Bulk silicon process offset compensation method

Abstract

The invention relates to the field of micro electro mechanical systems, in particular to a bulk silicon process offset compensation method, which comprises the following steps of: etching an etching surface of a test substrate according to a preset pattern to obtain an offset pattern embedded in the test substrate; a plurality of observation points easy to recognize are arranged in the preset graph, and the distance between the observation points and the center position of the preset graph is recorded as the polar radius. A plurality of offset points exist in the offset graph, a plurality of offset marks are arranged on the mark surface of the test base body, and the offset marks, the offset points and the observation points are in one-to-one correspondence. The offset of each offset mark is detected, the compensation coefficient is calculated in combination with the polar radius, the preset pattern is scaled according to the compensation coefficient to obtain the compensation pattern, and therefore the deviation between the pattern obtained through etching and the preset pattern is small. The method has relatively high universality, does not limit parameters of an etching process, does not influence the etching efficiency, and has relatively high practicability.

Description

Technical Field

[0001] The invention relates to the field of micro-electromechanical systems, and in particular to a bulk silicon process offset compensation method. Background Art

[0002] When etching bulk silicon, since the etching gas flow is provided by a single nozzle, there is a slight difference in the angle between the ion bombardment at the center and edge of the silicon wafer, resulting in a certain angle of the groove formed by etching. Since the etching depth in the bulk silicon process is usually large, which may reach hundreds of microns, the inclination of the groove will cause a large deviation between its bottom surface and the position of the opening, that is, the etching pattern formed at the bottom of the groove is different from the shape of the preset pattern, resulting in a pattern deviation.

[0003] At present, in order to reduce this deviation, the angle of the groove formed by etching is usually adjusted by adjusting the gas flow rate, reducing the etching rate, etc., so as to reduce the problem of internal pattern deviation. However, this method reduces the etching rate and affects production efficiency. Summary of the invention

[0004] The object of the present invention is to provide a method for compensating for bulk silicon process offset without affecting the etching rate.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A bulk silicon process offset compensation method, comprising:

[0007] A plurality of observation points are set on a preset graph, each of which is a key point in the preset graph, and the distance from any observation point to the center point of the preset graph is recorded as a polar diameter;

[0008] Providing a test substrate made of the same material as the target substrate, the test substrate having an etched surface and a marking surface opposite to the etched surface, the marking surface being formed with a plurality of offset marks corresponding to the observation points;

[0009] The etched surface of the test substrate is etched with the preset pattern to form a pattern groove, the bottom surface of the pattern groove away from the etched surface of the test substrate is an offset pattern, the offset pattern is embedded in the test substrate, the distance between the offset pattern and the marked surface of the test substrate is a marking thickness, the offset pattern can be directly observed from the marked surface of the test substrate, and the position on the offset pattern corresponding to the observation point is an offset point;

[0010] Observe the offset points and the offset marks from the marking surface of the test substrate, measure and record the offset between each offset point and the corresponding offset mark, wherein the offset is a vector;

[0011] A compensation coefficient is calculated according to the offset of each offset mark and the polar diameter of the corresponding observation point;

[0012] The preset graph is scaled according to the compensation coefficient to obtain a compensation graph.

[0013] Optionally, calculating the compensation coefficient according to the offset of each offset mark and the polar diameter of the corresponding observation point includes:

[0014] Calculating an average value of the offsets of the offset marks to obtain an average value;

[0015] The difference between the offset amount of each offset mark and the average amount is used as a calculation amount to obtain a radial amount close to the direction of the polar diameter;

[0016] The ratio of the radial value of each offset mark to the polar diameter is calculated, and the average value is taken as the compensation coefficient.

[0017] Optionally, a plurality of observation points with the same polar diameter are grouped together, and the accuracy of the polar diameter is any value between 1 mm and 10 mm.

[0018] Optionally, each of the offset marks comprises a measuring ruler configured in the shape of a ruler, wherein the measuring ruler has an origin corresponding to the observation point, a direction line passing through the origin, and a plurality of indicating scales arranged along the direction line.

[0019] Optionally, each of the offset marks includes at least two mutually perpendicular direction lines, and the indicating scale is provided on any of the direction lines.

[0020] Optionally, each of the offset marks includes a plurality of sets of the measuring rulers, each of the measuring rulers includes only one direction line, and the plurality of direction lines are separated from each other.

[0021] Optionally, the distance between two adjacent origins of the same offset mark in a direction parallel to one of the direction lines is any value between 50 μm and 300 μm, and / or the distance between two adjacent origins of the same offset mark in a direction perpendicular to the direction line is any value between 50 μm and 300 μm.

[0022] Optionally, the value of the radial quantity is the Euclidean norm value of the readings on the two direction lines of the offset mark.

[0023] Optionally, the mark thickness is less than or equal to 2 μm.

[0024] Optionally, the marking surface of the test substrate is formed with a transparent observation layer, and the offset pattern is embedded in the observation layer.

[0025] The beneficial effect of the present invention is that: by detecting the offset of the positions corresponding to multiple observation points after the preset pattern is etched under preset conditions, the offset degree of the offset pattern relative to the preset pattern is quantified, and the compensation coefficient is calculated. The preset pattern is scaled by the compensation coefficient to obtain a compensation pattern, and the compensation pattern is etched under the same conditions, so that the offset between the obtained pattern and the preset pattern is effectively suppressed, thereby achieving compensation for the offset. Since the method obtains the compensation coefficient after detection with the preset pattern and etching conditions, it does not limit the shape of the pattern and the etching conditions, has strong universality and does not affect the etching rate.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the bulk silicon process offset compensation method shown in the first embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the arrangement of observation points shown in the first embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of the offset mark after part of the indicating scale is hidden as shown in the first embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the structure of the test substrate after etching shown in the first embodiment of the present invention.

[0031] Legend: 101-preset pattern, 102-observation point, 1-test substrate, 11-etching surface, 12-marking surface, 2-pattern groove, 21-offset pattern, 3-offset mark, 31-measuring ruler, 311-origin, 312-direction line, 313-indicator scale, 314-indicator mark. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] In the scheme applied for protection of the present invention, when it is necessary to form a preset pattern 101 by etching on a target substrate with preset parameters through a bulk silicon process, it is necessary to first detect the deviation degree on a test substrate 1 of the same material as the target substrate with the preset parameters, and perform offset compensation based on the deviation degree in combination with the preset pattern 101 to obtain a compensated pattern as an etching template, and then use the compensated pattern to etch on the target substrate with the preset parameters through a bulk silicon process, thereby obtaining an etched pattern with a smaller deviation from the preset pattern 101.

[0037] See also Figure 1 The bulk silicon process offset compensation method claimed in the present invention includes:

[0038] S100, setting a plurality of observation points 102 on a preset graph 101, each observation point 102 being a key point in the preset graph 101, and recording the distance from any observation point 102 to the center point of the preset graph 101 as a polar diameter.

[0039] S200 , providing a test substrate 1 made of the same material as the target substrate, wherein the test substrate 1 has an etched surface 11 and a marking surface 12 opposite to the etched surface 11 , and a plurality of offset marks 3 are formed on the marking surface 12 , each corresponding to each observation point 102 .

[0040] S300, etching the etched surface 11 of the test substrate 1 with a preset pattern 101 to form a pattern groove 13, the bottom surface of the pattern groove 13 away from the etched surface 11 of the test substrate 1 is an offset pattern 21, the offset pattern 21 is embedded in the test substrate 1, the distance between the offset pattern 21 and the marking surface 12 of the test substrate 1 is the marking thickness, the offset pattern 21 can be directly observed from the marking surface 12 of the test substrate 1, and the position on the offset pattern 21 corresponding to the observation point 102 is the offset point.

[0041] S400 , observing the offset points and the offset marks 3 from the marking surface 12 of the test substrate 1 , respectively measuring and recording the offset between each offset point and the corresponding offset mark 3 , where the offset is a vector.

[0042] S500 , calculating a compensation coefficient according to the offset of each offset mark 3 and the polar diameter of the corresponding observation point 102 .

[0043] S600 , scaling the preset graph 101 according to the compensation coefficient to obtain a compensated graph.

[0044] By detecting the offset of the positions corresponding to multiple observation points 102 after the preset pattern 101 is etched by the bulk silicon process with preset parameters, the offset degree of the offset pattern 21 relative to the preset pattern 101 is quantified, and the compensation coefficient is calculated. The preset pattern 101 is scaled by the compensation coefficient to obtain a compensation pattern, and the compensation pattern is etched under the same conditions, so that the offset between the obtained pattern and the preset pattern 101 can be effectively suppressed, thereby achieving compensation for the offset. The key points in the preset pattern 101 are used as observation points 102, which facilitates the capture of the offset points on the offset pattern 21, thereby measuring the offset. Since the compensation coefficient is obtained after the method is detected with the preset pattern and etching conditions, it does not limit the shape of the pattern and the etching conditions, has strong universality and does not affect the etching rate.

[0045] In some embodiments, step S500 includes:

[0046] S510, calculating the average value of the offset amounts of the offset marks 3 to obtain an average amount.

[0047] S520, using the difference between the offset amount of each offset mark 3 and the average amount as a calculation amount, to obtain a radial amount in a direction close to the polar radius.

[0048] S530, calculating the ratio of the radial value to the polar value of each offset mark 3, and taking the average value as the compensation coefficient.

[0049] By calculating the average amount and the calculated amount, the system deviation caused by the lithography alignment is eliminated. Since the offset is a vector, the values ​​of the offset in different directions are different. Obtaining the radial amount through the calculated amount helps to obtain vectors pointing in similar directions for each offset mark, which is convenient for scaling.

[0050] In some embodiments, a plurality of observation points 102 with the same polar diameter are grouped together, and the accuracy of the polar diameter is any value between 1 mm and 10 mm, for example, any value between 1 mm, 3 mm, 5 mm, 8 mm and 10 mm. By adjusting the accuracy of the polar diameter, the selection of the observation point 102 is facilitated, thereby taking into account the requirements that each observation point 102 is a key point in the preset figure 101 and that the plurality of observation points 102 have the same polar diameter.

[0051] In some embodiments, each offset mark 3 includes a measuring ruler 31 configured in the shape of a ruler, the measuring ruler 31 having an origin 311 corresponding to the observation point 102, a direction line 312 passing through the origin 311, and a plurality of indicator scales 313 arranged along the direction line 312, so as to facilitate direct reading of the offset value.

[0052] In some embodiments, each offset mark 3 includes at least two mutually perpendicular direction lines 312, and an indicator scale 313 is provided on any direction line 312. Since the offset direction and distance of each offset point relative to the offset mark 3 are uncertain, measurement is performed in two mutually perpendicular directions to facilitate accurate measurement of the offset value.

[0053] In some embodiments, each offset mark 3 includes multiple sets of measuring rulers 31, each measuring ruler 31 includes only one direction line 312, and the multiple direction lines 312 are separated from each other. The offsets in two directions are measured respectively with two adjacent origins 311, so that the two direction lines 312 are separated from each other, so as to prevent confusion of the indicating scales 313 on different direction lines 312 when reading.

[0054] In some embodiments, the distance between two adjacent origins 311 of the same offset mark 3 in a direction parallel to a direction line 312 is any value in the range of 50 μm to 300 μm, for example, any value in the range of 50 μm, 100 μm, 150 μm, 200 μm, 250 μm and 300 μm, and / or the distance in a direction perpendicular to the direction line 312 is any value in the range of 50 μm to 300 μm, for example, any value in the range of 50 μm, 100 μm, 150 μm, 200 μm, 250 μm and 300 μm, and the distances between the two origins 311 in the two directions are the same or different. This helps prevent the two direction lines 312 from intersecting, and helps prevent the measurement error caused by the excessive distance between adjacent origins 311 from being too large.

[0055] In some embodiments, the value of the radial quantity is the Euclidean norm value of the readings on the two direction lines 312 of the offset mark 3, which is convenient for calculation.

[0056] In some embodiments, the marking thickness is less than or equal to 2 μm, for example, it can be any value among 0.5 μm, 1 μm, 1.5 μm and 2 μm, which helps to ensure that the offset pattern 21 can be observed from the marking surface 12 of the test substrate 1 .

[0057] In some embodiments, the marking surface 12 of the test substrate 1 is formed with a transparent observation layer, and the offset pattern 21 is embedded in the observation layer, which facilitates direct observation of the position of the offset point and eliminates the need for precise control of the thickness of the test substrate 1, thereby helping to reduce operational difficulty.

[0058] Please refer to the following examples for details.

[0059] Embodiment 1:

[0060] A preferred embodiment of the present application needs to form a preset pattern 101 on the surface of the target substrate through a bulk silicon process. The etching parameters in the process are preset parameters, and the etching depth is a preset depth.

[0061] See also Figure 1 The bulk silicon process offset compensation method in this embodiment includes:

[0062] S100, setting a plurality of observation points 102 on a preset graph 101, each observation point 102 being a key point in the preset graph 101, and recording the distance from any observation point 102 to the center point of the preset graph 101 as a polar diameter.

[0063] S200 , providing a test substrate 1 made of the same material as the target substrate, wherein the test substrate 1 has an etched surface 11 and a marking surface 12 opposite to the etched surface 11 , and a plurality of offset marks 3 are formed on the marking surface 12 , each corresponding to each observation point 102 .

[0064] S300, etching the etched surface 11 of the test substrate 1 with a preset pattern 101 to form a pattern groove 13, the bottom surface of the pattern groove 13 away from the etched surface 11 of the test substrate 1 is an offset pattern 21, the offset pattern 21 is embedded in the test substrate 1, the distance between the offset pattern 21 and the marking surface 12 of the test substrate 1 is the marking thickness, the offset pattern 21 can be directly observed from the marking surface 12 of the test substrate 1, and the position on the offset pattern 21 corresponding to the observation point 102 is the offset point.

[0065] S400 , observing the offset points and the offset marks 3 from the marking surface 12 of the test substrate 1 , respectively measuring and recording the offset between each offset point and the corresponding offset mark 3 , where the offset is a vector.

[0066] S500 , calculating a compensation coefficient according to the offset of each offset mark 3 and the polar diameter of the corresponding observation point 102 .

[0067] S600 , scaling the preset graph 101 according to the compensation coefficient to obtain a compensated graph.

[0068] In step S100, the outer contour of the preset pattern 101 is matched with the silicon wafer. 13 key points that are easy to identify are selected in the preset pattern 101 as observation points 102, and are named in numerical order. The polar diameter of each observation point 102 is measured and recorded, and the accuracy of the polar diameter is 1mm, and errors below the accuracy are ignored. Figure 2 , observation point No. 102 is set at the center of the preset figure 101, and the polar diameter is 0; the polar diameters of observation points No. 1 to No. 8 are all 70 mm, and are scattered around observation point No. 102; the polar diameters of observation points No. 9 to No. 12 are all 40 mm, and are scattered around observation point No. 102. The arrangement of observation points No. 1 to No. 12 is relatively uniform as a whole.

[0069] In step S200, the test substrate 1 is a silicon wafer with the same diameter as the target substrate. Figure 3 and Figure 4 , the test substrate 1 has an etched surface 11 and a marking surface 12 relative to each other, and the distance between the etched surface 11 and the marking surface 12 of the test substrate 1 is its thickness. The thickness of the test substrate 1 is matched with the preset depth and is 1.3 μm greater than the preset depth. An offset mark 3 is arranged at the position corresponding to each observation point 102 on the test substrate 1. The offset mark 3 includes four measuring rulers 31, each measuring ruler 31 includes an origin 311, a direction line 312 passing through the origin 311, and a plurality of indicating scales 313 evenly arranged along the direction line 312, and each indicating scale 313 is marked with an indicating mark 314 indicating the distance between it and the origin 311. In this embodiment, the offset mark 3 is constructed as a square with a side length of 100 μm, with the center point and four corner points of the square as the end points of the offset mark 3, and the end points of each offset mark 3 closest to the center point of the test substrate 1 correspond to each observation point 102 of the preset figure 101. Each origin 311 of the offset mark 3 is located at the midpoint of each side of the square, and the direction line 312 is perpendicular to each side of the square, has a length of 90 μm, and the origin 311 is located at the center of the direction line 312. The structure and setting direction of each offset mark 3 are the same.

[0070] In step S300, since the material of the test substrate 1 is known and the etching parameters are preset parameters, the depth of the pattern groove 13 formed by etching is equal to the preset depth, and the thickness of the test substrate 1 is selected in accordance with the preset depth, so the marking thickness is a controllable known quantity, which is 1.3 μm in this application. Since the observation point 102 is selected as a key point for easy identification, the offset point corresponding to the observation point 102 in the offset pattern 21 is easy to identify.

[0071] In step S400, due to the small thickness of the mark, when observing from the mark surface 12 of the test substrate 1, the portion where the offset pattern 21 is formed is light-transmissive due to the small thickness, so the position of the offset point can be directly observed from the mark surface 12 of the test substrate 1. Since each mark point in this embodiment is the end point of the straight line in the preset pattern 101, the offset direction and distance of any offset point relative to the position corresponding to the observation point 102 can be detected through four groups of indicators 314. The offset situation is recorded by the offset amount, which is a vector. The positive and negative indicate the direction and the absolute value indicates the distance. The offset amounts on two different direction lines 312 can fully describe its offset situation.

[0072] In step S500, the system deviation caused by the photolithography alignment is eliminated by taking an average, and the offset in the direction close to the polar radius is quantified by calculating the Euclidean norm values ​​of the offsets in two different directions. The compensation coefficient is calculated based on this, which has a high credibility. This step specifically includes:

[0073] S510, calculating the average value of the offset amounts of the offset marks 3 to obtain an average amount.

[0074] S520, using the difference between the offset amount of each offset mark 3 and the average amount as a calculation amount, to obtain a radial amount in a direction close to the polar radius.

[0075] S530, calculating the ratio of the radial value to the polar value of each offset mark 3, and taking the average value as the compensation coefficient.

[0076] The offset recorded in step S400 and the values ​​calculated in step S400 are shown in Table 1 below.

[0077] Table 1:

[0078]

[0079] It can be seen from the above table that the compensation coefficient in this embodiment is 0.346×10 -3 Since the ratio of the radial quantity to the polar diameter corresponding to the 13th observation point 102 is an invalid null value, the average value of the ratio of the radial quantity to the polar diameter corresponding to the 1st to 12th observation points 102 is used as the compensation coefficient.

[0080] In step S600, according to the observation results in Table 1, it can be seen that the offset pattern 21 is enlarged compared with the preset pattern 101, so the compensation pattern needs to be obtained by reducing the preset pattern 101, and the amount of its diameter to be reduced is 0.346×10 -3 times, and the preset graphic 101 is reduced according to this value to obtain a compensated graphic.

[0081] This embodiment also includes step S700, etching the compensation pattern on the etching surface 11 of another test substrate 1, setting the etching parameters to the preset parameters, and obtaining the etching pattern. Detecting and recording the offset between each offset mark 3 and the corresponding point on the offset mark 3. The radial amount calculated according to the offset is shown in Table 2 below.

[0082] Table 2:

[0083] Corresponding observation point number 1 2 3 4 5 6 7 Radial value (μm) 1.23 0.23 -0.62 -0.36 -1.39 -1.00 -0.54 Corresponding observation point number 8 9 10 11 12 13 - Radial value (μm) -0.58 0.55 0.70 -0.07 0.78 0.00 -

[0084] By comparing the data in Table 1 and Table 2, it can be seen that the shape of the etched pattern obtained by etching the compensation pattern is similar to the preset pattern 101, the deviation is small, and the deviation compensation is effectively achieved.

[0085] Embodiment 2:

[0086] The difference between this embodiment and the first embodiment is that the structure of the test substrate 1 in this embodiment is the same as that of the target substrate, which is a silicon wafer with a transparent silicon dioxide film layer deposited on one surface. The silicon dioxide film layer is the observation layer, and the marking surface 12 is the surface of the observation layer away from the silicon wafer. The thickness of the observation layer is 8 μm, and the marking thickness is 5 μm.

[0087] Embodiment 2:

[0088] The only difference between this embodiment and the first embodiment is that in this embodiment, the side length of the square is 1 mm, and multiple sets of measuring rulers 31 are arranged on each side with a spacing of 50 μm. When measuring the offset, multiple sets of measuring rulers 31 are used to measure separately, and the average is taken after removing the values ​​with larger deviations.

[0089] The beneficial effect of the present invention is to provide a bulk silicon process offset compensation method, which has strong universality and does not affect the etching rate, and can effectively suppress the offset of the etching pattern in subsequent batch production through only one compensation.

[0090] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The above-mentioned 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 invention patent. It should be pointed out that, for ordinary technicians in this field, several variations 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 patent of the present invention shall be subject to the attached claims.

Claims

1. A bulk silicon process offset compensation method, characterized in that: include: A plurality of observation points (102) are set on a preset graph (101), each of the observation points (102) being a key point within the preset graph (101), and the distance from any of the observation points (102) to the center point of the preset graph (101) is recorded as a polar diameter; A test substrate (1) made of the same material as the target substrate is provided, the test substrate (1) comprising an etched surface (11) and a marking surface (12) opposite to the etched surface (11), a plurality of offset marks (3) respectively corresponding to the observation points (102) being formed on the marking surface (12); The etched surface (11) of the test substrate (1) is etched with the preset pattern (101) to form a pattern groove (13); the bottom surface of the pattern groove (13) away from the etched surface (11) of the test substrate (1) is an offset pattern (21); the offset pattern (21) is embedded in the test substrate (1); the distance between the offset pattern (21) and the marking surface (12) of the test substrate (1) is a marking thickness; the offset pattern (21) can be directly observed from the marking surface (12) of the test substrate (1); and the position on the offset pattern (21) corresponding to the observation point (102) is an offset point; Observing the offset points and the offset marks (3) from the marking surface (12) of the test substrate (1), respectively measuring and recording the offset between each offset point and the corresponding offset mark (3), wherein the offset is a vector; Calculating a compensation coefficient according to the offset of each offset mark (3) and the polar diameter of the corresponding observation point (102); The preset graph (101) is scaled according to the compensation coefficient to obtain a compensation graph.

2. The method according to claim 1, characterized in that The compensation coefficient calculated according to the offset of each offset mark (3) and the polar diameter of the corresponding observation point (102) includes: Calculating the average value of the offset values ​​of the offset marks (3) to obtain an average value; The difference between the offset amount of each offset mark (3) and the average amount is used as a calculation amount to obtain a radial amount close to the direction of the polar diameter; The ratio of the radial value of each offset mark (3) to the polar diameter is calculated, and the average value is taken as the compensation coefficient.

3. The method according to claim 2, characterized in that A plurality of observation points (102) having the same polar diameter form a group, and the accuracy of the polar diameter is any value between 1 mm and 10 mm.

4. The method according to claim 2, characterized in that Each of the offset marks (3) comprises a measuring ruler (31) configured in the shape of a ruler, wherein the measuring ruler (31) has an origin (311) corresponding to the observation point (102), a direction line (312) passing through the origin (311), and a plurality of indicating scales (313) arranged along the direction line (312).

5. The method according to claim 4, characterized in that Each of the offset marks (3) comprises at least two mutually perpendicular direction lines (312), and the indicating scale (313) is arranged on any of the direction lines (312).

6. The method according to claim 5, characterized in that Each of the offset marks (3) comprises a plurality of sets of measuring rulers (31), each of the measuring rulers (31) comprises only one direction line (312), and the plurality of direction lines (312) are separated from each other.

7. The method according to claim 6, characterized in that The distance between two adjacent origins (311) of the same offset mark (3) in a direction parallel to a direction line (312) is any value between 50 μm and 300 μm, and / or the distance between two adjacent origins (311) in a direction perpendicular to the direction line (312) is any value between 50 μm and 300 μm.

8. The method according to claim 7, characterized in that The value of the radial quantity is the Euclidean norm value of the readings on the two direction lines (312) of the offset mark (3).

9. The method according to claim 1, characterized in that The mark thickness is less than or equal to 2 μm.

10. The method according to claim 1, characterized in that The marking surface (12) of the test substrate (1) is formed with a transparent observation layer, and the offset pattern (21) is embedded in the observation layer.

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