A photomask verification method based on photomask manufacturing error effects

Abstract

The application provides a photomask verification method based on photomask manufacturing error effect, comprising the following steps: S1: based on the provided design pattern, screening a region with a design size less than a minimum design size plus a first predetermined value as a Target inspection area; S2: based on a photomask inspection standard, performing OPC correction on the design pattern to obtain a corrected pattern; S3: based on the corrected pattern, screening a region from the photomask manufacturing size rule limit to a second predetermined value as a POST OPC inspection area on the basis of the Target inspection area; S4: performing simulation and MEEF analysis on the POST OPC inspection area, and selecting a region exceeding a MEEF predetermined value as a MEEF inspection area; and S5: determining a new photomask inspection standard for the MEEF inspection area. MEEF is introduced into photomask verification to avoid bridging caused by photomask error; simulation screening is performed near the minimum design size and the photomask manufacturing size limit, the simulation range is reduced, and the real risk hot spot is found.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to a photomask verification method based on photomask fabrication error effects. Background Technology

[0002] The Mask Error Enhancement Factor (MEEF) quantitatively represents the influence of feature size errors on the mask on the feature size errors of the pattern in the photoresist. With a large MEEF value, the mask linewidth needs strict control, and locations with high MEEF values ​​are prone to problems during exposure, resulting in dead pixels. In traditional Optical Proximity Correction (OPC) processes, only the contour curve is controlled; basic design checks, contour checks, and Mask Rule Checks (MRC) do not adequately address potential danger areas with large MEEF values. The quality control measurement patterns for masks are primarily regular one-dimensional patterns. As layout complexity increases, mask corrections gradually approach the mask's manufacturing limits. This necessitates timely simulation to identify locations with large MEEF values ​​while focusing on the contour, redefining more reasonable mask inspection rules to avoid bridging defects caused by mask errors. Simulating the entire layout results in a large amount of data, potentially leading to numerous errors that are difficult to identify. Therefore, a mask verification method based on photomask manufacturing error effects is needed to accurately simulate and identify real risk hotspots, define more reasonable mask inspection rules, and prevent potential mask defects. Summary of the Invention

[0003] This invention addresses all or part of the problems in the prior art by providing a photomask verification method based on photomask fabrication error effects. It introduces the MEEF factor into photomask verification, simulating and screening areas with large MEEF values ​​near the minimum lithography value and the limit size of the photomask fabrication, predicting potential risks, and redefining photomask inspection specifications to avoid actual bridging defects caused by photomask errors. Furthermore, it eliminates the need to simulate the entire layout, narrowing the simulation scope and enabling accurate simulation to identify real risk hotspots.

[0004] This invention provides a photomask verification method based on photomask fabrication error effects, comprising the following steps: S1: providing a design pattern, and based on the design pattern, selecting regions with design sizes smaller than the minimum design size plus a first predetermined value as Target inspection areas; S2: performing OPC correction on the design pattern based on photomask inspection standards to obtain a corrected pattern; S3: based on the Target inspection areas and the corrected pattern, selecting regions with sizes within the range of photomask manufacturing size rule limits plus or minus a second predetermined value as POST OPC inspection areas; S4: performing simulation on the POST OPC inspection areas to obtain simulated graphics and performing MEEF analysis, selecting regions with MEEF values ​​exceeding the predetermined MEEF value as MEEF inspection areas; S5: determining new photomask inspection standards for the MEEF inspection areas. By simulating and selecting regions with large MEEF values ​​near the minimum design size and photomask manufacturing limit size, the simulation range is narrowed, enabling more accurate identification of risk hotspots. Regions with large MEEF values ​​indicate photomask fabrication errors that directly affect actual wafer data. In these regions, the influence of errors is fully considered when redetermining the photomask inspection rules for the MEEF inspection areas.

[0005] In step S1, the first predetermined value is selected based on the minimum design size, which is the minimum size requirement for the size of the design pattern, and the design pattern that meets the minimum design size is provided.

[0006] In step S1, the minimum design dimensions include the minimum line width design dimension, the minimum spacing design dimension, the minimum design dimension from corner to straight line, and the minimum design dimension from corner to corner. Hot spots are prone to appear in narrow spaces, and defects are prone to occur in the photolithography process. This helps to determine more realistic risk hot spots.

[0007] In step S1, the first predetermined value is 10% of the minimum design size. The target inspection area is selected by focusing on the region near the minimum design size, thus narrowing the scope for subsequent simulations and improving simulation accuracy.

[0008] In step S2, the OPC verification includes Table-driven OPC and Model-based OPC verification. After verification, a correction pattern is obtained, and subsequent POST OPC check area definition is performed based on the correction pattern.

[0009] In step S3, the second predetermined value is increased by 20% based on the limit of the mask manufacturing size rule. Bridging risks are most likely to be found in the area near the limit of the mask manufacturing size, and the POST OPC inspection area is screened near the limit of the mask manufacturing size.

[0010] In step S4, the predetermined MEEF value is 4. In areas with a large MEEF value, the error in the mask fabrication will be amplified during the exposure process, which is prone to problems and the formation of bad pixels.

[0011] The photomask inspection standard is the bridging verification standard used in the OPC correction, and the bridging verification standard is selected based on the minimum design size.

[0012] In step S5, the new photomask inspection standard is defined as: New photomask inspection standard = Minimum design size - (Minimum design size – Photomask inspection standard) * 50%. By resetting a more stringent photomask inspection standard, variations in the manufacturing process are reduced, the defect rate is lowered, and product reliability is improved. Compared with the prior art, the beneficial effects of this invention mainly include the following: Introducing the MEEF factor into photomask verification, redefining more reasonable photomask inspection rules based on locations with larger MEEF values, and avoiding actual bridging defects due to photomask errors. Simultaneously, simulating and screening areas with larger MEEF values ​​near the minimum design size and the photomask manufacturing limit size allows for prediction of potential risks. This eliminates the need to simulate the entire layout, narrowing the simulation scope, reducing the amount of data, minimizing errors, and making it easier to identify more realistic risk hotspots. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of a photomask verification method based on photomask fabrication error effects according to the present invention;

[0015] Figure 2 To design a graphic pattern diagram;

[0016] Figure 3 A graphical representation of the Target inspection area after filtering S1;

[0017] Figure 4 This is a schematic diagram of S2 after OPC correction;

[0018] Figure 5 This is a graphical representation of the POST OPC check area after filtering in S3.

[0019] Figure 6 This is a graphical representation of the results after S4 simulation.

[0020] Figure 7This is a schematic diagram of the confirmation of the MEEF inspection area in S5. Detailed Implementation

[0021] The following description and accompanying drawings fully illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Some portions and features of some embodiments may be included in or replace portions and features of other embodiments.

[0022] This embodiment provides a photomask verification method based on the error effect of photomask fabrication. Figure 1 This is a flowchart of a photomask verification method based on photomask fabrication error effects. This embodiment takes a minimum design size of 60nm for the design pattern spacing as an example, and specifically includes the following steps: S1: Provide a design pattern, such as... Figure 2 As shown, based on the design pattern, regions with design sizes smaller than the minimum design size plus a first predetermined value are selected as Target inspection areas. The first predetermined value is selected based on the minimum design size, which is the minimum size requirement for the design pattern. The minimum design size includes the minimum line width design size, the minimum spacing design size, the minimum design size from corner to straight line, and the minimum design size from corner to corner. The first predetermined value is 10% of the minimum design size. In this embodiment, for a minimum spacing design size of 60nm, the first predetermined value is 6. Regions with spacing less than 66nm are defined as Target inspection areas. Figure 3 The area shown within the dashed line.

[0023] S2: Based on the photomask inspection standard, the design pattern is modified using OPC to obtain a modified pattern. OPC modification includes Table-driven OPC and Model-based OPC. The modified pattern is shown below. Figure 4 The shaded area;

[0024] S3: Based on the Target inspection area and the modified pattern, select areas whose dimensions are within or above the limits of the photomask manufacturing size rules up to the second predetermined value as POST OPC inspection areas; such as Figure 5 The area shown within the dashed line has a second predetermined value of 20% above the limit of the photomask manufacturing size rule. In this embodiment, the limit rule for photomask manufacturing spacing is 40nm, so the second predetermined value is 48nm. Based on the selected Target inspection area, the area with a spacing between 40nm and 48nm is selected as the POST OPC inspection area.

[0025] S4: Simulate the POST OPC check area to obtain a simulation graphic and perform MEEF analysis. Select the area where the MEEF value exceeds the predetermined MEEF value as the MEEF check area; the simulation graphic is as follows: Figure 6 As shown by the dashed line, specifically, the predetermined value of MEEF is 4, as... Figure 6 The location indicated by the middle arrow. After two rounds of region filtering, the simulation scope was narrowed, the amount of simulation data was reduced, the probability of errors was lowered, more accurate simulation results were obtained, and more accurate risk hotspots were identified.

[0026] S5: Determine a new photomask inspection standard for the selected MEEF inspection areas. Since areas with large MEEFs have photomask fabrication errors that directly affect the actual wafer data, a new photomask inspection standard needs to be determined in these areas, taking full account of the error impact. Based on the new photomask inspection standard, OPC correction is performed on the design pattern to obtain a new corrected pattern. The new photomask inspection standard is: New photomask inspection standard = Minimum design size - (Minimum design size – Photomask inspection standard) * 50%. The photomask inspection standard is the bridging verification standard used in the OPC correction, and the bridging verification standard is selected based on the minimum design size. Figure 7 As shown, in this embodiment, the minimum design size for the spacing is 60nm, and the photomask inspection standard is selected as 56nm. If the MEEF value of the simulated pattern at this position is large, a new photomask inspection standard needs to be determined. The new photomask inspection standard is updated to: 60 - (60 - 56) * 50% = 58nm. It needs to be corrected according to the new standard of 58nm to reduce errors in the manufacturing process, reduce the defect rate, and improve the reliability and consistency of the product. It should be understood that some commonly used English terms or letters used in this application for the purpose of clear description are only used for exemplary reference and not for limiting interpretation or specific usage, and should not be used to limit the scope of protection of this application based on their possible Chinese translations or specific letters. It should also be noted that in this document, 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 photomask verification method based on photomask fabrication error effects, characterized in that, Includes the following steps: S1: Provide a design pattern, and based on the design pattern, filter out areas whose design size is smaller than the minimum design size plus a first predetermined value as the Target inspection area; S2: Based on the photomask inspection standard, the design pattern is modified by OPC to obtain the modified pattern; the photomask inspection standard is the bridging verification standard used for the OPC modification, and the bridging verification standard is selected according to the minimum design size; S3: Based on the Target inspection area and the modified pattern, select areas whose size is within the range of the limit of the photomask manufacturing size rule and above to the second predetermined value as POST OPC inspection areas; S4: Simulate the POST OPC inspection area to obtain a simulation graphic and perform MEEF analysis. Select the area where the MEEF value exceeds the predetermined MEEF value as the MEEF inspection area. S5: Determine a new photomask inspection standard for the selected MEEF inspection areas. The new photomask inspection standard is defined as: New photomask inspection standard = Minimum design size - (Minimum design size – Photomask inspection standard) * 50%.

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

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

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

6. The photomask verification method based on photomask fabrication 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 photomask manufacturing size rule.

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

Images