CN119132989A - Method and device for verifying measurement accuracy - Google Patents
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Abstract
The embodiment of the disclosure provides a method and a device for verifying measurement accuracy. The method comprises the steps of 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 an IDM measuring 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 reference overlay error measurement accuracy indexes of the scanning electron microscope according to the reference overlay error measurement parameters, obtaining to-be-verified overlay error measurement accuracy indexes of the IDM measuring machine according to the to-be-verified overlay error measurement accuracy indexes and the to-be-verified overlay error measurement accuracy indexes, and obtaining an overlay error measurement accuracy verification result of the IDM measuring machine. The present disclosure is capable of determining the accuracy of IDM measurements.
Description
Technical Field
The present disclosure relates to the field of semiconductor testing technologies, and in particular, to a method and apparatus for verifying measurement accuracy.
Background
In the preparation process of the semiconductor, an Overlay error value (Overlay) is an important index for measuring the alignment precision and the yield guarantee of the current layer and the previous layer. An overlay error value is typically obtained by taking a picture of the wafer during processing using a scanning electron microscope (Scanning electron microscope, SEM). With the development of technology, it has appeared to measure overlay error using an IDM (chip scale, in Die Metrology) measuring machine, but it is not possible to determine whether the measured overlay error value is accurate.
The above information disclosed in the background section is only for enhancement of understanding of the background of the disclosure and thus it may include information that does not form a related art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
The embodiment of the disclosure provides a method and a device for verifying measurement accuracy, which can determine the measurement accuracy of an IDM measuring machine.
The embodiment of the disclosure provides a method for verifying measurement accuracy, which comprises the steps of 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 the to-be-verified overlay error measurement parameters of the sample wafer through an IDM measuring 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 accuracy index of the scanning electron microscope according to the reference overlay error measurement parameters, obtaining a to-be-verified overlay error measurement accuracy index of the IDM measuring machine according to the to-be-verified overlay error measurement accuracy index, and obtaining an overlay error measurement accuracy verification result of the IDM measuring machine according to the reference overlay error measurement accuracy index and the to-be-verified overlay error measurement accuracy index.
In some embodiments of the disclosure, obtaining a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter comprises 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, and 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 comprises a reference average slope value and a reference slope standard deviation.
In some embodiments of the present disclosure, the reference overlay error measurement parameters further comprise a reference repetition standard deviation, and the reference overlay error measurement accuracy index is obtained using the following formula:
Wherein A 1 is the reference overlay error measurement accuracy, M3 sigma 11 is the first reference overlay error value, mu 12 is the reference average slope value, 3 sigma 12 is the reference slope standard deviation, 3 sigma 13 is the reference mask standard deviation, 3 sigma 14 is the reference difference standard deviation, 3 sigma 15 is the reference repetition standard deviation, M3 sigma 11 2*(3σ12 2+(μ12-1)2) is the reference slope accuracy index, and 3 sigma 13 2+3σ14 2-3σ15 2 is the reference standard deviation accuracy index.
In some embodiments of the disclosure, obtaining an overlay error measurement accuracy index to be verified of the IDM measuring machine according to the overlay error measurement parameter to be verified includes 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, and 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 comprises an average slope value to be verified and a standard deviation of the slope to be verified.
In some embodiments of the present disclosure, the overlay error measurement parameters to be verified further include a repetition standard deviation to be verified, and the overlay error measurement accuracy index to be verified is obtained using the following formula:
Wherein A 2 is the overlay error measurement accuracy index to be verified, M3 sigma 21 is the first overlay error value to be verified, mu 22 is the average slope value to be verified, 3 sigma 22 is the slope standard deviation to be verified, 3 sigma 23 is the mask standard deviation to be verified, 3 sigma 24 is the difference standard deviation to be verified, 3 sigma 25 is the repetition standard deviation to be verified, M3 sigma 21 2*(3σ22 2+(μ22-1)2) is the slope accuracy index to be verified, and 3 sigma 23 2+3σ24 2-3σ25 2 is the standard deviation accuracy index to be verified.
In some embodiments of the disclosure, the method further includes obtaining a clamping value according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified, obtaining a comparison difference value through the scanning electron microscope and the IDM measuring machine, and obtaining an overlay error measurement accuracy verification result of the IDM measuring machine according to the clamping value and the comparison difference value.
In some embodiments of the present disclosure, the control value is obtained using the following formula:
Wherein S is a clamping control value, A 1 is the reference overlay error measurement accuracy index, and A 2 is the overlay error measurement accuracy index to be verified.
In some embodiments of the present disclosure, obtaining a 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 control value.
In some embodiments of the disclosure, obtaining a comparison value through the scanning electron microscope and the IDM measurement machine includes 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 or the second overlay error value to be verified from the IDM measurement machine, and obtaining the comparison 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.
The embodiment of the disclosure also provides a device for verifying the measurement accuracy, which comprises an acquisition unit, a processing unit and a verification unit.
The acquisition unit is used for acquiring reference overlay error measurement parameters of a sample wafer through a scanning electron microscope, wherein the 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, the acquisition unit is also used for acquiring the overlay error measurement parameters to be verified of the sample wafer through an IDM measuring machine, the overlay error measurement parameters to be verified comprise a first overlay error value, 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 for acquiring a reference overlay error measurement precision index of the scanning electron microscope according to the reference overlay error measurement parameters, the processing unit is also used for acquiring an overlay error measurement precision index to be verified of the IDM measuring machine according to the overlay error measurement precision index to be verified, and the verification unit is used for acquiring an overlay error measurement precision verification result of the IDM measuring machine according to the reference overlay error measurement precision index and the overlay error measurement precision index to be verified.
As can be seen from the above technical solutions, the method for verifying measurement accuracy according to the embodiments of the present disclosure has at least one of the following advantages and positive effects:
In the embodiment of the disclosure, the reference overlay error measurement parameter is obtained through the scanning electron microscope, the reference overlay error measurement accuracy index of the scanning electron microscope is obtained according to the reference overlay error measurement parameter calculation, the overlay error measurement parameter to be verified is obtained through the IDM measuring machine, the overlay error measurement accuracy index to be verified of the IDM measuring machine is obtained according to the overlay error measurement parameter calculation to be verified, the reference overlay error accuracy index of the scanning electron microscope can be used as a reference, the overlay error measurement accuracy index to be verified of the IDM measuring machine is used for obtaining the accuracy verification result of the overlay error measurement of the IDM measuring machine, and whether the overlay error measured by the IDM measuring machine is accurate or not is obtained. The method takes the precision obtained by the scanning electron microscope as a reference, so that the method is simple, and the reliability of the accuracy verification result of the overlay error measurement of the obtained IDM measuring machine is improved.
Drawings
The above and other features and advantages of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.
FIG. 1 is a flow chart of a method of verifying metrology accuracy in accordance with some embodiments of the present disclosure;
FIG. 2 is a flow chart of step S130 of FIG. 1, shown in some embodiments of the present disclosure;
FIG. 3 is a flow chart of step S140 of FIG. 1, shown in some embodiments of the present disclosure;
FIG. 4 is a flow chart illustrating obtaining a stuck value and comparing differences according to some embodiments of the present disclosure;
FIG. 5 is a flow chart of step S420 of FIG. 4, shown in some embodiments of the present disclosure;
FIG. 6 is a schematic diagram of scribe line transfer patterns on a sample wafer using an ASR (ASML SELF REFERENCE, ASR self-reference) mask, as shown in some embodiments of the present disclosure;
FIG. 7 is a block diagram of an apparatus for verifying metrology accuracy, shown in some embodiments of the present disclosure;
FIG. 8 is a schematic diagram of a computer device shown in some embodiments of the present disclosure;
FIG. 9 is a schematic diagram of a computer-readable storage medium illustrating some embodiments.
Reference numerals illustrate:
100. sample wafer, 101, chip area, 102, dicing streets, 200, ASR mask, 201, sub-area.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus detailed descriptions thereof will be omitted.
In the following description of various exemplary embodiments of the present disclosure, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration various exemplary structures in which aspects of the disclosure may be practiced. It is to be understood that other specific arrangements of parts, structures, example devices, systems, and steps may be used, and structural and functional modifications may be made without departing from the scope of the present disclosure. Moreover, although the terms "over," "between," "within," and the like may be used in this specification to describe various exemplary features and elements of the disclosure, these terms are used herein for convenience only, e.g., in accordance with the directions of examples in the drawings. Nothing in this specification should be construed as requiring a particular three-dimensional orientation of structures to fall within the scope of this disclosure. Furthermore, the terms "first," "second," and the like in the claims are used merely as labels, and are not intended to limit the numerals of their objects.
The flow diagrams depicted in the figures are exemplary only, and do not necessarily include all of the elements and operations/steps, nor must they be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the order of actual execution may be changed according to actual situations.
In addition, in the description of the present disclosure, the meaning of "a plurality" is at least two, such as two, three, etc., unless specifically defined otherwise.
In the process of semiconductor manufacturing, it is necessary to determine whether the current layer being processed is aligned with the previous layer, so as to ensure the effectiveness of the current layer production and processing, and thus, it is necessary to accurately obtain the overlay error value of the current layer and the previous layer. Usually, a scanning electron microscope is used to shoot pictures of a wafer in a process, and an overlay error value is obtained according to the pictures, so that the method is ideal overlay error measurement equipment. The scanning electron microscope may be a high voltage scanning electron microscope (High voltage scanning electron microscope, HV SEM), which is an instrument commonly used in the art, and will not be described in detail herein.
Based on the development of semiconductor technology, can also use IDM measuring machine to measure the overlay error, and unlike scanning electron microscope, IDM measuring machine adopts the optics principle 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 is found whether the accuracy of the IDM measurement apparatus is reliable, or whether the setting of the measurement recipe in the IDM measurement apparatus is accurate, and there is no relevant verification method.
Based on this, the embodiment of the disclosure provides a method for verifying measurement accuracy, which includes the following steps S110 to S150.
S110, obtaining reference overlay error measurement parameters of the 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.
S120, obtaining to-be-verified overlay error measurement parameters of the sample wafer through an IDM measuring 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.
S130, obtaining a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameters.
And S140, obtaining the measurement precision index of the overlay error to be verified of the IDM measuring machine according to the measurement parameter of the overlay error to be verified.
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.
In the embodiment of the disclosure, the reference overlay error measurement parameter is obtained through the scanning electron microscope, the reference overlay error measurement accuracy index of the scanning electron microscope is obtained according to the reference overlay error measurement parameter calculation, the overlay error measurement parameter to be verified is obtained through the IDM measuring machine, the overlay error measurement accuracy index to be verified of the IDM measuring machine is obtained according to the overlay error measurement parameter calculation to be verified, the reference overlay error accuracy index of the scanning electron microscope can be used as a reference, the overlay error measurement accuracy index to be verified of the IDM measuring machine is used for obtaining the accuracy verification result of the overlay error measurement of the IDM measuring machine, and whether the measurement formula of the IDM measuring machine is accurate and feasible is further obtained. The method takes the precision obtained by the scanning electron microscope as a reference, so that the method is simple, and the reliability of the accuracy verification result of the overlay error measurement of the obtained IDM measuring machine is improved.
The method for verifying measurement accuracy according to the embodiments of the present disclosure is described in detail below.
In the embodiment of the disclosure, the overlay error values measured by using the scanning electron microscope and the IDM measuring machine are the overlay errors obtained by measuring (AEI) of the etched sample wafer. Before this, the bias during the lithographic process can be obtained using post-lithographic measurement (ADI), and then the resist is compensated for based on the bias, correcting the bias generated by the lithographic process to zero.
Then, the chip area of the sample wafer is etched, and as shown in fig. 6, the sample wafer 100 includes the chip area 101 and the dicing streets 102, and after the process, dicing is performed at the dicing streets 102 to divide the wafer into a plurality of chips. In fig. 6, a sample wafer 100 is shown, along with an enlarged portion of a chip area 101 in the sample wafer 100, an enlarged portion of an ASR mask 200 disposed over a scribe line 102, and an enlarged portion of a sub-area 201 of the ASR mask 200, respectively. The ASR mask 200 is disposed in the scribe line 102 of the sample wafer 100, and the ASR mask 200 is an alignment mark mask of asmai, and is mainly used for post-etch measurement, and is used for supplementing post-lithography measurement after etching. The ASR mask 200 is provided with a plurality of sub-regions 201, and each sub-region 201 is designed with error values generated by processes such as manufacturing process and measurement, and the error range is typically-5 to 5, and then different errors, for example-1 and-2.
The overlay error value of each exposure area of the etched sample wafer 100 is measured, the sample wafer 100 is scanned and shot by the scanning electron microscope, the picture of the sample wafer 100 is obtained, meanwhile, the scanning electron microscope generates original data (Raw data), a first reference overlay error value is obtained according to the original data, the area where the obtained overlay error value is located corresponds to the subarea 202 of the ASR mask 200, for example, the first reference overlay error value is-2, the value of the subarea corresponding to the ASR mask is-1, namely, the input value (set) is-1, the output value (get) is-2, and the two are different, so that the error is generated in the etching process. This error needs to be removed before the next wafer is etched, and thus 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.
The ASR mask 200 is provided with a plurality of sub-regions 201, each of which sub-regions 201 has a different designed error value (input value). Measuring each exposure region of the etched sample wafer 100 to obtain a plurality of output values, fitting the plurality of input values and the plurality of output values to obtain a straight line, and obtaining the slope of the straight line of each exposure region. Using the ASR mask 200 and all exposure area fits of the sample wafer 100, a plurality of straight lines are obtained, the plurality of straight lines have a plurality of slopes, and an average slope value of the plurality of slopes is taken, where the average slope value may be the reference slope value in S110. After calculating the average value of the plurality of slopes, a residual error may be calculated, which is a slope value-average slope value for each exposure region, and the standard deviation 3σ of the slope may be calculated according to the Bessel formula. Thus, the reference slope value may include an average slope value and a slope standard deviation 3σ (3σ may be 3σ 12 in the following description). The process of obtaining the to-be-verified slope value by using the IDM is substantially the same as the process of obtaining the reference slope value by using the scanning electron microscope, and can be obtained by a person skilled in the art through an operating machine, which is not described herein.
S110, obtaining reference overlay error measurement parameters of the sample wafer 100 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.
The first reference Overlay error value is an 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 of the ASR mask to the array area of the sample wafer 100.
S120, obtaining to-be-verified overlay error measurement parameters of the sample wafer 100 through an IDM measuring 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.
The IDM measuring machine is used for measuring the sample wafer 100 to obtain the original data of the sample wafer 100, and meanwhile, the IDM measuring machine outputs the original data and the ASR mask data, and the overlay error measurement parameters to be verified are calculated through the data.
The first overlay error value to be verified is an overlay error value measured by the IDM measuring machine, the slope value to be verified may be an average value of slopes of a plurality of fitting lines obtained in different exposure areas, and the obtaining process may refer to the obtaining process of the scanning electron microscope, which is not described herein. 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 of the ASR mask to the array area of the sample wafer 100.
S130, obtaining a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameters.
In some embodiments, as shown in fig. 2, S130 may include the following steps S210 to S230.
S210, obtaining a reference slope precision index according to the first reference overlay error value and the reference slope value.
In some embodiments, the reference slope value may include a reference average slope value μ 12 and a reference slope standard deviation 3σ 12.
The precision index of the reference slope may be m3σ 11 2*(3σ12 2+(μ12-1)2), where m3σ 11 may represent the first reference overlay error value. M3σ 11 is an integer, which squares the first reference overlay error value.
In other embodiments, the reference slope value may include only the reference average slope value μ 12, and the reference slope precision index may be m3σ 11 2*(μ12-1)2.
S220, obtaining a reference standard deviation precision index according to the reference mask standard deviation and the reference difference standard deviation.
Wherein, the reference mask standard deviation can be represented by 3σ 13, the reference difference standard deviation can be represented by 3σ 14, and then the reference standard deviation accuracy index can be 3σ 13 2+3σ14 2.
S230, obtaining a reference overlay error measurement accuracy index according to the reference slope accuracy index and the reference standard deviation accuracy index.
In some embodiments, the reference overlay error measurement accuracy index may be obtained by the following equation (1).
Wherein A1 is reference overlay error measurement precision, M3 sigma 11 2*(μ12-1)2 is reference slope precision index, and 3 sigma 13 2+3σ14 2 is reference standard deviation precision index.
In other embodiments, the reference overlay error measurement accuracy index may be obtained by the following equation (2).
Wherein A1 is reference overlay error measurement accuracy, M3σ 11 2*(3σ12 2+(μ12-1)2) is reference slope accuracy index, 3σ 13 2+3σ14 2 is reference standard deviation accuracy index.
In other embodiments, the reference overlay error measurement parameter further comprises a reference repeat standard deviation, which refers to the standard deviation generated during the course of the repeat measurement. The reference repetition standard deviation may be expressed as 3σ 15, and then the reference overlay error measurement accuracy index may be obtained using the following equation (3).
Wherein A1 is reference overlay error measurement accuracy, M3σ 11 2*(3σ12 2+(μ12-1)2) is reference slope accuracy index, 3σ 13 2+3σ14 2-3σ15 2 is reference standard deviation accuracy index.
In other embodiments, the reference overlay error measurement accuracy index may be obtained by the following equation (4).
Wherein A1 is reference overlay error measurement accuracy, M3σ 11 2*(3σ12 2+(μ12-1)2) is a reference slope accuracy index, and 3σ 13 2+3σ14 2-3σ15 2 is a reference standard deviation accuracy index.
Note that 3σ xx in the formula represents an entirety, and 3σ xx 2 represents a square of a value of 3σ xx. Among the above three formulas, formula (3) is more accurate than formulas (1), (2) and (4). In the reference standard deviation accuracy index, 3 sigma 13 2 and 3 sigma 14 2 already include one reference repetition standard deviation 3 sigma 15 2, so 3 sigma 15 2 is added twice, and subtracting one 3 sigma 15 2 leads to more accurate results.
The values of the reference overlay error measurement accuracy indexes A1 and A1 can be calculated through the formulas in the embodiment, so that the accuracy of the overlay error measurement of the scanning electron microscope can be reflected, and the measurement error can be understood. The following describes measurement data in actual measurement.
In the actual measurement of the scanning electron microscope, two sets of data obtained are taken as an example. In the first group, the obtained first reference overlay error value m3σ 11 is 1.7, the reference average slope value μ 12 is 0.72, the reference slope standard deviation 3σ 12 is 0.05, the reference mask standard deviation 3σ 13 is 1.27, the reference difference standard deviation 3σ 14 is 0.93, the reference repetition standard deviation 3σ 15 is 0.4, and the reference overlay error measurement accuracy index A1 is 1.59 when substituted into the formula (3) as an example.
In the second group, the obtained first reference overlay error value m3σ 11 is 4.6, the reference average slope value μ 12 is 0.96, the reference slope standard deviation 3σ 12 is 0.05, the reference mask standard deviation 3σ 13 is 1.77, the reference difference standard deviation 3σ 14 is 1.19, the reference repetition standard deviation 3σ 15 is 0.28, and the reference overlay error measurement accuracy index A1 is 2.13 when substituted into the formula (3) as an example.
The two sets of data can show that the reference overlay error measurement accuracy index obtained by the first set of data has smaller value, smaller error and higher accuracy.
And S140, obtaining the measurement precision index of the overlay error to be verified of the IDM measuring machine according to the measurement parameter of the overlay error to be verified.
In some embodiments, S140 may include steps S310-S330 as follows.
S310, obtaining a slope precision index to be verified according to the first overlay error value to be verified and the slope value to be verified.
In some embodiments, the slope value to be verified may include a mean slope value to be verified μ 22 and a standard deviation of slope to be verified 3σ 22.
The slope precision index to be verified may be m3σ 21 2*(3σ22 2+(μ22-1)2), where m3σ 21 may represent the first overlay error value to be verified. M3σ 21 is an integer, which squares the first overlay error value to be verified.
In other embodiments, the slope value to be verified may include only the average slope value μ 22 to be verified, and the slope precision index to be verified may be m3σ 21 2*(μ22-1)2.
S320, obtaining the standard deviation accuracy index to be verified according to the standard deviation of the mask to be verified and the standard deviation of the difference to be verified.
The standard deviation of the mask to be verified can be expressed by 3 sigma 23, the standard deviation of the difference to be verified can be expressed by 3 sigma 24, and the precision index of the standard deviation to be verified can be 3 sigma 23 2+3σ24 2.
S330, 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.
In some embodiments, the overlay error measurement accuracy index to be verified may be obtained by the following equation (5).
Wherein A2 is the overlay error measurement precision to be verified, M3σ 21 2*(μ22-1)2 is the slope precision index to be verified, and 3σ 23 2+3σ24 2 is the standard deviation precision index to be verified.
In other embodiments, the overlay error measurement accuracy index to be verified may be obtained by the following equation (6).
Wherein A2 is the overlay error measurement precision to be verified, M3σ 21 2*(3σ22 2+(μ22-1)2) is the slope precision index to be verified, and 3σ 23 2+3σ24 2 is the standard deviation precision index to be verified.
In other embodiments, the overlay error measurement parameters to be verified further include a repetition standard deviation to be verified, which refers to a standard deviation generated during the repeated measurements. The repeated standard deviation to be verified can be expressed by 3 sigma 25, and then the following formula (7) can be adopted to obtain the measurement accuracy index of the overlay error to be verified.
Wherein A2 is the overlay error measurement precision to be verified, M3σ 21 2*(3σ22 2+(μ22-1)2) is the slope precision index to be verified, and 3σ 23 2+3σ24 2-3σ25 2 is the standard deviation precision index to be verified.
In other embodiments, the following equation (8) may be used to obtain the overlay error measurement accuracy index to be verified.
Wherein A2 is the measurement precision of the overlay error to be verified, M3σ 21 2*(3σ22 2+(μ22-1)2) is the precision index of the slope to be verified, and 3σ 23 2+3σ24 2-3σ25 2 is the standard deviation precision index to be verified.
As in the previous examples, 3σ xx in the formula represents an entirety, and 3σ xx 2 represents the square of the value of 3σ xx. Of the three formulas described above, formula (7) is more accurate than formulas (5), (6) and (8). In the standard deviation accuracy index to be verified, 3 sigma 23 2 and 3 sigma 24 2 already comprise one repeated standard deviation 3 sigma 25 2 to be verified, so 3 sigma 25 2 is added twice, and one 3 sigma 25 2 is subtracted to enable the result to be more accurate.
The values of the measurement precision indexes A2 and A2 of the overlay error to be verified can be calculated through the formulas in the embodiment, so that the precision of the measurement overlay error of the IDM measuring machine can be reflected, and the measurement error can be understood. The following describes measurement data in actual measurement.
In the actual measurement of the IDM measuring machine, for example, a certain process of the semiconductor, such as a bit line etching process, is taken as an example, and two sets of data are still obtained as an example. And the first group of data measured by the IDM measuring machine corresponds to the first group of data measured by the scanning electron microscope, and the second group of data measured by the IDM measuring machine corresponds to the second group of data measured by the scanning electron microscope.
For example, in the first set of data measured by the IDM measuring machine, the obtained first overlay error value m3σ 21 is 2.17, the average slope value μ 22 to be verified is 1.11, the standard deviation 3σ 22 of the slope to be verified is 0.03, the standard deviation 3σ 23 of the mask to be verified is 0.48, the standard deviation 3σ 24 of the difference to be verified is 0.46, the repeated standard deviation to be verified 3σ 25 to be verified is 0.1, and the overlay error measurement accuracy index A2 to be verified can be obtained by substituting the formula (7) into the formula (7) as an example.
For example, in the second set of data measured by the IDM measuring machine, the obtained first overlay error value m3σ 21 is 3.89, the average slope value μ 22 to be verified is 0.97, the standard deviation 3σ 22 of the slope to be verified is 0.08, the standard deviation 3σ 23 of the mask to be verified is 1.2, the standard deviation 3σ 24 of the difference to be verified is 0.36, the repeated standard deviation 3σ 25 to be verified is 0.18, and the overlay error measurement accuracy index A2 to be verified can be obtained by substituting the first overlay error value into the formula (7) as an example.
The two sets of data can show that the reference overlay error measurement accuracy index obtained by the first set of data has smaller value, smaller error and higher accuracy.
From the above, the value of the reference overlay error measurement accuracy index A1 obtained from the first set of data of the scanning electron microscope is 1.59, and the value of the overlay error measurement accuracy index A2 to be verified obtained from the first set of data of the idm measuring machine is 0.7. The value of the reference overlay error measurement precision index A1 obtained by the second group of data of the scanning electron microscope is 2.13, and the value of the overlay error measurement precision index A2 to be verified obtained by the second group of data of the IDM measuring machine table is 1.29. The value 0.7 of A2 obtained according to the first group of data is smaller than the value 1.59 of A1, and the value 1.29 of A2 measured according to the second group is smaller than the value 2.13 of A1, so that the measurement accuracy of the IDM measuring machine is higher than that of a scanning electron microscope, the error is smaller, the measurement formula arranged in the IDM measuring machine can be verified to be more accurate, the measured overlay error value is more accurate, the measurement formula of the IDM can be released, and yellow light compensation is performed.
In some embodiments, as shown in FIG. 4, the method for verifying the measurement accuracy further includes the following steps S410 to S430.
And S410, obtaining a clamping control value according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified.
After the values of the reference overlay error measurement accuracy index A1 and the overlay error measurement accuracy index A2 to be verified are obtained in the above embodiment, a clamping value may be further obtained.
In some embodiments, the following equation (9) may be used to obtain the clamping value:
S represents a card control value, and shows the total error of the scanning electron microscope and the IDM measuring machine. For example, the reference overlay error measurement accuracy index A1 obtained in the above embodiment is 1.59, and the overlay error measurement accuracy to be verified A2 is 0.7, and the obtained control value S is 1.74.
In other embodiments, obtaining the control value based on 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 control value. The following formula (10) can be used to obtain the clamping value:
S=A1+A2 (10)
Wherein S represents a clamping control value which is the total error of the scanning electron microscope and the IDM measuring machine. For example, the reference overlay error measurement accuracy index A1 obtained in the above embodiment is 1.59, and the overlay error measurement accuracy to be verified A2 is 0.7, and the obtained control value S is 2.29.
S420, obtaining a comparison difference value through a scanning electron microscope and an IDM measuring machine.
In some embodiments, as shown in fig. 5, the step S420 of obtaining the comparison difference value by the scanning electron microscope and the IDM measuring machine may include the following steps S510 to S530.
S510, obtaining a first reference overlay error value or a second reference overlay error value from the scanning electron microscope.
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 measurement accuracy index of the overlay error to be verified in the above embodiment, for example, 1.7 or 4.6 in the above embodiment. The second reference overlay error value may be a value of an overlay error obtained by measuring the sample wafer 100 again, or may be a value of an overlay error obtained by measuring other wafers, which is not particularly limited herein.
S520, obtaining a first overlay error value to be verified or a second overlay error value to be verified from the IDM measuring machine.
The first overlay error value to be verified is a first overlay error value to be verified measured from the sample wafer 100, and the first overlay error value to be verified may be an overlay error value to be verified in the above embodiment, for example, 2.17 or 3.89 in the above embodiment, where the overlay error measurement accuracy index to be verified is obtained. The second overlay error value to be verified may be the overlay error value obtained by measuring the sample wafer 100 again, or may be the overlay error value obtained by measuring other wafers, which is not particularly limited herein.
It should be noted that, the second reference overlay error value needs to 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 measuring the sample wafer 100 again by the scanning electron microscope, the second overlay error value to be verified should also be the value of the overlay error obtained by measuring the sample wafer 100 again by the IDM measuring machine.
S530, obtaining a comparison value according to the first reference overlay error value and the first to-be-verified overlay error value or according to the second reference overlay error value and the second to-be-verified overlay error value.
Specifically, the comparison difference value may be obtained by using the difference value between the first reference overlay error value and the first overlay error value to be verified, or by using the difference value 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 to facilitate comparison.
For example, when the first reference overlay error value 1.7 and the first to-be-verified overlay error value 2.17 are used to obtain the comparison difference value, the comparison difference value may be 2.17-1.7=0.47 (or |1.7-2.17|=0.47), and when the first reference overlay error value is 4.6, the first to-be-verified overlay error value 3.89, the second reference overlay error value and the second to-be-verified overlay error value are used, the calculation process for obtaining the comparison difference value is the same, and is not repeated herein.
S430, obtaining an accuracy verification result of the overlay error measurement of the IDM measuring machine according to the clamping control value and the comparison difference value.
Specifically, the card control value and the comparison difference value are compared, if the comparison difference value is smaller than or equal to the card control value, the accuracy verification result of the overlay error measurement of the IDM measuring machine is obtained, namely the overlay error value to be verified measured by the IDM measuring machine meets the accuracy requirement, and the measurement formula arranged in the IDM measuring machine is accurate. If the comparison difference is larger than the clamping control value, the accuracy verification result of the overlay error measurement of the IDM measuring machine is obtained and is not passed, namely the overlay error value to be verified measured by the IDM measuring machine does not meet the accuracy requirement, the measurement formula set in the IDM measuring machine is inaccurate, and the measurement formula cannot be adopted. For example, the control value S obtained according to the above embodiment is 1.74, and the comparison difference is 0.47,0.47 and less than 1.74, so that the accuracy verification result of the overlay error measurement of the IDM measuring machine can be determined to be passed.
In summary, in the embodiment of the disclosure, the reference overlay error measurement parameter is obtained through the scanning electron microscope, the reference overlay error measurement accuracy index of the scanning electron microscope is obtained according to the reference overlay error measurement parameter, the overlay error measurement parameter to be verified is obtained through the IDM measurement machine, the overlay error measurement accuracy index to be verified of the IDM measurement machine is obtained according to the overlay error measurement parameter to be verified, the reference overlay error accuracy index of the scanning electron microscope can be used as a reference, and the overlay error measurement accuracy verification result of the IDM measurement machine is obtained through the overlay error measurement accuracy index to be verified of the IDM measurement machine, so as to obtain whether the measurement formula of the IDM measurement machine is accurate and feasible. The method takes the precision obtained by the scanning electron microscope as a reference, so that the method is simple, and the reliability of the accuracy verification result of the overlay error measurement of the obtained IDM measuring machine is improved.
As shown in fig. 7, the embodiment of the disclosure further provides an apparatus 700 for verifying measurement accuracy, where the apparatus 700 includes an obtaining unit 701, a processing unit 702, and a verifying unit 703.
The obtaining unit 701 is configured to obtain, by using a scanning electron microscope, a reference overlay error measurement parameter of the sample wafer 100, where the overlay error measurement parameter includes a first reference overlay error value, a reference slope value, a reference mask standard deviation, and a reference difference standard deviation.
The obtaining unit 701 is further configured to obtain, by using an IDM measurement machine, an overlay error measurement parameter to be verified of the sample wafer 100, where the overlay error measurement parameter to be verified includes 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 702 is configured to obtain a reference overlay error measurement accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter.
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.
The verification unit 703 is configured 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.
In some embodiments of the present disclosure, the processing unit 702 is further configured to obtain a reference slope precision index according to the first reference overlay error value and the reference slope value, obtain a reference standard deviation precision index according to the reference mask standard deviation and the reference difference standard deviation, and obtain a reference overlay error measurement precision index according to the reference slope precision index and the reference standard deviation precision index.
In some embodiments of the present disclosure, the reference slope value comprises a reference average slope value and a reference slope standard deviation.
In some embodiments of the present disclosure, the reference overlay error measurement parameter further comprises 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):
Wherein A 1 is reference overlay error measurement accuracy, M3σ 11 is a first reference overlay error value, mu 12 is a reference average slope value, 3σ 12 is a reference slope standard deviation, 3σ 13 is a reference mask standard deviation, 3σ 14 is a reference difference standard deviation, 3σ 15 is a reference repetition standard deviation, M3σ 11 2*(3σ12 2+(μ12-1)2) is a reference slope accuracy index, and 3σ 13 2+3σ14 2-3σ15 2 is a reference standard deviation accuracy index.
In some embodiments of the present disclosure, the processing unit 702 is further configured to obtain a slope precision index to be verified according to the first overlay error value to be verified and the slope value to be verified, obtain a standard deviation precision index to be verified according to the mask standard deviation to be verified and the difference standard deviation to be verified, and obtain an overlay error measurement precision index to be verified according to the slope precision index to be verified and the standard deviation precision index to be verified.
In some embodiments of the present disclosure, the slope value to be verified includes a mean slope value to be verified and a standard deviation of the slope to be verified.
In some embodiments of the present disclosure, the overlay error measurement parameters to be verified further comprise 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 by using the following formula (7):
Wherein A 2 is an overlay error measurement accuracy index to be verified, M3 sigma 21 is a first overlay error value to be verified, mu 22 is an average slope value to be verified, 3 sigma 22 is a slope standard deviation to be verified, 3 sigma 23 is a mask standard deviation to be verified, 3 sigma 24 is a difference standard deviation to be verified, 3 sigma 25 is a repetition standard deviation to be verified, M3 sigma 21 2*(3σ22 2+(μ22-1)2) is a slope accuracy index to be verified, and 3 sigma 23 2+3σ24 2-3σ25 2 is a standard deviation accuracy index to be verified.
In some embodiments of the present disclosure, the verification unit 703 is further configured to obtain a clamping value according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified, obtain a comparison difference value through the scanning electron microscope and the IDM measurement machine, and obtain an accuracy verification result of the overlay error measurement of the IDM measurement machine according to the clamping value and the comparison difference value.
In some embodiments of the present disclosure, the verification unit 703 is further configured to obtain a clamping value using the following formula (9):
Wherein S is a clamping control value, A 1 is a reference overlay error measurement accuracy index, and A 2 is an overlay error measurement accuracy index to be verified.
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 the clamping value.
In some embodiments of the present disclosure, the verification unit 703 is further configured to obtain a first overlay error value to be verified or a second overlay error value to be verified from the IDM measurement machine, and obtain a comparison 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.
In summary, the device 700 of the embodiment of the disclosure can use the precision 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 obtained IDM measuring machine is improved.
The embodiment of the disclosure also provides computer equipment. As shown in fig. 8, a computer device in an embodiment of the disclosure may include one or more processors 801, memory 802, and input-output interfaces 803. The processor 801 is connected to the memory 802 and the input/output interface 803, respectively, and as shown in fig. 8, the processor 801, the memory 802, and the input/output interface 803 are connected via a bus 804. The memory 802 is used for storing a computer program comprising program instructions, the input output interface 803 is used for receiving data and outputting data, such as for data interaction between a host and a computer device or for data interaction between virtual machines in a host, and the processor 801 is used for executing the program instructions stored by the memory 802.
The processor 801 may perform operations of obtaining a reference overlay error measurement parameter of the sample wafer 100 by using a scanning electron microscope, where the reference overlay error measurement parameter includes a first reference overlay error value, a reference slope value, a reference mask standard deviation, and a reference difference standard deviation, obtaining an overlay error measurement parameter to be verified of the sample wafer 100 by using an IDM measurement machine, where the overlay error measurement parameter to be verified includes the first overlay error value, the reference slope value to be verified, the mask standard deviation, and the 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 an overlay error measurement accuracy index to be verified of the IDM measurement machine according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified, and obtaining an overlay error measurement accuracy verification result of the IDM measurement machine according to the reference overlay error measurement accuracy index and the overlay error measurement accuracy index to be verified.
In some possible implementations, the processor 801 may be a central processing module (central processing unit, CPU), which may also be other general purpose processors, digital signal processors (DIGITAL SIGNAL processors, DSPs), application Specific Integrated Circuits (ASICs), off-the-shelf programmable gate arrays (FPGAs) 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 or the like.
The memory 802 may include read only memory and random access memory, and provides instructions and data to the processor 801 and the input output interface 803. A portion of memory 802 may also include non-volatile random access memory. For example, the memory 802 may also store information of device type.
In a specific implementation, the computer device may execute, through each built-in functional module, an implementation manner provided by each step in any method embodiment described above, and specifically may refer to an implementation manner provided by each step in a diagram shown in the method embodiment described above, which is not described herein again.
The disclosed embodiments perform the steps of the methods shown in any of the embodiments described above by providing a computer device comprising a processor 801, an input-output interface 803, and a memory 802, and retrieving a computer program in the memory 802 by the processor 801.
The embodiment of the disclosure further provides a computer readable storage medium 900, as shown in fig. 9, where the computer readable storage medium 900 stores a computer program, and the computer program is adapted to be loaded by the processor 801 and execute the method for verifying measurement accuracy provided by each step in any of the foregoing embodiments, and specifically refer to the implementation manner provided by each step in any of the foregoing embodiments, which is not described herein again.
In addition, the description of the beneficial effects of the same method is omitted. For technical details not disclosed in the embodiments of the computer-readable storage medium 900 related to the present disclosure, please refer to the description of the method embodiments of the present disclosure. As an example, a computer program can be deployed to be executed on one computer device or on multiple computer devices at one site or distributed across multiple sites and interconnected by a communication network.
The computer readable storage medium 900 may be an internal storage unit of a computer device provided in any of the foregoing embodiments, for example, a hard disk or a 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 (SD) card, a flash memory card (FLASH CARD), etc. that are provided on the computer device. Further, the computer-readable storage medium 1000 may also include both internal storage units and external storage devices of the computer 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.
The disclosed embodiments also provide a computer program product or computer program comprising computer instructions stored in the computer-readable storage medium 900. The computer instructions are read from the computer-readable storage medium 900 by a processor of a computer device, which executes the computer instructions, causing the computer device to perform the methods provided in the various alternatives in any of the embodiments described above.
The computer device, the computer readable storage medium, the computer program product or the computer program provided by the embodiment of the disclosure can use the reference overlay error precision index of the scanning electron microscope as a reference, obtain the accuracy verification result of the overlay error measurement of the IDM measuring machine by the to-be-verified overlay error measurement precision index of the IDM measuring machine, and further obtain whether the measurement formula of the IDM measuring machine is accurate and feasible. The method takes the precision obtained by the scanning electron microscope as a reference, so that the method is simple, and the reliability of the accuracy verification result of the overlay error measurement of the obtained IDM measuring machine is improved.
It is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the disclosure. The disclosure is capable of other embodiments and of being practiced and carried out in various ways. The foregoing variations and modifications are within the scope of the present disclosure. It should be understood that the present disclosure disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present disclosure. The embodiments described in this specification illustrate the best mode known for carrying out the disclosure and will enable those skilled in the art to utilize the disclosure.
Claims (10)
1. A method of verifying measurement accuracy, comprising:
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 an IDM measuring 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 accuracy index of the scanning electron microscope according to the reference overlay error measurement parameter;
Obtaining an overlay error measurement accuracy index to be verified of the IDM measuring machine according to the overlay error measurement parameter to be verified;
And 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.
2. The method of claim 1, wherein obtaining the reference overlay error measurement accuracy index of the scanning electron microscope based on the reference overlay error measurement parameter comprises:
obtaining a reference slope precision index according to the first reference overlay error value and the reference slope value;
Obtaining a reference standard deviation precision 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 comprises a reference average slope value and a reference slope standard deviation.
3. The method of claim 2, wherein the reference overlay error measurement parameters further comprise a reference repetition standard deviation, and wherein the reference overlay error measurement accuracy index is obtained using the formula:
Wherein A 1 is the reference overlay error measurement accuracy, M3 sigma 11 is the first reference overlay error value, mu 12 is the reference average slope value, 3 sigma 12 is the reference slope standard deviation, 3 sigma 13 is the reference mask standard deviation, 3 sigma 14 is the reference difference standard deviation, 3 sigma 15 is the reference repetition standard deviation, M3 sigma 11 2*(3σ12 2+(μ12-1)2) is the reference slope accuracy index, and 3 sigma 13 2+3σ14 2-3σ15 2 is the reference standard deviation accuracy index.
4. The method of claim 1, wherein obtaining the overlay error measurement accuracy indicator to be verified for the IDM measurement tool according to the overlay error measurement parameter to be verified comprises:
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 standard deviation accuracy indexes to be verified according to the standard deviation of the mask to be verified and the standard deviation of the difference 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 comprises an average slope value to be verified and a standard deviation of the slope to be verified.
5. The method of claim 4, wherein the overlay error measurement parameters to be verified further comprise a repetition standard deviation to be verified, the overlay error measurement accuracy index to be verified is obtained using the following formula:
Wherein A 2 is the overlay error measurement accuracy index to be verified, M3 sigma 21 is the first overlay error value to be verified, mu 22 is the average slope value to be verified, 3 sigma 22 is the slope standard deviation to be verified, 3 sigma 23 is the mask standard deviation to be verified, 3 sigma 24 is the difference standard deviation to be verified, 3 sigma 25 is the repetition standard deviation to be verified, M3 sigma 21 2*(3σ22 2+(μ22-1)2) is the slope accuracy index to be verified, and 3 sigma 23 2+3σ24 2-3σ25 2 is the standard deviation accuracy index to be verified.
6. The method according to any one of claims 1 to 5, further comprising:
obtaining a clamping 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 value 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 according to the clamping control value and the comparison difference value.
7. The method of claim 6, wherein the control value is obtained using the formula:
Wherein S is a clamping control value, A 1 is the reference overlay error measurement accuracy index, and A 2 is the overlay error measurement accuracy index to be verified.
8. The method of claim 6, wherein obtaining a clamping value based on the reference overlay error measurement accuracy indicator and the overlay error measurement accuracy indicator to be verified comprises:
And summing the reference overlay error measurement precision index and the overlay error measurement precision index to be verified to obtain the clamping control value.
9. The method of claim 6, wherein obtaining a comparison difference by the scanning electron microscope and the IDM measurement tool comprises:
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 measuring machine;
and obtaining the comparison difference value according to the first reference overlay error value and the first to-be-verified overlay error value or according to the second reference overlay error value and the second to-be-verified overlay error value.
10. An apparatus for verifying measurement accuracy, comprising:
the acquisition unit is used for acquiring reference overlay error measurement parameters of the sample wafer through the scanning electron microscope, wherein the 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;
The acquisition unit is further used for acquiring to-be-verified overlay error measurement parameters of the sample wafer through an IDM measuring 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;
the processing unit is used for obtaining 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 for obtaining the overlay error measurement accuracy index to be verified of the IDM measuring machine according to the overlay error measurement parameter to be verified;
And the verification unit is used for 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.
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