Method for processing auxiliary graphics using visual editing graphics database

Abstract

The present invention discloses a method for processing auxiliary graphics by using a visual editing graphic database, comprising: step S1, establishing a target graphic database; the target graphic database comprises a plurality of target graphics, each target graphic comprises a main graphic and an auxiliary graphic; step S2, defining the size of a graphic search range; step S3, defining limiting conditions for graphic matching; the limiting conditions comprise the anchor point of the main graphic and the line width size range of the auxiliary graphic; step S4, performing a graphic scan on the entire test layout, finding a matching graphic that meets the limiting conditions, marking the matching graphic and outputting the matching graphic and the marked layout data; step S5, determining at least one auxiliary graphic based on the layout data of the matching graphic.

Description

Technical Field

[0001] The invention relates to the field of semiconductor integrated circuit manufacturing, and in particular to a method for processing auxiliary graphics by using a visual editing graphic database. Background Art

[0002] In the advanced semiconductor integrated circuit manufacturing process, the original design layout has become more complicated due to the use of model-based optical proximity correction (OPC). In actual process manufacturing, the increasingly narrow process window has become a major challenge in the lithography process. In order to obtain a larger process window, it is proposed to add a sub-resolution auxiliary pattern (SRAF) near the main pattern to help the main pattern to obtain better imaging. At the same time, a process window suitable for large-scale production can be obtained in production, which enhances the stability of production. At present, the commonly used methods to improve the process window in the industry are: adding slender auxiliary patterns on the edge of isolated linear patterns can improve the depth of focus, and placing auxiliary patterns at the sidelobe of dense patterns can enhance the image contrast, thereby improving the process window.

[0003] At present, the commonly used method flow for optimizing auxiliary graphics SRAF (such as Figure 1 As shown in the figure): first determine a main graphic anchor point for observing the auxiliary graphic SRAF, that is, determine the line width size of the main graphic and the distance between adjacent main graphics; select a series of auxiliary graphics SRAFs with the same line width size of the auxiliary graphics SRAF according to the empirical value, and different spacing between the auxiliary graphics SRAF and the main graphic and the spacing between adjacent auxiliary graphics SRAF, locate and record the coordinate position of the anchor point of this group of auxiliary graphics SRAF series in the test layout; starting from the first-order equal line width series auxiliary graphics SRAF with the smallest line width size, use a line width scanning electron microscope (CDSEM) to observe whether this group of auxiliary graphics SRAF can be exposed on the wafer, and measure the line width of the auxiliary graphics SRAF inserted The line width size of the anchor point of RAF on the wafer; increase the line width size to the second-order equal-line width series auxiliary graphics SRAF, and use CDSEM to observe whether the auxiliary graphics SRAF can be exposed on the wafer and the line width size of the anchor point with this auxiliary graphics SRAF inserted on the wafer; similarly, increase the line width size in sequence, and use CDSEM to observe the exposure of the auxiliary graphics SRAF on the wafer and the line width size of the anchor point, until the auxiliary graphics SRAF line width size increases to a certain value, the auxiliary graphics SRAF farthest from the main graphics will be exposed on the wafer, indicating that this order of equal-line width series auxiliary graphics SRAF will be exposed on the wafer, and CDSEM observation and measurement can be terminated. Count the types of auxiliary graphics SRAF that are not exposed on the wafer, and calculate the process window size of the main graphics anchor point with these auxiliary graphics SRAF inserted, and determine the optimal auxiliary graphics SRAF type based on the results.

[0004] However, this method has the following problems: 1) It is necessary to manually search and record the coordinate positions of the anchor points of the auxiliary graphics SRAF of the equal line width series with all different line width values ​​inserted in the layout data, which is a time-consuming and inefficient process; 2) CDSEM needs to observe and verify many types and graphics of auxiliary graphics SRAF, which is a large workload, time-consuming and inefficient; 3) In the process of optimizing the auxiliary graphics SRAF, fewer dimensions are considered, usually only the exposure status of the auxiliary graphics SRAF and the size of the process window. In the process with smaller and smaller process nodes, the consideration results will not be sufficient and accurate. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for processing auxiliary graphics using a visual editing graphic database, comprising:

[0006] Step S1, establishing a target graphics database;

[0007] The target graphic database includes a plurality of target graphics, each of which includes a main graphic and an auxiliary graphic;

[0008] Step S2, defining the size of the graphic search range;

[0009] Step S3, defining limiting conditions for graphic matching;

[0010] The limiting conditions include the anchor point of the main figure and the line width size range of the auxiliary figure;

[0011] Step S4, scanning the entire test layout, finding a matching pattern that meets the specified conditions, marking the matching pattern and outputting the matching pattern and the marked layout data.

[0012] Step S5, determining at least one auxiliary pattern according to the layout data of the matching pattern.

[0013] Preferably, in step S3, the anchor point of the main figure includes the line width of the main figure and the distance between the main figure and adjacent main figures.

[0014] Preferably, the limiting condition further includes an offset of a line width size of the auxiliary pattern.

[0015] Preferably, in step S4, there are multiple matching graphics that meet the limiting conditions.

[0016] Preferably, in step S4, the main graphic and the auxiliary graphic in the matching graphic are marked with two different graphics, the main graphic is marked with a first marking graphic, and the auxiliary graphic is marked with a second marking graphic.

[0017] Preferably, the first marking pattern and the second marking pattern are different in shape and / or size.

[0018] Preferably, the plurality of matching graphics are classified, and matching graphics matching the same target graphic are classified into one category, and only the layout data of one matching graphic is output for each category.

[0019] Preferably, in step S5, at least one auxiliary pattern is determined by performing an OPC operation on the layout data of the output matching pattern.

[0020] Preferably, the auxiliary pattern is determined based on the first parameter, the second parameter, the third parameter, the fourth parameter and the fifth parameter output by the OPC operation;

[0021] The first parameter is the normalized image logarithmic slope Nils (Normalized Image Log Slope);

[0022] The second parameter is a mask error enhancement factor Meef (mask error enhancement factor);

[0023] The third parameter is a process variation band PV band (process variation band);

[0024] The fourth parameter is process window DOF (depth of focus);

[0025] The fifth parameter is the maximum optical intensity Imax (max intensity).

[0026] Preferably, the principle of evaluating and determining the auxiliary graph is that the fifth parameter Imax is less than the OPC model threshold, and measures the ratio of the first parameter to the fourth parameter (Nils / DOF), and the ratio of the second parameter to the third parameter (Meef / PVband).

[0027] The larger the ratio of the first parameter to the fourth parameter is, the better it is; the smaller the ratio of the second parameter to the third parameter is, the better it is.

[0028] Compared with the prior art, the present invention uses a visual editing graphic database to quickly locate all auxiliary graphic types that meet the requirements in the test layout, and through further OPC simulation operations, the optimal auxiliary graphic is determined from multiple dimensions such as the Imax of the auxiliary graphic and the Nils, PVband and process window of the main graphic. This method greatly shortens the time to determine the optimal auxiliary graphic type and improves resource utilization, evaluates and considers the auxiliary graphics in multiple dimensions, and improves the accuracy of OPC. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A schematic flow chart of a method for optimizing auxiliary graphics SRAF in the prior art;

[0030] Figure 2 and Figure 3 Schematic diagram of target graphics and matching graphics in a specific implementation manner.

[0031] Figure 4 The present invention is a flowchart of a method for processing auxiliary graphics by visually editing a graphics database. DETAILED DESCRIPTION

[0032] Example 1

[0033] In the method for processing auxiliary graphics using a visual editing graphic database provided in this embodiment, the visual editing graphic database uses a PMatch database system, such as Figure 4 As shown, the following steps are included

[0034] Step S1, establishing a target graphic database, the database includes a plurality of target graphics, each target graphic includes a main graphic and an auxiliary graphic;

[0035] Step S2, defining the size of the graphic search range, that is, the length and width of the search range;

[0036] Step S3, defining the limiting conditions for pattern matching, the limiting conditions include the anchor point of the main pattern and the line width size (SBW) range of the auxiliary pattern; the limiting conditions may also include the offset of the line width size of the auxiliary pattern

[0037] The anchor points of the main graphic include the line width (CD) of the main graphic and the pitch (Pitch) between the main graphic and the adjacent main graphic.

[0038] Step S4, scanning the entire test layout, finding a matching pattern that meets the specified conditions, marking the matching pattern and outputting the matching pattern and the marked layout data. For example, the output layout data includes a matching pattern layer and a marked pattern layer. There may be multiple matching patterns that meet the specified conditions.

[0039] The main graph and the auxiliary graph are marked with two different graphs, the main graph is marked with a first marking graph, and the auxiliary graph is marked with a second marking graph, and the first marking graph and the second marking graph have different shapes and / or sizes. This can provide better reference and convenience for subsequent OPC simulation operation processing.

[0040] Preferably, the matching patterns are classified, and the matching patterns matching the same target pattern are classified into one category, that is, all the matching patterns that are repeatedly matched are classified into one category, and only the layout data of one matching pattern is output in each category. This can reduce the time for subsequent OPC data reading and simulation processing, and improve efficiency and resource utilization.

[0041] Step S5, determining at least one auxiliary pattern according to the layout data of the matching pattern.

[0042] The following is a more specific example.

[0043] In PMatch, a target graphics database including main graphics and auxiliary graphics is established, and the size of the graphics search range is defined as follows: Figure 3 As shown in a.

[0044] The constraints for defining graph matching are as follows:

[0045] The anchor points of the main pattern include the line width size (CD) of the main pattern, the pitch between the main pattern and the adjacent main pattern, CD = 65nm, Pitch = 280nm. The line width size (SBW) of the auxiliary pattern is 13nm-24nm, that is, the width range between e6 and e8, and the width range between e14 and e16. At the same time, the offset conditions of the line width size of the auxiliary pattern are also defined, such as Figure 3 The dotted boxes in a indicate that e6, e8, e14, and e16 can move 10 nm to the left / right, respectively.

[0046] Search and locate the entire test layout, and add mark outputs to the main graphics and auxiliary graphics in the matching graphics that match the target graphics, that is, the first mark graphic layer matching the main graphic position and the second mark graphic layer matching the auxiliary graphic position; Figure 3 c is the position of all matching graphics in the test layout that match the target graphics;

[0047] In addition, by classifying the matching graphics, more concise layout data can be output.

[0048] Example 2

[0049] Based on the first embodiment, in step S5, this embodiment adopts a method of performing an OPC operation on the layout data of the output matching pattern to determine at least one auxiliary pattern.

[0050] An exemplary determination method is described as follows, wherein the auxiliary pattern is determined by evaluating a first parameter, a second parameter, a third parameter, a fourth parameter, and a fifth parameter output by an OPC operation.

[0051] The first parameter is the normalized image logarithmic slope Nils (Normalized Image Log Slope), which refers to the change of image intensity relative to distance;

[0052] The second parameter is the mask error enhancement factor Meef (mask error enhancement factor);

[0053] The third parameter is the process variation band (PV band), which refers to the difference between the minimum and maximum profiles produced by different process window conditions. The PV band is a measure of the stability of mask printing when the lithography equipment has normal variations.

[0054] The fourth parameter is the process window DOF (depth of focus);

[0055] The fifth parameter is the maximum optical intensity Imax (max intensity);

[0056] The parameters involved in the main figure are Nils (normalized image log slope), Meef (mask error enhancement factor), PV band (process variation band) and process window (depth of focus, abbreviated as DOF); the parameter involved in the auxiliary figure is the maximum optical intensity Imax (max intensity, abbreviated as Imax).

[0057] Based on the results of each parameter, a comprehensive evaluation is performed to determine the optimal type of one or more auxiliary graphics.

[0058] The principle for evaluating and determining the auxiliary pattern is that the fifth parameter Imax is less than the OPC model threshold, that is, the Imax of the auxiliary pattern should not touch the OPC model threshold, that is, the auxiliary pattern should not have the risk of being exposed on the wafer; under the premise that the auxiliary pattern is not exposed, the ratio of the first parameter to the fourth parameter (Nils / DOF) and the ratio of the second parameter to the third parameter (Meef / PV band) are measured; the larger the ratio of the first parameter to the fourth parameter, the better, and the smaller the ratio of the second parameter to the third parameter, the better.

[0059] Following the more specific example in Example 1, in step S5, the OPC simulation operation is performed on the simplified layout data, and the Imax value of the auxiliary graphics and the Nils, Meef, PVband and DOF values ​​of the main graphics with different auxiliary graphics series inserted are output respectively; the optimal auxiliary graphics are determined according to the principle that the Imax of the auxiliary graphics should be less than the OPC model threshold, the larger the Nils / DOF value of the main graphics and the smaller the Meef / PVband value.

[0060] Based on the comprehensive evaluation of the results, the optimal auxiliary pattern is determined to be 15-80-60: that is, the line width of the auxiliary pattern is 15nm, the distance between the auxiliary pattern and the main pattern is 80nm, and the spacing between adjacent auxiliary patterns is 60nm.

Claims

1. A method for processing auxiliary graphics using a visual editing graphic database, characterized in that: include: Step S1, establishing a target graphics database; The target graphic database includes a plurality of target graphics, each of which includes a main graphic and an auxiliary graphic; Step S2, defining the size of the graphic search range; Step S3, defining limiting conditions for graphic matching; The limiting conditions include the anchor point of the main figure and the line width size range of the auxiliary figure; Step S4, scanning the entire test layout, finding a matching pattern that meets the specified conditions, marking the matching pattern and outputting the matching pattern and the marked layout data; Step S5, determining at least one auxiliary pattern according to the layout data of the matching pattern; In the step S5, at least one auxiliary pattern is determined by performing an OPC operation on the layout data of the output matching pattern; Determine the auxiliary pattern based on the first parameter, the second parameter, the third parameter, the fourth parameter and the fifth parameter output by the OPC operation; The first parameter is the normalized image logarithmic slope Nils; The second parameter is a mask error enhancement coefficient Meef; The third parameter is the process window variation band PV band; The fourth parameter is the process window DOF; The fifth parameter is the maximum optical intensity; The principle of evaluating and determining the auxiliary graph is that the fifth parameter Imax is less than the OPC model threshold, and the ratio of the first parameter to the fourth parameter (Nils / DOF), and the ratio of the second parameter to the third parameter (Meef / PV band) are measured; The larger the ratio of the first parameter to the fourth parameter is, the better it is; the smaller the ratio of the second parameter to the third parameter is, the better it is.

2. The method for processing auxiliary graphics according to claim 1, characterized in that: In step S3, the anchor point of the main figure includes the line width of the main figure and the distance between the main figure and adjacent main figures.

3. The method for processing auxiliary graphics according to claim 2, characterized in that: The limiting condition also includes an offset of a line width size of the auxiliary pattern.

4. The method for processing auxiliary graphics according to claim 1, characterized in that: In the step S4, there are multiple matching patterns that meet the limiting conditions.

5. The method for processing auxiliary graphics according to claim 1, characterized in that: In the step S4, the main graph and the auxiliary graph in the matching graph are marked with two different graphs, the main graph is marked with a first marking graph, and the auxiliary graph is marked with a second marking graph.

6. The method for processing auxiliary graphics according to claim 5, characterized in that: The first marking pattern and the second marking pattern have different shapes and / or sizes.

7. The method for processing auxiliary graphics according to claim 4, characterized in that: The plurality of matching patterns are classified, and the matching patterns matching the same target pattern are classified into one category, and only the layout data of one matching pattern is output for each category.

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