Method and device for verifying measurement accuracy

Abstract

The embodiment of the invention provides a method and device for verifying measurement accuracy. The method comprises the following steps: obtaining reference overlay error measurement parameters of a sample wafer through a scanning electron microscope, wherein the reference overlay error measurement parameters comprise a first reference overlay error value, a reference slope value, a reference mask standard deviation and a reference difference standard deviation; obtaining to-be-verified overlay error measurement parameters of the sample wafer through the IDM measurement machine, wherein the to-be-verified overlay error measurement parameters comprise a first to-be-verified overlay error value, a to-be-verified reference slope value, a to-be-verified mask standard deviation and a to-be-verified difference standard deviation; obtaining a reference overlay error measurement precision index of the scanning electron microscope according to the reference overlay error measurement parameter; obtaining a to-be-verified overlay error measurement precision index of the IDM measurement machine according to the to-be-verified overlay error measurement parameter; and according to the reference overlay error measurement precision index and the overlay error measurement precision index to be verified, obtaining an accuracy verification result of the overlay error measurement of the IDM measurement machine. According to the invention, the accuracy of IDM measurement can be determined.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor testing technology, and more particularly to a method and device for verifying measurement accuracy. Background Art

[0002] In the semiconductor manufacturing process, the overlay error value is an important indicator to measure the alignment accuracy and yield guarantee between the current layer and the previous layer. Usually, a scanning electron microscope (SEM) is used to take pictures of the wafer in the process to obtain the overlay error value. With the development of technology, the use of IDM (In Die Metrology) measuring machines to measure the overlay error has emerged, but it is not certain whether the measured overlay error value is accurate.

[0003] The above information disclosed in this background section is only for enhancement of understanding of the background of the present disclosure and therefore it may include information that does not constitute the relevant technology that is already known to one of ordinary skill in the art. Summary of the invention

[0004] The embodiments of the present disclosure provide a method and device for verifying measurement accuracy, which can determine the measurement accuracy of an IDM measurement machine.

[0005] The disclosed embodiment provides a method for verifying measurement accuracy, comprising: obtaining reference overlay error measurement parameters of a sample wafer through a scanning electron microscope, the reference overlay error measurement parameters comprising a first reference overlay error value, a reference slope value, a reference mask standard deviation and a reference difference standard deviation; obtaining overlay error measurement parameters to be verified of the sample wafer through an IDM measuring machine, the overlay error measurement parameters to be verified comprising a first overlay error value to be verified, a reference slope value to be verified, a mask standard deviation to be verified and a difference standard deviation to be verified; obtaining reference overlay error measurement accuracy indicators of the scanning electron microscope according to the reference overlay error measurement parameters; obtaining overlay error measurement accuracy indicators of the IDM measuring machine according to the overlay error measurement parameters to be verified; obtaining an accuracy verification result of the overlay error measurement of the IDM measuring machine according to the reference overlay error measurement accuracy indicators and the overlay error measurement accuracy indicators to be verified.

[0006] In some embodiments of the present disclosure, a reference overlay error measurement accuracy index of the scanning electron microscope is obtained according to the reference overlay error measurement parameters, including: obtaining a reference slope accuracy index according to the first reference overlay error value and the reference slope value; obtaining a reference standard deviation accuracy index according to the reference mask standard deviation and the reference difference standard deviation; obtaining the reference overlay error measurement accuracy index according to the reference slope accuracy index and the reference standard deviation accuracy index; wherein the reference slope value includes a reference average slope value and a reference slope standard deviation.

[0007] In some embodiments of the present disclosure, the reference overlay error measurement parameter further includes a reference repetition standard deviation; the reference overlay error measurement accuracy index is obtained using the following formula:

[0008]

[0009] Where A1 is the reference overlay error measurement accuracy, M3σ 11 is the first reference overlay error value, μ 12 is the reference average slope value, 3σ 12 is the reference slope standard deviation, 3σ 13 is the standard deviation of the reference mask; 3σ 14 is the reference difference standard deviation; 3σ 15 is the reference replicate standard deviation; M3σ 11 2 *(3σ 12 2 +(μ 12 -1) 2 ) is the reference slope accuracy index; 3σ 13 2 +3σ 14 2 -3σ 15 2 is the reference standard deviation accuracy indicator.

[0010] In some embodiments of the present disclosure, obtaining the overlay error measurement accuracy index of the IDM measuring machine to be verified according to the overlay error measurement parameter to be verified includes: obtaining the slope accuracy index to be verified according to the first overlay error value to be verified and the slope value to be verified; obtaining the standard deviation accuracy index to be verified according to the mask standard deviation to be verified and the difference standard deviation to be verified; obtaining the overlay error measurement accuracy index to be verified according to the slope accuracy index to be verified and the standard deviation accuracy index to be verified. Wherein, the slope value to be verified includes the average slope value to be verified and the slope standard deviation to be verified.

[0011] In some embodiments of the present disclosure, the to-be-verified overlay error measurement parameter further includes a to-be-verified repetition standard deviation; the to-be-verified overlay error measurement accuracy index is obtained using the following formula:

[0012]

[0013] Among them, A2 is the measurement accuracy index of the overlay error to be verified, M3σ 21 is the first overlay error value to be verified, μ 22 is the average slope value to be verified, 3σ 22 is the standard deviation of the slope to be verified, 3σ 23 is the standard deviation of the mask to be verified; 3σ 24 is the standard deviation of the difference to be verified; 3σ 25 is the repeated standard deviation to be verified; M3σ 21 2 *(3σ 22 2 +(μ 22 -1) 2 ) is the slope accuracy index to be verified; 3σ 23 2 +3σ 24 2 -3σ 25 2 is the standard deviation accuracy indicator to be verified.

[0014] In some embodiments of the present disclosure, the method also includes: obtaining a card control value based on the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified; obtaining a comparison difference through the scanning electron microscope and the IDM measuring machine; and obtaining an accuracy verification result of the overlay error measurement of the IDM measuring machine based on the card control value and the comparison difference.

[0015] In some embodiments of the present disclosure, the card control value is obtained using the following formula:

[0016]

[0017] Wherein, S is the card control value, A1 is the reference overlay error measurement accuracy index, and A2 is the overlay error measurement accuracy index to be verified.

[0018] In some embodiments of the present disclosure, obtaining a card control value according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified includes: summing the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified to obtain the card control value.

[0019] In some embodiments of the present disclosure, a comparative difference is obtained by using the scanning electron microscope and the IDM measuring machine, including: obtaining the first reference overlay error value or the second reference overlay error value from the scanning electron microscope; obtaining the first overlay error value to be verified or the second overlay error value to be verified from the IDM measuring machine; obtaining the comparative difference based on the first reference overlay error value and the first overlay error value to be verified or based on the second reference overlay error value and the second overlay error value to be verified.

[0020] The embodiment of the present disclosure also provides a device for verifying measurement accuracy, including an acquisition unit, a processing unit and a verification unit.

[0021] The acquisition unit is used to obtain the reference overlay error measurement parameters of the sample wafer through a scanning electron microscope, and the overlay error measurement parameters include a first reference overlay error value, a reference slope value, a reference mask standard deviation and a reference difference standard deviation; the acquisition unit is also used to obtain the overlay error measurement parameters to be verified of the sample wafer through an IDM measuring machine, and the overlay error measurement parameters to be verified include a first overlay error value to be verified, a reference slope value to be verified, a mask standard deviation to be verified and a difference standard deviation to be verified; the processing unit is used to obtain the reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameters; the processing unit is also used to obtain the overlay error measurement accuracy index to be verified of the IDM measuring machine according to the overlay error measurement parameters to be verified; the verification unit is used to obtain the accuracy verification result of the overlay error measurement of the IDM measuring machine according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified.

[0022] It can be seen from the above technical solutions that the method for verifying measurement accuracy in the embodiment of the present disclosure has at least one of the following advantages and positive effects:

[0023] In the disclosed embodiment, a reference overlay error measurement parameter is obtained through a scanning electron microscope, and a reference overlay error measurement accuracy index of the scanning electron microscope is calculated based on the reference overlay error measurement parameter. An overlay error measurement parameter to be verified is obtained through an IDM measuring machine, and an overlay error measurement accuracy index to be verified of the IDM measuring machine is calculated based on the overlay error measurement parameter to be verified. The reference overlay error accuracy index of the scanning electron microscope is used as a reference, and the accuracy verification result of the overlay error measurement of the IDM measuring machine is obtained through the overlay error measurement accuracy index to be verified of the IDM measuring machine, thereby determining whether the overlay error measured by the IDM measuring machine is accurate. This method uses the accuracy obtained by the scanning electron microscope as a reference, which makes the method simple, and improves the reliability of the accuracy verification result of the overlay error measurement of the IDM measuring machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other features and advantages of the present disclosure will become more apparent by describing in detail example embodiments thereof with reference to the attached drawings.

[0025] Figure 1 A flowchart of a method for verifying measurement accuracy according to some embodiments of the present disclosure;

[0026] Figure 2 Some embodiments of the present disclosure are shown Figure 1 Flow chart of step S130 in FIG.

[0027] Figure 3 Some embodiments of the present disclosure are shown Figure 1 Flow chart of step S140 in FIG.

[0028] Figure 4 A flowchart showing obtaining a card control value and comparing a difference value is provided for some embodiments of the present disclosure;

[0029] Figure 5 Some embodiments of the present disclosure are shown Figure 4 Flow chart of step S420 in FIG.

[0030] Figure 6 A schematic diagram of transferring a pattern of a scribe line on a sample wafer using an ASR (ASML Self Reference) mask in some embodiments of the present disclosure;

[0031] Figure 7 A block diagram of an apparatus for verifying measurement accuracy according to some embodiments of the present disclosure;

[0032] Figure 8 A schematic diagram of the structure of a computer device according to some embodiments of the present disclosure;

[0033] Fig. 9 A schematic diagram of a computer-readable storage medium is shown for disclosing some embodiments.

[0034] Description of reference numerals:

[0035] 100, sample wafer; 101, chip area; 102, dicing road; 200, ASR mask; 201, sub-area. DETAILED DESCRIPTION

[0036] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their detailed description will be omitted.

[0037] In the following description of different exemplary embodiments of the present disclosure, reference is made to the accompanying drawings, which form a part of the present disclosure and in which different exemplary structures that can implement multiple aspects of the present disclosure are shown by way of example. It should be understood that other specific schemes of components, structures, exemplary devices, systems and steps can be used, and structural and functional modifications can be made without departing from the scope of the present disclosure. Moreover, although the terms "above", "between", "within", etc. may be used in this specification to describe different exemplary features and elements of the present disclosure, these terms are used herein only for convenience, such as according to the direction of the examples in the accompanying drawings. Nothing in this specification should be construed as requiring a specific three-dimensional direction of the structure to fall within the scope of the present disclosure. In addition, the terms "first", "second", etc. in the claims are used only as marks and are not numerical limitations on their objects.

[0038] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0039] In addition, in the description of the present disclosure, “plurality” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0040] In the semiconductor manufacturing process, it is necessary to determine whether the current layer being processed is aligned with the previous layer to ensure the effectiveness of the production and processing of the current layer, so it is necessary to accurately obtain the overlay error value between the current layer and the previous layer. Usually, a scanning electron microscope is used to take pictures of the wafer in the process, and the overlay error value is obtained based on the pictures. It is an ideal overlay error measurement device. Among them, the scanning electron microscope can be a high voltage scanning electron microscope (HV SEM), which is a commonly used instrument in this technical field and will not be described in detail here.

[0041] Based on the development of semiconductor technology, the IDM measuring machine can also be used to measure the overlay error. Unlike the scanning electron microscope, the IDM measuring machine uses optical principles to measure the overlay error. The measurement recipe is set in the IDM measuring machine, and the measurement is performed according to the measurement recipe. However, during the measurement process, it was found that there is no relevant verification method for whether the accuracy of the IDM measuring machine is reliable, or whether the measurement recipe setting in the IDM measuring machine is accurate.

[0042] Based on this, an embodiment of the present disclosure provides a method for verifying measurement accuracy, including the following steps S110 to S150.

[0043] S110: Obtain reference overlay error measurement parameters of the sample wafer through a scanning electron microscope, where the reference overlay error measurement parameters include a first reference overlay error value, a reference slope value, a reference mask standard deviation, and a reference difference standard deviation.

[0044] S120: obtaining the to-be-verified overlay error measurement parameters of the sample wafer through the IDM measurement machine, wherein the to-be-verified overlay error measurement parameters include a first to-be-verified overlay error value, a to-be-verified reference slope value, a to-be-verified mask standard deviation, and a to-be-verified difference standard deviation.

[0045] S130: Obtaining a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter.

[0046] S140: Obtaining an overlay error measurement accuracy index to be verified of the IDM measurement machine according to the overlay error measurement parameter to be verified.

[0047] S150: Obtaining an accuracy verification result of the overlay error measurement of the IDM measuring machine according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified.

[0048] In the disclosed embodiment, a reference overlay error measurement parameter is obtained through a scanning electron microscope, and a reference overlay error measurement accuracy index of the scanning electron microscope is calculated based on the reference overlay error measurement parameter. The overlay error measurement parameter to be verified is obtained through an IDM measuring machine, and the overlay error measurement accuracy index to be verified of the IDM measuring machine is calculated based on the overlay error measurement parameter to be verified. The reference overlay error accuracy index of the scanning electron microscope is used as a reference, and the accuracy verification result of the overlay error measurement of the IDM measuring machine is obtained through the overlay error measurement accuracy index to be verified of the IDM measuring machine, thereby obtaining whether the measurement formula of the IDM measuring machine is accurate and feasible. This method uses the accuracy obtained by the scanning electron microscope as a reference, which makes the method simple, and improves the reliability of the accuracy verification result of the overlay error measurement of the IDM measuring machine.

[0049] The following is a detailed description of the method for verifying measurement accuracy according to an embodiment of the present disclosure.

[0050] In the disclosed embodiment, the overlay error values ​​measured by the scanning electron microscope and the IDM measuring machine are all overlay errors obtained by the measurement (AEI) after the sample wafer is etched. Prior to this, the deviation in the lithography process can be obtained by the measurement (ADI) after lithography, and then the photoresist is compensated according to the deviation to correct the deviation generated by the lithography process to zero.

[0051] Then the chip area of ​​the sample wafer is etched, such as Figure 6 As shown, the sample wafer 100 includes a chip area 101 and a dicing street 102 . After the manufacturing process, dicing is performed at the dicing street 102 to cut the wafer into a plurality of chips. Figure 6 , respectively show a sample wafer 100, an enlarged portion of a chip area 101 in the sample wafer 100, an enlarged portion of an ASR mask 200 disposed on a cutting path 102, and an enlarged portion of a sub-area 201 of the ASR mask 200. An ASR mask 200 is disposed in the cutting path 102 of the sample wafer 100. The ASR mask 200 is an alignment mark mask of ASML, which is mainly used for measurement after etching. After the measurement of etching, it is used to supplement the measurement after photolithography. A plurality of sub-areas 201 are disposed on the ASR mask 200. Error values ​​caused by processes such as manufacturing and measurement are designed in each sub-area 201. Generally, the error range is -5 to 5. Different errors are designed in the plurality of sub-areas 201 of the ASR mask 200, for example, -1, -2...5.

[0052] The overlay error value of each exposure area of ​​the etched sample wafer 100 is measured, and the scanning electron microscope scans and photographs the sample wafer 100 to obtain a picture of the sample wafer 100. At the same time, the scanning electron microscope generates raw data (Rawdata), and the first reference overlay error value is obtained based on these raw data. The area where the overlay error value is obtained corresponds to the sub-area 202 of the ASR mask 200. For example, the first reference overlay error value is -2, and the value of the corresponding sub-area of ​​the ASR mask is -1, that is, the input value (set) is -1, and the output value (get) is -2, which is not the same, indicating that an error has occurred in the etching process. Before etching the next wafer, the error needs to be eliminated, so the next wafer is moved, for example, the wafer is moved to the right by 1, so that the input value and the output value are the same.

[0053] The ASR mask 200 is provided with a plurality of sub-regions 201, and the error value (input value) designed in each sub-region 201 is different. Each exposure area of ​​the etched sample wafer 100 is measured to obtain a plurality of output values, and the plurality of input values ​​and output values ​​are fitted to obtain a straight line, and the slope of the straight line of each exposure area is obtained. The ASR mask 200 and all exposure areas of the sample wafer 100 are fitted to obtain a plurality of straight lines, and the plurality of straight lines have a plurality of slopes. The average slope value of the plurality of slopes is taken, and the average slope value can be the reference slope value in S110. In addition, after calculating the average value of the plurality of slopes, the residual error can also be calculated, and the residual error is the slope value of each exposure area minus the average slope value. According to the Bessel formula, the slope standard deviation 3σ can be calculated. Therefore, the reference slope value may include the average slope value and the slope standard deviation 3σ (3σ may be the 3σ described later). 12The process of obtaining the slope value to be verified by using IDM is roughly the same as the process of obtaining the reference slope value by the scanning electron microscope mentioned above. Those skilled in the art can obtain it by operating the machine, and will not be described in detail here.

[0054] S110: obtaining reference overlay error measurement parameters of the sample wafer 100 through a scanning electron microscope, wherein the reference overlay error measurement parameters include a first reference overlay error value, a reference slope value, a reference mask standard deviation, and a reference difference standard deviation.

[0055] The first reference overlay error value is the overlay error value (Overlay) of the sample wafer 100 measured by the scanning electron microscope, and the reference slope value may include the reference average slope value obtained in the above description. The reference mask standard deviation refers to the standard deviation of the ASR mask from the target linear relationship during the measurement process. The reference difference standard deviation refers to the standard deviation generated by the ASR mask to the array area of ​​the sample wafer 100.

[0056] S120: obtaining the to-be-verified overlay error measurement parameters of the sample wafer 100 through the IDM measurement machine, wherein the to-be-verified overlay error measurement parameters include a first to-be-verified overlay error value, a to-be-verified reference slope value, a to-be-verified mask standard deviation, and a to-be-verified difference standard deviation.

[0057] The sample wafer 100 is measured by using an IDM measuring machine to obtain the original data of the sample wafer 100 . Meanwhile, the IDM measuring machine outputs the original data and the data of the ASR mask, and the overlay error measurement parameters to be verified are calculated through these data.

[0058] Among them, the first overlay error value to be verified is the overlay error value measured by the IDM measuring machine, and the slope value to be verified can be the average value of the slopes of multiple fitting straight lines obtained in different exposure areas. The acquisition process can refer to the acquisition process of the above-mentioned scanning electron microscope, which will not be repeated here. The standard deviation of the mask to be verified refers to the standard deviation of the ASR mask from the target linear relationship during the measurement process. The standard deviation of the difference to be verified refers to the standard deviation generated by the ASR mask to the array area of ​​the sample wafer 100.

[0059] S130: Obtaining a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter.

[0060] In some embodiments, Figure 2 As shown, S130 may include the following steps S210 to S230.

[0061] S210: Obtain a reference slope accuracy indicator according to the first reference overlay error value and the reference slope value.

[0062] In some embodiments, the reference slope value may include a reference average slope value μ 12 and the reference slope standard deviation 3σ 12 .

[0063] Then the accuracy index of the reference slope can be M3σ 11 2 *(3σ 12 2 +(μ 12 -1) 2 ), where M3σ 11 It can represent the first reference overlay error value. 11 is an integral, and its square is the square of the first reference overlay error value.

[0064] In some other embodiments, the reference slope value may only include the reference average slope value μ 12 , then the reference slope accuracy index can be M3σ 11 2 *(μ 12 -1) 2 .

[0065] S220: Obtain a reference standard deviation accuracy index according to the reference mask standard deviation and the reference difference standard deviation.

[0066] Among them, the reference mask standard deviation can be expressed as 3σ 13 The reference difference standard deviation can be expressed as 3σ 14 The reference standard deviation accuracy index can be expressed as 3σ 13 2 +3σ 14 2 .

[0067] S230: Obtain a reference overlay error measurement accuracy index according to a reference slope accuracy index and a reference standard deviation accuracy index.

[0068] In some embodiments, the reference overlay error measurement accuracy index may be obtained by the following formula (1).

[0069]

[0070] Among them, A1 is the reference overlay error measurement accuracy, M3σ 11 2 *(μ 12 -1) 2 is the reference slope accuracy indicator, 3σ 13 2 +3σ 14 2 It is the reference standard deviation accuracy indicator.

[0071] In some other embodiments, the reference overlay error measurement accuracy index may be obtained by the following formula (2).

[0072]

[0073] Among them, A1 is the reference overlay error measurement accuracy, M3σ 11 2 *(3σ 12 2 +(μ 12 -1) 2 ) is the reference slope accuracy index, 3σ 13 2 +3σ 14 2 It is the reference standard deviation accuracy indicator.

[0074] In some other embodiments, the reference overlay error measurement parameter also includes a reference repetition standard deviation, which refers to the standard deviation generated during repeated measurements. The reference repetition standard deviation can be expressed as 3σ 15 If , then the following formula (3) can be used to obtain the reference overlay error measurement accuracy index.

[0075]

[0076] Among them, A1 is the reference overlay error measurement accuracy, M3σ 11 2 *(3σ 12 2 +(μ 12 -1) 2 ) is the reference slope accuracy index, 3σ 13 2 +3σ 14 2 -3σ 15 2 It is the reference standard deviation accuracy indicator.

[0077] In some other embodiments, the reference overlay error measurement accuracy index may be obtained by the following formula (4).

[0078]

[0079] Among them, A1 is the reference overlay error measurement accuracy, M3σ 11 2 *(3σ 12 2 +(μ 12 -1) 2 ) is the accuracy index of the reference slope, 3σ 13 2 +3σ14 2 -3σ 15 2 It is the reference standard deviation accuracy indicator.

[0080] It should be noted that the 3σ in the formula xx Represents a whole, 3σ xx 2 Indicates 3σ xx The square of the value of . Among the above three formulas, formula (3) is more accurate than formula (1), formula (2) and formula (4). In the reference standard deviation accuracy index, due to 3σ 13 2 and 3σ 14 2 A reference replicate with a standard deviation of 3σ has been included for each 15 2 , thus, 3σ has been added twice 15 2 , so subtract a 3σ 15 2 It will make the results more accurate.

[0081] The reference overlay error measurement accuracy index A1 can be calculated by the formula in the above embodiment. The value of A1 can reflect the accuracy of the overlay error measured by the scanning electron microscope and can also be understood as the measurement error. The following is an explanation based on the measurement data in actual measurement.

[0082] In the actual measurement of the scanning electron microscope, two sets of data are obtained as an example. In the first set, the first reference overlay error value M3σ is obtained. 11 is 1.7, the reference average slope value μ 12 is 0.72, the reference slope standard deviation is 3σ 12 0.05, reference mask standard deviation 3σ 13 is 1.27, the reference difference standard deviation is 3σ 14 0.93, reference repeat standard deviation 3σ 15 is 0.4. Taking formula (3) as an example, substituting it into formula (3) yields the reference overlay error measurement accuracy index A1 to be 1.59.

[0083] In the second group, the first reference overlay error value M3σ is obtained 11 is 4.6, the reference average slope value μ 12 is 0.96, the reference slope standard deviation is 3σ 12 0.05, reference mask standard deviation 3σ 13 is 1.77, the reference difference standard deviation is 3σ 14 1.19, reference repeat standard deviation 3σ 15is 0.28. Taking formula (3) as an example, substituting it into formula (3) yields the reference overlay error measurement accuracy index A1 to be 2.13.

[0084] From the above two sets of data, it can be seen that the value of the reference overlay error measurement accuracy index obtained by the first set of data is smaller, the error is smaller, and the accuracy is higher.

[0085] S140: Obtaining an overlay error measurement accuracy index to be verified of the IDM measurement machine according to the overlay error measurement parameter to be verified.

[0086] In some embodiments, S140 may include the following steps S310 to S330.

[0087] S310: Obtaining a slope accuracy index to be verified according to the first overlay error value to be verified and the slope value to be verified.

[0088] In some embodiments, the slope value to be verified may include an average slope value μ to be verified. 22 and the slope standard deviation 3σ to be verified 22 .

[0089] Then the slope accuracy index to be verified can be M3σ 21 2 *(3σ 22 2 +(μ 22 -1) 2 ), where M3σ 21 It can represent the first overlay error value to be verified. 21 is a whole, and its square is the square of the first overlay error value to be verified.

[0090] In some other embodiments, the slope value to be verified may only include the average slope value μ to be verified. 22 , then the slope accuracy index to be verified can be M3σ 21 2 *(μ 22 -1) 2 .

[0091] S320: Obtaining a standard deviation accuracy index to be verified according to the mask standard deviation to be verified and the difference standard deviation to be verified.

[0092] Among them, the standard deviation of the mask to be verified can be expressed as 3σ 23 Indicates that the standard deviation of the difference to be verified can be expressed as 3σ 24 Indicates that the standard deviation accuracy index to be verified can be 3σ 23 2 +3σ 24 2 .

[0093] S330: Obtaining an overlay error measurement accuracy index to be verified according to the slope accuracy index to be verified and the standard deviation accuracy index to be verified.

[0094] In some embodiments, the overlay error measurement accuracy index to be verified can be obtained by the following formula (5).

[0095]

[0096] Among them, A2 is the measurement accuracy of the overlay error to be verified, M3σ 21 2 *(μ 22 -1) 2 is the slope accuracy index to be verified, 3σ 23 2 +3σ 24 2 It is the standard deviation accuracy indicator to be verified.

[0097] In some other embodiments, the overlay error measurement accuracy index to be verified may be obtained by the following formula (6).

[0098]

[0099] Among them, A2 is the measurement accuracy of the overlay error to be verified, M3σ 21 2 *(3σ 22 2 +(μ 22 -1) 2 ) is the slope accuracy index to be verified, 3σ 23 2 +3σ 24 2 It is the standard deviation accuracy indicator to be verified.

[0100] In some other embodiments, the overlay error measurement parameter to be verified also includes a repeated standard deviation to be verified, and the repeated standard deviation to be verified refers to the standard deviation generated in the process of repeated measurement. The repeated standard deviation to be verified can be expressed as 3σ 25 If it is represented, the following formula (7) can be used to obtain the measurement accuracy index of the overlay error to be verified.

[0101]

[0102] Among them, A2 is the measurement accuracy of the overlay error to be verified, M3σ 21 2 *(3σ 22 2 +(μ 22 -1) 2 ) is the slope accuracy index to be verified, 3σ23 2 +3σ 24 2 -3σ 25 2 It is the standard deviation accuracy indicator to be verified.

[0103] In some other embodiments, the following formula (8) may be used to obtain the overlay error measurement accuracy index to be verified.

[0104]

[0105] Among them, A2 is the measurement accuracy of the overlay error to be verified, M3σ 21 2 *(3σ 22 2 +(μ 22 -1) 2 ) is the accuracy index of the slope to be verified, 3σ 23 2 +3σ 24 2 -3σ 25 2 It is the standard deviation accuracy indicator to be verified.

[0106] The same as the above embodiment is that the 3σ in the formula xx Represents a whole, 3σ xx 2 Indicates 3σ xx The square of the value of . Among the above three formulas, formula (7) is more accurate than formula (5), formula (6) and formula (8). Among the standard deviation accuracy indicators to be verified, due to 3σ 23 2 and 3σ 24 2 A replicate with a standard deviation of 3σ has been included for each 25 2 , thus, 3σ has been added twice 25 2 , so subtract a 3σ 25 2 It will make the results more accurate.

[0107] The formula in the above embodiment can be used to calculate the overlay error measurement accuracy index A2 to be verified. The value of A2 can reflect the accuracy of the IDM measuring machine in measuring overlay error, and can also be understood as the measurement error. The following is an explanation based on the measurement data in actual measurement.

[0108] In the actual measurement of the IDM measuring machine, for example, a certain semiconductor process, such as a bit line etching process, is taken as an example, and the two sets of data obtained are taken as an example. The first set of data measured by the IDM measuring machine corresponds to the first set of data measured by the scanning electron microscope, and the second set of data measured by the IDM measuring machine corresponds to the second set of data measured by the scanning electron microscope.

[0109] For example, in the first set of data measured by the IDM measuring machine, the first overlay error value M3σ to be verified is obtained 21 is 2.17, and the average slope value μ is to be verified 22 is 1.11, and the slope standard deviation 3σ is to be verified 22 0.03, the standard deviation of the mask to be verified is 3σ 23 is 0.48, and the standard deviation of the difference to be verified is 3σ 24 0.46, to be verified repeated standard deviation 3σ 25 is 0.1. Taking formula (7) as an example, substituting it into formula (7) can yield that the overlay error measurement accuracy index A2 to be verified is 0.7.

[0110] For example, in the second set of data measured by the IDM measuring machine, the first overlay error value M3σ to be verified is obtained 21 is 3.89, and the average slope value μ is to be verified 22 is 0.97, and the slope standard deviation 3σ is to be verified 22 is 0.08, and the standard deviation of the mask to be verified is 3σ 23 is 1.2, and the standard deviation of the difference to be verified is 3σ 24 0.36, to be verified, repeated standard deviation 3σ 25 is 0.18. Taking formula (7) as an example, substituting it into formula (7) can yield the overlay error measurement accuracy index A2 to be verified as 1.29.

[0111] From the above two sets of data, it can be seen that the value of the reference overlay error measurement accuracy index obtained by the first set of data is smaller, the error is smaller, and the accuracy is higher.

[0112] From the above content, it can be seen that the value of the reference overlay error measurement accuracy index A1 obtained by the first set of data of the scanning electron microscope is 1.59, and the value of the overlay error measurement accuracy index A2 obtained by the first set of data of the IDM measuring machine is 0.7. The value of the reference overlay error measurement accuracy index A1 obtained by the second set of data of the scanning electron microscope is 2.13, and the value of the overlay error measurement accuracy index A2 obtained by the second set of data of the IDM measuring machine is 1.29. The value of A2 of 0.7 obtained according to the first set of data is less than the value of A1 of 1.59, and the value of A2 of 1.29 measured according to the second set is less than the value of A1 of 2.13. It can be seen that the measurement accuracy of the IDM measuring machine is higher than that of the scanning electron microscope, and the error is smaller. Therefore, it can be verified that the measurement formula set in the IDM measuring machine is more accurate, and the measured overlay error value is more accurate. The measurement formula of the IDM can be released to compensate for the yellow light.

[0113] In some embodiments, Figure 4 As shown, the method for verifying the measurement accuracy also includes the following steps S410-S430.

[0114] S410: Obtaining a card control value according to a reference overlay error measurement accuracy index and an overlay error measurement accuracy index to be verified.

[0115] After obtaining the values ​​of the reference overlay error measurement accuracy index A1 and the to-be-verified overlay error measurement accuracy index A2 in the above embodiment, the card control value may be further obtained.

[0116] In some embodiments, the card control value can be obtained using the following formula (9):

[0117]

[0118] Wherein, S represents the control value, which reflects the total error of the scanning electron microscope and the IDM measuring machine. For example, in the above embodiment, the reference overlay error measurement accuracy index A1 obtained is 1.59, and the overlay error measurement accuracy A2 to be verified is 0.7, then the control value S obtained is 1.74.

[0119] In other embodiments, obtaining the card control value according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified includes: summing the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified to obtain the card control value. That is, the card control value can be obtained by using the following formula (10):

[0120] S=A1+A2 (10)

[0121] Wherein, S represents the control value, which is the total error of the scanning electron microscope and the IDM measuring machine. For example, in the above embodiment, the reference overlay error measurement accuracy index A1 is 1.59, and the overlay error measurement accuracy A2 to be verified is 0.7, then the control value S is 2.29.

[0122] S420: Obtain comparative differences through scanning electron microscope and IDM measuring machine.

[0123] In some embodiments, Figure 5 As shown, obtaining the comparison difference by using the scanning electron microscope and the IDM measuring machine in S420 may include the following steps S510 to S530.

[0124] S510: Obtain a first reference overlay error value or a second reference overlay error value from a scanning electron microscope.

[0125] The first reference overlay error value is a first reference overlay error value measured from the sample wafer 100, and the first reference error value may be a reference overlay error value for obtaining the overlay error measurement accuracy index to be verified in the above embodiment, such as 1.7 or 4.6 in the above embodiment. The second reference overlay error value may be an overlay error value obtained by measuring the sample wafer 100 again, or an overlay error value obtained by measuring other wafers, and is not specifically limited here.

[0126] S520: Obtain a first overlay error value to be verified or a second overlay error value to be verified from an IDM measurement machine.

[0127] The first overlay error value to be verified is the first overlay error value to be verified measured from the sample wafer 100, and the first overlay error value to be verified can be the overlay error value to be verified for obtaining the overlay error measurement accuracy index in the above embodiment, such as 2.17 or 3.89 in the above embodiment. The second overlay error value to be verified can be the overlay error value obtained by measuring the sample wafer 100 again, or it can be the overlay error value obtained by measuring other wafers, and is not specifically limited here.

[0128] It should be noted that the second reference overlay error value must correspond to the second overlay error value to be verified, that is, when the second reference overlay error value is the value of the overlay error obtained by the scanning electron microscope measuring the sample wafer 100 again, then the second overlay error value to be verified should also be the value of the overlay error obtained by the IDM measuring machine measuring the sample wafer 100 again.

[0129] S530: Obtain a comparison difference value according to the first reference overlay error value and the first overlay error value to be verified or according to the second reference overlay error value and the second overlay error value to be verified.

[0130] Specifically, the comparison difference may be obtained by using the difference between the first reference overlay error value and the first overlay error value to be verified, or by using the difference between the second reference overlay error value and the second overlay error value to be verified. The difference may be the absolute value of the difference between the two for comparison.

[0131] For example, when the comparison difference is obtained using the first reference overlay error value of 1.7 and the first overlay error value to be verified of 2.17, the comparison difference can be 2.17-1.7=0.47 (or |1.7-2.17|=0.47). When the first reference overlay error value is 4.6, the first overlay error value to be verified is 3.89, and the second reference overlay error value and the second overlay error value to be verified are used, the calculation process for obtaining the comparison difference is the same and will not be repeated here.

[0132] S430: Obtaining an accuracy verification result of the overlay error measurement of the IDM measuring machine according to the card control value and the comparison difference.

[0133] Specifically, the card control value and the comparison difference are compared. If the comparison difference is less than or equal to the card control value, the accuracy verification result of the overlay error measurement of the IDM measuring machine is passed, that is, the overlay error value to be verified measured by the IDM measuring machine meets the accuracy requirements, and the measurement formula set in the IDM measuring machine is accurate. If the comparison difference is greater than the card control value, the accuracy verification result of the overlay error measurement of the IDM measuring machine is failed, that is, the overlay error value to be verified measured by the IDM measuring machine does not meet the accuracy requirements, the measurement formula set in the IDM measuring machine is inaccurate, and the measurement formula cannot be used. For example, according to the card control value S obtained in the above embodiment, the comparison difference is 0.47, and 0.47 is less than 1.74, then it can be judged that the accuracy verification result of the overlay error measurement of the IDM measuring machine is passed.

[0134] In summary, in the disclosed embodiment, a reference overlay error measurement parameter is obtained through a scanning electron microscope, and a reference overlay error measurement accuracy index of the scanning electron microscope is calculated based on the reference overlay error measurement parameter. An overlay error measurement parameter to be verified is obtained through an IDM measuring machine, and an overlay error measurement accuracy index to be verified of the IDM measuring machine is calculated based on the overlay error measurement parameter to be verified. The reference overlay error accuracy index of the scanning electron microscope is used as a reference, and the accuracy verification result of the overlay error measurement of the IDM measuring machine is obtained through the overlay error measurement accuracy index to be verified of the IDM measuring machine, thereby obtaining whether the measurement formula of the IDM measuring machine is accurate and feasible. This method uses the accuracy obtained by the scanning electron microscope as a reference, which makes the method simple, and improves the reliability of the accuracy verification result of the overlay error measurement of the IDM measuring machine.

[0135] like Figure 7As shown, the embodiment of the present disclosure further provides a device 700 for verifying measurement accuracy. The device 700 includes an acquisition unit 701 , a processing unit 702 , and a verification unit 703 .

[0136] The acquisition unit 701 is used to obtain reference overlay error measurement parameters of the sample wafer 100 through a scanning electron microscope, and the overlay error measurement parameters include a first reference overlay error value, a reference slope value, a reference mask standard deviation, and a reference difference standard deviation.

[0137] The acquisition unit 701 is further used to obtain the to-be-verified overlay error measurement parameters of the sample wafer 100 through the IDM measurement machine, the to-be-verified overlay error measurement parameters including the first to-be-verified overlay error value, the to-be-verified reference slope value, the to-be-verified mask standard deviation and the to-be-verified difference standard deviation;

[0138] The processing unit 702 is used to obtain a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter.

[0139] The processing unit 702 is further configured to obtain an overlay error measurement accuracy index to be verified of the IDM measurement machine according to the overlay error measurement parameter to be verified.

[0140] The verification unit 703 is used to obtain an accuracy verification result of the overlay error measurement of the IDM measurement machine according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified.

[0141] In some embodiments of the present disclosure, the processing unit 702 is also used to obtain a reference slope accuracy index based on the first reference overlay error value and the reference slope value; to obtain a reference standard deviation accuracy index based on the reference mask standard deviation and the reference difference standard deviation; and to obtain a reference overlay error measurement accuracy index based on the reference slope accuracy index and the reference standard deviation accuracy index.

[0142] In some embodiments of the present disclosure, the reference slope value includes a reference average slope value and a reference slope standard deviation.

[0143] In some embodiments of the present disclosure, the reference overlay error measurement parameter also includes a reference repetition standard deviation. The processing unit 702 is further configured to obtain a reference overlay error measurement accuracy index using the following formula (3):

[0144]

[0145] Among them, A1 is the reference overlay error measurement accuracy, M3σ 11 is the first reference overlay error value, μ 12 is the reference average slope value, 3σ 12 is the reference slope standard deviation, 3σ 13is the reference mask standard deviation; 3σ 14 is the reference difference standard deviation; 3σ 15 is the reference repeated standard deviation; M3σ 11 2 *(3σ 12 2 +(μ 12 -1) 2 ) is the reference slope accuracy index; 3σ 13 2 +3σ 14 2 -3σ 15 2 It is the reference standard deviation accuracy indicator.

[0146] In some embodiments of the present disclosure, the processing unit 702 is also used to obtain a slope accuracy index to be verified based on the first overlay error value to be verified and the slope value to be verified; to obtain a standard deviation accuracy index to be verified based on the mask standard deviation to be verified and the difference standard deviation to be verified; and to obtain an overlay error measurement accuracy index to be verified based on the slope accuracy index to be verified and the standard deviation accuracy index to be verified.

[0147] In some embodiments of the present disclosure, the slope value to be verified includes an average slope value to be verified and a slope standard deviation to be verified.

[0148] In some embodiments of the present disclosure, the overlay error measurement parameter to be verified also includes a repetition standard deviation to be verified. The processing unit 702 is further configured to obtain an overlay error measurement accuracy index to be verified using the following formula (7):

[0149]

[0150] Among them, A2 is the measurement accuracy index of the overlay error to be verified, M3σ 21 is the first overlay error value to be verified, μ 22 is the average slope value to be verified, 3σ 22 is the standard deviation of the slope to be verified, 3σ 23 is the standard deviation of the mask to be verified; 3σ 24 is the standard deviation of the difference to be verified; 3σ 25 is the repeated standard deviation to be verified; M3σ 21 2 *(3σ 22 2 +(μ 22 -1) 2 ) is the slope accuracy index to be verified; 3σ 23 2 +3σ 24 2 -3σ 252 It is the standard deviation accuracy indicator to be verified.

[0151] In some embodiments of the present disclosure, the verification unit 703 is also used to obtain a card control value based on a reference overlay error measurement accuracy index and an overlay error measurement accuracy index to be verified; obtain a comparison difference through a scanning electron microscope and an IDM measuring machine; and obtain an accuracy verification result of the overlay error measurement of the IDM measuring machine based on the card control value and the comparison difference.

[0152] In some embodiments of the present disclosure, the verification unit 703 is further configured to obtain the card control value by using the following formula (9):

[0153]

[0154] Wherein, S is the card control value, A1 is the reference overlay error measurement accuracy index, and A2 is the overlay error measurement accuracy index to be verified.

[0155] In some embodiments of the present disclosure, the verification unit 703 is further configured to sum the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified to obtain a card control value.

[0156] In some embodiments of the present disclosure, the verification unit 703 is also used to obtain a first overlay error value to be verified or a second overlay error value to be verified from the IDM measuring machine; and obtain a comparison difference value based on the first reference overlay error value and the first overlay error value to be verified or based on the second reference overlay error value and the second overlay error value to be verified.

[0157] In summary, the device 700 of the embodiment of the present disclosure can use the accuracy obtained by the scanning electron microscope as a reference, the verification process is simple, and the reliability of the accuracy verification result of the overlay error measurement of the IDM measurement machine is improved.

[0158] The present disclosure also provides a computer device. Figure 8 As shown, the computer device in the embodiment of the present disclosure may include one or more processors 801, a memory 802, and an input / output interface 803. The processor 801 is connected to the memory 802 and the input / output interface 803, respectively. Figure 8 As shown, the processor 801, the memory 802 and the input / output interface 803 are connected via a bus 804. The memory 802 is used to store a computer program, which includes program instructions, and the input / output interface 803 is used to receive and output data, such as for data exchange between a host machine and a computer device, or for data exchange between virtual machines in a host machine; the processor 801 is used to execute the program instructions stored in the memory 802.

[0159] Among them, the processor 801 can perform the following operations: obtain reference overlay error measurement parameters of the sample wafer 100 through a scanning electron microscope, the reference overlay error measurement parameters include a first reference overlay error value, a reference slope value, a reference mask standard deviation and a reference difference standard deviation; obtain overlay error measurement parameters to be verified of the sample wafer 100 through an IDM measuring machine, the overlay error measurement parameters to be verified include a first overlay error value to be verified, a reference slope value to be verified, a mask standard deviation to be verified and a difference standard deviation to be verified; obtain the reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameters; obtain the overlay error measurement accuracy index of the IDM measuring machine according to the overlay error measurement parameters to be verified; obtain the accuracy verification result of the overlay error measurement of the IDM measuring machine according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified.

[0160] In some feasible implementations, the processor 801 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0161] The memory 802 may include a read-only memory and a random access memory, and provide instructions and data to the processor 801 and the input / output interface 803. A portion of the memory 802 may also include a non-volatile random access memory. For example, the memory 802 may also store information about the device type.

[0162] In a specific implementation, the computer device can execute the implementation methods provided by the various steps in any of the above method embodiments through its built-in functional modules. For details, please refer to the implementation methods provided by the various steps in the figure shown in the above method embodiments, which will not be repeated here.

[0163] The embodiment of the present disclosure provides a computer device, including a processor 801, an input / output interface 803, and a memory 802. The processor 801 obtains a computer program in the memory 802 to execute each step of the method shown in any of the above embodiments.

[0164] The present disclosure also provides a computer-readable storage medium 900. Fig. 9 As shown, the computer-readable storage medium 900 stores a computer program, which is suitable for being loaded by the processor 801 and executing the method for verifying measurement accuracy provided in each step of any of the above embodiments. For details, please refer to the implementation method provided in each step of any of the above embodiments, which will not be repeated here.

[0165] In addition, the description of the beneficial effects of the same method will not be repeated. For technical details not disclosed in the computer-readable storage medium 900 embodiment involved in the present disclosure, please refer to the description of the method embodiment of the present disclosure. As an example, the computer program can be deployed to execute on one computer device, or on multiple computer devices located in one location, or on multiple computer devices distributed in multiple locations and interconnected by a communication network.

[0166] The computer-readable storage medium 900 may be an internal storage unit of the computer device provided in any of the aforementioned embodiments, such as a hard disk or memory of the computer device. The computer-readable storage medium 900 may also be an external storage device of the computer device, such as a plug-in hard disk, a smart memory card (smart media card, SMC), a secure digital (secure digital, SD) card, a flash card (flash card), etc. equipped on the computer device. Further, the computer-readable storage medium 1000 may also include both an internal storage unit of the computer device and an external storage device. The computer-readable storage medium 900 is used to store the computer program and other programs and data required by the computer device. The computer-readable storage medium 900 may also be used to temporarily store data that has been output or is to be output.

[0167] The embodiment of the present disclosure also provides a computer program product or a computer program, which includes a computer instruction, and the computer instruction is stored in a computer-readable storage medium 900. The processor of the computer device reads the computer instruction from the computer-readable storage medium 900, and the processor executes the computer instruction, so that the computer device executes the method provided in various optional manners in any of the above embodiments.

[0168] The computer device, computer-readable storage medium, and computer program product or computer program provided by the embodiments of the present disclosure can use the reference overlay error accuracy index of the scanning electron microscope as a reference, and obtain the accuracy verification result of the overlay error measurement of the IDM measuring machine through the overlay error measurement accuracy index to be verified of the IDM measuring machine, thereby obtaining whether the measurement formula of the IDM measuring machine is accurate and feasible. The method uses the accuracy obtained by the scanning electron microscope as a reference, which makes the method simple and improves the reliability of the obtained accuracy verification result of the overlay error measurement of the IDM measuring machine.

[0169] It should be understood that the present disclosure does not limit its application to the detailed structure and arrangement of the components proposed in this specification. The present disclosure can have other embodiments and can be implemented and executed in a variety of ways. The aforementioned variations and modifications fall within the scope of the present disclosure. It should be understood that the present disclosure disclosed and defined in this specification extends to all alternative combinations of two or more individual features mentioned or evident in the text and / or the drawings. All these different combinations constitute multiple alternative aspects of the present disclosure. The embodiments described in this specification illustrate the best mode known for implementing the present disclosure and will enable those skilled in the art to adopt the present disclosure.

Claims

1. A method for verifying measurement accuracy, characterized in that: include: Obtaining reference overlay error measurement parameters of the sample wafer by a scanning electron microscope, wherein the reference overlay error measurement parameters include a first reference overlay error value, a reference slope value, a reference mask standard deviation, and a reference difference standard deviation; Obtaining the overlay error measurement parameters to be verified of the sample wafer by an IDM measuring machine, wherein the overlay error measurement parameters to be verified include a first overlay error value to be verified, a reference slope value to be verified, a mask standard deviation to be verified, and a difference standard deviation to be verified; Obtaining a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter; Obtaining the overlay error measurement accuracy index to be verified of the IDM measurement machine according to the overlay error measurement parameter to be verified; According to the reference overlay error measurement accuracy index and the to-be-verified overlay error measurement accuracy index, an accuracy verification result of the overlay error measurement of the IDM measurement machine is obtained.

2. The method according to claim 1, characterized in that Obtaining a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter includes: Obtaining a reference slope accuracy index according to the first reference overlay error value and the reference slope value; Obtaining a reference standard deviation accuracy index according to the reference mask standard deviation and the reference difference standard deviation; Obtaining the reference overlay error measurement accuracy index according to the reference slope accuracy index and the reference standard deviation accuracy index; The reference slope value includes a reference average slope value and a reference slope standard deviation.

3. The method according to claim 2, characterized in that The reference overlay error measurement parameters also include a reference repetition standard deviation; The reference overlay error measurement accuracy index is obtained using the following formula: Where A1 is the reference overlay error measurement accuracy, M3σ 11 is the first reference overlay error value, μ 12 is the reference average slope value, 3σ 12 is the reference slope standard deviation, 3σ 13 is the standard deviation of the reference mask; 3σ 14 is the reference difference standard deviation; 3σ 15 is the reference replicate standard deviation; M3σ 11 2 *(3σ 12 2 +(μ 12 -1) 2 ) is the reference slope accuracy index; 3σ 13 2 +3σ 14 2 -3σ 15 2 is the reference standard deviation accuracy indicator.

4. The method according to claim 1, characterized in that: Obtaining the overlay error measurement accuracy index to be verified of the IDM measurement machine according to the overlay error measurement parameter to be verified, including: Obtaining a slope accuracy index to be verified according to the first overlay error value to be verified and the slope value to be verified; Obtaining a standard deviation accuracy index to be verified according to the mask standard deviation to be verified and the difference standard deviation to be verified; Obtaining the to-be-verified overlay error measurement accuracy index according to the to-be-verified slope accuracy index and the to-be-verified standard deviation accuracy index; The slope value to be verified includes an average slope value to be verified and a standard deviation of the slope to be verified.

5. The method according to claim 4, characterized in that The overlay error measurement parameter to be verified also includes a repeated standard deviation to be verified; The following formula is used to obtain the overlay error measurement accuracy index to be verified: Among them, A2 is the measurement accuracy index of the overlay error to be verified, M3σ 21 is the first overlay error value to be verified, μ 22 is the average slope value to be verified, 3σ 22 is the standard deviation of the slope to be verified, 3σ 23 is the standard deviation of the mask to be verified; 3σ 24 is the standard deviation of the difference to be verified; 3σ 25 is the repeated standard deviation to be verified; M3σ 21 2 *(3σ 22 2 +(μ 22 -1) 2 ) is the slope accuracy index to be verified; 3σ 23 2 +3σ 24 2 -3σ 25 2 is the standard deviation accuracy indicator to be verified.

6. The method according to any one of claims 1 to 5, characterized in that Also includes: Obtaining a card control value according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified; Obtaining a comparison difference by using the scanning electron microscope and the IDM measuring machine; According to the card control value and the comparison difference, an accuracy verification result of the overlay error measurement of the IDM measuring machine is obtained.

7. The method according to claim 6, characterized in that The card control value is obtained using the following formula: Wherein, S is the card control value, A1 is the reference overlay error measurement accuracy index, and A2 is the overlay error measurement accuracy index to be verified.

8. The method according to claim 6, characterized in that Obtaining a card control value according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified, including: The reference overlay error measurement accuracy index and the to-be-verified overlay error measurement accuracy index are summed to obtain the card control value.

9. The method according to claim 6, characterized in that Obtaining a comparative difference through the scanning electron microscope and the IDM measuring machine includes: Obtaining the first reference overlay error value or the second reference overlay error value from the scanning electron microscope; Obtaining the first to-be-verified overlay error value or the second to-be-verified overlay error value from the IDM measurement machine; The comparison difference value is obtained according to the first reference overlay error value and the first overlay error value to be verified or according to the second reference overlay error value and the second overlay error value to be verified.

10. A device for verifying measurement accuracy, characterized in that: include: An acquisition unit, used for obtaining reference overlay error measurement parameters of a sample wafer through a scanning electron microscope, wherein the overlay error measurement parameters include a first reference overlay error value, a reference slope value, a reference mask standard deviation, and a reference difference standard deviation; The acquisition unit is also used to obtain the to-be-verified overlay error measurement parameters of the sample wafer through the IDM measurement machine, wherein the to-be-verified overlay error measurement parameters include a first to-be-verified overlay error value, a to-be-verified reference slope value, a to-be-verified mask standard deviation, and a to-be-verified difference standard deviation; A processing unit, used for obtaining a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter; The processing unit is also used to obtain the overlay error measurement accuracy index to be verified of the IDM measurement machine according to the overlay error measurement parameter to be verified; The verification unit is used to obtain the accuracy verification result of the overlay error measurement of the IDM measurement machine according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified.

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