OPC model correction method, photomask manufacturing method and photoetching method

Abstract

The invention provides a correction method of an OPC model, a method for manufacturing a photomask and a photoetching method. The correction method of the OPC model comprises the following steps: firstly, establishing an initial OPC model; and correcting the initial OPC model to obtain a corrected OPC model, and checking the convergence degree of the corrected OPC model until the corrected OPC model converges, and then entering the next step. In the step of correcting the initial OPC model, the correction times are adjusted according to the convergence degree of the corrected OPC model, so that the effect of reducing the running time under the condition of not influencing the correction accuracy of the OPC model is achieved, that is, each client layout file corresponds to different OPC model correction times; according to the method, when the correction times of the OPC model are smaller than the correction times in the standard file, the redundant times do not need to be corrected, and when the correction times of the OPC model are larger than the correction times in the standard file, the problem that time is wasted to run to the OPCV under the conditions that the correction times are not enough and the OPC model is not corrected in place is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to an OPC model correction method, a photomask manufacturing method and a photolithography method. Background Art

[0002] With the continuous miniaturization of process nodes, in order to improve the process window and yield, the OPC (optical proximity correction) model is an indispensable part of today's semiconductor process. However, the simulation calculation of the OPC model is often accompanied by a large amount of resources and time. How to reduce the run time without affecting the accuracy is a problem that all semiconductor manufacturers need to solve.

[0003] When developing the existing OPC model, the effects of different revision times on the results are tested. After development is completed, in order not to affect the performance of the subsequent tape out (the final stage of design completion and preparation for sending data to the manufacturer), the recipe (process file) is fixed to form a golden recipe (standard process file). However, after mass production begins, there are thousands of customer layout file DBs (Data Base) that need to be revised, and not every customer layout file DB is suitable for the original revision times. There may be insufficient revision times, the OPC model is not revised in place, and time is wasted running OPCV (OPC Verify). Summary of the invention

[0004] The purpose of the present invention is to provide an OPC model correction method, a method for making a photomask and a lithography method to solve the problem that the number of corrections in the standard OPC model cannot be fully applicable to each customer layout file DB, and the OPC model may not be corrected enough, the OPC model is not corrected in place, and time is wasted on running OPC verification.

[0005] In order to solve the above technical problems, the present invention provides a method for correcting an OPC model, comprising:

[0006] Establish the initial OPC model;

[0007] Modifying the initial OPC model to obtain a modified OPC model, and performing a convergence check on the modified OPC model until the modified OPC model converges and then proceeding to the next step, wherein the number of times the initial OPC model is modified is adjusted according to the convergence check result of the modified OPC model;

[0008] The corrected OPC model is verified to check the accuracy of the corrected OPC model. If the corrected OPC model meets the standards, a photomask is manufactured using the corrected OPC model.

[0009] Optionally, the method of modifying the initial OPC model to obtain a modified OPC model includes:

[0010] Step S21: performing a first correction step on the initial OPC model and checking the convergence of the OPC model after the first correction step. If the OPC model after the first correction step converges, then the correction of the initial OPC model is terminated. If the OPC model after the first correction step does not converge, then a first non-convergent area is marked, and step S22 is executed.

[0011] Step S22: performing a second correction step on the first non-convergent area of ​​the OPC model after the first correction step and checking the convergence of the OPC model after the second correction step; if the OPC model after the second correction step converges, then ending the correction of the OPC model after the first correction step; if the OPC model after the second correction step does not converge, then marking the second non-convergent area and executing step S23;

[0012] Step S23: Execute the third correction step on the second non-convergent area of ​​the OPC model after the second correction step and check the convergence of the OPC model after the third correction step. If the OPC model after the third correction step converges, end the correction of the OPC model after the second correction step. If the OPC model after the third correction step does not converge, continue to mark the third non-convergent area and continue to correct the OPC model after the third correction step until the OPC model converges.

[0013] Optionally, the number of corrections of the initial OPC model includes the number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step.

[0014] Optionally, the number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step are at least greater than once.

[0015] Optionally, the number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step decrease in sequence.

[0016] Optionally, the method for establishing the initial OPC model includes:

[0017] Get the target graphics;

[0018] Performing a wiring process according to the target pattern and obtaining wafer data;

[0019] The wafer data is used to perform initial OPC modeling.

[0020] Optionally, the step of performing a wiring process according to the target pattern and obtaining wafer data includes:

[0021] Designing a test pattern and making a test mask according to the test pattern;

[0022] The test pattern is transferred to a wafer using the test mask, an actual pattern is formed on the wafer, and wafer data obtained by testing the actual pattern is acquired.

[0023] Optionally, the method for verifying the modified OPC model includes:

[0024] Performing OPC model processing on the test pattern to obtain a simulation pattern;

[0025] The simulation graphic is verified; if the verification passes, it is determined that the simulation graphic is correct.

[0026] Based on the same inventive concept, the present invention also provides a method for making a photomask, using an OPC model corrected by the OPC model correction method as described above to obtain a simulation pattern, and transferring the simulation pattern to a photomask to form a mask pattern.

[0027] Based on the same inventive concept, the present invention also provides a photolithography method, comprising: using the method for making a photomask as described above to make a mask pattern, and using an exposure process and a development process to transfer the mask pattern to a wafer to form a photolithography pattern on the wafer.

[0028] In the method for correcting the OPC model provided by the present invention, an initial OPC model is first established; the initial OPC model is corrected to obtain a corrected OPC model, and the corrected OPC model is checked for convergence until the corrected OPC model converges and then enters the next step, wherein the number of corrections of the initial OPC model is adjusted according to the convergence check result of the corrected OPC model; the corrected OPC model is verified to check the accuracy of the corrected OPC model, and if it meets the standard, the photomask is made with the corrected OPC model. In the step of correcting the initial OPC model, the present invention adjusts the number of corrections according to the convergence of the corrected OPC model to achieve the effect of reducing the running time without affecting the accuracy of the OPC model correction, that is, each type of customer layout file DB corresponds to a different number of OPC model corrections. When the number of corrections of the OPC model is less than the number of corrections in the fixed file, there is no need to correct the redundant number of times. When the number of corrections of the OPC model is greater than the number of corrections in the fixed file, the problem of wasting time running OPCV when the number of corrections is insufficient and the OPC model is not corrected in place is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0030] Figure 1 It is a flow chart of a method for correcting an OPC model according to an embodiment of the present invention.

[0031] Figure 2 1 is a process diagram of step S20 in the method for correcting the OPC model according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0033] As used in the present invention, the singular forms "one", "an" and "the" include plural objects, the term "or" is usually used to include the meaning of "and / or", the term "several" is usually used to include the meaning of "at least one", and the term "at least two" is usually used to include the meaning of "two or more". In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first", "second" and "third" can explicitly or implicitly include one or at least two of the features. In addition, as used in the present invention, an element is arranged on another element, which usually only indicates that there is a connection, coupling, matching or transmission relationship between the two elements, and the connection, coupling, matching or transmission between the two elements can be direct or indirect through an intermediate element, and cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, an element can be in any orientation such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Figure 1 FIG. 1 is a flow chart of a method for correcting an OPC model according to an embodiment of the present invention. Figure 1 As shown, this embodiment provides a method for correcting an OPC model, including:

[0035] Step S10, establishing an initial OPC model;

[0036] Step S20, modifying the initial OPC model to obtain a modified OPC model, and performing a convergence check on the modified OPC model until the modified OPC model converges and then proceeding to the next step, wherein the number of modifications of the initial OPC model is adjusted according to the convergence check result of the modified OPC model;

[0037] Step S30 , verifying the corrected OPC model to check the accuracy of the corrected OPC model, and if it meets the standard, manufacturing a photomask with the corrected OPC model.

[0038] In step S10, the method for establishing the initial OPC model includes:

[0039] Step S11, obtaining a target graphic;

[0040] Step S12, performing a wiring process according to the target pattern and obtaining wafer data;

[0041] Step S13, using the wafer data to perform initial OPC modeling.

[0042] In step S11, a target graphic is obtained, and the target graphic is a customer layout file DB (Data Base). After mass production begins, there are thousands of customer layout file DBs that need to be corrected, and different customer layout file DBs require different numbers of OPC model corrections.

[0043] In step S12, the steps of performing layout processing according to the target pattern and obtaining wafer data include: designing a test pattern and making a test mask according to the test pattern; transferring the test pattern to a wafer using the test mask, forming an actual pattern on the wafer, and obtaining wafer data obtained by testing the actual pattern. After the layout process, a main or frame operation is also included to perform a design rule check such as a DRC check or an AG check.

[0044] In step S12 and step S13, the wafer data includes the line width, coordinates, size and spacing of the graphics. Specifically, the wafer data corresponds to the mask data layout, and multiple wafer data are obtained by collecting experimental data on actual silicon wafers under specific lithography process conditions, wherein each wafer data can be obtained by sampling. Usually, a mask data layout has multiple wafer graphics, and each wafer graphic corresponds to a wafer data. It should be noted that one wafer data corresponds to multiple sets of parameters of a wafer graphic, and the above multiple sets of parameters include but are not limited to the line width, coordinates, size and spacing of the graphics.

[0045] Figure 2 FIG. 2 is a process diagram of step S20 in the method for correcting the OPC model according to an embodiment of the present invention. Figure 2 As shown, in step S20, the method of modifying the initial OPC model to obtain a modified OPC model includes:

[0046] Step S21: Execute the first correction step on the initial OPC model and check the convergence of the OPC model after the first correction step. If the OPC model after the first correction step converges, end the correction of the initial OPC model. If the OPC model after the first correction step does not converge, mark the first non-convergence area and execute step S22.

[0047] Step S22: Execute the second correction step on the first non-convergent area of ​​the OPC model after the first correction step and check the convergence of the OPC model after the second correction step. If the OPC model after the second correction step converges, end the correction of the OPC model after the first correction step. If the OPC model after the second correction step does not converge, mark the second non-convergent area and execute step S23.

[0048] Step S23: Execute the third correction step on the second non-convergent area of ​​the OPC model after the second correction step and check the convergence of the OPC model after the third correction step. If the OPC model after the third correction step converges, end the correction of the OPC model after the second correction step. If the OPC model after the third correction step does not converge, continue to mark the third non-convergent area and continue to correct the OPC model after the third correction step until the OPC model converges.

[0049] The number of corrections of the initial OPC model includes the number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step. The number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step are at least greater than one. The number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step are successively reduced. In this embodiment, the number of corrections in the first correction step is, for example, 4 times, the number of corrections in the second correction step is, for example, 3 times, and the number of corrections in the third correction step is, for example, 2 times. In the prior art, the number of corrections in the OPC model is fixed, for example, 7 times. Some customer layout file DBs only need to be corrected 4 times, and the OPC model after the first correction step can converge. At this time, the verification step of the OPC model can be entered after the first correction step is completed. Some customer layout file DBs only need to be corrected 6 times, and the OPC model after the second correction can converge. At this time, the verification step of the OPC model can be entered after the second correction step is completed. There are also some customers whose layout file DB has not converged after 7 corrections. If the verification step of the OPC model is entered according to the 7 corrections of the fixed file, the verification of the OPC model will definitely not meet the standard, that is, it is a waste of time to perform the verification step of the OPC model when the OPC model has not been corrected in place. Those skilled in the art can set the number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step according to actual conditions, and this embodiment does not limit this.

[0050] In this embodiment, in the step of correcting the initial OPC model, the number of corrections is adjusted according to the convergence of the corrected OPC model, so as to achieve the effect of reducing the running time without affecting the accuracy of the OPC model correction. That is, each type of customer layout file DB corresponds to a different number of OPC model corrections. When the number of corrections of the OPC model is less than the number of corrections in the standard file, there is no need to correct the redundant number of corrections. When the number of corrections of the OPC model is greater than the number of corrections in the standard file, it avoids the problem of wasting time running OPCV when the number of corrections is insufficient and the OPC model is not corrected in place.

[0051] In step S30, the method for verifying the modified OPC model includes:

[0052] Step S31, performing OPC model processing on the test pattern to obtain a simulation pattern;

[0053] Step S32, verifying the simulation graph; if the verification passes, it is determined that the simulation graph is correct; if the verification fails, the OPC model is re-established.

[0054] This embodiment also provides a method for manufacturing a photomask, using an OPC model corrected by the OPC model correction method as described above to obtain a simulation pattern, and transferring the simulation pattern to a photomask to form a mask pattern.

[0055] This embodiment also provides a photolithography method, comprising: using the above-mentioned method for making a photomask to make a mask pattern, and transferring the mask pattern to a wafer using an exposure process and a development process to form a photolithography pattern on the wafer.

[0056] In summary, in the method for correcting the OPC model provided by the embodiment of the present invention, an initial OPC model is first established; the initial OPC model is corrected to obtain a corrected OPC model, and the corrected OPC model is checked for convergence until the corrected OPC model converges and then enters the next step, wherein the number of corrections of the initial OPC model is adjusted according to the convergence check result of the corrected OPC model; the corrected OPC model is verified to check the accuracy of the corrected OPC model, and if it meets the standard, the corrected OPC model is used to make a photomask. In the step of correcting the initial OPC model, the present invention adjusts the number of corrections according to the convergence of the corrected OPC model, so as to achieve the effect of reducing the running time without affecting the accuracy of the OPC model correction, that is, each type of customer layout file DB corresponds to a different number of OPC model corrections. When the number of corrections of the OPC model is less than the number of corrections in the fixed file, there is no need to correct the redundant number of times. When the number of corrections of the OPC model is greater than the number of corrections in the fixed file, the problem of wasting time running OPCV when the number of corrections is insufficient and the OPC model is not corrected in place is avoided.

[0057] In addition, it should be recognized that although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belongs to the scope of protection of the technical solution of the present invention.

Claims

1. A method for correcting an OPC model, characterized in that: include: Establish the initial OPC model; Modifying the initial OPC model to obtain a modified OPC model, and performing a convergence check on the modified OPC model until the modified OPC model converges and then proceeding to the next step, wherein the number of times the initial OPC model is modified is adjusted according to the convergence check result of the modified OPC model; The corrected OPC model is verified to check the accuracy of the corrected OPC model. If the corrected OPC model meets the standards, a photomask is manufactured using the corrected OPC model.

2. The method for correcting the OPC model according to claim 1, characterized in that: The method of modifying the initial OPC model to obtain a modified OPC model comprises: Step S21: performing a first correction step on the initial OPC model and checking the convergence of the OPC model after the first correction step. If the OPC model after the first correction step converges, then the correction of the initial OPC model is terminated. If the OPC model after the first correction step does not converge, then a first non-convergent area is marked, and step S22 is executed. Step S22: performing a second correction step on the first non-convergent area of ​​the OPC model after the first correction step and checking the convergence of the OPC model after the second correction step; if the OPC model after the second correction step converges, then ending the correction of the OPC model after the first correction step; if the OPC model after the second correction step does not converge, then marking the second non-convergent area and executing step S23; Step S23: Execute the third correction step on the second non-convergent area of ​​the OPC model after the second correction step and check the convergence of the OPC model after the third correction step. If the OPC model after the third correction step converges, end the correction of the OPC model after the second correction step. If the OPC model after the third correction step does not converge, continue to mark the third non-convergent area and continue to correct the OPC model after the third correction step until the OPC model converges.

3. The method for correcting the OPC model according to claim 2, characterized in that: The number of corrections of the initial OPC model includes the number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step.

4. The method for correcting the OPC model according to claim 2 or 3, characterized in that: The number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step are at least greater than once.

5. The method for correcting the OPC model according to claim 2 or 3, characterized in that: The number of corrections in the first correction step, the number of corrections in the second correction step, and the number of corrections in the third correction step decrease in sequence.

6. The method for correcting the OPC model according to claim 1, characterized in that: The method for establishing the initial OPC model includes: Get the target graphics; Performing a wiring process according to the target pattern and obtaining wafer data; The wafer data is used to perform initial OPC modeling.

7. The method for correcting the OPC model according to claim 6, characterized in that: The steps of performing a wiring process according to the target pattern and obtaining wafer data include: Designing a test pattern and making a test mask according to the test pattern; The test pattern is transferred to a wafer using the test mask, an actual pattern is formed on the wafer, and wafer data obtained by testing the actual pattern is acquired.

8. The method for correcting the OPC model according to claim 7, characterized in that: The method for verifying the modified OPC model includes: Performing OPC model processing on the test pattern to obtain a simulation pattern; The simulation graphic is verified; if the verification passes, it is determined that the simulation graphic is correct.

9. A method for making a photomask, characterized in that: The OPC model corrected by the correction method of the OPC model according to claims 1 to 8 is used to obtain a simulation pattern, and the simulation pattern is transferred to a photomask to form a mask pattern.

10. A photolithography method, characterized in that: include: The mask pattern manufactured by the method for manufacturing a photomask as claimed in claim 9 is transferred to a wafer by using an exposure process and a development process to form a photolithography pattern on the wafer.

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