A method for removing high-risk silicon grains in silicon wafers

Abstract

The present invention relates to the field of semiconductor manufacturing technology, and specifically discloses a method for eliminating high-risk silicon grains in a silicon wafer, which includes: obtaining a mapping diagram of a silicon wafer after a probe station test, wherein defective silicon grains in the silicon wafer on the mapping diagram are marked with a defective mark; assigning a weight value according to the different positions of each silicon grain on the mapping diagram; calculating the weighted yield of each silicon grain according to the weight value of the position of each silicon grain and the position of the defective mark; comparing the weighted yield of each silicon grain with the weighted yield threshold, and marking the determined high-risk silicon grains with a defective mark according to the comparison result. The method for eliminating high-risk silicon grains in a silicon wafer provided by the present invention can effectively eliminate high-risk silicon grains located around electrically defective products, thereby effectively improving the reliability of the packaged product and meeting customer demand for high-reliability products.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a method for removing high-risk silicon grains in a silicon wafer. Background Art

[0002] After the semiconductor wafer is taped out, the entire silicon wafer needs to be electrically tested to screen out defective products. For the screened defective products, ink dots will be marked by the probe station, and the wafer loading machine will perform image recognition on the entire silicon wafer in the subsequent welding process. Figure 1 The figure shows a schematic diagram of a silicon wafer with ink dots after being identified. The selected good silicon grains are then welded to a lead frame and packaged into corresponding devices.

[0003] Although silicon grains with ink dots cannot be processed by suction, silicon grains around the ink dots will be indiscriminately sucked by the machine and installed on the lead frame. Although the silicon grains around the defective silicon grains with ink dots appear to be electrically good in the initial test, the risk factor of failure in reliability verification after packaging is still high. Therefore, products using silicon grains surrounded by ink dots will have very high quality risks.

[0004] Therefore, how to eliminate high-risk silicon grains in silicon wafers has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] The present invention provides a method for eliminating high-risk silicon grains in a silicon wafer, which solves the problem in the related art that high-risk silicon grains located around electrically defective products in a silicon wafer cannot be eliminated.

[0006] As one aspect of the present invention, a method for removing high-risk silicon grains in a silicon wafer is provided, which comprises:

[0007] Obtaining a mapping image of a silicon wafer after being tested by a probe station, wherein defective silicon grains in the silicon wafer are marked with a defective mark on the mapping image;

[0008] Assigning a weight value according to the different positions of each silicon grain on the mapping map;

[0009] Calculate the weighted yield of each silicon grain according to the weight value of the location of each silicon grain and the location of the defective mark;

[0010] The weighted yield of each silicon grain is compared with the weighted yield threshold, and the high-risk silicon grains are marked with defective labels based on the comparison results.

[0011] Furthermore, the weight value is assigned according to the different positions of each silicon grain on the mapping diagram, including:

[0012] Setting a selection box of size N*N, and moving the selection box in sequence along each silicon grain on the map, and making the silicon grain to be tested be located at the center of the selection box each time, wherein N is an odd number greater than or equal to 3;

[0013] The silicon grains in the selection box are divided into risk echelons according to their distances from the silicon grains to be tested;

[0014] Different weight values ​​are assigned to each silicon grain in the current selection box according to different risk echelons.

[0015] Furthermore, dividing the silicon grains in the selection box into risk echelons according to the distances from the silicon grains to be tested includes:

[0016] Determine the silicon crystal grains located directly above, directly below, directly to the left, and directly to the right of the silicon crystal grain to be tested in the selection box as the first risk echelon;

[0017] Determine the silicon crystal grains located in the upper left, upper right, lower left and lower right of the silicon crystal grain to be tested in the selection box as the second risk echelon;

[0018] The silicon grains in the selection box excluding the above directions are determined as the third risk tier.

[0019] Furthermore, assigning different weight values ​​to each silicon grain in the current selection box according to different risk echelons includes:

[0020] All silicon grains in the first risk echelon are assigned a first weight value, all silicon grains in the second risk echelon are assigned a second weight value, and all silicon grains in the third risk echelon are assigned a third weight value, wherein the first weight value is greater than the second weight value, and the second weight value is greater than the third weight value.

[0021] Further, the weighted yield rate of each silicon grain is calculated according to the weight value of the position of each silicon grain and the position of the defective mark, including:

[0022] Calculate the total weight score of the selection box according to the number of silicon grains in different risk echelons in the selection box and the weight value corresponding to the risk echelon;

[0023] Determine the risk echelon where the bad mark is located, and recalculate the weight score of the selection box after subtracting the number of bad marks from the number of silicon grains in the risk echelon where the bad mark is located;

[0024] Calculate the ratio of the weight score of the current selection box to the total weight score of the selection box to obtain the weighted yield of the silicon grain to be tested;

[0025] The above calculation method is repeated to obtain the weighted yield of each silicon grain.

[0026] Further, the total weight score of the selection box is calculated according to the number of silicon grains in different risk echelons in the selection box and the weight values ​​corresponding to the risk echelons, including:

[0027] Calculate the number of silicon grains in the first risk echelon, the second risk echelon, and the third risk echelon in the selection box respectively;

[0028] Calculating a weight value of the first risk echelon according to the number of silicon grains in the first risk echelon and the first weight value;

[0029] Calculating a weight value of the second risk echelon according to the number of silicon grains in the second risk echelon and a second weight value;

[0030] Calculating the value of the third risk echelon according to the number of silicon grains in the third risk echelon and the third weight value;

[0031] The total weight score of the selection box is calculated by summing up the weight value of the first risk tier, the weight value of the second risk tier, and the weight value of the third risk tier.

[0032] Further, the step of determining the risk echelon where the bad identification is located, and recalculating the weight score of the selection box after subtracting the number of the bad identification from the number of silicon grains in the risk echelon where the bad identification is located, comprises:

[0033] When the bad label is in any one or both of the first risk echelon, the second risk echelon and the third risk echelon, the weight value of the risk echelon where the bad label is located is calculated by subtracting the number of silicon grains remaining after the bad label from the number of silicon grains in the risk echelon where the bad label is located and the weight value corresponding to the risk echelon; the risk echelons without bad labels are calculated according to the number of silicon grains and the corresponding weight value to obtain the weight value of each risk echelon, and the weight values ​​of the three risk echelons are summed to obtain the weight score of the selection box;

[0034] When the bad identification is respectively in the first risk echelon, the second risk echelon and the third risk echelon, the weight value of each risk echelon is calculated by subtracting the remaining number of silicon grains from the bad identification from the number of silicon grains in the first risk echelon, the second risk echelon and the third risk echelon and the weight value corresponding to each risk echelon, and the weight values ​​of the three risk echelons are summed to obtain the weight score of the selection box.

[0035] Furthermore, a selection box of size N*N is set, and the selection box is moved in sequence along each silicon grain on the map, and each time the silicon grain to be tested is located at the center of the selection box, including:

[0036] A 5*5 selection box is set, and the 5*5 selection box is moved in sequence along each silicon grain after removing the edge area on the mapping image, and each time the silicon grain to be tested is moved, it is located at the center of the 5*5 selection box.

[0037] Furthermore, all silicon grains located in the upper edge region of the mapping map are determined to be in the third risk tier.

[0038] Furthermore, the weighted yield of each silicon grain is compared with the weighted yield threshold, and the determined high-risk silicon grains are marked with a bad mark according to the comparison result, including:

[0039] If the weighted yield of the silicon grain is not less than the weighted yield threshold, the silicon grain is determined to be a low-risk silicon grain;

[0040] If the weighted yield of the silicon grain is less than the weighted yield threshold, the silicon grain is determined to be a high-risk silicon grain, and the high-risk silicon grain is determined to be a defective product and marked with a defective mark.

[0041] The method for eliminating high-risk silicon grains in a silicon wafer provided by the present invention calculates the weighted yield of each silicon grain in the silicon wafer to determine the risk level of each silicon grain, thereby effectively eliminating high-risk silicon grains located around electrically defective products, thereby effectively improving the reliability of the packaged product and meeting customer demand for high-reliability products. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0043] Figure 1 This is a mapping diagram formed after the silicon wafer is tested by the probe station.

[0044] Figure 2 The present invention is a flow chart of a method for eliminating high-risk silicon grains in a silicon wafer.

[0045] Figure 3 This is a schematic diagram of the distribution of risk tiers in the selection box provided by the present invention.

[0046] Figure 4 A schematic diagram of the selection box provided by the present invention moving in a mapping diagram.

[0047] Figure 5a A schematic diagram of weight score calculation provided by the present invention when the bad identification is in the first risk tier.

[0048] Figure 5b for Figure 5aSchematic representation of the calculation results displayed in the map.

[0049] Figure 6a A schematic diagram of weight score calculation provided by the present invention when the bad identification is in the second risk tier.

[0050] Figure 6b for Figure 6a Schematic representation of the calculation results displayed in the map.

[0051] Figure 7a The present invention provides a schematic diagram of calculating the weight score when the bad identification is in the third risk tier.

[0052] Figure 7b for Figure 7a Schematic representation of the calculation results displayed in the map.

[0053] Figure 8a A schematic diagram of weight score calculation when the bad identification is in the first risk echelon, the second risk echelon and the third risk echelon provided by the present invention.

[0054] Figure 8b for Figure 8a Schematic representation of the calculation results displayed in the map.

[0055] Figure 9a A schematic diagram of calculating the total weight score of a selection box provided by the present invention when the selection box is located in an edge area.

[0056] Figure 9b A schematic diagram of weight score calculation when the selection box provided by the present invention is located in the edge area and the bad mark is located in the first risk tier.

[0057] Fig.9c for Figure 9b Schematic representation of the calculation results displayed in the map.

[0058] Fig.10 This is a schematic diagram showing the weighted yield after final calculation provided by the present invention. DETAILED DESCRIPTION

[0059] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0060] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment 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 making creative work should fall within the scope of protection of the present invention.

[0061] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0062] In this embodiment, a method for removing high-risk silicon grains in a silicon wafer is provided. Figure 2 : is a flow chart of a method for eliminating high-risk silicon grains in a silicon wafer according to an embodiment of the present invention. Figure 2 As shown, including:

[0063] S110, obtaining a mapping diagram of a silicon wafer after being tested by a probe station, wherein defective silicon grains in the silicon wafer are marked with a defective mark on the mapping diagram;

[0064] It should be understood that after the semiconductor wafer is taped out, the entire silicon wafer needs to be tested for electrical performance, that is, the silicon wafer is tested by a probe station. After the test is completed, the defective products will be marked with ink dots for identification, so as to screen out the good silicon grains that have passed the electrical performance test. The silicon wafer after the test is formed into a mapping map, as shown in Figure 1 As shown, the defective silicon crystal grains with ink dots are marked with a bad mark. In the embodiment of the present invention, the bad mark is specifically represented by "NG", that is, Figure 1 NG in the mapping diagram indicates defective silicon grains after being tested by the probe station.

[0065] S120, assigning a weight value according to the different locations of each silicon grain on the mapping map;

[0066] In the embodiment of the present invention, the following may be specifically included:

[0067] Setting a selection box of size N*N, and moving the selection box in sequence along each silicon grain on the map, and making the silicon grain to be tested be located at the center of the selection box each time, wherein N is an odd number greater than or equal to 3;

[0068] The silicon grains in the selection box are divided into risk echelons according to their distances from the silicon grains to be tested;

[0069] Different weight values ​​are assigned to each silicon grain in the current selection box according to different risk echelons.

[0070] Specifically, in the embodiment of the present invention, the following may be further included:

[0071] A 5*5 selection box is set, and the 5*5 selection box is moved in sequence along each silicon grain after removing the edge area on the mapping image, and each time the silicon grain to be tested is moved, it is located at the center of the 5*5 selection box.

[0072] like Figure 3 As shown, it is a 5*5 selection box. Figure 1 Each time the silicon crystal grain to be tested moves sequentially on the map shown in the figure, each time the silicon crystal grain to be tested is located at the center of the selection box, that is, at Figure 3 The X position of the

[0073] When moving, the edge area on the map is not included in the range of the silicon grain to be tested. Figure 1 All silicon grains except those in the edge areas are included in the range of silicon grains to be tested. Each silicon grain to be tested must be located at the center of the selection box when the selection box is moved to its position, and then the weighted yield of the silicon grain to be tested is calculated.

[0074] Figure 4 , a schematic diagram of a 5*5 selection box at positions X1, X2, and X3 is shown. It should be understood that the selection box moves sequentially, for example, Figure 4 Taking the direction shown as an example, you can move from left to right along the silicon wafer to each silicon grain in turn, and each silicon grain to be tested is located in the center of the selection box. Figure 4 The selection box 100 is displayed at the X1 position, wherein the silicon grain 110 to be tested is located at its center position, and the silicon grain adjacent to the right side of the silicon grain 110 to be tested is the position where the center position of the selection box is located when it moves next time.

[0075] In the selection box, all silicon grains except the silicon grain to be tested at the center position are assigned weight values ​​according to their distances from the center position.

[0076] It should also be understood that when there is no NG mark in the selection box, the final calculated yield of each silicon grain in the selection box is 100%. When the silicon grain to be tested is exactly marked with NG, that is, when the center of the selection box is exactly marked with NG, the yield of the silicon grain to be tested is 0%.

[0077] In the embodiment of the present invention, dividing the silicon grains in the selection box into risk echelons according to the distances from the silicon grains to be tested includes:

[0078] Determine the silicon crystal grains located directly above, directly below, directly to the left, and directly to the right of the silicon crystal grain to be tested in the selection box as the first risk echelon;

[0079] Determine the silicon crystal grains located in the upper left, upper right, lower left and lower right of the silicon crystal grain to be tested in the selection box as the second risk echelon;

[0080] The silicon grains in the selection box excluding the above directions are determined as the third risk tier.

[0081] like Figure 3 As shown, the silicon grains located directly above, directly below, directly to the left and directly to the right of the silicon grain X to be tested in the selection box are all determined as the first risk echelon, that is, the positions represented by the letter A are all determined as the first risk echelon; the silicon grains located in the upper left, upper right, lower left and lower right of the silicon grain X to be tested in the selection box are all determined as the second risk echelon, that is, the positions represented by the letter B are all determined as the second risk echelon; the other positions in the selection box except the above positions are all determined as the third risk echelon, that is, the positions represented by the letter C are all determined as the third risk echelon.

[0082] Specifically, assigning different weight values ​​to each silicon grain in the current selection box according to different risk echelons includes:

[0083] All silicon grains in the first risk echelon are assigned a first weight value, all silicon grains in the second risk echelon are assigned a second weight value, and all silicon grains in the third risk echelon are assigned a third weight value, wherein the first weight value is greater than the second weight value, and the second weight value is greater than the third weight value.

[0084] In the embodiment of the present invention, it should be understood that the silicon grains at the position of the letter A are all assigned a first weight value, the silicon grains at the position of the letter B are all assigned a second weight value, and the silicon grains at the position of the letter C are all assigned a third weight value, and the first weight value is greater than the second weight value, and the second weight value is greater than the third weight value.

[0085] Preferably, as shown in Table 1 below, the first weight value may be 1, the second weight value may be 0.618, and the third weight value may be 0.382.

[0086] Table 1 Weight value table

[0087] Region Weight A 1 B 0.618 C 0.382

[0088] It should be understood that the specific weight value can be set as needed and is not limited here.

[0089] S130, calculating the weighted yield of each silicon grain according to the weight value of the location of each silicon grain and the location of the defective mark;

[0090] In the embodiment of the present invention, the following may be specifically included:

[0091] S131. Calculate the total weight score of the selection box according to the number of silicon grains in different risk echelons in the selection box and the weight values ​​corresponding to the risk echelons.

[0092] More specifically, it may include:

[0093] Calculate the number of silicon grains in the first risk echelon, the second risk echelon, and the third risk echelon in the selection box respectively;

[0094] Calculating a weight value of the first risk echelon according to the number of silicon grains in the first risk echelon and the first weight value;

[0095] Calculating a weight value of the second risk echelon according to the number of silicon grains in the second risk echelon and a second weight value;

[0096] Calculating the value of the third risk echelon according to the number of silicon grains in the third risk echelon and the third weight value;

[0097] The total weight score of the selection box is calculated by summing up the weight value of the first risk tier, the weight value of the second risk tier, and the weight value of the third risk tier.

[0098] As shown in Table 2 below, combined Figure 3 From the selection box shown, it can be seen that the number of silicon grains in the first risk echelon A is 4, the number of silicon grains in the second risk echelon B is 4, and the number of silicon grains in the third risk echelon C is 16. The total weight score of the selection box is 4*1+4*0.618+16*0.382=12.584.

[0099] Table 2 Weighted total score calculation table

[0100]

[0101] It should be noted that the silicon grains located in the upper edge region of the mapping diagram are all determined to be in the third risk tier.

[0102] That is, when the selection box moves to the edge area, the silicon grains in the edge area are all determined to be in the third risk tier, that is, the weight values ​​of the silicon grains distinguished by the edge are all assigned the third weight value.

[0103] S132, determining the risk echelon where the bad mark is located, and recalculating the weight score of the selection box after dividing the number of the bad marks by the number of silicon grains in the risk echelon where the bad marks are located.

[0104] In the embodiment of the present invention, the following may be specifically included:

[0105] When the bad label is in any one or both of the first risk echelon, the second risk echelon and the third risk echelon, the weight value of the risk echelon where the bad label is located is calculated by subtracting the number of silicon grains remaining after the bad label from the number of silicon grains in the risk echelon where the bad label is located and the weight value corresponding to the risk echelon; the risk echelons without bad labels are calculated according to the number of silicon grains and the corresponding weight value to obtain the weight value of each risk echelon, and the weight values ​​of the three risk echelons are summed to obtain the weight score of the selection box;

[0106] When the bad identification is respectively in the first risk echelon, the second risk echelon and the third risk echelon, the weight value of each risk echelon is calculated by subtracting the remaining number of silicon grains from the bad identification from the number of silicon grains in the first risk echelon, the second risk echelon and the third risk echelon and the weight value corresponding to each risk echelon, and the weight values ​​of the three risk echelons are summed to obtain the weight score of the selection box.

[0107] For example, if the bad sign is in the first risk tier, such as Figure 5a and Figure 5b As shown, the position directly below the silicon grain X to be tested is a bad mark, and the number of silicon grains in the first risk echelon is reduced by 1, leaving 3. The weight score of the recalculated selection box is: 3*1+4*0.618+16*0.382=11.584.

[0108] S133, calculating the ratio of the weight score of the current selection box to the total weight score of the selection boxes, and obtaining the weight yield of the silicon grain to be tested;

[0109] The ratio of the weight score of the above selection box to the total weight score of the above selection box is calculated as 11.584 / 12.584=92.1%. Therefore, the weight yield of the silicon grain to be tested is =92.1%. Figure 5a and Figure 5b shown.

[0110] For example, Figure 6a and Figure 6bAs shown, when the defective mark is located in the second risk echelon, for example, located at the lower left position of the silicon grain to be tested, the number of silicon grains in the second risk echelon is subtracted by 1, and the weight score of the selection box is recalculated to be 4*1+3*0.618+16*0.382=11.966, and the weighted yield of the silicon grain X to be tested is 11.966 / 12.584=95.1%.

[0111] For example, Figure 7a and Figure 7b As shown, when the defective mark is in the third risk tier, the number of silicon grains in the third risk tier is subtracted by 1, and the weight score of the selection box is recalculated to be 4*1+4*0.618+15*0.382=12.202, and the weighted yield of the silicon grain X to be tested is 12.202 / 12.584=97.0%.

[0112] For example, Figure 8a and Figure 8b As shown, when there is a bad mark in each of the first risk echelon, the second risk echelon and the third risk echelon, the number of silicon grains in each risk echelon is subtracted by 1, and the weight score of the selection box is recalculated to be 3*1+3*0.618+15*0.382=10.584, and the weighted yield of the silicon grain X to be tested is 10.584 / 12.584=84.1%.

[0113] For example, Figure 9a , Figure 9b and Fig.9c As shown, when the selection box moves to the edge area, as mentioned above, the silicon grains in the edge area are all determined to be in the third risk echelon, that is, the weight values ​​of the silicon grains distinguished by the edge are all assigned the third weight value. At this time, if the bad mark is located in the first risk echelon, the silicon grain data in the edge area is 9 in total (two of which originally belonged to the second risk echelon and were determined to be in the third risk echelon because they were located in the edge area). The number of silicon grains originally in the third risk echelon is 9, then The total number of silicon grains in the third risk echelon is 9+9=18, and the total weight score of the current selection box is recalculated to be 4*1+2*0.618+18*0.382=12.112. After subtracting 1 from the silicon grain data in the first risk echelon, the weight score of the current selection box is recalculated to be 3*1+2*0.618+18*0.382=11.112. The weight yield of the current silicon grain X to be tested is 11.112 / 12.112=91.7%.

[0114] It should be noted here that Figure 5b , Figure 6b , Figure 7b , Figure 8b and Fig.9cThe "1" in the selection box does not represent a weight, but is a mark in the mapping diagram to distinguish good silicon grains from defective silicon grains after the electrical performance test. As mentioned above, defective silicon grains are marked as "NG" and good silicon grains in the mapping diagram are marked as "1".

[0115] The above calculation method is repeated to obtain the weighted yield of each silicon grain.

[0116] It should be understood that by moving the selection box, the weighted yield of each silicon grain in the map can be calculated. Fig.10 As shown, this is a schematic diagram showing the weighted yield after the final calculation.

[0117] S140, comparing the weighted yield of each silicon crystal grain with the weighted yield threshold, and marking the determined high-risk silicon crystal grains with a defective mark according to the comparison result.

[0118] In the embodiment of the present invention, the following may be specifically included:

[0119] If the weighted yield of the silicon grain is not less than the weighted yield threshold, the silicon grain is determined to be a low-risk silicon grain;

[0120] If the weighted yield of the silicon grain is less than the weighted yield threshold, the silicon grain is determined to be a high-risk silicon grain, and the high-risk silicon grain is determined to be a defective product and marked with a defective mark.

[0121] It should be understood that, for example, the weighted yield threshold can be set to 92%. In the above example, the silicon grains X to be tested with a weighted yield lower than 92% are all identified as high-risk silicon grains, and the silicon grains X to be tested with a weighted yield higher than 92% are all identified as low-risk silicon grains. Finally, the high-risk silicon grains are determined as defective products in the mapping diagram and marked with defective identifications. For example, these defective identifications can still be marked with "NG".

[0122] It should also be understood that the weighted yield threshold can be set as needed and is not limited here.

[0123] In summary, the method for eliminating high-risk silicon grains in a silicon wafer provided in an embodiment of the present invention calculates the weighted yield of each silicon grain in the silicon wafer to determine the risk level of each silicon grain, thereby effectively eliminating high-risk silicon grains located around electrically defective products, thereby effectively improving the reliability of the packaged product and meeting customer demand for high-reliability products.

[0124] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for removing high-risk silicon grains from a silicon wafer, characterized in that: include: Obtaining a mapping image of a silicon wafer after being tested by a probe station, wherein defective silicon grains in the silicon wafer are marked with a defective mark on the mapping image; Assigning a weight value according to the different positions of each silicon grain on the mapping map; Calculate the weighted yield of each silicon grain according to the weight value of the location of each silicon grain and the location of the defective mark; The weighted yield of each silicon crystal grain is compared with the weighted yield threshold, and the determined high-risk silicon crystal grains are marked as defective according to the comparison result; The step of assigning a weight value according to the different positions of each silicon grain on the mapping diagram includes: Setting a selection box of size N*N, and moving the selection box in sequence along each silicon grain on the map, and making the silicon grain to be tested be located at the center of the selection box each time, wherein N is an odd number greater than or equal to 3; The silicon grains in the selection box are divided into risk echelons according to their distances from the silicon grains to be tested; Different weight values ​​are assigned to each silicon grain in the current selection box according to different risk echelons; The step of dividing the silicon grains in the selection box into risk echelons according to their distances from the silicon grains to be tested includes: Determine the silicon crystal grains located directly above, directly below, directly to the left, and directly to the right of the silicon crystal grain to be tested in the selection box as the first risk echelon; Determine the silicon crystal grains located in the upper left, upper right, lower left and lower right of the silicon crystal grain to be tested in the selection box as the second risk echelon; The silicon grains in the selection box except the above directions are determined as the third risk tier; The method of assigning different weight values ​​to each silicon grain in the current selection box according to different risk echelons includes: Assign a first weight value to all silicon grains in the first risk echelon, assign a second weight value to all silicon grains in the second risk echelon, and assign a third weight value to all silicon grains in the third risk echelon, wherein the first weight value is greater than the second weight value, and the second weight value is greater than the third weight value; The step of calculating the weighted yield of each silicon grain according to the weight value of the location of each silicon grain and the location of the defective mark includes: Calculate the total weight score of the selection box according to the number of silicon grains in different risk echelons in the selection box and the weight value corresponding to the risk echelon; Determine the risk echelon where the bad mark is located, and recalculate the weight score of the selection box after subtracting the number of bad marks from the number of silicon grains in the risk echelon where the bad mark is located; Calculate the ratio of the weight score of the current selection box to the total weight score of the selection box to obtain the weighted yield of the silicon grain to be tested; Repeat the above calculation to calculate the ratio of the weight score of the current selection box to the total weight score of the selection boxes to obtain the weighted yield of each silicon grain.

2. The elimination method according to claim 1, characterized in that: The method of calculating the total weight score of the selection box according to the number of silicon grains in different risk echelons in the selection box and the weight values ​​corresponding to the risk echelons includes: Calculate the number of silicon grains in the first risk echelon, the second risk echelon, and the third risk echelon in the selection box respectively; Calculating a weight value of the first risk echelon according to the number of silicon grains in the first risk echelon and the first weight value; Calculating a weight value of the second risk echelon according to the number of silicon grains in the second risk echelon and a second weight value; Calculating the value of the third risk echelon according to the number of silicon grains in the third risk echelon and the third weight value; The total weight score of the selection box is calculated by summing up the weight value of the first risk tier, the weight value of the second risk tier, and the weight value of the third risk tier.

3. The elimination method according to claim 1, characterized in that: The step of determining the risk echelon where the bad identification is located, and recalculating the weight score of the selection box after subtracting the number of the bad identification from the number of silicon grains in the risk echelon where the bad identification is located, includes: When the bad label is in any one or both of the first risk echelon, the second risk echelon and the third risk echelon, the weight value of the risk echelon where the bad label is located is calculated by subtracting the number of silicon grains remaining after the bad label from the number of silicon grains in the risk echelon where the bad label is located and the weight value corresponding to the risk echelon; the risk echelons without bad labels are calculated according to the number of silicon grains and the corresponding weight value to obtain the weight value of each risk echelon, and the weight values ​​of the three risk echelons are summed to obtain the weight score of the selection box; When the bad identification is respectively in the first risk echelon, the second risk echelon and the third risk echelon, the weight value of each risk echelon is calculated by subtracting the remaining number of silicon grains from the bad identification from the number of silicon grains in the first risk echelon, the second risk echelon and the third risk echelon and the weight value corresponding to each risk echelon, and the weight values ​​of the three risk echelons are summed to obtain the weight score of the selection box.

4. The elimination method according to claim 1, characterized in that: Setting a selection box of size N*N, and moving the selection box in sequence along each silicon grain on the mapping diagram, and making the silicon grain to be tested located at the center of the selection box each time the selection box is moved, comprising: A 5*5 selection box is set, and the 5*5 selection box is moved in sequence along each silicon grain after removing the edge area on the mapping image, and each time the silicon grain to be tested is moved, it is located at the center of the 5*5 selection box.

5. The elimination method according to claim 4, characterized in that: The silicon grains located in the upper edge region of the mapping map are all determined to be in the third risk tier.

6. The elimination method according to claim 1, characterized in that: The weighted yield of each silicon grain is compared with the weighted yield threshold, and the determined high-risk silicon grains are marked with a bad mark according to the comparison result, including: If the weighted yield of the silicon grain is not less than the weighted yield threshold, the silicon grain is determined to be a low-risk silicon grain; If the weighted yield of the silicon grain is less than the weighted yield threshold, the silicon grain is determined to be a high-risk silicon grain, and the high-risk silicon grain is determined to be a defective product and marked with a defective mark.

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