a current test area photo, where the current test area photo includes a graphic of the target pad 10 .

[0049] The current test area photo can be taken by an optical film thickness measurement device, which is a photo of the measurement area where the target pad 10 on the wafer to be tested is located. The optical film thickness measurement device is, for example, SpectraFilm from KLA. TMF1 Thin Film Measurement System. Before obtaining the current test area photo, the existing functions of the system can be used to determine the center of the wafer, then the wafer is moved and aligned at least once to obtain feature points near the target pad 10, and then a photo of the current test area including the target pad 10 is taken.

[0050] Reference Figure 5 Optionally, the outer contour of the current test area photo has a first photo length side L1a', a second photo length side L2a', a first photo width side W1a' and a second photo width side W2a', the first photo length side L1a' is in the same direction as the first extended length side L1a, the second photo length side L2a' is in the same direction as the second extended length side L2a, the first photo width side W1a' is in the same direction as the first extended width side W1a, and the second photo width side W2a' is in the same direction as the second extended width side W2a. As an example, the first photo length side L1a' and the second photo length side L2a' extend along the length direction of the target pad 10 in the current test area photo, and the first photo width side W1a' and the second photo width side W2a' extend along the width direction of the target pad 10 in the current test area photo. However, this is not limited to this. Due to errors, at least one side of the current test area photo may also be non-parallel to the side of the target pad 10 in the photo. As mentioned above, in the photo of the current measurement area taken by positioning the wafer using the optical film thickness measurement device, the target pad 10 may not be located at the center point of the photo, but may be offset from the center point of the photo.

[0051] Reference Figure 3 Then, step S4 is executed to determine whether the graphic offset of the target pad 10 in the current test area photo is less than the set threshold value compared with the ideal measurement area pattern. If so, the current test area photo is determined to be valid, and the optical film thickness measuring device uses the center point of the current test area photo as the measurement position. If not, the current test area photo is determined to be invalid, and correction advice is fed back to make the graphic offset less than the set threshold value.

[0052] Specifically, step S4 may include the following process:

[0053] Reference Figure 5, measuring the current measurement area photo, obtaining a first spacing RR1 between the first photo length side L1a' and the target pad 10, a second spacing RR2 between the second photo length side L2a' and the target pad 10, a third spacing RR3 between the first photo width side W1a' and the target pad 10, and a fourth spacing RR4 between the second photo width side W2a' and the target pad 10 in the current test area photo, optionally, each of the first spacing RR1, the second spacing RR2, the third spacing RR3 and the fourth spacing RR4 can be measured multiple times, and the corresponding first spacing RR1, the second spacing RR2, the third spacing RR3 and the fourth spacing RR4 can be obtained according to the average value or the minimum value of the multiple measurement values;

[0054] Determine whether the absolute value of the difference between the first spacing RR1 and the first expansion amount TR1, the absolute value of the difference between the second spacing RR2 and the second expansion amount TR2, the absolute value of the difference between the third spacing RR3 and the third expansion amount TR3, and the absolute value of the difference between the fourth spacing RR4 and the fourth expansion amount TR4 are all less than the set threshold value. If so, determine that the current test area photo is valid, and make the optical film thickness measuring device use the center point of the current test area photo as the measurement position. If not, determine that the current test area photo is invalid and feedback the correction advice.

[0055] The correction opinion is obtained based on at least one of the difference between the first spacing RR1 and the first expansion amount TR1, the difference between the second spacing RR2 and the second expansion amount TR2, the difference between the third spacing RR3 and the third expansion amount TR3, and the difference between the fourth spacing RR4 and the fourth expansion amount TR4. For example, based on the information of these differences, the offset direction of the current target pad 10 in the current measurement area photo can be obtained. In order to make it located at the center point of the measurement area photo, the wafer can be moved in the direction of reducing the offset by a corresponding distance. The correction opinion can, for example, give the wafer moving direction and the distance to be moved to reduce the offset, but is not limited to this. In another embodiment, the camera on the optical film thickness measurement device (the camera is used to take the measurement area photo) can be moved to reduce the offset of the target pad 10 in the measurement area photo, or the wafer and the camera on the optical film thickness measurement device can be moved simultaneously to reduce the offset of the target pad 10 in the measurement area photo.

[0056] After adjusting the relative position of the camera of the optical film thickness measurement device and the wafer according to the correction opinion, the film thickness measurement calibration method may also include the following process: obtaining the updated current test area photo again, and judging whether the graphic offset of the target pad 10 in the updated current test area photo is greater than the set threshold value compared with the ideal measurement area pattern, and providing information on whether the updated current test area photo is valid or invalid and the corresponding correction opinion according to the judgment result. This correction process can be repeated multiple times until the relative position of the camera of the optical film thickness measurement device and the wafer is adjusted according to the correction opinion, and the graphic offset of the target pad 10 in the updated current test area photo is less than the set threshold value, at which time the corresponding instruction can be output so that the optical film thickness measurement device can perform optical film thickness measurement with the center point of the updated current test area photo as the measurement position.

[0057] The above-mentioned film thickness measurement and calibration method can be executed by a computer processor in the form of computer instructions, or can be executed using multiple functional modules of a computer. For example, the film thickness measurement and calibration method can be stored in various storage media in the form of computer instructions. When the executable instructions are executed by the processor, the above-mentioned film thickness measurement and calibration method can be executed.

[0058] The embodiment of the present invention also relates to a film thickness measurement calibration system. The film thickness measurement calibration system is used to calibrate the measurement position when measuring the thickness of a film to be measured on a wafer using an optical film thickness measurement device, wherein the cutting path area of ​​the wafer has a target pad 10 at a target measurement position, and the film to be measured covers the surface of the target pad 10.

[0059] Reference Figure 6 , the film thickness measurement calibration system may include a data acquisition module, a pattern construction module, a photo call module and an analysis module; the data acquisition module is configured to obtain the length and width data of the target pad 10 and the length and width data of the test area photo collected by the optical film thickness measurement device; the pattern construction module is configured to construct an ideal measurement area pattern, the outer contour of the ideal measurement area pattern is the same as the measurement area photo and takes the target pad 10 as the center point, the photo call module is configured to obtain the current test area photo, and the current test area photo contains the graphic of the target pad 10; the analysis module is configured to determine whether the graphic offset of the target pad 10 in the current test area photo is less than a set threshold value compared with the ideal measurement area pattern, if so, the current test area photo is determined to be valid, so that the optical film thickness measurement device uses the center point of the current test area photo as the measurement position, if not, the current test area photo is determined to be invalid and feedback is given to correct the graphic offset less than the set threshold value.

[0060] Reference Figure 4 and Figure 5 Optionally, the target pad 10 has a first length side L1, a second length side L2, a first width side W1 and a second width side W2; Figure 4 As shown, the outer peripheral contour of the ideal measurement area pattern has a first extended length side L1a formed by translating the straight line covering the first length side L1 in the direction away from the second length side L2 by the first extension amount TR1, a second extended length side L2a formed by translating the straight line covering the second length side L2 in the direction away from the first length side L1 by the second extension amount TR2, a first extended width side W1a formed by translating the straight line covering the first width side W1 in the direction away from the second width side W2 by the third extension amount TR3, and a second extended width side W2a formed by translating the straight line covering the second width side W2 in the direction away from the first width side W1 by the fourth extension amount TR4; and the absolute value of the difference between the first extension amount TR1 and the second extension amount TR2 is less than the length setting error, and the absolute value of the difference between the third extension amount TR3 and the fourth extension amount TR4 is less than the width setting error.

[0061] The outer contour of the current test area photo has a first photo length side L1a', a second photo length side L2a', a first photo width side W1a' and a second photo width side W2a', the first photo length side L1a' is in the same direction as the first extended length side L1a, the second photo length side L2a' is in the same direction as the second extended length side L2a, the first photo width side W1a' is in the same direction as the first extended width side W1a, and the second photo width side W2a' is in the same direction as the second extended width side W2a.

[0062] Further, refer to Figure 6, the analysis module may include a measuring unit and a data processing unit; the measuring unit is configured to measure the current measurement area photo to obtain a first spacing RR1 between the first photo length side L1a' and the target pad 10, a second spacing RR2 between the second photo length side L2a' and the target pad 10, a third spacing RR3 between the first photo width side W1a' and the target pad 10, and a fourth spacing RR4 between the second photo width side W2a' and the target pad 10 in the current test area photo; the data processing unit is configured to determine Determine whether the absolute value of the difference between the first spacing RR1 and the first expansion amount TR1, the absolute value of the difference between the second spacing RR2 and the second expansion amount TR2, the absolute value of the difference between the third spacing RR3 and the third expansion amount TR3, and the absolute value of the difference between the fourth spacing RR4 and the fourth expansion amount TR4 are all less than the set threshold. If so, determine that the current test area photo is valid, and make the optical film thickness measuring device use the center point of the current test area photo as the measurement position. If not, determine that the current test area photo is invalid and feedback the correction advice.

[0063] The various modules of the film thickness measurement and calibration system correspond to the various steps of the film thickness measurement and calibration method in the aforementioned embodiment, and can calibrate the measurement position when the optical film thickness measurement device is used to measure the thickness of the film to be measured on the wafer. Therefore, the various modules of the film thickness measurement and calibration system can be understood with reference to the description of the film thickness measurement and calibration method in the aforementioned embodiment. It should be noted that the embodiments described above are merely schematic, wherein the modules or units described as separate components may or may not be physically separated, and the components described as modules or units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units, and some or all of the modules may be selected according to actual needs to achieve the purpose of the disclosed scheme. For example, the film thickness measurement and calibration system can be integrated with an optical film thickness measurement device to facilitate automatic calibration of the measurement position when the film thickness is measured using the optical film thickness measurement device.

[0064] The film thickness measurement calibration method and film thickness measurement calibration system described in the above embodiments can calibrate the measurement position when using an optical film thickness measurement device to measure the thickness of a film to be measured on a wafer, wherein a current test area photograph is compared with an ideal measurement area pattern with the target pad 10 as the center point, and it is determined whether the graphic offset of the target pad in the current test area photograph is less than a set threshold value compared to the ideal measurement area pattern. If so, it is determined that the current test area photograph is valid, and the optical film thickness measurement device uses the center point of the current test area photograph as the measurement position. If not, it is determined that the current test area photograph is invalid and the corresponding correction intention is fed back. It can be seen that by comparing the current test area photograph with the ideal measurement area pattern, information on whether the target pad 10 in the current test area photograph is basically at the center point of the photograph can be obtained, and adjustment can be made according to the correction opinion to calibrate the target pad in the direction of the center point of the photograph. This helps to reduce the risk of abnormal measurement results due to the offset of the target pad position in the measurement area photograph. When the center point of the corrected current test area photograph is used as the measurement position, since the target pad 10 is basically at the center point of the photograph, it can be ensured that the measurement spot falls within the target pad range, thereby helping to obtain accurate optical film thickness measurement results.

[0065] It should be noted that the embodiments of this specification are described in a progressive manner. For the film thickness measurement and calibration system disclosed in the embodiments, since it corresponds to the film thickness measurement and calibration method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0066] The above description is only a description of the preferred embodiment of the present invention, and is not any limitation on the scope of rights of the present invention. Any technical personnel in this field can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A film thickness measurement and calibration method, characterized in that: The film thickness measurement calibration method is used to calibrate the measurement position when measuring the thickness of a film to be measured on a wafer using an optical film thickness measurement device, wherein a cutting path area of ​​the wafer has a target pad at a target measurement position, and the film to be measured covers the surface of the target pad. The film thickness measurement calibration method comprises: Acquire the length and width data of the target pad and the length and width data of the test area photograph collected by the optical film thickness measurement device; Constructing an ideal measurement area pattern, wherein the outer peripheral contour of the ideal measurement area pattern is the same as the measurement area photograph and the target pad is used as the center point; Acquire a current test area photo, wherein the current test area photo includes a graphic of the target pad; Determine whether the graphic offset of the target pad in the current test area photo is less than a set threshold value compared to the ideal measurement area pattern. If so, determine that the current test area photo is valid, and make the optical film thickness measurement device use the center point of the current test area photo as the measurement position. If not, determine that the current test area photo is invalid, and feedback correction advice to make the graphic offset less than the set threshold value.

2. The film thickness measurement calibration method according to claim 1, characterized in that: Also includes: After adjusting the relative positions of the camera used by the optical film thickness measurement device to take the test area photo and the wafer according to the correction opinion, an updated current test area photo is obtained, and it is determined whether the graphic offset of the target pad in the updated current test area photo is greater than the set threshold compared with the ideal measurement area pattern, and information on whether the updated current test area photo is valid or invalid and corresponding correction opinions are given based on the judgment result.

3. The film thickness measurement calibration method according to claim 1, characterized in that: The pattern of the target pad has a first length side, a second length side, a first width side and a second width side; the outer contour of the ideal measurement area pattern has a first extended length side formed by translating a straight line covering the first length side in a direction away from the second length side by a first extension amount, a second extended length side formed by translating a straight line covering the second length side in a direction away from the first length side by a second extension amount, a first extended width side formed by translating a straight line covering the first width side in a direction away from the second width side by a third extension amount, and a second extended width side formed by translating a straight line covering the second width side in a direction away from the first width side by a fourth extension amount.

4. The film thickness measurement calibration method according to claim 3, characterized in that: An absolute value of a difference between the first extension amount and the second extension amount is smaller than a length setting error, and an absolute value of a difference between the third extension amount and the fourth extension amount is smaller than a width setting error.

5. The film thickness measurement calibration method according to claim 3, characterized in that: The outer contour of the current test area photo has a first photo length side in the same direction as the first extended length side, a second photo length side in the same direction as the second extended length side, a first photo width side in the same direction as the first extended width side, and a second photo width side in the same direction as the second extended width side.

6. The film thickness measurement calibration method according to claim 3, characterized in that: Determining whether the pattern offset of the target pad in the current test area photo is greater than a set threshold compared to the ideal measurement area pattern includes: Measuring the current measurement area photo to obtain, in the current test area photo, a first spacing between the length side of the first photo and the target pad, a second spacing between the length side of the second photo and the target pad, a third spacing between the width side of the first photo and the target pad, and a fourth spacing between the width side of the second photo and the target pad; Determine whether the absolute value of the difference between the first spacing and the first expansion amount, the absolute value of the difference between the second spacing and the second expansion amount, the absolute value of the difference between the third spacing and the third expansion amount, and the absolute value of the difference between the fourth spacing and the fourth expansion amount are all less than the set threshold; if so, determine that the current test area photograph is valid, and make the optical film thickness measurement device use the center point of the current test area photograph as the measurement position; if not, determine that the current test area photograph is invalid and feedback the correction advice.

7. The film thickness measurement calibration method according to claim 6, characterized in that: The correction advice is obtained based on at least one of the difference between the first spacing and the first expansion amount, the difference between the second spacing and the second expansion amount, the difference between the third spacing and the third expansion amount, and the difference between the fourth spacing and the fourth expansion amount.

8. A film thickness measurement and calibration system, characterized in that: Used to calibrate the measurement position when measuring the thickness of a film to be measured on a wafer using an optical film thickness measurement device, wherein the cutting road area of ​​the wafer has a target pad at a target measurement position, and the film to be measured covers the surface of the target pad. The film thickness measurement calibration system comprises: A data acquisition module configured to acquire the length and width data of the target pad and the length and width data of the test area photograph collected by the optical film thickness measurement device; A pattern construction module configured to construct an ideal measurement area pattern, wherein the outer peripheral contour of the ideal measurement area pattern is the same as the measurement area photo and takes the target pad as a center point; a photo calling module, configured to obtain a photo of a current test area, wherein the photo of the current test area includes a graphic of the target pad; and The analysis module is configured to determine whether the graphic offset of the target pad in the current test area photo is less than a set threshold value compared to the ideal measurement area pattern. If so, the current test area photo is determined to be valid, and the optical film thickness measurement device uses the center point of the current test area photo as the measurement position. If not, the current test area photo is determined to be invalid and feedback is given to correct the graphic offset to be less than the set threshold value.

9. The film thickness measurement and calibration system according to claim 8, characterized in that: The pattern of the target pad has a first length side, a second length side, a first width side and a second width side; the outer contour of the ideal measurement area pattern has a first extended length side formed by translating a straight line covering the first length side in a direction away from the second length side by a first extension amount, a second extended length side formed by translating a straight line covering the second length side in a direction away from the first length side by a second extension amount, a third extended width side formed by translating a straight line covering the first width side in a direction away from the second width side by a third extension amount, and a second extended width side formed by translating a straight line covering the second width side in a direction away from the first width side by a fourth extension amount; and the absolute value of the difference between the first extension amount and the second extension amount is less than a length setting error, and the absolute value of the difference between the third extension amount and the fourth extension amount is less than a width setting error.

10. The film thickness measurement and calibration system according to claim 9, characterized in that: The outer contour of the current test area photo has a first photo length side, a second photo length side, a first photo width side and a second photo width side, the first photo length side is in the same direction as the first extended length side, the second photo length side is in the same direction as the second extended length side, the first photo width side is in the same direction as the first extended width side, and the second photo width side is in the same direction as the second extended width side; the analysis module includes: a measuring unit configured to measure the current measurement area photo to obtain a first spacing between the length side of the first photo and the target pad, a second spacing between the length side of the second photo and the target pad, a third spacing between the width side of the first photo and the target pad, and a fourth spacing between the width side of the second photo and the target pad in the current measurement area photo; The data processing unit is configured to determine whether the absolute value of the difference between the first spacing and the first expansion amount, the absolute value of the difference between the second spacing and the second expansion amount, the absolute value of the difference between the third spacing and the third expansion amount, and the absolute value of the difference between the fourth spacing and the fourth expansion amount are all less than the set threshold value. If so, it is determined that the current test area photo is valid, and the optical film thickness measuring device uses the center point of the current test area photo as the measurement position; if not, it is determined that the current test area photo is invalid and the correction advice is fed back.

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