CN112099316B - Correction method and system of optical proximity correction model - Google Patents
Correction method and system of optical proximity correction model Download PDFInfo
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- CN112099316B CN112099316B CN201910525750.3A CN201910525750A CN112099316B CN 112099316 B CN112099316 B CN 112099316B CN 201910525750 A CN201910525750 A CN 201910525750A CN 112099316 B CN112099316 B CN 112099316B
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
- G03F7/70433—Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
- G03F7/70441—Optical proximity correction [OPC]
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/36—Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
Abstract
A correction method and system of optical proximity correction model, the correction method includes: providing a layout with an original graph and an initial mask layer; patterning the initial mask layer through the layout to form a mask layer; corresponding to the original pattern in the mask pattern layer is a measurement pattern, and the measurement pattern has a characteristic size; sequentially carrying out first measurement and second measurement on the measurement graph to respectively obtain a first measurement characteristic size and a second measurement characteristic size; obtaining the actual size of the measurement pattern through the first measurement characteristic size and the second measurement characteristic size; the optical proximity correction model is corrected based on the actual size. Compared with the situation that the dimension obtained by measuring the graph at one time is used as the actual dimension of the measured graph, the method obtains the actual dimension of the measured graph, corrects the optical proximity correction model based on the actual dimension, and enables the obtained error function to be more accurate and the optical proximity correction model to be more accurate.
Description
Technical Field
The embodiment of the invention relates to the field of semiconductor manufacturing, in particular to a method and a system for correcting an optical proximity correction model.
Background
In the integrated circuit manufacturing process, photolithography is the driving force for the development of the integrated circuit manufacturing process, and is one of the most complicated techniques. The improvement of the photolithography technique has an important significance for the development of integrated circuits compared to other single manufacturing techniques, and the process accuracy of the photolithography technique directly affects the yield of semiconductor products.
However, as the size of semiconductor devices is reduced with the rapid development of integrated circuit designs, distortion occurs during the transfer of patterns onto wafers, and the patterns formed on the wafers are distorted and deviated from the reticle patterns. The distortion phenomenon is mainly caused by Optical Proximity Effect (OPE).
In order to solve the above problems, an Optical Proximity Correction (OPC) method is usually used to correct errors in the photolithography process, where the OPC method is to pre-process a mask plate before photolithography, and pre-correct the mask plate so that the amount of correction and compensation can exactly compensate the optical proximity effect caused by an exposure system, and therefore, a mask plate made of layout data after OPC is used to obtain an expected target pattern on a wafer after photolithography.
Disclosure of Invention
The embodiment of the invention provides a method and a system for correcting an optical proximity correction model, so that the optical proximity correction model is more accurate.
To solve the above problem, an embodiment of the present invention provides a method for calibrating an optical proximity correction model, including: providing a layout with an original graph and an initial mask layer; imaging the initial mask layer through the layout to form a mask layer; corresponding to the original graph in the mask graph layer is a measurement graph, and the measurement graph has a characteristic size; sequentially carrying out first measurement and second measurement on the measurement graph to respectively obtain a first measurement characteristic size and a second measurement characteristic size; obtaining the actual size of the measurement pattern through the first measurement characteristic size and the second measurement characteristic size; and correcting the optical proximity correction model based on the actual size.
Correspondingly, an embodiment of the present invention further provides a correction system for an optical proximity correction model, including: the layout comprises an original graph and is used for imaging an initial mask graph layer to obtain a mask graph layer, wherein the mask graph layer is provided with a measurement graph, the measurement graph corresponds to the original graph, and the measurement graph has a characteristic dimension; the measuring unit is suitable for sequentially carrying out first measurement and second measurement on the measurement graph to respectively obtain a first measurement characteristic size and a second measurement characteristic size; an actual size obtaining unit adapted to obtain an actual size of the measurement pattern from the first measurement feature size and the second measurement feature size; and the correcting unit is used for correcting the optical proximity correction model according to the actual size.
Compared with the prior art, the technical scheme of the embodiment of the invention has the following advantages:
the embodiment of the invention sequentially carries out first measurement and second measurement on the measurement graph to respectively obtain a first measurement characteristic size and a second measurement characteristic size. The method generally adopts a critical dimension scanning electron microscope to measure the dimension of the measurement graph, and the dimension of the measurement graph shrinks in the measurement process, the first measurement characteristic dimension is obtained after the actual dimension of the measurement graph shrinks, and the second measurement characteristic dimension is obtained on the basis of the shrinking of the first measurement characteristic dimension.
Drawings
FIG. 1 is a schematic flow chart of a method for correcting an optical proximity correction model;
FIG. 2 is a schematic view of a process for measuring the actual dimension of a pattern according to the optical proximity correction model calibration method of the present invention;
FIG. 3 is a flowchart illustrating an overall process of a first embodiment of the optical proximity correction model calibration method according to the present invention;
FIG. 4 is a schematic diagram of the layout structure in the optical proximity correction model calibration method of the present invention;
FIG. 5 is a schematic diagram illustrating a structure of a mask layer in the optical proximity correction model calibration method according to the present invention;
FIG. 6 is a schematic diagram of a simulated pattern in the optical proximity correction model calibration method according to the present invention;
FIG. 7 is a flowchart illustrating an overall process of a second embodiment of the optical proximity correction model calibration method according to the present invention;
FIG. 8 is a schematic diagram of a first embodiment of an optical proximity correction model calibration system according to the present invention;
FIG. 9 is a schematic structural diagram of a second embodiment and a third embodiment of an optical proximity correction model calibration system according to the present invention.
Detailed Description
As known in the art, optical proximity correction is used to form a desired target pattern on a wafer. However, the accuracy of the optical proximity correction still needs to be improved.
Referring to fig. 1, a flow chart of a method for correcting an optical proximity correction model is shown.
The optical proximity correction model calibration method comprises the following steps:
step s1, providing a layout with an original graph (layout) and an initial mask layer. Step s2, imaging the initial mask layer through the layout to form a mask layer; and the mask layer corresponding to the original pattern is a measurement pattern, and the measurement pattern has a characteristic size. And s3, measuring the measurement graph once to obtain the characteristic size of the measurement graph. And step s4, simulating the original graph by using an optical proximity correction model to obtain a simulated graph. And s5, measuring the simulation graph to obtain a first size. And s6, providing an error function, and judging whether the convergence of the error function value meets the requirement of optical proximity correction or not according to the characteristic size and the first size.
It should be noted that step s4 and step s5 are executed after step s1 and before step s 6.
Specifically, when the convergence of the error function value meets the requirement of the optical proximity correction, step s7 is executed to complete the correction of the optical proximity correction model; and when the convergence of the error function does not meet the requirement of the optical proximity correction, executing the step s8, correcting the optical proximity correction model, and returning to execute the steps s4 to s6 until the convergence of the error function value meets the requirement of the optical proximity correction.
In the step s3, a material of the mask layer is usually a photoresist, and the measurement pattern in the mask layer is usually measured by using a Critical Dimension Scanning Electron Microscope (CDSEM) to obtain a feature size of the measurement pattern, where the feature size measured by the CDSEM is generally considered as an actual size of the measurement pattern, and in an actual process, during the measurement of the size of the measurement pattern by using the CDSEM, an electron beam emitted by an electron gun may cause a chemical bond of the photoresist to break, which causes a reduction in the feature size of the measurement pattern, and further causes the measured feature size to be smaller than the actual size of the measurement pattern. And because the original patterns have diversity, for example, the feature sizes of the original patterns are different, and the pitches of the original patterns are the same; or the feature sizes of the original patterns are the same, and the pitches of the original patterns are different; or, the feature size of each original pattern and the pitch of the original patterns are different. The diversity of the original pattern easily causes different losses of different measurement patterns in the process of measuring the measurement pattern by the CDSEM, and the accuracy of the optical proximity correction model is low.
In order to solve the technical problem, in the embodiment of the present invention, the first measurement and the second measurement are sequentially performed on the measurement pattern to obtain a first measurement feature size and a second measurement feature size, respectively. The method generally adopts a critical dimension scanning electron microscope to measure the dimension of the measurement graph, and the dimension of the measurement graph shrinks in the measurement process, the first measurement characteristic dimension is obtained after the actual dimension of the measurement graph shrinks, and the second measurement characteristic dimension is obtained based on the shrinkage of the first measurement characteristic dimension.
In order to make the aforementioned objects, features and advantages of the embodiments of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below.
Referring to fig. 2, a schematic flow chart of the method for correcting the optical proximity correction model according to the embodiment of the present invention for measuring the actual dimension of the pattern is shown.
Referring to fig. 4 in combination, step S1: a layout 100 with an original pattern 101 and an initial mask layer (not shown in the figure) are provided.
The original pattern 101 is a preset pattern that needs to be generated in the initial mask layer, and the layout 100 may be determined according to different semiconductor process requirements.
The layout 100 is stored in a layout file. The layout file refers to a layout file which is designed and formed by using an EDA tool and contains a design graph. Generally, the layout file is a layout file that has passed DRC (design rule check) verification.
In this embodiment, the file format of the layout 100 is a GDS format. In other embodiments, the file format of the layout may also be other formats such as OASIS.
The original pattern 101 is a standard pattern for correcting the optical proximity correction model. By adding the original graph 101 into the layout 100, the data computation amount in the process of correcting the optical proximity correction model can be obviously reduced, so that the correction efficiency of the optical proximity correction model is improved.
In this embodiment, the original pattern 101 is in the shape of a long strip, the outline of the original pattern 101 is surrounded by a plurality of edges, and the original pattern 101 has a certain extending direction. And subsequently, imaging the initial mask layer through the layout 100 to form a mask layer, wherein a measurement graph corresponds to the original graph 101 in the mask layer. In other embodiments, the shape of the original pattern may be a shape required by other processes.
In this embodiment, the material of the initial mask pattern layer is a photoresist. In other embodiments, the material of the initial mask layer may also be other materials suitable for receiving a pattern.
It should be noted that, in this embodiment, the initial mask layer is located on the physical wafer.
The two sides of the original pattern 101 in the extending direction are respectively provided with a measuring point a1 and a measuring point a2, and the connecting line of the measuring point a1 and the measuring point a2 is perpendicular to the extending direction of the original pattern 101. In other embodiments, the measurement points a1 and a2 on the two sides of the original pattern extending direction may not be perpendicular.
In this embodiment, the ordinate of the measurement point a1 is equal to the ordinate of the measurement point a 2. In other embodiments, the two measurement points are equal in abscissa.
The measuring point a1 and the measuring point a2 are used for obtaining the first measuring characteristic dimension and the second measuring characteristic dimension in a subsequent process.
Referring to fig. 5 in combination, step S2: imaging the initial mask layer through the layout 100 to form a mask layer 200; the mask layer 200 is a measurement pattern 201 corresponding to the original pattern 101, and the measurement pattern 201 has a characteristic dimension.
And transmitting the original graph 101 in the layout 100 to the mask graph layer 200 to form a measurement graph 201, so as to prepare for obtaining a first measurement characteristic dimension and a second measurement characteristic dimension according to the measurement graph 201 in a subsequent process.
In this embodiment, the step of forming the mask layer 200 includes: and processing the initial mask layer by adopting a photoetching process to form the mask layer 200.
In this embodiment, the measurement pattern 201 corresponds to the measurement point a1, which is the measurement point a3, and corresponds to the measurement point a2, which is the measurement point a4. Therefore, the characteristic dimension value of the measurement pattern 201 is the distance between the measurement point a3 and the measurement point a4.
It should be noted that the material of the mask pattern layer 200 is a photoresist, the region of the measurement pattern 201 in the mask pattern layer 200 is a photoresist region, and the size of the measurement pattern 201 is reduced in the subsequent measurement process. In other embodiments, the measurement pattern region in the mask pattern layer may also be a region where the photoresist is removed, and the size of the measurement pattern may become larger in the subsequent measurement process.
S3, sequentially carrying out first measurement and second measurement on the measurement graph 201 to respectively obtain a first measurement characteristic dimension CD 1 And a second measured feature size CD 2 。
During the first measurement and the second measurement of the measurement pattern 201, the measurement pattern 201 may shrink, resulting in a first measured feature dimension CD obtained by the first measurement 1 And is smaller than the actual dimension of the measurement pattern 201, and the ratio of the first measurement feature size to the actual dimension of the measurement pattern 201 is equal to the ratio of the second measurement feature size to the first measurement feature size. The embodiment of the invention measures the first measurement characteristic dimension CD 1 And a second measurement feature size CD 2 And is prepared for obtaining the actual size of the measurement pattern 201 subsequently.
In this embodiment, it is assumed that the actual dimension of the measurement pattern 201 is CD 0 First measurement of the characteristic dimension CD 1 And a second measured feature size CD 2 And actual size CD 0 Is expressed by the following formulas (1) and (2)
CD 1 ＝CD 0 (1+k) (1)
CD 2 ＝CD 1 (1+k) (2)
Wherein, CD 0 To measure the actual dimensions of the pattern 201; CD (compact disc) 1 Obtaining a first measurement characteristic size after the first measurement; CD (compact disc) 2 Is a second measured feature size obtained after the second measurement.
In other embodiments, the actual dimension of the measurement pattern is C 0 After each measurement, the measurement pattern is 1+ k times of the measurement pattern size before measurement, and the measurement pattern is measured for n times to obtain the nth measurement characteristic size C n As shown in formula (3);
C n ＝C 0 (1+k) n (3)
wherein n is an integer greater than 0; c 0 Measuring the actual size of the pattern; c n Is the n-th measured characteristic dimension obtained by measuring the measured dimension n times.
Obtaining the first measured feature size C n Then, m-n measurement is performed on the measurement pattern to obtain a second feature measurement dimension C m As shown in equation (4);
C m ＝C 0 (1+k) m (4)
wherein m is an integer greater than n; c m The measurement pattern is measured m times to obtain the m-th measurement characteristic size.
In this embodiment, the critical dimension scanning electron microscope is used to perform the first measurement and the second measurement to obtain a first measurement feature dimension CD 1 And a second measured feature size CD 2 . CDSEM is a common instrument used to measure feature size of a feature 201 in semiconductor manufacturing processes, and the operation principle is as follows: an electron beam emitted from an electron gun is converged by a condenser lens, passes through an aperture (aperture), and reaches the measurement pattern 201, and secondary electrons emitted are captured by a detector and converted into an electric signal to obtain a two-dimensional image, and the characteristic dimension of the measurement pattern 201 is accurately measured based on information of the two-dimensional image.
It should be noted that, during the first measurement and the second measurement performed by the cd-sem, the electron beam emitted from the electron gun may cause the chemical bond of the photoresist to break, resulting in the feature size of the measurement pattern 201 being reduced.
Specifically, the first measurement and the second measurement are performed to measure the distance between the measurement point a3 and the measurement point a4 in the measurement pattern 201.
It should be noted that the layout 100 has a plurality of identical original graphs 101; correspondingly, in the step of forming the mask layer 200 by patterning the initial mask layer through the layout 100, a plurality of measurement patterns 201 corresponding to the same original patterns 101 are formed in the mask layer 200;
performing the first measurement to obtain the first measurement characteristic dimension CD 1 Comprises the following steps: measuring the plurality of measurement patterns 201 to obtain a plurality of first measurement data; averaging the first measurement data to obtain a first measurement characteristic dimension CD 1 。
In the embodiment of the present invention, a plurality of measurement patterns 201 are formed in the mask layer 200 by patterning the initial mask layer through the same layout 100, so that the uniformity of the plurality of measurement patterns 201 is good, and a first measurement feature size CD is obtained by averaging a plurality of first measurement data 1 The first measurement error is reduced, and the first measurement characteristic dimension CD is favorably improved 1 To the accuracy of (2).
Correspondingly, the second measurement is performed to obtain the second measurement characteristic dimension CD 2 Comprises the following steps: after the first measurement, the second measurement is performed on the plurality of measurement patterns 201 to obtain a plurality of second measurement data, and the second measurement data is averaged to obtain the second measurement characteristic dimension CD 2 。
In the embodiment of the present invention, the uniformity of the plurality of measurement patterns 201 is high, and accordingly, after the first measurement is performed on the plurality of measurement patterns 201, the shrinkage uniformity of the measurement patterns 201 is high, and the second measurement data obtained by the second measurement is averaged to obtain the second measurement characteristic dimension CD 2 The second measurement error is reduced, and the second measurement characteristic dimension CD is favorably improved 2 To the accuracy of (2).
Step S4, measuring the characteristic dimension CD through the first measurement 1 And a second measured feature size CD 2 Obtaining the actual dimension CD of the measurement pattern 201 0 。
The dimensions of the measurement pattern 201 are typically measured using a CD scanning electron microscope, and during the measurement the dimensions of the measurement pattern 201 shrink, the first measurement feature dimension CD 1 Is measuring the actual dimension CD of the pattern 0 Obtained after shrinking, said second measured characteristic dimension CD 2 Is based on a first measured characteristic dimension CD 1 Based on the first measurement characteristic dimension CD, compared with the situation that the dimension obtained by measuring the graph once is taken as the actual dimension of the measured graph 1 And a second measurement feature size CD 2 Obtaining the actual dimension CD of the measurement pattern 201 0 The actual size CD 0 More precisely, and therefore, based on the actual size CD 0 The optical proximity correction model is corrected, so that the obtained error function is more accurate, and the optical proximity correction model is more accurate.
In this embodiment, in the process of performing the first measurement and the second measurement by using the cd-sem, the electron beam emitted from the cd-sem is incident on the measurement pattern 201, the measurement pattern 201 shrinks, and the ratio of the first measurement feature size to the actual size of the measurement pattern 201 is equal to the ratio of the second measurement feature size to the first measurement feature size, and the actual size of the measurement pattern 201 is obtained by combining the formula (1) and the formula (2)
Where k is the shrinkage factor of the measurement profile 201 in the first and second measurements.
Therefore, the actual dimension CD of the measurement pattern 201 0 For the first measurement of the characteristic dimension CD 1 Is divided by the second measured feature size CD 2 The obtained value.
In this embodiment, the first measurement and the second measurement refer to a first measurement performed after the measurement pattern 201 is formed and a second measurement performed immediately after the first measurement.
In other embodiments, according to equations (3) and (4), the shrinkage factor k is obtained as shown in equation (6);
after obtaining the shrinkage factor k, according to a first measured characteristic dimension C 1 And a shrinkage factor k, and the actual size C can be obtained by using the formula (7) 0
Continuing with reference to FIG. 2, step S5, based on actual dimension C 0 And correcting the optical proximity correction model.
The first measurement feature size CD 1 Is to measure the actual dimension CD of the pattern 0 Obtained after shrinking, said second measured characteristic dimension CD 2 Is based on a first measured characteristic dimension CD 1 Based on the first measurement characteristic dimension CD, compared with the situation that the dimension obtained by measuring the graph once is taken as the actual dimension of the measured graph, the invention uses the first measurement characteristic dimension CD 1 And a second measured feature size CD 2 Obtaining the actual dimension CD of the measurement pattern 201 0 The actual size CD 0 More accurate, and therefore, based on the actual size CD 0 The optical proximity correction model is corrected, so that the obtained error function is more accurate, and the optical proximity correction model is more accurate.
In this embodiment, the actual size C is based on 0 The correction of the optical proximity correction model refers to the correction of an error function of the optical proximity correction model.
In this embodiment, the error function of the optical proximity correction model is a root mean square value of an error.
Specifically, the actual dimension CD is calculated using equation (8) as the error function 0 And the characteristic dimension CD of the simulation graph i,s RMS;
wherein w i Is the weight of the measurement profile 201; CD (compact disc) i,w For the actual dimension CD of the measurement pattern 201 0 (ii) a The CD i,s Simulating the characteristic size of the graph; n is the sampling amount, and i is an integer from 1 to N.
The method for correcting the optical proximity correction model further comprises the following steps: after the layout 100 is provided, a detection process is performed. The detection process comprises the following steps: step S6 and step S7.
FIG. 3 is a flowchart illustrating an overall process of the method for correcting an optical proximity correction model according to a first embodiment of the present invention. Referring to fig. 3 and 6 in combination, in step S6, the original pattern 101 is simulated by using an optical proximity correction model, so as to obtain a simulated pattern 301.
In this embodiment, the optical proximity correction model is a model-based optical proximity correction model. The optical proximity correction model is typically constructed by optimizing fitting coefficients (fitting coefficients) in a model form, and the calibration of the optical proximity correction model is a cyclic iterative process. Since the original patterns 101 in different layouts 100 have differences, in this step, the optical proximity correction model is an initial optical proximity correction model, i.e. the optical proximity correction model has a set of initial fitting parameters.
In this embodiment, the optical proximity correction model is a Compact Model (CM).
For example, the optical proximity correction model is shown in equation (9),
wherein, c in the formula (9) 0 、c 1 、c 2 、c 3 、c 4 、c 5 、c 6 、c 7 、c 8 、c 9 、c 10 、c 11 、c 12 、c 13 、c 14 And c 15 Is a fitting coefficient in an optical proximity correction model。
With continuing reference to FIG. 3, step S7 obtains the characteristic dimension CD of the simulation graph 301 i,s A third measured feature size.
Obtaining the third measured feature size provides for subsequent preparation of an optical proximity correction model.
In the simulation graph 301, the measurement point a5 and the measurement point a6 correspond to the measurement point a1 and the measurement point a2 in the original graph 101, respectively.
The process of obtaining the third measurement feature size is to obtain the distance between the measurement point a5 and the measurement point a6. The process of obtaining the measurement point a5 and the measurement point a6 is not described in detail in the prior art.
It should be noted that, the step S6 and the step S7 may be executed after the layout 100 is provided, and the order should not be written according to the description herein, but the step S6 and the step S7 are considered to be executed after the step S5.
With continuing reference to fig. 3, in step S8, the method for correcting the optical proximity correction model further includes: providing an error function; obtaining the actual dimension C of the measurement pattern 201 0 And after the third characteristic dimension is measured, according to the actual dimension CD 0 And a third measurement feature size, determining whether the convergence of the error function value RMS meets the requirements for optical proximity correction based on the error function.
In other embodiments, the error function of the optical proximity correction model may also set the error for the edge. An Edge Placement Error (EPE) is used to represent the difference between the actual value and the target value.
When the convergence of the error function value satisfies the requirement of the optical proximity correction, step S9, the correction of the optical proximity correction model is completed.
And when the convergence of the error function value does not meet the requirement of the optical proximity correction, re-executing the detection process until the convergence of the error function value RMS meets the requirement of the optical proximity correction.
Specifically, the step of obtaining the simulation graph further comprises: for each fitting coefficient in the optical proximity correction model (for example:c 0 、c 1 、c 2 、c 3 、c 4 、c 5 、c 6 、c 7 、c 8 、c 9 、c 10 、c 11 、c 12 、c 13 、c 14 and c 15 ) And continuously correcting until the error function value RMS is not converged any more, obtaining a group of fitting parameters which can meet the requirement of optical proximity correction, thereby completing the correction of the optical proximity correction model and further improving the precision of the optical proximity correction model.
In this embodiment, a gradient algorithm is used to obtain the optical proximity correction model. Specifically, the gradient algorithm includes a conjugate gradient method or a shivering-down method.
FIG. 7 is a flowchart illustrating a second embodiment of the optical proximity correction model calibration method according to the present invention.
The same parts in the embodiments of the present invention and the first embodiment are not described herein again, and the differences between the embodiments of the present invention and the first embodiment are:
in step S1, a plurality of the original graphics 101 are provided.
Specifically, the original patterns 101 are different in characteristic size among the original patterns 101, and the pitches of the original patterns 101 are the same; or, the feature sizes of the original patterns 101 are the same, and the pitches of the original patterns 101 are different; alternatively, the feature size of the plurality of original patterns 101 and the pitch of the original patterns 101 are different.
It should be noted that, in this embodiment, a plurality of the original patterns 101 exist in one layout 100. In other embodiments, a plurality of the original graphics may also be located in different layouts.
In step S2, the initial mask layer is patterned through the layout 100 to form a mask layer 200, and a plurality of measurement patterns 201 corresponding to the plurality of original patterns 101 are formed in the mask layer 200.
In step S3, the distance between the measurement patterns 201 is also obtained in the step of performing the first measurement on the measurement patterns 201.
In step S4, the step of obtaining the actual size of the measurement pattern from the first measurement feature size and the second measurement feature size includes: obtaining a plurality of sets of first measurement feature sizes CD corresponding to the plurality of measurement patterns 201 1 And a second measured feature size CD 2 (ii) a According to the first measurement characteristic dimension CD 1 Second measurement of the characteristic dimension CD 2 Obtaining a second measurement feature CD of each measurement pattern 201 2 And a first measured feature dimension CD 1 Is compared with the first measured characteristic dimension CD 1 The ratio of (a) to (b); obtaining said ratio, and said first measured feature size CD 1 And a correspondence table of the pitch of the measurement pattern 201.
In step S4, the correspondence table is obtained, but the actual dimension CD of the measurement pattern is not obtained 0 。
In step S5, based on the actual size CD 0 And correcting the optical proximity correction model.
The step of correcting the optical proximity correction model based on the actual size comprises: providing a first measured feature dimension CD 1 And measuring the distance between the patterns 201 according to the first measurement feature size CD 1 Measuring the distance between the graphs 201 and the corresponding table to obtain the ratio; according to the first measurement characteristic dimension CD of the measurement pattern 201 1 And the ratio, the actual dimension CD of the measurement pattern 201 is obtained 0 。
Specifically, the ratio is obtained by using the formula (10)
k＝(CD 2 -CD 1 )/CD 1 (10)
It should be noted that the ratio is the contraction factor.
In particular, according to a first measurement characteristic dimension CD of the measurement pattern 1 And a shrinkage factor k, the actual size of the measurement pattern 201 can be obtained by using the formula (10)CD 0 。
It should be further noted that, in the present embodiment, in the actual correction process, after the correspondence table is obtained, only step S5 needs to be executed to obtain the actual size CD 0 。
In the embodiment of the present invention, the actual dimension CD of the measurement pattern 201 is obtained 0 And said first measured characteristic dimension CD 1 And after the corresponding table of the space of the measurement graph 201, according to a first measurement characteristic dimension CD obtained in the subsequent measurement process 1 And measuring the distance between the patterns 201, the actual dimension CD of the pattern 201 can be obtained quickly 0 Obtaining the actual dimension CD of the measurement pattern 201 is simplified 0 The step (2).
Correspondingly, the embodiment of the invention also provides a correction system of the optical proximity correction model. Referring to FIG. 8, a schematic structural diagram of a first embodiment of the correction system of the optical proximity correction model of the present invention is shown.
With combined reference to fig. 4 to 6, the correction system of the optical proximity correction model includes: the layout unit 10 includes an original pattern 101 (shown in fig. 4) and is configured to pattern an initial mask layer (not shown in the figure) to obtain a mask layer 200 (shown in fig. 5), where the mask layer 200 has a measurement pattern 201 (shown in fig. 5), the measurement pattern 201 corresponds to the original pattern 101, and the measurement pattern 201 has a feature size; a measuring unit 20 adapted to sequentially perform a first measurement and a second measurement on the measurement pattern 201 to obtain a first measurement characteristic dimension CD 1 (not shown) and a second measured feature size CD 2 (not shown in the figures); an actual dimension obtaining unit 30 adapted to obtain an actual dimension CD of the measurement pattern 201 based on the first and second measurement feature sizes 0 (ii) a A correction unit 40 for correcting the CD according to the actual size 0 (not shown) the optical proximity correction model is corrected.
The optical proximity correction model is corrected by adopting the correction system of the optical proximity correction model, the layout unit 10 is provided with an original graph 101, and the graph unit corrects the original graph in the layout unit 10The initial pattern 101 is transferred to a mask pattern layer 200, a measurement pattern 201 in the mask pattern layer 200 corresponds to the original pattern 101, and the measurement unit 20 sequentially performs a first measurement and a second measurement on the measurement pattern 201 to obtain a first measurement characteristic dimension CD respectively 1 And a second measured feature size CD 2 . The dimensions of the measurement feature 201 are typically measured using a CD scanning electron microscope, and during the measurement the dimensions of the measurement feature 201 shrink, the first measurement feature CD 1 Is to measure the actual dimension CD of the pattern 201 0 Obtained after shrinking, said second measured characteristic dimension CD 2 Is based on a first measured characteristic dimension CD 1 Based on the first measurement characteristic dimension CD, compared with the situation that the dimension obtained by measuring the graph by one time is taken as the actual dimension of the measured graph 1 And a second measured feature size CD 2 Obtaining the actual dimension CD of the measurement pattern 201 0 More accurate, and therefore, based on the actual size CD 0 The optical proximity correction model is corrected, so that the obtained error function is more accurate, and the optical proximity correction model is more accurate.
The layout unit 10 includes an original pattern 101, and is configured to pattern an initial mask layer to obtain a mask layer 200, where the mask layer 200 has a measurement pattern 201, the measurement pattern 201 corresponds to the original pattern 101, and the measurement pattern 201 has a characteristic dimension.
The original pattern 101 is a preset pattern that needs to be generated in the initial mask layer, and the layout unit 10 may be determined according to different semiconductor process requirements.
The layout unit 10 is stored in a layout file. The layout file refers to a layout file which is designed and formed by using an EDA tool and contains a design graph. Generally, the layout file is a layout file that has passed DRC (design rule check) verification.
In this embodiment, the file format of the layout unit 10 is a GDS format. In other embodiments, the file format of the layout may also be other formats such as OASIS.
The original pattern 101 is a standard pattern for correcting the optical proximity correction model. By adding the original graph 101 to the layout unit 10, the data computation amount in the process of correcting the optical proximity correction model can be remarkably reduced, and the correction efficiency of the optical proximity correction model can be improved.
In this embodiment, the original pattern 101 is in the shape of a long bar. Specifically, the outline of the original figure 101 is surrounded by a plurality of edges, and the original figure 101 has a certain extending direction. In other embodiments, the shape of the original pattern may be a shape required by other processes.
It should be noted that, two edges in the extending direction of the original pattern 101 respectively have a measuring point a1 (as shown in fig. 4) and a measuring point a2 (as shown in fig. 4), and a connecting line of the measuring point a1 and the measuring point a2 is perpendicular to the extending direction of the original pattern 101. In other embodiments, the two measurement points on the two sides of the original pattern in the extending direction may not be perpendicular.
In this embodiment, the ordinate of the measurement point a1 is equal to the ordinate of the measurement point a 2. In other embodiments, the two measurement points are equal in abscissa.
The measurement points a1 and a2 are used for the measurement unit 20 to obtain a first measurement characteristic dimension CD according to the measurement pattern 201 1 And a second measured feature size CD 2 Preparation is made.
It should be noted that the material of the mask pattern layer 200 is a photoresist, the region of the measurement pattern 201 in the mask pattern layer 200 is a photoresist region, and the size of the measurement pattern 201 is reduced in the subsequent measurement process. In other embodiments, the measurement pattern region in the mask pattern layer 200 may also be a region where the photoresist is removed, and the size of the measurement pattern may become larger in the subsequent measurement process.
It should be noted that, in this embodiment, the initial mask pattern layer is located on the physical wafer.
In this embodiment, the initial mask layer is suitable for patterning by a photolithography method to obtain the mask layer 200.
In this embodiment, the measurement graph 201 corresponds to the measurement point a1, which is a measurement point a3 (as shown in fig. 5), and corresponds to the measurement point a2, which is a measurement point a4 (as shown in fig. 5). Therefore, the characteristic dimension value of the measurement pattern 201 is the distance between the measurement point a3 and the measurement point a4.
A measuring unit 20 adapted to sequentially perform a first measurement and a second measurement on the measurement pattern 201 to obtain a first measurement characteristic dimension CD 1 And a second measurement feature size CD 2 。
A measurement unit 20, wherein during the first measurement and the second measurement of the measurement pattern 201, the measurement pattern 201 will shrink, resulting in a first measurement feature CD obtained by the first measurement 1 Smaller than the actual dimension CD of the measurement pattern 201 0 And the first measured feature size CD 1 And the actual dimension CD of the measurement pattern 201 0 Is equal to the second measured feature size CD 2 And the first measured characteristic dimension CD 1 The ratio of (a) to (b). The embodiment of the invention measures the first measurement characteristic dimension CD 1 And a second measured feature size CD 2 Obtaining the actual size CD of the measurement pattern 201 for the actual size obtaining unit 30 0 And (4) preparing.
In this embodiment, it is assumed that the actual dimension of the measurement pattern 201 is CD 0 First measurement of characteristic dimension CD 1 And a second measurement feature size CD 2 And actual size CD 0 Is expressed by the following formulas (1) and (2)
CD 1 ＝CD 0 (1+k) (1)
CD 2 ＝CD 1 (1+k) (2)
Wherein, CD 0 To measure the actual dimensions of the pattern 201; CD (compact disc) 1 Obtaining a first measurement characteristic size after the first measurement; CD (compact disc) 2 Is a second measured feature size obtained after the second measurement.
In other embodiments, the first measurement feature size and the second measurement feature size may be obtained by measuring a measurement pattern for multiple times, where an actual size of the measurement pattern is C 0 After each measurement the measurement chartThe shape is 1+ k times of the measurement pattern size before measurement, and the measurement pattern is measured for n times to obtain the nth measurement characteristic size C n As shown in equation (3);
C n ＝C 0 (1+k) n (3)
wherein n is an integer greater than 0; c 0 Measuring the actual size of the pattern; c n Is the n-th measured characteristic dimension obtained by measuring the measured dimension n times.
Obtaining the first measured feature size C n Then, m-n measurement is carried out on the measurement pattern to obtain a second characteristic measurement dimension C m As shown in equation (4);
C m ＝C 0 (1+k) m (4)
wherein m is an integer greater than n; c m The measurement pattern is measured m times to obtain the m-th measurement characteristic size.
In this embodiment, the measurement unit includes: critical dimension scanning electron microscope.
Specifically, the first measurement and the second measurement are performed to measure the distance between the measurement point a3 and the measurement point a4 in the measurement pattern 201.
It should be noted that the layout unit 10 has a plurality of identical original patterns 101, and the mask layer 200 has a plurality of measurement patterns 201; the first measurement feature dimension CD 1 To perform the first measurement on the plurality of measurement patterns 201, an average value of a plurality of first measurement data is obtained.
In the embodiment of the present invention, the plurality of measurement patterns 201 are formed in the mask layer 200 by patterning the initial mask layer using the same layout unit 10, so that the uniformity of the plurality of measurement patterns 201 is good, and the first measurement feature CD is obtained by averaging the plurality of first measurement data 1 The first measurement error is reduced, and the first measurement characteristic dimension CD is favorably improved 1 To the accuracy of (2).
In this embodiment, the second measurement feature CD 2 For a plurality of said testsThe quantity graph 201 performs the second measurement, and obtains an average value of a plurality of second measurement data.
In the embodiment of the present invention, the uniformity of the plurality of measurement patterns 201 is high, and accordingly, after the first measurement is performed on the plurality of measurement patterns 201, the shrinkage uniformity of the measurement patterns 201 is high, and the second measurement data obtained by the second measurement is averaged to obtain the second measurement characteristic dimension CD 2 The second measurement error is reduced, and the second measurement characteristic dimension CD is favorably improved 2 To the accuracy of (2).
A real dimension obtaining unit 30 adapted to obtain a first measured feature dimension CD 1 And a second measured feature size CD 2 Obtaining the actual dimension CD of the measurement pattern 201 0 。
The dimension of the measurement pattern 201 is usually measured by a critical dimension scanning electron microscope, and during the measurement process, the chemical bond of the photoresist corresponding to the measurement pattern 201 is broken, which results in a smaller feature size of the measured dimension. The invention measures the characteristic dimension CD through the first measurement 1 And a second measured feature size CD 2 Obtaining the actual dimension CD of the measurement pattern 201 0 The actual size CD 0 More accurate, and therefore, based on the actual size CD 0 The optical proximity correction model is corrected, so that the obtained error function is more accurate, and the optical proximity correction model is more accurate.
In this embodiment, the actual dimension CD of the measurement pattern 201 0 For the first measurement of the characteristic dimension CD 1 Is divided by the second measured feature size CD 2 The value of (c).
The first measurement feature size CD 1 And the actual dimension CD of the measurement pattern 201 0 Is equal to the second measured feature size CD 2 And the first measured characteristic dimension CD 1 In combination with the formula (1) and the formula (2), the actual size of the measurement pattern 201 is obtained as
Where k is the shrinkage factor of the measurement profile 201 in the first and second measurements.
In this embodiment, the first measurement and the second measurement refer to a first measurement performed after the measurement pattern 201 is formed and a second measurement performed immediately after the first measurement.
In other embodiments, according to equations (3) and (4), the shrinkage factor k is obtained as shown in equation (6);
after obtaining the shrinkage factor k, according to a first measured characteristic dimension C 1 And a contraction factor k, and the actual size can be obtained by using the formula (7)
In this embodiment, the calibration unit 40 is based on the actual size CD 0 And correcting the optical proximity correction model.
Based on the actual size CD 0 The optical proximity correction model is corrected, so that the obtained error function is more accurate, and the optical proximity correction model is more accurate.
In this embodiment, the actual size C is based on 0 The correction of the optical proximity correction model refers to the correction of an error function of the optical proximity correction model.
In this embodiment, the error function of the optical proximity correction model is a root mean square value of an error.
Specifically, the actual dimension CD is calculated using equation (8) as the error function 0 And the feature size CD of the simulation graph 301 (shown in FIG. 6) i,s RMS;
wherein, the w i Is the weight of the measurement profile 201; the CD i,w For the actual dimension CD of the measurement pattern 201 0 (ii) a The CD i,s Is the characteristic dimension of the simulated graphics 301; n is the sampling amount, and i is an integer from 1 to N.
Referring to fig. 9, a schematic diagram of a second embodiment of the semiconductor structure of the present invention is shown.
In the embodiment of the present invention, the same points as those in the first embodiment are not described in detail, but the differences are as follows:
the correction system of the optical proximity correction model further comprises: a detection unit 50 adapted to perform a detection process; the detection unit 50 includes: a simulation unit 51 adapted to simulate the original pattern 101 by using an optical proximity correction model to obtain a simulated pattern 301; an analog size obtaining unit 52 adapted to obtain a feature size CD of the analog pattern 301 i,s A third measured feature size.
In this embodiment, the optical proximity correction model is a Compact Model (CM).
For example, the optical proximity correction model is shown in equation (9),
wherein, c in the formula (9) 0 、c 1 、c 2 、c 3 、c 4 、c 5 、c 6 、c 7 、c 8 、c 9 、c 10 、c 11 、c 12 、c 13 、c 14 And c 15 Are fitting coefficients in the optical proximity correction model.
As shown in formula (9), a simulated graph 301 is obtained by using an optical proximity correction model, and in the simulated graph 301, the measurement point a5 (shown in fig. 6) and the measurement point a6 (shown in fig. 6) are respectively corresponding to the measurement point a1 and the measurement point a2 in the original graph 101.
The correction system for the optical proximity correction model further comprises: a decision unit 60 adapted to provide an error function based on said actual size CD 0 And a third measurement feature size, determining whether the convergence of the error function value satisfies the requirement of optical proximity correction according to the error function.
When the convergence of the error function value meets the requirement of optical proximity correction, the correction of the optical proximity correction model is completed.
Is adapted to control said detection unit 50 to re-execute the detection process when the convergence of the error function values does not meet the requirement for optical proximity correction.
Specifically, the simulation unit 51 further corrects each fitting coefficient (e.g., c) in the model for optical proximity correction 0 、c 1 、c 2 、c 3 、c 4 、c 5 、c 6 、c 7 、c 8 、c 9 、c 10 、c 11 、c 12 、c 13 、c 14 And c 15 ) And continuously correcting until the error function value RMS is not converged any more, obtaining a group of fitting parameters which can meet the requirement of optical proximity correction, completing the correction of the optical proximity correction model, and improving the precision of the optical proximity correction model.
It should be noted that the optical proximity correction model in the simulation unit 51 is obtained by a gradient algorithm.
With continued reference to fig. 9, a schematic diagram of a third embodiment of the semiconductor structure of the present invention is shown.
The second embodiment differs from the first embodiment in that the measuring unit 20 is further adapted to measure the pitch of the measurement pattern 201 in the first measurement.
The actual-size obtaining unit 30 further includes: a storage unit 31 that stores a correspondence table including: a second measurement feature CD of the measurement pattern 2 And a firstMeasuring characteristic dimension CD 1 And the first measured characteristic dimension CD 1 To said first measured feature size CD 1 And the corresponding relation of the pitch of the measurement pattern 201; an actual dimension obtaining unit further adapted to obtain a first measured characteristic dimension CD 1 The distance between the measurement patterns 201 and the corresponding table to obtain the ratio; a first measurement feature dimension CD based on the measurement pattern 1 And the ratio, the actual dimension CD of the measurement pattern 201 is obtained by using the formula (7) 0 。
In the embodiment of the invention, the actual dimension CD of the measurement graph 201 is obtained 0 And the first measured characteristic dimension CD 1 And after measuring the corresponding table of the space of the pattern 201, according to a first measured characteristic dimension CD obtained in the subsequent measurement process 1 And measuring the distance between the patterns 201, the actual dimension CD of the pattern 201 can be obtained quickly 1 Obtaining the actual dimension CD of the measurement pattern 201 is simplified 0 The step (2).
Although the embodiments of the present invention are disclosed above, the embodiments of the present invention are not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present embodiments, and it is intended that the scope of the present embodiments be defined by the appended claims.
Claims (21)
1. A method for correcting an optical proximity correction model, comprising:
providing a layout with an original graph and an initial mask layer;
imaging the initial mask layer through the layout to form a mask layer; the mask layer is a measurement graph corresponding to the original graph, and the measurement graph has a characteristic size;
sequentially carrying out first measurement and second measurement on the measurement graph to respectively obtain a first measurement characteristic size and a second measurement characteristic size;
obtaining an actual dimension of the measurement pattern by the first measurement feature dimension and the second measurement feature dimension, wherein a ratio of the first measurement feature dimension to the actual dimension of the measurement pattern is equal to a ratio of the second measurement feature dimension to the first measurement feature dimension;
and correcting the optical proximity correction model based on the actual size.
2. The method of calibrating an optical proximity correction model according to claim 1, wherein the actual dimension of the measurement pattern is a square of a first measured feature size divided by a second measured feature size.
3. The method for calibrating an optical proximity correction model of claim 1, wherein the first measurement and the second measurement are performed using a cd-sem.
4. The method for correcting an optical proximity correction model according to claim 1, wherein a plurality of identical original patterns are provided in the layout;
imaging the initial mask layer through the layout to form a mask layer, wherein a plurality of measurement graphs corresponding to the same original graphs are formed in the mask layer; performing the first measurement, the step of obtaining the first measured feature size comprising: measuring the plurality of measurement graphs to obtain a plurality of first measurement data; and averaging the first measurement data to obtain a first measurement characteristic size.
5. The method of calibrating an optical proximity correction model according to claim 4, wherein performing the second measurement to obtain the second measured feature size comprises: and after the first measurement is carried out, carrying out second measurement on the plurality of measurement graphs to obtain a plurality of second measurement data, and averaging the second measurement data to obtain a second measurement characteristic size.
6. The method for calibrating an optical proximity correction model according to claim 1, wherein the material of the mask layer is a photoresist.
7. The method for calibrating an optical proximity correction model according to claim 1, wherein the initial mask layer is processed using a photolithography process to form the mask layer.
8. The method for correcting an optical proximity correction model according to claim 1, wherein the number of the original patterns is plural, and the method comprises:
the characteristic sizes of the original graphs are different, and the intervals of the original graphs are the same;
or the feature sizes of the original patterns are the same, and the pitches of the original patterns are different;
or the characteristic sizes of the original graphs and the intervals of the original graphs are different;
a plurality of measuring patterns corresponding to the plurality of original patterns are formed in the mask pattern layer;
in the step of performing the first measurement on the measurement pattern, the distance between the measurement patterns is also obtained; the step of obtaining the actual dimension of the measurement pattern from the first measurement feature size and the second measurement feature size comprises: obtaining a plurality of sets of first and second measured feature sizes corresponding to the plurality of measurement patterns; obtaining the ratio of the difference value between the second measurement characteristic dimension and the first measurement characteristic dimension of each measurement pattern to the first measurement characteristic dimension according to the first measurement characteristic dimension and the second measurement characteristic dimension; obtaining a corresponding table of the ratio, the first measurement characteristic size and the distance between the measurement patterns;
the step of performing the correction includes: providing a first measurement characteristic size and a measurement pattern interval, and obtaining the ratio according to the first measurement characteristic size, the measurement pattern interval and the corresponding table; and obtaining the actual size of the measurement graph according to the first measurement characteristic size of the measurement graph and the ratio.
9. The method for correcting an optical proximity correction model according to claim 1 or 8, wherein providing the layout further comprises: executing a detection process;
the detection process comprises the following steps: simulating the original graph by using an optical proximity correction model to obtain a simulated graph; obtaining the characteristic dimension of the simulation graph as a third measurement characteristic dimension;
the method for correcting the optical proximity correction model further comprises the following steps: providing an error function; after the actual size and the third measurement characteristic size of the measurement graph are obtained, whether the convergence of an error function value meets the requirement of optical proximity correction or not is judged according to the actual size and the third measurement characteristic size and the error function;
when the convergence of the error function value meets the requirement of optical proximity correction, completing the correction of the optical proximity correction model; and re-executing the step of detecting when the convergence of the error function value does not meet the requirement of optical proximity correction.
10. The method for correcting an optical proximity correction model according to claim 9, wherein the optical proximity correction model is obtained by using a gradient algorithm when convergence of the error function values does not satisfy a requirement for optical proximity correction.
11. The method for correcting an optical proximity correction model according to claim 9, wherein the method comprises
wherein, the w i Is the weight of the measurement pattern; the CD i,w The actual size of the measurement pattern is taken as the actual size of the measurement pattern; the CD i,s For simulating graphicsThe characteristic dimension of (a); n is the sampling amount, and i is an integer from 1 to N.
12. A system for correcting an optical proximity correction model, comprising:
the layout comprises an original graph and is used for imaging an initial mask graph layer to obtain a mask graph layer, wherein the mask graph layer is provided with a measurement graph, the measurement graph corresponds to the original graph, and the measurement graph has a characteristic dimension;
the measuring unit is suitable for sequentially carrying out first measurement and second measurement on the measurement graph to respectively obtain a first measurement characteristic size and a second measurement characteristic size;
an actual size obtaining unit adapted to obtain an actual size of the measurement pattern from the first measurement feature size and a second measurement feature size, a ratio of the first measurement feature size to the actual size of the measurement pattern being equal to a ratio of the second measurement feature size to the first measurement feature size;
and the correcting unit is used for correcting the optical proximity correction model according to the actual size.
13. The system for calibrating an optical proximity correction model according to claim 12, wherein the actual dimension of the measurement pattern is a square of a first measured feature size divided by a second measured feature size.
14. The system for correcting an optical proximity correction model according to claim 12, wherein the measuring unit comprises: critical dimension scanning electron microscopy.
15. The system for calibrating an optical proximity correction model according to claim 12, wherein said layout has a plurality of identical said original patterns, and said mask layer has a plurality of said measurement patterns;
the first measurement feature size is an average value of a plurality of first measurement data obtained by performing the first measurement on the plurality of measurement patterns.
16. The system for calibrating an optical proximity correction model according to claim 15, wherein the second measurement feature size is an average of a plurality of second measurement data obtained by performing the second measurement on a plurality of measurement patterns.
17. The system for correcting an optical proximity correction model according to claim 12, wherein the material of the mask layer is a photoresist.
18. The system for correcting an optical proximity correction model according to claim 12, wherein the measuring unit is further adapted to measure a pitch of the measurement pattern in a first measurement;
the actual-size obtaining unit includes: a storage unit that stores a correspondence table including: the ratio of the difference value between the second measurement characteristic size and the first measurement characteristic size of the measurement pattern to the first measurement characteristic size and the corresponding relation between the first measurement characteristic size and the interval of the measurement pattern;
the actual size obtaining unit is further adapted to obtain the ratio according to the first measurement feature size, the measurement pattern pitch and the corresponding table; and obtaining the actual size of the measurement pattern according to the first measurement characteristic size of the measurement pattern and the ratio.
19. The system for correcting an optical proximity correction model according to claim 12 or 18, wherein the system for correcting an optical proximity correction model further comprises: a detection unit adapted to perform a detection process;
the detection unit includes: the simulation unit is suitable for simulating the original graph by using an optical proximity correction model to obtain a simulated graph; a simulated dimension obtaining unit adapted to obtain a feature dimension of the simulated pattern as a third measured feature dimension;
the correction system for the optical proximity correction model further comprises: the judging unit is suitable for providing an error function and judging whether the convergence of the error function value meets the requirement of optical proximity correction or not according to the actual size and the third measured characteristic size and the error function;
the method is suitable for completing the correction of the optical proximity correction model when the convergence of the error function value meets the requirement of the optical proximity correction;
and the detection unit is suitable for controlling the detection unit to execute the detection process again when the convergence of the error function value does not meet the requirement of optical proximity correction.
20. The system for calibrating an optical proximity correction model according to claim 19, wherein the optical proximity correction model in said simulation unit is obtained by a gradient algorithm.
21. The system for correcting an optical proximity correction model of claim 19, wherein the system employs
wherein, the w i Is the weight of the measurement pattern; the CD i,w The actual size of the measurement pattern is taken as the actual size of the measurement pattern; the CD i,s Simulating the characteristic size of the graph; n is the sampling amount, and i is an integer from 1 to N.
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