Overlay error compensation method

Abstract

The present disclosure provides an overlay error compensation method, which relates to the field of semiconductor technology and is used to solve the technical problem of poor accuracy of overlay error. The overlay error correction method includes: obtaining a first overlay error value of the third alignment mark of the to-be-processed layer of the wafer relative to the first alignment mark of the target layer; obtaining a second overlay error value of the third alignment mark of the to-be-processed layer of the wafer relative to the second alignment mark of the target layer, wherein the first alignment mark and the second alignment mark are arranged at intervals; determining the actual overlay error value of the third alignment mark of the to-be-processed layer of the wafer relative to the first alignment mark and the second alignment mark according to the first overlay error value and the second overlay error value; and compensating the first overlay error value and the second overlay error value respectively according to the actual overlay error value. The present disclosure can ensure that the third alignment mark of the to-be-processed layer can be aligned with the first alignment mark and the second alignment mark of the target layer.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of semiconductor technology, and in particular to an overlay error compensation method. Background Art

[0002] During wafer production and processing, it is necessary to determine whether the current processing layer (current layer) is aligned with the target layer (previous layer) to ensure the effectiveness of production and processing of the processing layer. In related technologies, the position deviation between the alignment mark in the processing layer and the alignment mark in the target layer can be measured through optical signals, and the overlay error between the previous layer and the current layer can be calculated.

[0003] However, the overlay error obtained by the above method has poor accuracy, thereby reducing the alignment accuracy of the wafer. Summary of the Invention

[0004] The embodiments of the present disclosure provide an overlay error compensation method for improving the accuracy of the overlay error and thereby improving the alignment accuracy of the wafer.

[0005] A first aspect of an embodiment of the present disclosure provides an overlay error compensation method, comprising:

[0006] Acquire a first overlay error value of a third alignment mark of a to-be-processed layer of the wafer relative to a first alignment mark of a target layer;

[0007] Obtaining a second overlay error value of a third alignment mark of a to-be-processed layer of the wafer relative to a second alignment mark of the target layer, wherein the first alignment mark and the second alignment mark are arranged at intervals;

[0008] Determining an actual overlay error value of the third alignment mark of the to-be-processed layer of the wafer relative to the first alignment mark and the second alignment mark according to the first overlay error value and the second overlay error value;

[0009] The first overlay error value and the second overlay error value are compensated respectively according to the actual overlay error value.

[0010] In some embodiments, determining, based on the first overlay error value and the second overlay error value, an actual overlay error value of the third alignment mark of the to-be-processed layer of the wafer relative to the first alignment mark and the second alignment mark includes:

[0011] Obtain a first weight coefficient and a second weight coefficient;

[0012] The actual overlay error value is determined according to the difference between the sum of the product of the first overlay error value and the first weight coefficient and the product of the second overlay error value and the second weight coefficient and the sum of the first weight coefficient and the second weight coefficient.

[0013] In some embodiments, the step of obtaining the first weight coefficient and the second weight coefficient includes:

[0014] Obtaining a first residual and a second residual, wherein the first residual is used to represent a positional offset of the third alignment mark relative to the first alignment mark after compensating the first overlay error value using a first compensation parameter; and the second residual is used to represent a positional offset of the third alignment mark relative to the second alignment mark after compensating the second overlay error value using a second compensation parameter;

[0015] A first weight coefficient and a second weight coefficient are determined according to the first residual amount and the second residual amount.

[0016] In some embodiments, the first overlay error value is used as a first compensation parameter to compensate for the position of the third alignment mark of the to-be-processed layer, and a position offset of the third alignment mark of the to-be-processed layer relative to the first alignment mark of the target layer after compensation is obtained to obtain the first residual amount;

[0017] The second overlay error value is used as the second compensation parameter to compensate the position of the third alignment mark of the layer to be processed, and the position offset of the third alignment mark of the layer to be processed relative to the second alignment mark of the target layer after compensation is obtained to obtain the second residual amount.

[0018] In some embodiments, there are multiple third alignment marks; and the method further includes:

[0019] obtaining a first compensated overlay error value of each of the third alignment marks relative to the first alignment mark after compensating the first overlay error value itself; and obtaining a second compensated overlay error value of each of the third alignment marks relative to the second alignment mark after compensating the second overlay error value itself;

[0020] A plurality of the first compensation overlay error values ​​and a plurality of the second compensation overlay error values ​​are respectively input into a preset iterative model; and a first residual amount and a second residual amount are respectively obtained through output results of the preset iterative model.

[0021] In some embodiments, determining the first weight coefficient and the second weight coefficient according to the first residual amount and the second residual amount includes:

[0022] The first weight coefficient and the second weight coefficient are determined based on the fact that the ratio of the first residual amount to the second residual amount is equal to the ratio of the first weight coefficient to the second weight coefficient, and the sum of the first weight coefficient and the second weight coefficient is equal to a constant value.

[0023] In some embodiments, if the first residual amount is greater than the second residual amount, the first weight coefficient is greater than the second weight coefficient.

[0024] In some embodiments, obtaining a first overlay error value of a third alignment mark of a to-be-processed layer of a wafer relative to a first alignment mark of a target layer includes:

[0025] In a first direction, determining, based on the optical signal, a first edge and a second edge of a third alignment mark opposite to the first alignment mark, and determining a third edge and a fourth edge of the first alignment mark opposite to each other;

[0026] measuring a first distance between the first edge and the third edge, and measuring a second distance between the third edge and the fourth edge by a measuring device;

[0027] The first overlay error value is determined according to the first distance and the second distance.

[0028] In some embodiments, the first overlay error value is determined based on an average of a difference between the first distance and the second distance.

[0029] In some embodiments, obtaining a second overlay error value of a third alignment mark of a to-be-processed layer of a wafer relative to a second alignment mark of a target layer includes:

[0030] In the first direction, determining, according to the optical signal, a fifth edge and a sixth edge of a third alignment mark opposite to the second alignment mark, and determining a seventh edge and an eighth edge of the second alignment mark opposite to each other;

[0031] measuring a third distance between the fifth edge and the seventh edge, and measuring a fourth distance between the sixth edge and the eighth edge by a measuring device;

[0032] The second overlay error value is determined according to an average value of a difference between the third distance and the fourth distance.

[0033] In the overlay error compensation method provided by the embodiment of the present disclosure, on the basis of obtaining the first overlay error value of the third alignment mark relative to the first alignment mark of the target layer, the second overlay error value of the third alignment mark relative to the second alignment mark of the target layer is also obtained, and the actual overlay error value is obtained based on the first overlay error and the second overlay error, and then the relative position of the layer to be processed and the target layer is adjusted according to the actual overlay error value to ensure that the third alignment mark of the layer to be processed can be aligned with the first alignment mark and the second alignment mark of the target layer, thereby improving the alignment accuracy of the layer to be processed, thereby improving the accuracy of the graphics of the layer to be processed. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A flowchart of an overlay error compensation method provided in an embodiment of the present disclosure;

[0035] Figure 2 A schematic diagram of a first alignment mark, a second alignment mark, and a third alignment mark provided in an embodiment of the present disclosure;

[0036] Figure 3 A schematic diagram of the initial alignment accuracy between the to-be-processed layer and the target layer provided in an embodiment of the present disclosure;

[0037] Figure 4 A schematic diagram of various position offsets after using the first overlay error value as a compensation coefficient in an embodiment of the present disclosure;

[0038] Figure 5 A schematic diagram of various position offsets after using the second overlay error value as a compensation coefficient in an embodiment of the present disclosure;

[0039] Figure 6 A schematic diagram of the final alignment accuracy between the layer to be processed and the target layer provided in an embodiment of the present disclosure.

[0040] Reference numerals:

[0041] 100: first alignment mark; 110: third edge; 120: fourth edge;

[0042] 200: second alignment mark; 210: seventh edge; 220: eighth edge;

[0043] 300 : third alignment mark; 310 : first edge; 320 : second edge; 330 : fifth edge; 340 : sixth edge. DETAILED DESCRIPTION

[0044] During the production and processing of semiconductors, for example, when a machine processes a wafer, a preset circuit pattern can be formed on each layer of the wafer through photolithography or other methods. In order to ensure the accuracy and effectiveness of the circuit pattern on each layer, the machine needs to detect whether the layer is aligned before processing the current layer to be processed (or the current layer). For example, the machine can record a layer that has been determined to be aligned as the target layer (or the previous layer), and then use optical signal measurement to obtain the overlay error (OVL) value between multiple alignment marks of the current layer to be processed and multiple alignment marks of the target layer. Finally, based on the overlay error, it is determined whether the layer to be processed is aligned with the target layer.

[0045] When the target layer (front layer) contains two graphics, when preparing the first graphic, the front layer can be used as the target layer for alignment to ensure the accuracy of the first graphic. When preparing the second graphic, the first graphic needs to be used as a reference; when the wafer's to-be-processed layer needs to be prepared, the optical signal measurement usually obtains the overlay error between the graphic in the to-be-processed layer and the first graphic in the target layer to measure whether the to-be-processed layer and the target layer are aligned. In the actual calibration process, the graphic in the to-be-processed layer is aligned with the first graphic in the target layer. However, when there is a deviation between the first graphic and the second graphic in the target layer, the graphic in the to-be-processed layer is not aligned with the second graphic in the target layer, and thus the alignment accuracy of the graphic in the to-be-processed layer and the second graphic in the target layer cannot be guaranteed.

[0046] In response to the above technical problems, an embodiment of the present disclosure provides an overlay error compensation method, which obtains a first overlay error value of the third alignment mark relative to the first alignment mark of the target layer, and also obtains a second overlay error value of the third alignment mark relative to the second alignment mark of the target layer. Based on the actual overlay error value obtained from the first overlay error and the second overlay error, the first overlay error value and the second overlay error value are compensated, that is, the relative position of the layer to be processed and the target layer is adjusted according to the actual overlay error value to ensure that the third alignment mark of the layer to be processed can be aligned with the first alignment mark and the second alignment mark of the target layer, thereby improving the alignment accuracy of the layer to be processed and thus improving the accuracy of the graphics of the layer to be processed.

[0047] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present disclosure.

[0048] The present disclosure provides an overlay error compensation method for improving the accuracy of calibration between the to-be-processed layer and the target layer. Figure 1 , the overlay error compensation method comprises the following steps:

[0049] S100: Acquire a first overlay error value of a third alignment mark of a to-be-processed layer of a wafer relative to a first alignment mark of a target layer.

[0050] Please refer to the attached Figure 2 The target layer includes a first alignment mark 100 and a second alignment mark 200. The first alignment mark 100 and the second alignment mark 200 are spaced apart. As an example, there may be a plurality of first alignment marks 100. There may also be a plurality of second alignment marks 200. To facilitate description of the positions of the first alignment marks 100 and the second alignment marks 200, the plurality of first alignment marks 100 may be divided into a plurality of first alignment mark groups, and the plurality of second alignment marks 200 may be divided into a plurality of second alignment mark groups. The plurality of first alignment mark groups are spaced apart along a first direction X, and the plurality of first alignment marks 100 in each first alignment mark group are spaced apart along a second direction Y. One of the second alignment mark groups is located between adjacent first alignment mark groups, and the plurality of second alignment marks 200 in the second alignment mark group are spaced apart along the second direction Y. The second alignment marks 200 in the second alignment mark group are offset from the first alignment marks 100 in the first alignment mark group.

[0051] The number of the third alignment marks 300 on the target layer can be multiple, and the multiple third alignment marks 300 are spaced apart along the first direction X, and the projection of each third alignment mark 300 on the target layer covers one first alignment mark group or one second alignment mark group.

[0052] It should be noted that the shapes of the first alignment mark 100, the second alignment mark 200 and the third alignment mark 300 are not limited to the following shapes. Figure 2 described in .

[0053] Attachment Figure 2 The arrangement of the first alignment mark 100 and the second alignment mark 200 can be understood as the arrangement of the alignment marks in one exposure unit in the target layer. Furthermore, multiple exposure units are provided on the target layer, and the positions and shapes of the alignment marks in each exposure unit are identical.

[0054] Exemplarily, step S110: in the first direction, determining, according to the optical signal, a first edge and a second edge of a third alignment mark opposite to the first alignment mark, and determining a third edge and a fourth edge of the first alignment mark opposite to each other.

[0055] According to the optical signal, the first edge 310 and the second edge 320 of the third alignment mark 300 in the first direction are determined to attach Figure 2 Taking the illustrated orientation as an example, when the shape of the third alignment mark 300 includes a bar, the first edge 310 is the left edge of the third alignment mark 300 , and the second edge 320 is the right edge of the third alignment mark 300 .

[0056] Then, according to the optical signal, the third edge 110 and the fourth edge 120 of the first alignment mark 100 in the first direction are determined. The third edge 110 and the fourth edge 120 are oppositely arranged, and the third edge 110 is close to the first edge 310 and the fourth edge 120 is close to the second edge 320.

[0057] When the first alignment mark 100 is circular or elliptical, the third edge 110 and the fourth edge 120 are the left and right endpoints of an axis of the first alignment mark 100 in the first direction and passing through the center of the first alignment mark 100. When the first alignment mark 100 is square, the third edge 110 and the fourth edge 120 are two sides of the square in the first direction.

[0058] Step S120: measuring a first distance between the first edge and the third edge, and measuring a second distance between the third edge and the fourth edge by using a measuring device.

[0059] In this example, the first distance is the vertical distance between the first edge 310 and the third edge 110, and the second distance is the vertical distance between the second edge 320 and the fourth edge 120. Figure 2 a1 in the second distance is the Figure 2 a2 in .

[0060] It should be noted that, in this embodiment, the measuring device may include an optical distance measuring device, but is not limited thereto.

[0061] Step S130: Determine a first overlay error value according to the first distance and the second distance.

[0062] For example, the first overlay error value is determined based on the average value of the difference between the first distance a1 and the second distance a2. To facilitate the description of the first overlay error value and the second overlay error value in the following embodiments, the first alignment mark is denoted as A, the second alignment mark is denoted as B, and the third alignment mark is denoted as C. The first overlay error value OVL C-LEA =(a1-a2) / 2.

[0063] Step S200: obtaining a second overlay error value of a third alignment mark of a to-be-processed layer of a wafer relative to a second alignment mark of a target layer, wherein the first alignment mark and the second alignment mark are arranged at intervals.

[0064] For example, in the first direction, the optical signal is used to determine the fifth edge 330 and the sixth edge 340 of the third alignment mark 300 that are opposite to the second alignment mark 200, and the seventh edge 210 and the eighth edge 220 that are opposite to the second alignment mark 200. The fifth edge 330 is adjacent to the seventh edge 210, and the sixth edge 340 is adjacent to the eighth edge 220.

[0065] It should be noted that the description of the fifth edge 330 and the sixth edge 340 can refer to the description of the first edge 310 and the second edge 320. The description of the seventh edge 210 and the eighth edge 220 can refer to the description of the third edge 110 and the fourth edge 120.

[0066] Next, a measuring device is used to measure a third distance b1 between the fifth edge 330 and the seventh edge 210, and a fourth distance b2 between the sixth edge 340 and the eighth edge 220. The third distance b1 is the vertical distance between the fifth edge 330 and the seventh edge 210. The fourth distance b2 is the vertical distance between the sixth edge 340 and the eighth edge 220.

[0067] The second overlay error value is determined based on the average value of the difference between the third distance b1 and the fourth distance b2. That is, the second overlay error value OVL C-LEB =(b1-b2) / 2.

[0068] Step S300 : determining an actual overlay error value of a third alignment mark of a to-be-processed layer of a wafer relative to the first alignment mark and the second alignment mark according to the first overlay error value and the second overlay error value.

[0069] Step S400: Compensating the first overlay error value and the second overlay error value respectively according to the actual overlay error value.

[0070] In this embodiment, on the basis of obtaining the first overlay error value of the third alignment mark 300 relative to the first alignment mark 100 of the target layer, the second overlay error value of the third alignment mark 300 relative to the second alignment mark 200 of the target layer is also obtained, and the actual overlay error value obtained based on the first overlay error value and the second overlay error value is compensated for the first overlay error value and the second overlay error value, that is, the position of the third alignment mark 300 relative to the first alignment mark 100 is accurately adjusted according to the actual overlay error value, and the position of the third alignment mark 300 relative to the second alignment mark 200 is adjusted, thereby ensuring that the third alignment mark 300 of the layer to be processed can be aligned with the first alignment mark 100 and the second alignment mark 200 of the target layer, thereby improving the alignment accuracy of the layer to be processed, thereby improving the accuracy of the pattern of the layer to be processed.

[0071] In one possible implementation, the step of determining an actual overlay error value of a third alignment mark of a to-be-processed layer of a wafer relative to the first alignment mark and the second alignment mark according to the first overlay error value and the second overlay error value includes:

[0072] Step S310: Obtain a first weight coefficient and a second weight coefficient.

[0073] Exemplarily, a first residual amount and a second residual amount are obtained.

[0074] In order to facilitate the description of the first residual below, it is better to record the first residual as Res C-LEA , and the second residual is recorded as Res C-LEB . Among them, Res is the abbreviation of Residual.

[0075] In this embodiment, the first residual amount Res C-LEA It is used to represent the position offset of the third alignment mark relative to the first alignment mark after compensating the first overlay error value using the first compensation parameter. C-LEB It is used to represent the position offset of the third alignment mark relative to the second alignment mark after the compensation for the second overlay error value according to the second compensation parameter.

[0076] It should be noted that there are multiple third alignment marks. Although the first compensation parameter is used to compensate for the first overlay error value, some third alignment marks are still misaligned with the first alignment marks. Therefore, the position offset of the compensated third alignment marks relative to the first alignment marks can be used as the first residual value Res. C-LEA Accordingly, although the second compensation parameter is used to compensate for the second overlay error value, there are still some third alignment marks that are not aligned with the second alignment marks. Therefore, the position offset of the compensated third alignment marks relative to the second alignment marks can be used as the second residual value Res C-LEB .

[0077] In one example, the first compensation parameter may be a first overlay error value; the position of the third alignment mark 300 of the to-be-processed layer is compensated using the first compensation parameter, and the position offset of the third alignment mark 300 of the to-be-processed layer relative to the first alignment mark 100 of the target layer after compensation is obtained to obtain the first residual amount Res C-LEA The second compensation parameter can be a second overlay error value; the position of the third alignment mark 300 of the to-be-processed layer is compensated using the second compensation parameter, and the position offset of the third alignment mark 300 of the to-be-processed layer relative to the second alignment mark 200 of the target layer after compensation is obtained to obtain the second residual amount Res C-LEBThen, a first weight coefficient and a second weight coefficient are determined based on the first residual amount and the second residual amount. The first weight coefficient and the second weight coefficient are related to the ratio of the first residual amount to the second residual amount. For example, the ratio of the first weight coefficient and the second weight coefficient is equal to the ratio of the first residual amount to the second residual amount, and the sum of the first weight coefficient and the second weight coefficient is equal to a fixed value.

[0078] In other words, the first weight coefficient and the second weight coefficient can be calculated by the following formula:

[0079] Formula (1) p / m = Res C-LEA / Res C-LEB ;

[0080] Formula (2) p+m=n;

[0081] Among them, p is the first weight coefficient, m is the second weight coefficient; Res C-LEA is the first residual, Res C-LEB is the second residual amount; n is a constant.

[0082] Substitute formula (1) into formula (2) to obtain the first weight coefficient p and the second weight coefficient m, respectively. It should be noted that the constant n in this embodiment can be a positive integer, for example, the constant n is 1.

[0083] Step S320: Determine the actual overlay error value according to the difference between the sum of the product of the first overlay error value and the first weight coefficient and the product of the second overlay error value and the second weight coefficient and the sum of the first weight coefficient and the second weight coefficient.

[0084] In other words, the actual overlay error value is calculated as follows:

[0085]

[0086] Among them, OVL C-LELE is the actual overlay error value, OVL C-LEA is the first overlay error value, OVL C-LEB is the second overlay error value, p is the first weight coefficient, and m is the second weight coefficient.

[0087] In this embodiment, the first overlay error value OVL may be given according to actual conditions. C-LEA and the second overlay error value OVL C-LEB Equipped with different weight coefficients to ensure the actual overlay error value OVL C-LELE It is more consistent with reality and has higher reliability, and can further improve the alignment accuracy of the third alignment mark 300 in the layer to be processed and the first alignment mark 100 and the second alignment mark 200 in the target layer, thereby improving the yield of the semiconductor structure.

[0088] Please refer to the attached Figure 3 , attached Figure 3 is a schematic diagram representing the initial alignment accuracy between the target layer and the layer to be processed. Figure 3 a represents the first overlay error value of the third alignment mark 300 in the to-be-processed layer relative to the first alignment mark 100 in the target layer, and the first overlay error value is 2.90 nm. Figure 3 b represents the second overlay error value of the third alignment mark 300 in the to-be-processed layer relative to the second alignment mark 200 in the target layer, and the second overlay error value is 4.40 nm. Figure 3 c represents the overlay error of the layer to be processed relative to the target layer, and the overlay error is 4.1nm. Figure 3 As can be seen from c, the alignment accuracy between the to-be-processed layer and the target layer is very poor, resulting in poor graphics accuracy in the to-be-processed layer.

[0089] Please refer to the attached Figure 4 , attached Figure 4 a represents the first overlay error value as the compensation parameter, and the first overlay error value OVL C-LEA Compensation is performed, and the position offset of the third alignment mark 300 of the to-be-processed layer relative to the first alignment mark 100 of the target layer after compensation is obtained. At this time, the position offset is 1.44 nm.

[0090] Attachment Figure 4 b represents the first overlay error value as the compensation parameter, and the second overlay error value OVL C-LEB Compensation is performed and the position offset of the third alignment mark 300 of the to-be-processed layer relative to the second alignment mark 200 of the target layer after compensation is obtained. The position offset at this time is 2.94. Figure 4 It can be concluded from a-4b that although the position offset of the third alignment mark 300 corresponding to the first alignment mark 100 and the second alignment mark 200 is reduced, the difference between the two is still large, which is not conducive to the exposure of the subsequent layer to be processed and the alignment accuracy will also be reduced.

[0091] Please refer to the attached Figure 5 , attached Figure 5 a represents the second overlay error value as the compensation parameter, and the first overlay error value OVL C-LEA Compensation is performed, and the position offset of the third alignment mark 300 of the to-be-processed layer relative to the first alignment mark 100 of the target layer after compensation is obtained. At this time, the position offset is 2.98.

[0092] Attachment Figure 5 b represents the second overlay error value as the compensation parameter, and the second overlay error value OVL C-LEBCompensation is performed, and the position offset of the third alignment mark 300 of the to-be-processed layer relative to the second alignment mark 200 of the target layer after compensation is obtained. The position offset at this time is 1.40.

[0093] This embodiment is based on the attached Figure 4 and attached Figure 5 The value of each position offset in determines the first residual value Res C-LEA and the second residual amount Res C-LEB The actual overlay error value is determined according to formula (1), formula (2) and formula (3); finally, the actual overlay error value is used to compensate the first overlay error value and the second overlay error value. C-LEA and the second residual amount Res C-LEB The selection includes the following methods:

[0094] The first way is to use the first overlay error value as the compensation parameter, and to calculate the first overlay error value OVL. C-LEA After compensation, the position offset 1.44 is obtained as the first residual Res C-LEA The first overlay error value is used as the compensation parameter, and the second overlay error value OVL is used as the compensation parameter. C-LEB After compensation, the position offset 2.74 is obtained as the second residual Res C-LEB .

[0095] According to formula (1), formula (2) and n=1, the first weight coefficient p is 0.33 and the second weight coefficient m is 0.67. Then, according to formula (3), the actual overlay error value OVL is obtained. C-LELE It is 3.905.

[0096] Afterwards, according to the actual overlay error value OVL C-LELE , for the first overlay error value OVL C-LEA and the second overlay error value OVL C-LEB Perform compensation exposure; finally, use the measurement tool to measure the first overlay error value OVL after compensation C-LEA and the second overlay error value OVL C-LEB Among them, the first overlay error value OVL C-LEA The second set error value is 2.40, OVL C-LEB is 3.60.

[0097] The second way is to use the second overlay error value as the compensation parameter to compensate the first overlay error value OVL. C-LEA After compensation, the position offset 2.98 is obtained as the first residual value Res C-LEA The second overlay error value is used as the compensation parameter, and the second overlay error value OVL C-LEBAfter compensation, the position offset 1.40 is obtained as the second residual Res C-LEB .

[0098] According to formula (1), formula (2) and n=1, the first weight coefficient p is 0.68 and the second weight coefficient m is 0.32. Then, according to formula (3), the actual overlay error value OVL is obtained. C-LELE It is 3.38.

[0099] Afterwards, according to the actual overlay error value OVL C-LELE , for the first overlay error value OVL C-LEA and the second overlay error value OVL C-LEB Perform compensation exposure; finally, use the measurement tool to measure the first overlay error value OVL after compensation C-LEA and the second overlay error value OVL C-LEB Among them, the first overlay error value OVL C-LEA The second set error value is 2.30, OVL C-LEB It is 3.20.

[0100] The third case: take the first overlay error value as the compensation parameter, and calculate the first overlay error value OVL C-LEA After compensation, the position offset 1.44 is obtained as the first residual Res C-LEA The second overlay error value is used as the compensation parameter, and the second overlay error value OVL C-LEB After compensation, the position offset 1.40 is obtained as the second residual Res C-LEB .

[0101] According to formula (1), formula (2) and n=1, the first weight coefficient p is 0.5 and the second weight coefficient m is 0.5. Then, according to formula (3), the actual overlay error value OVL is obtained. C-LELE is 3.65.

[0102] Afterwards, according to the actual overlay error value OVL C-LELE , for the first overlay error value OVL C-LEA and the second overlay error value OVL C-LEB Perform compensation exposure; finally, use the measurement tool to measure the first overlay error value OVL after compensation C-LEA and the second overlay error value OVL C-LEB The results after compensation are as shown in the attached Figure 6 As shown. Figure 6 It can be seen from FIG. 1 that after compensating the first overlay error value with the actual overlay error value, the first overlay error value of the third alignment mark 300 of the to-be-processed layer relative to the first alignment mark 100 of the target layer is 1.80. Figure 6 As can be seen from b, after compensating the second overlay error value with the actual overlay error value, the second overlay error value of the third alignment mark 300 of the to-be-processed layer relative to the second alignment mark 200 of the target layer is obtained to be 1.69. Figure 6 It can be concluded from c that, after comprehensively considering the actual overlay error value of the third alignment mark relative to the first / second alignment mark, the final overlay error value of the third alignment mark will also become smaller. Figure 3 The 4.10nm in the experiment was reduced to 1.90nm.

[0103] The fourth case: the second overlay error value is used as the compensation parameter, and the first overlay error value OVL is C-LEA After compensation, the position offset 2.98 is obtained as the first residual value Res C-LEA The first overlay error value is used as the compensation parameter, and the second overlay error value OVL is used as the compensation parameter. C-LEB After compensation, the position offset 2.74 is obtained as the second residual Res C-LEB .

[0104] According to formula (1), formula (2) and n=1, the first weight coefficient p is 0.53 and the second weight coefficient m is 0.47. Then, according to formula (3), the actual overlay error value OVL is obtained. C-LELE is 3.60.

[0105] Afterwards, according to the actual overlay error value OVL C-LELE , for the first overlay error value OVL C-LEA and the second overlay error value OVL C-LEB Perform compensation exposure; finally, use the measurement tool to measure the first overlay error value OVL after compensation C-LEA and the second overlay error value OVL C-LEB Among them, the first overlay error value OVL C-LEA The second set error value is 2.20, OVL C-LEB is 2.80.

[0106] Taking into account the above four compensation methods, this embodiment measures the final overlay error value and compares the difference between the two. That is, the closer the offset of the third alignment mark relative to the first alignment mark is to the offset of the third alignment mark relative to the second alignment mark, the more conducive it is to improving the alignment accuracy. From the above data analysis, it can be seen that the two smaller position offsets are used as the first residual amount Res C-LEA and the second residual amount Res C-LEB , the first weight coefficient p and the second weight coefficient m determined subsequently can be optimized. C-LELE , for the first overlay error value OVLC-LEA and the second overlay error value OVL C-LEB Compensation makes the first overlay error value OVL after compensation C-LEA and the second overlay error value OVL C-LEB The difference between them is minimized to ensure the alignment accuracy and reliability of the layer to be processed and the target layer.

[0107] And through the attachment Figure 3 and attached Figure 6 It is obvious from the comparison that Figure 3 In the previous example, only the first overlay error value of the third alignment mark relative to the first alignment mark and the second overlay error value of the third alignment mark relative to the second alignment mark were calculated separately, resulting in poor alignment accuracy between the processed layer and the target layer. This embodiment, however, comprehensively considers the first overlay error value and the second overlay error value, using the first overlay error value to compensate for itself and the second overlay error value to compensate for itself, thereby obtaining the minimum position offset. The first and second weight coefficients are then derived based on the minimum position offset, and the first and second overlay error values ​​are compensated for. This improves the alignment accuracy between the processed layer and the target layer, resulting in more accurate exposure of the processed layer.

[0108] In a possible implementation manner, the first residual amount Res C-LEA and the second residual amount Res C-LEB When the first weight coefficient p and the second weight coefficient m are the same, the proportions of the first weight coefficient p and the second weight coefficient m are the same, for example, the first weight coefficient p and the second weight coefficient m can both be 50%. In one example, when the sum of the first weight coefficient p and the second weight coefficient m is 1, the first weight coefficient p and the second weight coefficient m are both 0.5.

[0109] When the first residual amount Res C-LEA and the second residual amount Res C-LEB When they are different, the weight coefficient corresponding to the larger residual amount is greater than the weight coefficient corresponding to the smaller residual amount. In one example, if the first residual amount is greater than the second residual amount, the first weight coefficient is greater than the second weight coefficient. This setting can increase the first overlay error value OVL C-LEA The proportion of the third alignment mark 300 in the to-be-processed layer and the alignment accuracy of the first alignment mark 100 and the second alignment mark 200 in the target layer are improved to the greatest extent, thereby improving the yield of the semiconductor structure.

[0110] In a possible implementation, there are multiple third alignment marks 300; and the overlay error compensation method further includes:

[0111] After the first overlay error value is obtained to compensate for itself, a first compensated overlay error value of each third alignment mark 300 relative to the first alignment mark 100 is obtained. That is, after using the first overlay error value as a first compensation parameter and compensating for the first overlay error value, a first compensated overlay error value of each third alignment mark 300 relative to the first alignment mark 100 is obtained. It should be noted that the method for obtaining the first compensated overlay error value is the same as the method for obtaining the first overlay error value, and this embodiment will not be further described here.

[0112] After obtaining the second overlay error value to compensate for itself, the second compensated overlay error value of each third alignment mark 300 relative to the second alignment mark 200 is obtained; that is, using the second overlay error value as the second compensation parameter, and after compensating the second overlay error value, the second compensated overlay error value of each third alignment mark 300 relative to the second alignment mark 200 is obtained.

[0113] A plurality of first compensation overlay error values ​​and a plurality of second compensation overlay error values ​​are respectively input into a preset iterative model; and a first residual amount and a second residual amount are respectively obtained through output results of the preset iterative model.

[0114] Optionally, before the step of inputting multiple first compensated overlay error values ​​and multiple second compensated overlay error values ​​into the preset iterative model respectively, it also includes: training the preset model according to a preset training data set to obtain a preset iterative model; wherein the preset training data set includes first compensated overlay error value training samples, second compensated overlay error value training samples, first residual training samples corresponding to the first compensated overlay error value training samples, and second residual training samples corresponding to the second compensated overlay error value training samples.

[0115] In this embodiment, the first residual amount and the second residual amount are obtained by using a preset iterative model, which can improve the accuracy of the first residual amount and the second residual amount, and then ensure the reasonable adjustment of the ratio of the first weight coefficient p and the second weight coefficient m, so as to ensure the actual overlay error value OVL C-LELE It is more consistent with reality and has higher reliability, and can further improve the alignment accuracy of the third alignment mark 300 in the layer to be processed and the first alignment mark 100 and the second alignment mark 200 in the target layer, thereby improving the yield of the semiconductor structure.

[0116] In the aforementioned embodiments, the methods provided by the embodiments of the present disclosure have been described. To implement the various functions of the methods provided by the embodiments of the present disclosure, the device or apparatus that performs the methods may include hardware structures and / or software modules, and the aforementioned functions may be implemented in the form of hardware structures, software modules, or a combination of hardware structures and software modules. Whether a particular function is implemented in the form of hardware structures, software modules, or a combination of hardware structures and software modules depends on the specific application and design constraints of the technical solution.

[0117] As an example, an embodiment of the present disclosure further provides an overlay error compensation device, including:

[0118] A first acquisition module, the first acquisition module is used to obtain a first overlay error value of a third alignment mark of a to-be-processed layer of the wafer relative to a first alignment mark of a target layer;

[0119] a second acquisition module, the second acquisition module being used to acquire a second overlay error value of a third alignment mark of a to-be-processed layer of the wafer relative to a second alignment mark of the target layer;

[0120] A determination module is provided, wherein the determination module determines an actual overlay error value of a third alignment mark of the to-be-processed layer of the wafer relative to the first alignment mark and the second alignment mark according to the first overlay error value and the second overlay error value.

[0121] The compensation module compensates for the first and second overlay errors based on the actual overlay error value. This module then adjusts the relative position of the processing layer and the target layer to ensure that the third alignment mark of the processing layer is aligned with the first and second alignment marks of the target layer, thereby improving the alignment accuracy of the processing layer and thus improving the accuracy of the pattern of the processing layer.

[0122] It should be noted that it should be understood that the division of the various modules of the above device is merely a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. Moreover, these modules can all be implemented in the form of software called by a processing element; or they can all be implemented in the form of hardware; or some modules can be implemented in the form of software called by a processing element, and some modules can be implemented in the form of hardware. For example, the processing module can be a separately established processing element, or it can be integrated into a chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and called by a processing element of the above device to perform the functions of the above-mentioned module. The implementation of other modules is similar. In addition, these modules can all or partly be integrated together, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above modules can be completed by an integrated logic circuit of hardware in the processor element or instructions in the form of software.

[0123] For example, the above modules may also be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASICs), one or more microprocessors (digital signal processors (DSPs), or one or more field programmable gate arrays (FPGAs). For another example, when a module is implemented by a processing element calling a program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call a program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0124] The present disclosure also provides an overlay error compensation device, comprising: a memory and at least one processor. The memory stores computer-executable instructions; the at least one processor executes the computer-executable instructions stored in the memory, so that the overlay error compensation device implements the method described in any of the above embodiments.

[0125] The processor and the memory can communicate; illustratively, the processor and the memory communicate via a communication bus, the memory is used to store computer programs, and the processor is used to call the computer program in the memory to execute the overlay error compensation method shown in any of the above method embodiments.

[0126] The overlay error compensation device may further include a communication interface, which may include a transmitter and / or a receiver. Optionally, the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in the embodiments of the present application may be directly implemented as being executed by a hardware processor, or may be implemented by a combination of hardware and software modules in the processor.

[0127] An embodiment of the present disclosure provides a storage medium storing computer-executable instructions. When a processor executes the computer-executable instructions, the overlay error compensation method described in any of the above embodiments is implemented.

[0128] An embodiment of the present disclosure further provides a program product, which includes a computer program. When the computer program is executed by a processor, the overlay error compensation method described in any of the above embodiments is implemented.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A method for compensating overlay error, characterized in that: include: Acquire a first overlay error value of a third alignment mark of a to-be-processed layer of the wafer relative to a first alignment mark of a target layer; Obtaining a second overlay error value of a third alignment mark of a to-be-processed layer of the wafer relative to a second alignment mark of the target layer, wherein the first alignment mark and the second alignment mark are arranged at intervals; Determining an actual overlay error value of the third alignment mark of the to-be-processed layer of the wafer relative to the first alignment mark and the second alignment mark according to the first overlay error value and the second overlay error value; Compensating the first overlay error value and the second overlay error value respectively according to the actual overlay error value; Wherein, determining, according to the first overlay error value and the second overlay error value, an actual overlay error value of the third alignment mark of the to-be-processed layer of the wafer relative to the first alignment mark and the second alignment mark comprises: Obtaining a first weight coefficient and a second weight coefficient; Determine the actual overlay error value according to a difference between the sum of the product of the first overlay error value and the first weight coefficient and the product of the second overlay error value and the second weight coefficient and the sum of the first weight coefficient and the second weight coefficient; The calculation formula of the actual overlay error value is as follows: Among them, OVL C-LELE is the actual overlay error value, OVL C-LEA is the first overlay error value, OVL C-LEB is the second overlay error value, p is the first weight coefficient, and m is the second weight coefficient.

2. The overlay error compensation method according to claim 1, wherein: The steps of obtaining the first weight coefficient and the second weight coefficient include: Obtaining a first residual and a second residual, wherein the first residual is used to represent a positional offset of the third alignment mark relative to the first alignment mark after compensating the first overlay error value using a first compensation parameter; and the second residual is used to represent a positional offset of the third alignment mark relative to the second alignment mark after compensating the second overlay error value using a second compensation parameter; A first weight coefficient and a second weight coefficient are determined according to the first residual amount and the second residual amount.

3. The overlay error compensation method according to claim 2, wherein: Using the first overlay error value as a first compensation parameter, compensating the position of the third alignment mark of the to-be-processed layer, and obtaining a position offset of the third alignment mark of the to-be-processed layer relative to the first alignment mark of the target layer after compensation, so as to obtain the first residual amount; The second overlay error value is used as the second compensation parameter to compensate the position of the third alignment mark of the layer to be processed, and the position offset of the third alignment mark of the layer to be processed relative to the second alignment mark of the target layer after compensation is obtained to obtain the second residual amount.

4. The overlay error compensation method according to claim 3, wherein: The number of the third alignment marks is multiple; the method further includes: obtaining a first compensated overlay error value of each of the third alignment marks relative to the first alignment mark after compensating the first overlay error value itself; and obtaining a second compensated overlay error value of each of the third alignment marks relative to the second alignment mark after compensating the second overlay error value itself; A plurality of the first compensation overlay error values ​​and a plurality of the second compensation overlay error values ​​are respectively input into a preset iterative model; and a first residual amount and a second residual amount are respectively obtained through output results of the preset iterative model.

5. The overlay error compensation method according to claim 3, wherein: Determining a first weight coefficient and a second weight coefficient according to the first residual amount and the second residual amount includes: The first weight coefficient and the second weight coefficient are determined based on the fact that the ratio of the first residual amount to the second residual amount is equal to the ratio of the first weight coefficient to the second weight coefficient, and the sum of the first weight coefficient and the second weight coefficient is equal to a constant value.

6. The overlay error compensation method according to claim 5, characterized in that: If the first residual amount is greater than the second residual amount, the first weight coefficient is greater than the second weight coefficient.

7. The overlay error compensation method according to any one of claims 1 to 6, characterized in that: Obtaining a first overlay error value of a third alignment mark of a to-be-processed layer of a wafer relative to a first alignment mark of a target layer, comprising: In a first direction, determining, based on the optical signal, a first edge and a second edge of a third alignment mark opposite to the first alignment mark, and determining a third edge and a fourth edge of the first alignment mark opposite to each other; measuring a first distance between the first edge and the third edge, and measuring a second distance between the third edge and the fourth edge by a measuring device; The first overlay error value is determined according to the first distance and the second distance.

8. The overlay error compensation method according to claim 7, wherein: The first overlay error value is determined according to an average value of a difference between the first distance and the second distance.

9. The overlay error compensation method according to claim 7, wherein: Obtaining a second overlay error value of a third alignment mark of a to-be-processed layer of a wafer relative to a second alignment mark of the target layer, comprising: In the first direction, determining, according to the optical signal, a fifth edge and a sixth edge of a third alignment mark opposite to the second alignment mark, and determining a seventh edge and an eighth edge of the second alignment mark opposite to each other; measuring a third distance between the fifth edge and the seventh edge, and measuring a fourth distance between the sixth edge and the eighth edge by a measuring device; The second overlay error value is determined according to an average value of a difference between the third distance and the fourth distance.

Images