Method for adaptive filtering of height measurement curve in wafer processing

Abstract

The invention provides a height measurement curve self-adaptive filtering method in wafer processing, and belongs to the technical field of wafer invisible cutting. According to the method, firstly, amplitude limiting filtering is used for preprocessing, so that height measurement data in a data table is between the set compensation upper and lower limits of the piezoelectric motor, data outside a wafer fault can be controlled within the compensation upper and lower limits of the piezoelectric motor, the overall height measurement curve is smooth, and the compensation fluctuation of piezoelectricity at the fault is small; and then secondary filtering is used for conducting secondary screening treatment on data in the data table, abnormally-changed data in the data table is removed, and during machining, the piezoelectric motor can control laser to be at the fixed depth below the surface of the wafer all the time during adjustment, the straightness of the cutting section is improved, and the wafer cutting effect is obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer invisible cutting, and more specifically, relates to a method for adaptive filtering of height measurement curves in wafer processing. Background Art

[0002] After being cut, rolled, sliced, chamfered, polished, laser engraved and packaged, silicon ingots become the basic raw material for integrated circuit factories - wafers. There are many ways to cut wafers, the most common of which are grinding wheel cutting, laser cutting, scriber splitting, diamond wire cutting, etc. Among them, laser cutting technology is widely used in wafer cutting due to its non-contact, low damage and high precision.

[0003] For example, Chinese patent CN201811625821.9 discloses a method and system for laser processing wafers. This method is mainly aimed at wafers with a flat surface that is not prone to sudden changes. It mainly captures height data, fits a height curve, and finally controls the piezoelectric motor to process the cutting path through the captured height data. During this period, the processing of the height measurement data only includes a curve fitting unit. This cutting method cannot eliminate abnormal reflection data caused by laser reflection of the edge of the wafer or the metal coating in the cutting path, resulting in piezoelectric compensation compensating the value of this part according to the actual detection, resulting in excessive compensation and affecting the process effect. For another example, Chinese patent CN201610945090.6 discloses a height adjustment system for a laser cutting head and a height adjustment method thereof. This method mainly controls the height adjustment axis by obtaining a distance signal between the laser cutting head and the surface of the workpiece to adjust the distance between the laser cutting head and the surface of the workpiece. This method can better control the distance between the laser focus and the surface of the object, but for the metal coating in the wafer cutting groove, it cannot be cut at the height measured at the coating. This method cannot shield the area where the coating is higher than the cutting groove surface height, which will cause the cutting height of the coating area to be too high and the consistency of the cutting section height cannot be guaranteed.

[0004] For wafers with coatings in the cutting path and wafer edges and faults, the current laser cutting method cannot solve the problem of excessive compensation of the piezoelectric motor caused by sudden changes in height measurement data due to coatings, faults and chamfering of the outer arc edges, resulting in poor wafer cutting results. Summary of the invention

[0005] The purpose of the present invention is to provide a method for adaptive filtering of height measurement curves in wafer processing, which can reduce cracks near the wafer coating, solve problems such as excessive laser compensation caused by laser acting on the wafer coating, surface faults, and edges, improve the straightness of the cutting section, and significantly improve the wafer cutting effect.

[0006] To achieve the above object, the present invention provides a method for adaptive filtering of height measurement curves in wafer processing, comprising the following steps:

[0007] S1. Scan the wafer cutting path on the processing platform with a laser rangefinder, record the height measurement data of the laser rangefinder and the coordinate position of the X-axis of the processing platform, and obtain a one-to-one corresponding height measurement data-X-axis coordinate position data table;

[0008] S2, before writing the height measurement data collected in S1 into the data table, pre-processing the height measurement data in the data table by using a limiting filter, so that the height measurement data in the data table is between the set upper and lower limits of the compensation of the piezoelectric motor;

[0009] S3, performing secondary filtering on the height measurement data in the data table, so that the fluctuation trend evaluation value E of the height measurement data in the data table 评分 Not less than the critical value E 临界 , get the fitted height measurement curve;

[0010] S4. Controlling a piezoelectric motor to cut the wafer cutting lanes according to the fitted height measurement curve.

[0011] Furthermore, the preprocessing of the height measurement data in the data table by using the limiting filter comprises the following steps:

[0012] If the height measurement data collected by S1 is between the upper and lower compensation limits of the set piezoelectric motor, the height measurement data is written into the data table; if the height measurement data collected by S1 is not between the upper and lower compensation limits of the set piezoelectric motor, the height measurement data is defaulted to 0 and then written into the data table.

[0013] Furthermore, the upper and lower limits of the compensation of the piezoelectric motor are respectively the upper limit of the compensation H max and compensation lower limit H min , if the piezoelectric point motor range is S um, the compensation upper limit H max The maximum is 1 / 2S um, the compensation lower limit H min The minimum is -1 / 2S um. The range can be optimized according to the flatness of the wafer surface. Specifically, through the height measurement curve, it is observed that the overall height measurement fluctuation range is -10~15um. On this basis, it is expanded by 10um, that is, the upper and lower limits of the piezoelectric motor compensation range are -20~25um. This expansion value is generally taken as the flatness of the ceramic suction cup.

[0014] Furthermore, the secondary filtering of the height measurement data in the data table comprises the following steps:

[0015] Access through pointer or PLC address, dynamically move the pointer, take three consecutive data (Pa, Pb, Pc) in the height measurement data in the data table, straight line L1 is the line from Pa to Pb, straight line L2 is the line from Pb to Pc, the slope of straight line L1 is K1, the angle A1 is arctan(K1), the slope of straight line L2 is K2, the angle A2 is arctan(K2), if the absolute values ​​of A1 and A2 are both less than 70, then E 评分 =100, otherwise E 评分 =abs(A1+A2).

[0016] Furthermore, the critical value E 临界 The value is 5 to 15, which is set according to the actual process requirements.

[0017] Furthermore, if E 评分 <E 临界 , then remove the data Pb, write the data Pa and Pc into the data table and update the pointer; if E 评分 ≥E 临界 , then write these three consecutive data (Pa, Pb, Pc) into the data table and update the pointer.

[0018] Furthermore, the wafer is any one of a silicon-based IGBT, a MEMS, a silicon carbide-based MOSFET, and a diode wafer.

[0019] Furthermore, the wafer cutting road width is ≥20 μm, and the height difference within the cutting road does not exceed 80 μm.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] A method for adaptive filtering of a height measurement curve in wafer processing of the present invention first uses limiting filtering to pre-process the height measurement data in a data table of the height measurement data-X-axis coordinate position obtained by laser scanning, so that the height measurement data in the data table is between the upper and lower compensation limits of the set piezoelectric motor, and the data outside the wafer fault can be controlled within the upper and lower compensation limits of the piezoelectric motor, so that the overall height measurement curve is smooth and the piezoelectric compensation fluctuation at the fault is small; and then secondary filtering is used to perform secondary screening processing on the data in the data table, and the data with abnormal changes in the data table is eliminated. During processing, the piezoelectric motor can always control the laser to a fixed depth below the wafer surface during adjustment, thereby improving the straightness of the cutting section and significantly improving the wafer cutting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 A flow chart of a method for adaptive filtering of height measurement curves in wafer processing provided by an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of adaptive filtering of a height measurement curve for wafer edge faults and wafer outer edge arc chamfering provided in Embodiment 1 of the present invention;

[0025] Figure 3 A schematic diagram of adaptive filtering of a height measurement curve when a wafer cutting path contains a metal coating, provided in Embodiment 2 of the present invention.

[0026] Among them, the reference numerals in the figures are:

[0027] 1-wafer fault, 2-wafer outer edge arc chamfer, 3-without filter control, the height measurement data of the laser rangefinder at the circular arc chamfer, 4-with filter control, the height measurement data of the laser rangefinder at the circular arc chamfer, 5-without filter control, the height measurement data of the laser rangefinder at the wafer fault, 6-with filter control, the height measurement data of the laser rangefinder at the wafer fault, 7-metal coating on the surface of the wafer cutting path, 8-without filter control, the height measurement data of the laser rangefinder at the metal coating, 9-with filter control, the height measurement data of the laser rangefinder at the metal coating. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0030] Aiming at the phenomenon that the height measurement data changes suddenly due to the coating in the wafer cutting path or the chamfer and fault of the arc edge of the wafer, and solving the problem of excessive compensation of the piezoelectric motor caused by the sudden change of the height measurement data, an embodiment of the present invention provides a method for adaptive filtering of the height measurement curve in wafer processing, and the process is as follows: Figure 1As shown, the following steps are included:

[0031] S1. Scan the wafer cutting path on the processing platform with a laser rangefinder, record the height measurement data of the laser rangefinder and the coordinate position of the X-axis of the processing platform, and obtain a one-to-one corresponding height measurement data-X-axis coordinate position data table;

[0032] S2. Before writing the height measurement data collected in S1 into the data table, use a limiting filter to pre-process the height measurement data in the data table so that the height measurement data in the data table is between the set upper and lower limits of the compensation of the piezoelectric motor;

[0033] S3, perform secondary filtering on the height measurement data in the data table, so that the fluctuation trend evaluation value E of the height measurement data in the data table 评分 Not less than the critical value E 临界 , get the fitted height measurement curve;

[0034] S4. Controlling the piezoelectric motor to cut the wafer cutting lanes according to the fitted height measurement curve.

[0035] The roundness of the embodiment of the present invention includes but is not limited to silicon-based IGBT, MEMS, silicon carbide-based MOSFET, diode wafers, etc. Wafer outer edge chamfering is a mechanical process to make the wafer edge smooth, and the edge of the silicon wafer is corrected into an arc shape to improve the mechanical strength of the silicon wafer and reduce silicon wafer defects caused by stress concentration. Piezoelectric motor overcompensation refers to the over-compensation or untimely compensation of the piezoelectric motor due to large changes in height measurement data.

[0036] In the above step S1, the height measurement curve formed by connecting the height measurement data in the data table obtained in the embodiment of the present invention is a curve formed by scanning the surface undulation data of the wafer with a laser rangefinder. The minimum spot of the laser rangefinder is 20μm. The width of the wafer cutting path is ≥20μm, and the height difference within the cutting path cannot exceed 80μm. When the laser rangefinder is used to scan the wafer cutting path on the processing platform, the wafer is placed on the processing platform and the wafer is vacuum-adsorbed to ensure that the wafer is reliably fixed.

[0037] In the height measurement data-X-axis coordinate position data table obtained in the embodiment of the present invention, the height measurement data measured by the laser rangefinder and the X-axis coordinate are in a one-to-one correspondence.

[0038] In the above step S2, the stroke S of the piezoelectric motor of the embodiment of the present invention is 80 μm; the upper and lower limits of the compensation of the piezoelectric motor are set according to the highest and lowest points on the wafer surface to filter out invalid points not on the wafer. max The maximum is 1 / 2S = 40um, the compensation lower limit is H minThe minimum is -1 / 2S=-40um. The range can be optimized according to the flatness of the wafer surface. Specifically, through the height measurement curve, it is observed that the overall height measurement fluctuation range is -10~15um. On this basis, it is expanded by 10um, that is, the upper and lower limits of the piezoelectric motor compensation range are -20~25um. This expansion value is generally taken as the flatness of the ceramic suction cup.

[0039] Specifically, preprocessing the height measurement data in the data table using the limiting filter includes the following steps:

[0040] If the height measurement data collected by S1 is between the upper and lower limits of the compensation of the set piezoelectric motor, the height measurement data is written into the data table; if the height measurement data collected by S1 is not between the upper and lower limits of the compensation of the set piezoelectric motor, the height measurement data is defaulted to 0 and then written into the data table.

[0041] The limiting filter in the embodiment of the present invention mainly determines whether the currently acquired height measurement data is contained in the upper and lower limits of the piezoelectric motor compensation. If it is within the range, the actual data is input, and the height measurement data outside the range is defaulted to zero. The limiting filter is mainly used to process abnormal phenomena in the height measurement data at the wafer fault, so as to solve the problem of excessive compensation of the piezoelectric motor caused by sudden changes in the height measurement data due to wafer faults.

[0042] In the above step S3, the embodiment of the present invention performs secondary filtering on the altimetry data in the data table, including the following steps: in the process of altimetry movement, the pointer is accessed through the pointer or PLC address, and the pointer is dynamically moved to obtain three consecutive data (Pa, Pb, Pc) in the altimetry data in the data table. The straight line L1 is the line from Pa to Pb, and the straight line L2 is the line from Pb to Pc. The slope of the straight line L1 is K1, and the angle A1 is arctan (K1). The slope of the straight line L2 is K2, and the angle A2 is arctan (K2). If the absolute values ​​of A1 and A2 are both less than 70, then E 评分 =100, otherwise E 评分 = abs(A1+A2). Critical value E 临界 It is a value set according to actual process requirements. Generally, E 临界 is 5 to 15. 评分 <E 临界 , then remove the data Pb, write the data Pa and Pc into the data table and update the pointer; if E 评分 ≥E 临界 , then write these three consecutive data (Pa, Pb, Pc) into the data table and update the pointer.

[0043] The secondary filtering process of the embodiment of the present invention is to perform secondary filtering on the existing data in the data table, mainly by updating the pointer to access the data table in real time, obtaining the data before and after the pointer, evaluating the fluctuation trend and obtaining the evaluation value E. 评分. The secondary filtering of the embodiment of the present invention is a data processing algorithm, which mainly judges the trend of data and the change of line segment slope, etc., and is used to analyze the data in the table and make screening. A pointer is a method of accessing data in a data table, and is updated in real time according to the actual processing situation. Specifically, the embodiment of the present invention uses the slope of three consecutive data as an evaluation method for the fluctuation trend of the height measurement data in the data table. The slope evaluation method is one of the filtering methods, including but not limited to this method. The embodiment of the present invention can eliminate abnormal data caused by the laser rangefinder measuring the chamfer of the outer edge of the wafer or the metal coating in the cutting path through secondary filtering processing, thereby solving the problem of excessive compensation of the piezoelectric motor.

[0044] In the above step S4, the processing objective lens is fixed on the piezoelectric motor, and the piezoelectric motor drives the processing objective lens to perform real-time compensation according to the fitted height measurement curve. The controller controls the laser to emit light according to the fitted height measurement curve to cut the wafer cutting path.

[0045] A method for adaptively filtering a height measurement curve in wafer processing according to an embodiment of the present invention first pre-processes the height measurement data in a data table of the height measurement data obtained by laser scanning - the coordinate position of the X-axis - using a limiting filter, so that the height measurement data in the data table is between the set upper and lower limits of the compensation of the piezoelectric motor, and the data outside the wafer fault can be controlled within the upper and lower limits of the compensation of the piezoelectric motor, so that the overall height measurement curve is smooth and the piezoelectric compensation fluctuation at the fault is small; then a secondary filter is used to perform a secondary screening process on the data in the data table, and the data with abnormal changes in the data table is eliminated. During processing, the piezoelectric motor can always control the laser to a fixed depth below the wafer surface during adjustment, thereby improving the straightness of the cutting section and significantly improving the wafer cutting effect.

[0046] A method for adaptive filtering of height measurement curves in wafer processing according to an embodiment of the present invention uses adaptive filtering to screen the optimal value in real time according to the height measurement data, and filters the abnormal mutation value, so as to ensure the cutting effect. The embodiment of the present invention is aimed at wafers with coatings in the cutting path and the edges and faults of the wafers, and can solve the problem of excessive compensation of piezoelectric motors caused by sudden changes in height measurement data due to coatings, faults, and chamfering of the outer edge arcs, and can reduce cracks near the wafer coating, improve the straightness of the cutting section, and significantly improve the cutting effect.

[0047] Two specific embodiments are used below to illustrate a method for adaptive filtering of height measurement curves in wafer processing according to an embodiment of the present invention.

[0048] Example 1

[0049] Embodiment 1 of the present invention provides a method for adaptively filtering height measurement curves in wafer processing, for height measurement processing of wafer edge faults 1 and wafer outer edge chamfers 2, such as Figure 2 As shown:

[0050] Phenomenon: Wafer edge fault 1 is a critical position to distinguish whether the height measurement is outside or inside the wafer. In the process of entering the wafer from outside the wafer through the edge, the height measurement will suddenly change from abnormal data (such as change data 5, which is generally invalid data beyond the range, usually displayed as the maximum value) to the normal measurement value on the wafer surface. If it is not processed, the piezoelectric motor will be over-compensated or untimely during edge compensation. At this time, limiting filtering is required for preliminary height limitation.

[0051] The arc chamfer 2 at the outer edge of the wafer is generally higher than the cutting path. When entering the cutting path from the arc, a large height measurement change will also occur (such as change data 3). If no processing is done, it will cause the piezoelectric compensation to suddenly change from a high point to a lower point. Due to the hysteresis of the piezoelectric response, at the starting end of the cutting path, the laser will hit the surface of the cutting path, which is easy to produce debris and cause poor edge splitting effect.

[0052] In view of the above phenomenon, the specific implementation process of the method for adaptive filtering of the height measurement curve in the embodiment of the present invention is as follows:

[0053] (1) First, use the laser rangefinder to dynamically scan the cutting path and obtain the height measurement data; specifically, from the height measurement starting point P start Move to the height measurement end point P at a constant speed end And capture the height measurement data at the set sampling frequency to obtain the data table MAP <X 坐标 , H 测高 >. The sampling frequency is the frequency of data collection, which is generally the minimum time interruption of N systems, and N defaults to 1.

[0054] (2) In the above collection process, the collected H 测高 Before writing to the data table, the height measurement data is first preprocessed and the obtained H is filtered using a limiting filter. 测高 Locked at compensation upper limit H max and compensation lower limit H min If the piezoelectric motor stroke is 80um, the compensation upper limit H max The maximum is 40um, the compensation lower limit is H min The minimum is -40um, and the range can be optimized according to the flatness of the wafer surface. Specifically, through the height measurement curve, it is observed that the overall height measurement fluctuation range is -10~15um, then it is expanded by 10um on this basis, and the range is -20~25um. This expansion value is generally taken from the flatness of the ceramic suction cup. The height measurement data of the wafer edge fault 1 outside the cutting path or out of range can be limited. The default height measurement data is 0 (such as change data 6, 4); the limiting filter is mainly for the data at the wafer edge fault 1 and the wafer outer edge arc chamfer 2. The height measurement data of 0 is the height measurement data at the laser focus, and the default is 0 after calibration.

[0055] (3) Then, the generated data table is filtered twice: Specifically, in the process of collecting height measurement data, the data table MAP is filtered twice. <X 坐标 , H 测高 >The data obtained in the table are accessed through pointers or PLC addresses, and the pointer Ptr is dynamically moved. For the continuous n (based on the sampling frequency, generally 3≤n≤7) data in the MAP table, due to the influence of the above-mentioned limiting filter, the wafer outer height measurement data is dynamically set to 0 (such as change data 5), ​​and the height measurement data at the chamfer 2 of the outer edge of the wafer will also be higher than the height measurement in the actual cutting path (such as change data 3). Therefore, for this area, the search can be started from the beginning of the MAP table until the data is not 0, and the next 3 data are selected to evaluate the fluctuation trend and obtain the evaluation value E 评分 , taking one of the slope evaluation methods as an example, take three consecutive data (Pa, Pb, Pc), straight line L1 is the line from Pa to Pb, straight line L2 is the line from Pb to Pc, the slope of straight line L1 is K1, the angle A1 is arctan(K1), the slope of straight line L2 is K2, the angle A2 is arctan(K2), if the absolute values ​​of A1 and A2 are both less than 70, then E 评分 =100, otherwise E 评分 =abs(A1+A2). 临界 =10, if E 评分 <E 临界 , then remove the data Pb, write the data Pa and Pc into the data table and update the pointer; if E 评分 ≥E 临界 , then write these three consecutive data (Pa, Pb, Pc) into the data table and update the pointer, such as changing data 4, until the height measurement action is completed. The final fitted height measurement curve is as follows Figure 1 shown.

[0056] The n data is determined according to the acquisition frequency. The more data collected in the unit interval, the larger n is. In this embodiment, n is 3. The secondary filtering is to perform smoothing screening on the two areas of the circular chamfer to make the data close to the actual cutting height; the pointer or PLC address is determined according to the programming language, including but not limited to the above method.

[0057] (4) The fitted height measurement curve obtained above is fed back to the piezoelectric motor, and the piezoelectric motor drives the processing objective lens to perform real-time compensation according to the fitted height measurement curve. The controller controls the laser to emit light according to the fitted height measurement curve to cut the wafer cutting path.

[0058] Example 2

[0059] Embodiment 2 of the present invention provides a method for adaptively filtering a height measurement curve in wafer processing, for the height measurement processing of a wafer cutting path containing a metal coating 7, such as Figure 3 As shown:

[0060] Phenomenon: There is a metal coating 7 distributed in the wafer cutting path. When the laser rangefinder collects the height measurement data of these areas, the height of the coating itself or the data reflected by the infrared due to the material is abnormal (such as change data 8), resulting in a small mutation in the height measurement data, which is obviously different from the fluctuation trend of the wafer itself. These small mutations output to the piezoelectric motor will cause over-compensation, coupled with the influence of the light transmittance of the metal surface, which ultimately leads to the laser hitting the wafer surface or causing surface crack bifurcation when compensating for the height closest to the surface. It is also more likely to produce debris, affecting the final cutting effect.

[0061] In view of the above phenomenon, the specific implementation process of the method for adaptive filtering of the height measurement curve in the embodiment of the present invention is as follows:

[0062] (1) First, use the laser rangefinder to dynamically scan the cutting path and obtain the height measurement data; specifically, from the height measurement starting point P start Move to the height measurement end point P at a constant speed end And capture the height measurement data at the set sampling frequency to obtain the data table MAP <X 坐标 , H 测高 >.

[0063] (2) In the above collection process, the collected H 测高 Before writing to the data table, the height measurement data is first preprocessed and the obtained H is filtered using a limiting filter. 测高 Locked at compensation upper limit H max and compensation lower limit H min If the piezoelectric motor stroke is 80um, the compensation upper limit H max The maximum is 40um, the compensation lower limit is H min The minimum is -40um, and the range can be optimized according to the flatness of the wafer surface. Specifically, through the height measurement curve, it is observed that the overall height measurement fluctuation range is -10~15um, then it is expanded by 10um on this basis, and the range is -20~25um. This expansion value is generally taken from the flatness of the ceramic suction cup.

[0064] (3) Then, the generated data table is filtered twice: Specifically, in the process of collecting height measurement data, the data table MAP is filtered twice. <X 坐标 , H 测高>The data obtained in the table are accessed through pointers or PLC addresses, and the pointer Ptr is dynamically moved. For the continuous n (based on the sampling frequency, generally 3≤n≤7) data in the MAP table, the data outside the coating is relatively smooth, and the data on the metal coating 7 will change suddenly. For this phenomenon, the fluctuation trend is evaluated and the evaluation value E is obtained. 评分 Generally, the slope evaluation method can be used. Taking one of the slope evaluation methods as an example, take three consecutive data (Pa, Pb, Pc), straight line L1 is the line from Pa to Pb, straight line L2 is the line from Pb to Pc, the slope of straight line L1 is K1, the angle A1 is arctan(K1), the slope of straight line L2 is K2, the angle A2 is arctan(K2), if the absolute values ​​of A1 and A2 are both less than 70, then E 评分 =100, otherwise E 评分 = abs(A1+A2). Critical value E 临界 =10, if E 评分 <E 临界 , then remove the data Pb, write the data Pa and Pc into the data table and update the pointer; if E 评分 ≥E 临界 , then write these three consecutive data (Pa, Pb, Pc) into the data table and update the pointer, such as changing data 9, until the height measurement action is completed. The final fitted height measurement curve is as follows Figure 2 The sampling frequency is the frequency of data collection, which is generally the minimum time interruption of N systems. N defaults to 1. The n data is determined by the collection frequency. The more data collected in the unit interval, the larger n is. In this embodiment, n is 3. The secondary filtering is for the data of the metal coating 7 part.

[0065] (4) The fitted height measurement curve obtained above is fed back to the piezoelectric motor, and the piezoelectric motor drives the processing objective lens to perform real-time compensation according to the fitted height measurement curve. The controller controls the laser to emit light according to the fitted height measurement curve to cut the wafer cutting path.

[0066] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims

1. A method for adaptive filtering of height measurement curves in wafer processing, characterized in that: The following steps are involved: S1. Scan the wafer cutting path on the processing platform with a laser rangefinder, record the height measurement data of the laser rangefinder and the coordinate position of the X-axis of the processing platform, and obtain a one-to-one corresponding height measurement data-X-axis coordinate position data table; S2, before writing the height measurement data collected in S1 into the data table, pre-processing the height measurement data in the data table by using a limiting filter, so that the height measurement data in the data table is between the set upper and lower limits of the compensation of the piezoelectric motor; S3, performing secondary filtering on the height measurement data in the data table, so that the fluctuation trend evaluation value E of the height measurement data in the data table 评分 Not less than the critical value E 临界 , get the fitted height measurement curve; S4. Controlling a piezoelectric motor to cut the wafer cutting lanes according to the fitted height measurement curve.

2. The method for adaptive filtering of height measurement curves in wafer processing according to claim 1, characterized in that: The preprocessing of the height measurement data in the data table by using the limiting filter comprises the following steps: If the height measurement data collected by S1 is between the upper and lower compensation limits of the set piezoelectric motor, the height measurement data is written into the data table; if the height measurement data collected by S1 is not between the upper and lower compensation limits of the set piezoelectric motor, the height measurement data is defaulted to 0 and then written into the data table.

3. The method for adaptive filtering of height measurement curves in wafer processing according to claim 1, characterized in that: The upper and lower limits of the compensation of the piezoelectric motor are respectively the upper limit H max and compensation lower limit H min , if the piezoelectric motor stroke is Sum, the compensation upper limit H max The maximum is 1 / 2Sum, the compensation lower limit H min The minimum is -1 / 2Sum.

4. The method for adaptive filtering of height measurement curves in wafer processing according to claim 1, characterized in that: The secondary filtering of the height measurement data in the data table comprises the following steps: Access through pointer or PLC address, dynamically move the pointer, take three consecutive data (Pa, Pb, Pc) in the height measurement data in the data table, straight line L1 is the line from Pa to Pb, straight line L2 is the line from Pb to Pc, the slope of straight line L1 is K1, the angle A1 is arctan(K1), the slope of straight line L2 is K2, the angle A2 is arctan(K2), if the absolute values ​​of A1 and A2 are both less than 70, then E 评分 =100, otherwise E 评分 =abs(A1+A2).

5. The method for adaptive filtering of height measurement curves in wafer processing according to claim 4, characterized in that: The critical value E 临界 5 to 15.

6. The method for adaptive filtering of height measurement curves in wafer processing according to claim 4, characterized in that: If E 评分 <E 临界 , then remove the data Pb, write the data Pa and Pc into the data table and update the pointer; if E 评分 ≥E 临界 , then write these three consecutive data (Pa, Pb, Pc) into the data table and update the pointer.

7. A method for adaptive filtering of height measurement curves in wafer processing according to any one of claims 1 to 6, characterized in that: The wafer is any one of a silicon-based IGBT, a MEMS, a silicon carbide-based MOSFET, and a diode wafer.

8. A method for adaptively filtering height measurement curves in wafer processing according to any one of claims 1 to 6, characterized in that: The wafer cutting road width is ≥20 μm, and the height difference within the cutting road does not exceed 80 μm.

Images