Photomask verification method based on photomask manufacturing error effect

Abstract

The invention provides a photomask verification method based on a photomask manufacturing error effect, and the method comprises the following steps: S1, based on a provided design pattern, screening a region with a design size smaller than a minimum design size plus a first preset value as a Target inspection region; s2, on the basis of a photomask inspection standard, performing OPC correction on the design pattern to obtain a corrected pattern; s3, on the basis of the Target inspection area, based on the correction pattern, screening an area from the limit of the photomask manufacturing size rule to a second preset value as a POST OPC inspection area; s4, carrying out analogue simulation and MEEF analysis on the POST OPC inspection area, and selecting an area exceeding an MEEF preset value as an MEEF inspection area; and S5, determining a new photomask inspection standard for the MEEF inspection area. The MEEF is introduced into photomask verification to avoid bridging caused by photomask errors; simulation screening is carried out near the minimum design size and the photomask manufacturing size limit, the simulation range is narrowed, and real risk hotspots are found.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a photomask verification method based on a photomask manufacturing error effect. Background Art

[0002] The mask error enhancement factor (MEEF) quantitatively indicates the degree of influence of the feature size error on the mask on the feature size error in the photoresist. When the MEEF value is large, the line width of the mask needs to be strictly controlled. Locations with large MEEF values ​​are prone to problems during exposure, forming bad pixels.

[0003] In the traditional optical proximity correction (OPC) process, only the control of the contour curve is focused on, and basic design inspection, contour inspection and mask rule check (MRC) control do not pay enough attention to the potential danger zone with large MEEF. The quality control measurement pattern of the mask is mainly a regular one-dimensional pattern. As the complexity of the layout increases, the correction of the mask gradually approaches the limit production size of the mask. This requires timely simulation to find the position with large MEEF while paying attention to the contour, and redefine more reasonable mask inspection rules to avoid actual bridging defects caused by mask errors; at the same time, if the entire layout is simulated, the amount of data is too large, and there may be many errors, which are difficult to distinguish. In summary, it is necessary to provide a mask verification method based on the error effect of mask production, which can accurately simulate and find the real risk hotspots, define more reasonable mask inspection rules, and avoid potential risk defects of the mask. Summary of the invention

[0004] The present invention is to solve all or part of the problems of the above-mentioned prior art, and provides a mask verification method based on the error effect of mask production, introduces the MEEF factor into the mask verification, simulates and screens areas with large MEEF values ​​near the minimum lithography value and the limit size of mask production, predicts potential risks, and redefines the mask inspection specifications to avoid actual bridging defects caused by mask errors; at the same time, there is no need to simulate the entire layout, which reduces the simulation scope and can accurately simulate and find the real risk hotspots.

[0005] The present invention provides a photomask verification method based on the error effect of photomask manufacturing, comprising the following steps: S1: providing a design pattern, based on the design pattern, screening an area whose design size is less than the minimum design size plus a first predetermined value as a Target inspection area; S2: based on the photomask inspection standard, performing OPC correction on the design pattern to obtain a corrected pattern; S3: on the basis of the Target inspection area, based on the corrected pattern, screening an area whose size is within the range of the photomask manufacturing size rule limit and above to the second predetermined value as a POST OPC inspection area; S4: simulating the POST OPC inspection area to obtain a simulation graph and performing MEEF analysis, selecting an area whose MEEF value exceeds the MEEF predetermined value as a MEEF inspection area; S5: determining a new photomask inspection standard for the MEEF inspection area. By simulating and screening an area with a large MEEF value near the minimum design size and the photomask manufacturing limit size, the simulation range is narrowed, and the risk hotspot can be determined more accurately. For areas with a large MEEF, there is a photomask manufacturing error that directly affects the actual data of the wafer. In these areas, the photomask inspection rules for the MEEF inspection area are re-determined by fully considering the influence of the error.

[0006] In step S1, the first predetermined value is selected according to the minimum design size, the minimum design size is the minimum size requirement for the design pattern size, and the design pattern that meets the minimum design size is provided.

[0007] In step S1, the minimum design dimensions include the minimum design dimension of line width, the minimum design dimension of spacing, the minimum design dimension from corner to straight line, and the minimum design dimension from corner to corner. Hot spots are prone to occur in narrow spaces, and defects are prone to occur in the lithography process, so as to determine more realistic risk hot spots.

[0008] In step S1, the first predetermined value is: 10% of the minimum design size. The target inspection area is selected by focusing on the area near the minimum design size to narrow the scope for subsequent simulation and improve the simulation accuracy.

[0009] In step S2, the OPC verification includes Table-driven OPC and Model-based OPC verification, and a correction pattern is obtained after verification, and subsequent POST OPC inspection area definition is performed according to the correction pattern.

[0010] In step S3, the second predetermined value is 20% higher than the limit of the mask manufacturing size rule. In the area near the mask manufacturing limit, the bridging risk is most likely to be found, and the POST OPC inspection area is screened near the mask manufacturing limit size.

[0011] In step S4, the predetermined MEEF value is 4. In the area with a large MEEF value, the error in mask production will be magnified during the exposure process, which is prone to problems and bad pixels.

[0012] The mask inspection standard is a bridge verification standard used in the OPC correction, and the bridge verification standard is selected according to the minimum design size.

[0013] In step S5, the new mask inspection standard is defined as: new mask inspection standard = minimum design size - (minimum design size - mask inspection standard) * 50%. By resetting a stricter mask inspection standard, the variation in the manufacturing process is reduced, the defective rate is reduced, and the reliability of the product is improved.

[0014] Compared with the prior art, the beneficial effects of the present invention mainly include the following: introducing the MEEF factor into mask verification, redefining more reasonable mask inspection rules based on the position with larger MEEF, and avoiding the actual generation of bridging defects due to mask errors. At the same time, the area with larger MEEF value is simulated and screened near the minimum design size and the limit size of mask production, and the potential risks that may exist are predicted. It is not necessary to simulate the entire layout, which reduces the simulation scope, reduces the amount of data, has fewer errors, and is easy to find more realistic risk hotspots. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a flow chart of a photomask verification method based on photomask manufacturing error effect of the present invention;

[0017] Figure 2 To design a graphic pattern diagram;

[0018] Figure 3 Graphical diagram after screening the Target inspection area for S1;

[0019] Figure 4 This is a diagram of the S2 after OPC correction;

[0020] Figure 5 It is a graphic diagram of the screening POST OPC inspection area of ​​S3;

[0021] Figure 6 This is a graphic diagram after S4 simulation;

[0022] Figure 7 Schematic diagram of the MEEF inspection area confirmation of S5. DETAILED DESCRIPTION

[0023] The following description and accompanying drawings fully demonstrate specific embodiments of the present invention so that those skilled in the art can practice them. Other embodiments may include structural, logical, electrical, process and other changes. The embodiments represent possible variations only. Unless clearly required, separate components and functions are optional, and the order of operation may vary. The parts and features of some embodiments may be included in or replace the parts and features of other embodiments.

[0024] This embodiment provides a mask verification method based on the error effect of mask manufacturing. Figure 1 The flowchart of a mask verification method based on the error effect of mask manufacturing is shown in FIG. 1 . The embodiment takes the minimum design size of the design pattern spacing as 60 nm as an example, and specifically includes the following steps: S1: providing a design pattern, the design pattern is as follows: Figure 2 As shown, based on the design pattern, the area with a design size less than the first predetermined value is selected as the Target inspection area; the first predetermined value is selected based on the minimum design size, and the minimum design size is the minimum size requirement for the design pattern size. The minimum design size includes the minimum design size of the line width, the minimum design size of the spacing, the minimum design size from the corner to the straight line, and the minimum design size from the corner to the corner. The first predetermined value is 10% of the minimum design size. In this embodiment, for the minimum design size of the spacing of 60mm, the first predetermined value is 6, and the area with a spacing less than 66nm is defined as the Target inspection area, such as Figure 3 The area indicated by the dashed line.

[0025] S2: Based on the mask inspection standard, the design pattern is subjected to OPC correction to obtain a corrected pattern. The OPC correction includes Table-driven OPC and Model-based OPC. After the correction, a corrected pattern is obtained. The corrected pattern is as follows: Figure 4 The shaded part;

[0026] S3: Based on the Target inspection area, based on the correction pattern, select an area with a size within the range of or above the mask manufacturing size rule limit to a second predetermined value as a POST OPC inspection area; Figure 5 For the area shown in the middle dotted line, the second predetermined value is 20% based on the limit of the mask manufacturing size rule. In this embodiment, the mask manufacturing limit rule for the spacing is 40nm, so the second predetermined value is 48nm. Based on the screened Target inspection area, the area with a spacing of 40nm-48nm is screened as the POST OPC inspection area.

[0027] S4: Simulate the POST OPC inspection area to obtain a simulation graph and perform MEEF analysis, and select the area where the MEEF value exceeds the MEEF preset value as the MEEF inspection area; the simulation graph is as follows: Figure 6 As shown in the dashed line, specifically, the MEEF preset value is 4, such as Figure 6 The middle arrow points to the location. After two regional screenings, the simulation scope is narrowed, the amount of simulation data is reduced, the probability of errors is reduced, more accurate simulation results are obtained, and more accurate risk hotspots are screened out.

[0028] S5: Determine a new mask inspection standard for the screened MEEF inspection area. Since the area with larger MEEF has mask manufacturing errors, it directly affects the actual wafer data. Therefore, in these areas, the impact of errors must be fully considered and new mask inspection standards must be determined. Based on the new mask inspection standards, the design pattern is OPC corrected to obtain a new corrected pattern. The new mask inspection standard is: New mask inspection standard = minimum design size - (minimum design size - mask inspection standard) * 50%. The mask inspection standard is the bridge verification standard used for the OPC correction. The bridge verification standard is selected based on the minimum design size. Figure 7 As shown, in this embodiment, the minimum design size of the spacing is 60nm, and the mask inspection standard is selected as 56nm; if the MEEF value of the simulated pattern at this position is large, it is necessary to determine a new mask inspection standard, and the new mask inspection standard is updated to: 60-(60-56)*50%=58nm, which needs to be corrected with the new standard of 58nm to reduce errors in the manufacturing process, reduce the defective rate, and improve product reliability and consistency.

[0029] It should be understood that some commonly used English nouns or letters used in this application for the sake of clarity are only used for exemplary references rather than restrictive interpretations or specific usages, and the protection scope of this application should not be limited by their possible Chinese translations or specific letters. It should also be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

Claims

1. A mask verification method based on the error effect of photomask production, characterized in that: The steps include: S1: providing a design pattern, and based on the design pattern, selecting an area whose design size is smaller than a minimum design size plus a first predetermined value as a Target inspection area; S2: Based on the mask inspection standard, performing OPC correction on the design pattern to obtain a corrected pattern; S3: Based on the Target inspection area and the correction pattern, a region with a size within a range from a mask manufacturing size rule limit and above to a second predetermined value is selected as a POST OPC inspection area; S4: simulating the POST OPC inspection area to obtain a simulation graph and performing MEEF analysis, and selecting an area where the MEEF value exceeds a predetermined MEEF value as a MEEF inspection area; S5: Determine a new mask inspection standard for the screened MEEF inspection area.

2. The photomask verification method based on the photomask manufacturing error effect according to claim 1, characterized in that: In step S1, the first predetermined value is selected according to the minimum design size, and the minimum design size is the minimum size requirement for the design pattern size.

3. The photomask verification method based on the photomask manufacturing error effect according to claim 1, characterized in that: In step S1 , the minimum design dimensions include a minimum design dimension of line width, a minimum design dimension of spacing, a minimum design dimension from corner to straight line, and a minimum design dimension from corner to corner.

4. The photomask verification method based on the photomask manufacturing error effect according to claim 1, characterized in that: In step S1, the first predetermined value is: 10% of the minimum design size.

5. The photomask verification method based on the photomask manufacturing error effect according to claim 1, characterized in that: In step S2, the OPC correction includes Table-driven OPC and Model-based OPC correction.

6. The photomask verification method based on the photomask manufacturing error effect according to claim 1, characterized in that: In step S3, the second predetermined value is increased by 20% based on the limit of the mask manufacturing dimension rule.

7. The photomask verification method based on the photomask manufacturing error effect according to claim 1, characterized in that: In step S4, the predetermined value of MEEF is 4.

8. The photomask verification method based on the photomask manufacturing error effect according to claim 1, characterized in that: The mask inspection standard is a bridge verification standard used in the OPC correction, and the bridge verification standard is selected according to the minimum design size.

9. The photomask verification method based on the photomask manufacturing error effect according to claim 1, characterized in that: In step S5 , the new mask inspection standard is defined as: new mask inspection standard=minimum design size−(minimum design size−mask inspection standard)*50%.

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