Checking method of graph bridging and OPC modeling method

Abstract

The invention provides a pattern bridging test method and an OPC modeling method, and the method comprises the steps: providing an OPC model which comprises a plurality of initial patterns; changing an initial graph in the OPC model to obtain a changed graph; screening out a graph increase part of the changed graph compared with the initial graph; expanding the pattern increasing part to the periphery by a preset distance, and screening out an expanding area of the pattern increasing part to form an overlapping area with the adjacent initial pattern; and judging whether the pattern increasing part is in contact with the at least two overlapping areas, and if so, judging the pattern increasing part as a pattern bridging area. According to the method, the pattern bridging is detected by searching the overlapped region of the expanded region of the pattern increasing part and the initial pattern after the pattern increasing part is expanded, so that the detection method for the bridging pattern is optimized, the bridging condition of a single pattern can be detected, the detection result is perfected, and the omission ratio of the pattern bridging is reduced.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit technology, and particularly relates to a method for inspecting graphic bridging and an OPC modeling method. Background Art

[0002] With the rapid development of microelectronics technology, integrated circuit design and manufacturing have entered the nanometer stage. The size of the photomask pattern is close to or even smaller than the wavelength of the light used to form the lithographic pattern. Due to light wave diffraction and interference, there is a deviation between the lithographic pattern and the photomask pattern, that is, the Optical Proximity Effect (OPE). As a result, there are certain deformations and deviations between the actual lithographic pattern obtained on the silicon wafer and the photomask pattern. This error in lithography directly affects the production yield and circuit performance. To eliminate this error, it is necessary to perform pre-optical proximity correction (OPC) on the photomask pattern to compensate for the insufficient resolution of the optical system.

[0003] In OPC modeling, the layer graphic bridging check is a key step to ensure that the pattern after the lithography process will not cause accidental connection (short circuit) of adjacent structures due to proximity effects or other process deviations. However, the existing layer graphic bridging check methods in the prior art cannot detect the case of graphic bridging of a single graphic, resulting in missed detection of graphic bridging. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for inspecting graphic bridging and an OPC modeling method to solve the problem of missed detection of graphic bridging of a single graphic by the existing layer graphic bridging check method.

[0005] To solve the above technical problems, the present invention provides a method for inspecting graphic bridging, including:

[0006] Providing an OPC model, where the OPC model includes a plurality of initial graphics;

[0007] Changing the initial graphics in the OPC model to obtain a changed graphic;

[0008] Screening out the increased part of the graphic of the changed graphic compared to the initial graphic;

[0009] Expanding the increased part of the graphic by a predetermined distance in all directions, and screening out the overlapping area formed by the expanded area of the increased part of the graphic and the adjacent initial graphics;

[0010] Judging whether the increased part of the graphic is in contact with at least two of the overlapping areas. If so, it is judged as a graphic bridging area.

[0011] Optionally, changing the initial pattern in the OPC model includes adding sub-resolution assist features, modifying the initial pattern in the OPC model, or adjusting the initial pattern in the OPC model.

[0012] Optionally, the initial pattern for generating the pattern bridging region is a single initial pattern or two adjacent initial patterns.

[0013] Optionally, when the initial pattern for generating the pattern bridging region is two adjacent initial patterns, the shape of the initial pattern is rectangular or square.

[0014] Optionally, when the initial pattern for generating the pattern bridging region is a single initial pattern, the shape of the initial pattern is U-shaped.

[0015] Optionally, the predetermined distance by which the pattern addition part expands around is from 1 nm to 2 nm.

[0016] Optionally, it is determined whether the pattern addition part is in contact with at least two of the overlapping regions. If not, it is determined as a non-pattern bridging region.

[0017] Optionally, after it is determined as a pattern bridging region, the pattern of the pattern bridging region is modified until there is no pattern bridging region in the OPC model.

[0018] Optionally, the reason for generating the pattern bridging region includes a script error.

[0019] Based on the same inventive concept, the present invention also provides an OPC modeling method, including the inspection method for pattern bridging described in any one of the above.

[0020] In the inspection method for graphic bridging provided by the present invention, an OPC model is provided, and the OPC model includes a plurality of initial graphics; the initial graphics in the OPC model are changed to obtain the changed graphics; the graphic addition parts of the changed graphics compared with the initial graphics are screened out; the graphic addition parts are expanded a predetermined distance around, and the overlapping regions formed by the expanded regions of the graphic addition parts and the adjacent initial graphics are screened out; it is determined whether the graphic addition parts are in contact with at least two of the overlapping regions, and if so, it is determined as the graphic bridging region. The present invention detects graphic bridging by looking for the overlapping regions between the expanded regions of the graphic addition parts and the initial graphics after expanding the graphic addition parts. First, the graphic addition parts are expanded a predetermined distance around, then the overlapping regions between the expanded parts and the original graphics are found, and it is checked whether the contact between the graphic addition parts and the overlapping regions is at least two. If so, it indicates that graphic bridging occurs in the middle of the contact regions. The inspection method for bridging graphics is optimized, and the situation of single graphic bridging ignored in the existing inspection methods can be detected, the inspection results are improved, and the missed inspection rate of graphic bridging is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Those of ordinary skill in the art will understand that the provided drawings are used to better understand the present invention and do not constitute any limitation to the scope of the present invention. Among them:

[0022] Figure 1 is a flowchart of the inspection method for graphic bridging in an embodiment of the present invention.

[0023] Figure 2 is a schematic diagram of the first graphic addition part in an embodiment of the present invention.

[0024] Figure 3 is a schematic diagram of the second graphic addition part in an embodiment of the present invention.

[0025] Figure 4 is a schematic diagram of the third graphic addition part in an embodiment of the present invention.

[0026] Figure 5 is a schematic diagram of the fourth graphic addition part in an embodiment of the present invention.

[0027] Figure 6 is a schematic diagram of the fifth graphic addition part in an embodiment of the present invention.

[0028] Figure 7 is a schematic diagram of the second graphic addition part after expansion in an embodiment of the present invention.

[0029] Figure 8 is a schematic diagram of the fifth graphic addition part after expansion in an embodiment of the present invention.

[0030] Figure 9 It is a schematic diagram of the second type of figure in the embodiment of the present invention, where the extended area of the added part of the figure overlaps with the initial figure.

[0031] Figure 10 It is a schematic diagram of the fifth type of figure in the embodiment of the present invention, where the extended area of the added part of the figure overlaps with the initial figure.

[0032] In the attached drawings:

[0033] 11 - First initial figure; 12 - Second initial figure; 21 - First added part of the figure; 22 - Second added part of the figure; 22a - Extended area; 22b - Overlapping area. Detailed implementation manners

[0034] To make the objectives, advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the attached drawings and specific embodiments. It should be noted that the attached drawings are all in a very simplified form and not drawn to scale, and are only used to conveniently and clearly assist in explaining the objectives of the embodiments of the present invention. In addition, the structures shown in the attached drawings are often part of the actual structures. In particular, the attached drawings need to show different focuses, and sometimes different scales are used.

[0035] As used in the present invention, the singular forms "a", "an" and "the" include plural objects. The term "or" is usually used in the sense of including "and / or". The term "several" is usually used in the sense of including "at least one". The term "at least two" is usually used in the sense of including "two or more". In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", "third" may explicitly or implicitly include one or at least two of such features. In addition, as used in the present invention, when an element is provided on another element, it generally only means that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the two elements can be directly or indirectly connected, coupled, cooperated or transmitted 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 position such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] The inventors' research found that during the OPC modeling process, when some changes occur to the graphics (layers), such as adding sub-resolution assist features, modifying the graphics in the OPC model, adding bias, etc., it is necessary to check the differences between the changed graphics and the original graphics to verify whether the results of the changes are abnormal. One type of abnormality is that two graphics form a bridge. The bridge check in the prior art is to first find the added part of the changed graphics relative to the original graphics. This added part includes the graphic bridge, and then it is checked whether the added part contacts the original graphics. Contact with two or more graphics indicates that a graphic bridge has occurred. When there is a single graphic bridge, only one graphic will be contacted, and this bridge check method fails.

[0037] Based on this, the core idea of the present invention is to provide a method for checking graphic bridges. Specifically, an OPC model is provided, and the OPC model includes a plurality of initial graphics; the initial graphics in the OPC model are changed to obtain the changed graphics; the added graphic part of the changed graphics compared to the initial graphics is screened out; the added graphic part is expanded a predetermined distance around, and the overlapping area formed by the expanded area of the added graphic part and the adjacent initial graphics is screened out; it is determined whether the added graphic part contacts at least two of the overlapping areas. If so, it is determined as the graphic bridge area. The present invention detects graphic bridges by expanding the added graphic part and then finding the overlapping area between the expanded area of the added graphic part and the initial graphics. First, the added graphic part is expanded a predetermined distance around, and then the overlapping area between the expanded part and the original graphics is found. It is checked whether the contact between the added graphic part and the overlapping area is at least two. If so, it indicates that a graphic bridge occurs in the middle of the contacted area. The method for checking bridge graphics is optimized, and the situation of single graphic bridges ignored in the existing detection methods can be detected, improving the detection results and reducing the missed detection rate of graphic bridges.

[0038] The following description is made with reference to the accompanying drawings.

[0039] Figure 1 It is a flowchart of the method for checking graphic bridges according to an embodiment of the present invention. As Figure 1 shown, the present embodiment provides a method for checking graphic bridges, including:

[0040] Step S10: Provide an OPC model, and the OPC model includes a plurality of initial graphics;

[0041] Step S20: Change the initial graphics in the OPC model to obtain the changed graphics;

[0042] Step S30: Screen out the added graphic part of the changed graphics compared to the initial graphics;

[0043] Step S40: Expand the added part of the graph by a predetermined distance in all directions, and screen out the overlapping area formed by the expanded area of the added part of the graph and the adjacent initial graph;

[0044] Step S50: Determine whether the added part of the graph is in contact with at least two of the overlapping areas. If so, it is determined as a graph bridging area.

[0045] Figure 2 It is a schematic diagram of the first added part of the graph in the embodiment of the present invention. Figure 3 It is a schematic diagram of the second added part of the graph in the embodiment of the present invention. Figure 4 It is a schematic diagram of the third added part of the graph in the embodiment of the present invention. Figure 5 It is a schematic diagram of the fourth added part of the graph in the embodiment of the present invention. Figure 6 It is a schematic diagram of the fifth added part of the graph in the embodiment of the present invention. Figure 7 It is a schematic diagram after the second added part of the graph in the embodiment of the present invention is expanded. Figure 8 It is a schematic diagram after the fifth added part of the graph in the embodiment of the present invention is expanded. Figure 9 It is a schematic diagram of the overlapping area formed by the expanded area of the second added part of the graph and the initial graph in the embodiment of the present invention. Figure 10 It is a schematic diagram of the overlapping area formed by the expanded area of the fifth added part of the graph and the initial graph in the embodiment of the present invention. To make the above objects, features, and beneficial effects of the present invention more obvious and understandable, the following combines the accompanying drawings of the specification Figures 2 to 10 A detailed description of the specific embodiments of the present invention is given.

[0046] As Figures 2 to 6 shown, an OPC model is provided. The OPC model includes a plurality of initial graphs. The plurality of initial graphs are, for example, graphs on different layers, such as lithography graphs including corresponding gate etching graphs, etching graphs of the interconnect layer, or etching graphs of trenches. The initial graph includes a first initial graph 11 and a second initial graph 12. The first initial graph 11 is, for example, a rectangle or a square, and the second initial graph 12 is, for example, a U shape.

[0047] Please continue to refer to Figures 2 to 6, change the initial pattern in the OPC model to obtain a changed pattern. Changing the initial pattern in the OPC model includes adding sub-resolution assist features, correcting the initial pattern in the OPC model, or adjusting the initial pattern in the OPC model. Specifically, adjusting the initial pattern in the OPC model is, for example, adding bias. Adding bias (Bias Addition Before OPC Correction) is a design preprocessing method aimed at globally or locally adjusting the dimensions of the original design pattern before applying the OPC algorithm to pre-compensate for expected physical deformations (such as etch shrinkage, photoresist shrinkage, etc.) in the lithography process. This step can simplify the subsequent OPC correction complexity and improve the process robustness of the final pattern. The types of bias include positive bias and negative bias. Positive bias is to increase the line width of the lithography pattern or shorten the pitch, and is used to compensate for etch shrinkage (Etch Bias) or photoresist shrinkage. It is mainly used for patterns such as metal layers and polysilicon gates that are prone to thinning due to etching. Negative bias is to decrease the line width or increase the pitch, and is used to avoid pattern bridging or excessive swelling after lithography. It is mainly used for densely arranged contact holes (Via) or shallow trench isolation (STI) regions. Bias processing is a pre-step of OPC, aiming to reduce the process deviation amount that OPC needs to correct. OPC then makes fine adjustments (such as edge movement, adding scattering bars) for the remaining deviations (such as optical proximity effect). That is, correcting the initial pattern in the OPC model (OPC correction). Adding sub-resolution assist features (SRAF) is one of the key technologies of optical proximity correction (OPC). These patterns are added to the mask design, but because their sizes are smaller than the resolution of the lithography system, they will not be actually imaged onto the silicon wafer during the lithography process. Their main role is to improve the exposure quality of the main pattern by adjusting the light intensity distribution and optimizing the proximity effect, thereby enhancing the process window and the yield of chip manufacturing.

[0048] Please continue to refer to Figures 2 to 6 , screen out the pattern addition part of the changed pattern compared to the initial pattern; the pattern addition part includes a first pattern addition part 21 and a second pattern addition part 22. Since the first pattern addition part 21 does not contact the first initial pattern 11 on adjacent sides, it will not cause pattern bridging, as Figure 2 shown. The second pattern addition part 22 contacts the first initial pattern 11 on adjacent sides, which will cause pattern bridging, as Figure 3 shown. The second pattern addition part 22 contacts the first initial pattern 11 on adjacent three sides, which will cause pattern bridging, as Figure 4 shown. The second pattern addition part 22 contacts the first initial pattern 11 on adjacent four sides, which will cause pattern bridging, asFigure 5 As shown. When the added part 22 of the second figure touches a single initial U-shaped figure, it will also cause figure bridging, as Figure 6 shown. However, the existing script for judging figure bridging is:

[0049] bridge area = INTERACT area_add ori_layer>1(1)

[0050] where the bridge area is the figure bridging area, area_add is the added part of the figure, ori_layer is the initial figure, and INTERACT is an instruction in the SVRF (Standard Verification Rule Format, the standard rule description language for semiconductor physical verification) script, indicating that if one figure touches another figure, the previous figure will be found. However, figure bridging requires at least two contacts between the added part of the figure and the initial figure. For a single initial figure as Figure 6 shown, there is only one initial figure in contact with the added part of the figure. Therefore, in this bridging inspection method, the bridging of a single initial figure will be missed, that is, the existing bridging inspection method fails for a single initial figure.

[0051] As Figures 7 to 10 shown, expand the added part 22 of the second figure by a predetermined distance in all directions, and screen out the overlapping area 22b formed by the expanded area 22a of the added part 22 of the second figure and the adjacent initial figure. As Figure 7 and Figure 9 shown, the added part 22 of the second figure expands by a predetermined distance in all directions to form an expanded area 22a, and the expanded area 22a forms an overlapping area 22b with the first initial figure 11. Similarly, as Figure 8 and Figure 10 shown, the added part 22 of the second figure expands by a predetermined distance in all directions to form an expanded area 22a, and the expanded area 22a forms an overlapping area 22b with the second initial figure 12. The expanded predetermined distance d is, for example, 1 nm to 2 nm.

[0052] Please continue to refer to Figures 9 to 10 , in step S50, determine whether the added part of the second figure is in contact with at least two of the overlapping areas;

[0053] Step S51, if so, determine it as the figure bridging area.

[0054] Step S52, if not, determine it as the non-figure bridging area.

[0055] In this embodiment, the script for judging figure bridging is:

[0056] Bridge area = INTERACT area_add overlap>1(2)

[0057] Among them, the bridge area is the graphic bridging area, area_add is the graphic added part, overlap is the overlapping area, and INTERACT is an instruction in the SVRF (Standard Verification Rule Format, the standard rule description language for semiconductor physical verification) script, indicating that if one graphic touches another graphic, the previous graphic will be found. Graphic bridging requires at least two contacts between the added part of the second graphic and the overlapping area. By expanding the added part of the second graphic, the expanded area of the added part of the second graphic forms an overlapping area with the initial graphic. Whether it is graphic bridging of multiple initial graphics or a single initial graphic, at least two overlapping areas are formed. Therefore, graphic bridging of a single initial graphic can also be detected.

[0058] Specifically, the initial graphic that generates the graphic bridging area is a single initial graphic, two adjacent initial graphics, three adjacent initial graphics, four adjacent initial graphics, or more adjacent initial graphics. When the initial graphic that generates the graphic bridging area is two adjacent initial graphics, the shape of the initial graphic is a rectangle or a square. When the initial graphic that generates the graphic bridging area is a single initial graphic, the shape of the initial graphic is a U shape.

[0059] After determining the graphic bridging area, correct the graphic in the graphic bridging area and continue to perform graphic bridging inspection, looping in sequence until there is no graphic bridging area in the OPC model.

[0060] The reasons for generating the graphic bridging area also include script errors. Script errors include layer errors or performing operations such as moving and expanding graphics when correcting OPC. Script errors will cause one initial graphic to bridge with another initial graphic. If the above situation occurs, modify the script.

[0061] This embodiment also provides an OPC modeling method, including the inspection method for graphic bridging described in any one of the above.

[0062] In summary, in the inspection method for graphic bridging provided by the embodiments of the present invention, an OPC model is provided, and the OPC model includes a plurality of initial graphics; the initial graphics in the OPC model are changed to obtain the changed graphics; the graphic addition part of the changed graphics compared with the initial graphics is screened out; the graphic addition part is expanded a predetermined distance around, and the overlapping area formed by the expanded area of the graphic addition part and the adjacent initial graphics is screened out; it is determined whether the graphic addition part is in contact with at least two of the overlapping areas, and if so, it is determined as the graphic bridging area. The present invention detects graphic bridging by finding the overlapping area between the expanded area of the graphic addition part and the initial graphics after expanding the graphic addition part. First, the graphic addition part is expanded a predetermined distance around, then the overlapping area between the expanded part and the original graphics is found, and it is checked whether the contact between the graphic addition part and the overlapping area is at least two places. If so, it means that graphic bridging occurs in the middle of the contact area. The inspection method for bridging graphics is optimized, the situation of single graphic bridging ignored in the existing inspection methods can be detected, the inspection result is improved, and the missed inspection rate of graphic bridging is reduced.

[0063] It should be noted that the embodiments in this specification are described in a progressive manner, and the key points of each embodiment are the differences from other embodiments. The same and similar parts between the embodiments can be referred to each other. In addition, the different parts between the embodiments can also be combined and used with each other, and the present invention does not limit this.

[0064] In addition, it should also be recognized that although the present invention has been disclosed above with preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, many possible changes and modifications can be made to the technical solution of the present invention by using the technical content disclosed above, or it can be modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the scope of protection of the technical solution of the present invention.

Claims

1. A method for inspecting graphic bridging, characterized in that, Comprising: Providing an OPC model, the OPC model including a plurality of initial patterns; Changing the initial patterns in the OPC model to obtain changed patterns; Filtering out the pattern addition part of the changed patterns compared to the initial patterns; Expanding the pattern addition part by a predetermined distance in all directions, and filtering out the overlapping regions formed by the expanded regions of the pattern addition part and the adjacent initial patterns; Judging whether the pattern addition part is in contact with at least two of the overlapping regions, if so, judging it as a pattern bridging region.

2. The inspection method for graphic bridging according to claim 1, wherein Changing the initial patterns in the OPC model includes adding sub-resolution assist patterns, correcting the initial patterns in the OPC model, or adjusting the initial patterns in the OPC model.

3. The inspection method for graphic bridging according to claim 1, characterized in that, The initial pattern generating the pattern bridging region is a single initial pattern or two adjacent initial patterns.

4. The inspection method for graphic bridging according to claim 3, characterized in that, When the initial pattern generating the pattern bridging region is two adjacent initial patterns, the shape of the initial pattern is a rectangle or a square.

5. The inspection method for graphic bridging according to claim 3, characterized in that When the initial pattern generating the pattern bridging region is a single initial pattern, the shape of the initial pattern is a U shape.

6. The inspection method for graphic bridging according to claim 1, wherein The predetermined distance for expanding the pattern addition part in all directions is from 1 nm to 2 nm.

7. The inspection method for graphic bridging according to claim 1, characterized in that, Judging whether the pattern addition part is in contact with at least two of the overlapping regions, if not, judging it as a non-pattern bridging region.

8. The inspection method for graphic bridging according to claim 1, characterized in that, After judging it as a pattern bridging region, correcting the pattern of the pattern bridging region until there is no pattern bridging region in the OPC model.

9. The inspection method for graphic bridging according to claim 1, characterized in that, The reasons for generating the pattern bridging region include script errors.

10. An OPC modeling method, characterized in that, Including the inspection method for pattern bridging according to any one of claims 1 to 9.

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