JP2007286918A - Dangerous pattern extraction method and dangerous pattern extraction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently extract a dangerous pattern based on a pattern density rate. <P>SOLUTION: A dangerous pattern extraction method includes: calculating the existence density of a pattern as first pattern density PD1 in a density calculation area DA set so that an extracted dangerous pattern candidate DK can be included in a design pattern SP (S41); moving the density calculation area DA to the periphery of a central coordinate position CP of the dangerous pattern candidate DK and calculating the existence density of the pattern in the moved density calculation area DA as second pattern density PD2 (S61); and determining whether or not the dangerous pattern candidate DK is a dangerous pattern DP based on the pattern density rate PDR of the first pattern density PD1 and the second pattern density PD2 (S71). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a danger pattern extraction method and a danger pattern extraction apparatus. In particular, the present invention relates to a danger pattern extraction method and a danger pattern extraction apparatus for extracting a pattern having a small process margin as a danger pattern in a design pattern in which a plurality of patterns are arranged with a space therebetween.

  In manufacturing a semiconductor device, a fine pattern is processed on a wafer by using a lithography technique.

  Here, for example, after a resist film made of a photosensitive material is formed on the surface to be patterned, a photomask having a mask pattern formed on the design pattern is illuminated, and a mask pattern image generated by the illumination is illuminated on the wafer. The resist film formed thereon is exposed and transferred. Thereafter, the resist film to which the mask pattern image is transferred is developed to form a resist mask on the surface of the wafer. Then, pattern processing is performed by performing an etching process using the resist mask.

  In this lithography technique, optical proximity effect correction (OPC: Optical Proximity Effect Correction) is applied to the mask pattern in order to perform pattern processing so as to correspond to the design pattern. For example, corrections such as adding a figure to the mask pattern in advance or changing the size according to the density of the pattern are performed.

  OPC is classified into “rule-based OPC” and “model-based OPC”.

  “Rule-based OPC” is a method of generating an OPC pattern by defining an OPC pattern creation rule for each category and correcting the design pattern according to the defined creation rule. Specifically, first, based on the transfer result of the OPC test pattern, after obtaining the distortion amount due to the optical proximity effect that changes according to the width of the pattern and the distance to the adjacent pattern adjacent to the pattern, A correlation table is created that associates the amount of distortion, the width of the pattern, and the distance to the adjacent pattern adjacent to the pattern. Thereafter, a rule for changing the design pattern is created based on the correlation table, and correction is performed so as to correspond to this rule. This “rule-based OPC” is suitable for performing correction by examining the optical proximity effect of adjacent figures one-dimensionally, and is preferably applied to, for example, a line and space pattern.

  On the other hand, “model-based OPC” is a correction method using a model formed on the basis of a lithography simulation result, and the model can be calibrated based on the pattern transfer result to cope with a complicated process. It becomes possible. Specifically, by using a model formula for simulating the dimension after processing, correction is performed so that the dimension of the transferred pattern after processing matches the design pattern. This “model-based OPC” is suitable for performing correction by examining the optical proximity effect of adjacent figures two-dimensionally.

  However, as the demand for higher integration and higher operation speed in semiconductor devices increases, even when OPC is applied, it is sometimes difficult to perform pattern processing with sufficient accuracy. In particular, when variations occur in the process conditions such as the focal position in the exposure process, defects will occur in the part of the dangerous pattern arranged with a layout with a small process margin. May be difficult. For example, the above-described problem may be manifested because a portion that occurs in a layout range where the pattern density difference is narrow becomes a dangerous pattern that is greatly affected by variations in process conditions. For this reason, the manufacturing yield of the semiconductor device may be reduced, and the reliability of the device may be reduced.

  In order to improve this problem, a method has been proposed in which a process of extracting a dangerous pattern from a design pattern is performed, and when the dangerous pattern is extracted, the design pattern is corrected (for example, see Patent Document 1). ).

JP 2005-181523 A

  However, in the above method, since a dangerous pattern cannot be extracted unless OPC and optical simulation are performed, it may take a long time to feed back the presence or absence of this dangerous pattern to the designer. For this reason, working efficiency may be reduced.

  Accordingly, it is an object of the present invention to provide a danger pattern extraction method and a danger pattern extraction apparatus that can efficiently extract a danger pattern.

  In order to solve the above problems, the dangerous pattern extraction method of the present invention is a dangerous pattern extraction method for extracting a pattern having a small process margin as a dangerous pattern in a design pattern in which a plurality of patterns are arranged with a space therebetween. Then, based on the width of the pattern and the distance of the space, a first step of extracting a risk pattern candidate that is a candidate of the risk pattern from the plurality of patterns, and the risk extracted in the first step By dividing the design pattern so as to include the second step of calculating the coordinate position corresponding to the center as the center coordinate position in the pattern candidate, and the danger pattern candidate extracted in the first step in the design pattern After forming the density calculation area, the density is calculated at the center coordinate position calculated in the second step. A density in which the pattern exists in a third step of setting the density calculation area in the design pattern so that the center of the calculation area corresponds, and in the density calculation area set in the design pattern in the third step And the center of the density calculation area set in the third step is around the central coordinate position of the risk pattern candidate calculated in the second step. The density calculation area set in the third step so as to move from the center of the density calculation area set in the third step to the end of the density calculation area. In the fifth step of moving the design pattern to a plurality of positions in the design pattern, and in the density calculation area moved to the plurality of positions in the fifth step, the density of the pattern exists. A sixth step of calculating each as a second pattern density; the first pattern density calculated in the fourth step; and the second pattern density calculated in the sixth step; Is calculated as a pattern density ratio for each position of the density calculation area moved in the fifth step, and based on the pattern density ratio calculated in the seventh step, And an eighth step of determining whether the risk pattern candidate is the risk pattern.

  In order to solve the above-described problem, the danger pattern extraction device of the present invention is a danger pattern extraction device that extracts a pattern having a small process margin as a danger pattern in a design pattern in which a plurality of patterns are arranged with a space therebetween. Based on the width of the pattern and the distance of the space, the risk pattern candidate extraction means for extracting the risk pattern candidate as the risk pattern candidate from the plurality of patterns, and the risk pattern candidate extraction means A center coordinate position calculating means for calculating a coordinate position corresponding to the center as the center coordinate position in the danger pattern candidate, and the danger pattern candidate extracted by the danger pattern candidate extracting means in the design pattern. By dividing the design pattern, a density calculation area is formed. Then, a density calculation area setting unit that sets the density calculation area in the design pattern so that the center of the density calculation area corresponds to the center coordinate position calculated by the center coordinate position calculation means, and the center coordinates Density set in the design pattern so that the density calculation area centered on the center coordinate position calculated by the position calculation means includes the danger pattern candidates extracted by the danger pattern candidate extraction means in the design pattern A calculation area setting means; and a first pattern density calculation means for calculating a density at which the pattern exists in the density calculation area set in the design pattern by the density calculation area setting means as a first pattern density; The center of the density calculation area set by the density calculation area setting means is the center seat. The density calculation area so as to move around the center coordinate position of the danger pattern candidate calculated by the position calculation means and from the center of the density calculation area to the end of the density calculation area. Density calculation area moving means for moving the density calculation area set by setting means to a plurality of positions in the design pattern; and the density calculation area moved to a plurality of positions by the density calculation area moving means, A second pattern density calculating unit that calculates each density at which the pattern exists as a second pattern density; the first pattern density calculated by the first pattern density calculating unit; The ratio of the second pattern density calculated by the pattern density calculation means is calculated by the density calculation error moved by the density calculation area moving means. Pattern density ratio calculation means for calculating the pattern density ratio for each rear position, and whether or not the danger pattern candidate is the danger pattern based on the pattern density ratio calculated by the pattern density ratio calculation means Risk pattern judging means for judging

  ADVANTAGE OF THE INVENTION According to this invention, the danger pattern extraction method and danger pattern extraction apparatus which can extract a danger pattern efficiently can be provided.

  FIG. 1 is a block diagram showing a danger pattern extraction device 1 in an embodiment according to the present invention.

  As shown in FIG. 1, the danger pattern extraction device 1 of this embodiment has an input device 11, a central processing unit 21, and a display device 31, and a plurality of patterns are arranged with a space therebetween. In the design pattern, a pattern having a small process margin is extracted as a dangerous pattern. Each part will be described sequentially.

  The input device 11 is configured by operation devices such as a keyboard and a pointing device, and operation data is input by an operator, and the operation data is output to the central processing unit 21. In the present embodiment, data regarding the design pattern of the semiconductor device is input by the operator.

  The central processing unit 21 includes a computer and a storage device that stores a program for causing the computer to function as various means. In the present embodiment, the central processing unit 21 receives data related to a semiconductor device design pattern from the input device 11. Then, the central processing unit 21 extracts a danger pattern that is a pattern with a small process margin in the design pattern of the semiconductor device. Then, image data indicating the extraction result of the danger pattern is generated and output to the display device 31 for display.

  FIG. 2 is a block diagram showing the central processing unit 21 in the embodiment according to the present invention.

  As shown in FIG. 2, the central processing unit 21 includes a risk pattern candidate extraction unit 211, a center coordinate position calculation unit 212, a density calculation area setting unit 213, a first pattern density calculation unit 214, and a density calculation area. The moving unit 215, the second pattern density calculating unit 216, the pattern density ratio calculating unit 217, and the danger pattern determining unit 218 are provided, and the computer functions as each unit by the program as described above. Detailed operation of each means will be described later.

  The display device 31 includes a display device such as a CRT, and displays an image on a display screen. Here, the display device 31 displays the extraction result on the display screen based on image data indicating the extraction result of the danger pattern generated by the central processing unit 21.

  Below, operation | movement about the danger pattern extraction apparatus 1 of this embodiment is demonstrated.

  FIG. 3 is a flowchart showing the operation of the danger pattern extraction apparatus 1 in the embodiment according to the present invention.

  First, as shown in FIG. 3, extraction of the risk pattern candidate DK is performed (S11).

  Here, the danger pattern candidate extraction unit 211 extracts the danger pattern candidates DK that are candidates for the danger pattern DP from a plurality of patterns constituting the design pattern SP of the semiconductor device input from the input device 11. In the present embodiment, based on the pattern width and the space distance, a risk pattern candidate DK that is a risk pattern DP candidate in the design pattern SP is extracted. Specifically, the pattern width in a plurality of patterns constituting the design pattern SP is equal to or smaller than a predetermined reference value, and the distance of the space between the pattern and an adjacent pattern adjacent to the pattern changes. The dangerous pattern candidate extraction unit 211 extracts the portion as the dangerous pattern candidate DK.

  FIG. 4 is a plan view showing the danger pattern candidates DK extracted by the design pattern SP in the embodiment according to the present invention. 4A shows a part of the design pattern SP, and FIG. 4B shows a risk pattern candidate DK extracted by a part of the design pattern SP.

  As shown in FIG. 4A, in the present embodiment, the design pattern SP includes a first line pattern P1, a second line pattern P2, a third line pattern P3, and a fourth pattern as patterns. Line pattern P4. Here, each of the first line pattern P1, the second line pattern P2, the third line pattern P3, and the fourth line pattern P4 has a pattern width WP corresponding to the minimum design rule. Is formed.

  And about the 1st line pattern P1, the 2nd line pattern P2, and the 3rd line pattern P3, it mutually extends in the width direction x orthogonal to the extending direction y extended in a line form. They are lined up at an interval so that the directions to be parallel are parallel. Here, the space S1 between the first line pattern P1 and the second line pattern P2 and the space S2 between the second line pattern P2 and the third line pattern P3 are the minimum design. The space width WS1 corresponding to the rule is arranged. In the first line pattern P1, the second line pattern P2, and the third line pattern P3, the second line pattern P2 extends from the first line pattern P1 and the third line pattern P3. It is formed so as to protrude upward from the upper end portion in the existing direction. Further, the fourth line pattern P4 is arranged so as to separate the space 3 from the third line pattern P3 above the third line pattern P3 and is the same as the third line pattern P3. The second line patterns P2 are arranged with a space S1 therebetween so as to be parallel to the extending direction. Here, the space 3 between the second line pattern P2 and the third line pattern P3 is arranged to have a space width WS1 corresponding to the minimum design rule.

  In the design pattern SP, as shown in FIG. 4A, the second line pattern P2 is small in the width direction x between the first line pattern P1 and the third line pattern P3 that are adjacent patterns. Spaces S1 and S2 having a space width WS1 are provided. And about the space S4 of the part corresponding upward from the upper end part in the extending direction of the 1st line pattern P1 and the 3rd line pattern P3, it is larger than the space width WS2 smaller than the small space width WS1 in the width direction x. Is provided. And about the space S3 corresponding upwards from the lower end part in the extending direction of the 4th line pattern P4, the space | interval of the small space width WS1 is provided in the width direction x. Thus, in the second line pattern P2, the spaces S1, S2, S3, S4 of the small space width WS1 and the large space width WS2 exist in the width direction x. As described above, in the portion where the space width changes, the process margin may be reduced because the pattern density changes. Further, since the second line pattern P2 has the space width WS1 corresponding to the minimum design rule, the process margin may be reduced.

  For this reason, in the present embodiment, as shown in FIG. 4B, a portion where the distances of the spaces S1, S2, S3, and S4 change in the second line pattern P2 is defined and dangerous as the dangerous pattern candidate DK. The pattern candidate extraction means 211 extracts. For example, the lower end of the fourth line pattern P4 is defined as a position where a predetermined distance has been moved downward from a portion corresponding to the upper end of the first line pattern P1 and the third line pattern P3. The risk pattern candidate DK is extracted in a rectangular shape so that the upper end is the position moved by a predetermined distance upward from the portion corresponding to.

  Next, as shown in FIG. 3, it is determined whether or not the danger pattern candidate DK can be extracted (S13).

  Here, when the dangerous pattern candidate extraction unit 211 does not extract the dangerous pattern candidate DK in the above-described step (S11) (No), the process ends as shown in FIG.

  On the other hand, when the dangerous pattern candidate extraction unit 211 extracts the dangerous pattern candidate DK (Yes) in the above step (S11), the center coordinate position CP of the dangerous pattern candidate DK is changed as shown in FIG. Calculation is performed (S21).

  Here, as described above, the coordinate position corresponding to the center in the danger pattern candidate DK extracted by the danger pattern candidate extraction unit 211 is calculated by the center coordinate position calculation unit 212 as the center coordinate position CP.

  FIG. 5 is a plan view showing the center coordinate position CP calculated by the danger pattern candidate DK in the embodiment according to the present invention.

  In the present embodiment, as shown in FIG. 5, the coordinate position corresponding to the center in the extending direction y and the center in the width direction x in the danger pattern candidate DK is calculated as the center coordinate position CP.

  Next, as shown in FIG. 3, the density calculation area DA is set (S31).

  Here, the density calculation area DA is set by the density calculation area setting means 213.

  FIG. 6 is a plan view showing the density calculation area DA set by the design pattern SP in the embodiment according to the present invention.

  As shown in FIG. 6, the design pattern SP includes the risk pattern candidate DK extracted by the risk pattern candidate extraction unit 211, and the density calculation area at the center coordinate position CP calculated by the center coordinate position calculation unit 212. The density calculation area setting means 213 partitions and sets the density calculation area DA in the design pattern SP so that the center DC of the DA corresponds. For example, the density calculation area setting means 213 divides and sets the density calculation area DA into the design patterns SP so as to divide with a width twice as large as the minimum value of the space distance in the plurality of patterns. That is, as shown in FIG. 6, the density calculation area DA is partitioned and set so as to extend from the center in the width direction x to the outside at twice the pattern width WP corresponding to the minimum design rule. Thus, since the influence of the peripheral pattern is reduced by setting the density calculation area DA, the difference in pattern density described later can be calculated effectively.

  Next, as shown in FIG. 3, the first pattern density PD1 is calculated (S41).

  Here, the first pattern density calculating unit 214 calculates the first pattern density. Specifically, in the density calculation area DA set in the design pattern SP by the density calculation area setting means 213, the density at which the pattern exists is calculated as the first pattern density PD1 by the first pattern density calculation means 214. To do. That is, the first pattern density PD1 is obtained by calculating the ratio of the area of the pattern existing in the density calculation area DA.

  Next, as shown in FIG. 3, the density calculation area DA is moved (S51).

  Here, the density calculation area moving means 215 moves the density calculation area DA. Specifically, the center DC of the density calculation area DA set by the density calculation area setting means 213 is around the center coordinate position CP of the danger pattern candidate DK calculated by the center coordinate position calculation means 212. The density calculation area moving means 215 includes a plurality of density calculation areas DA set by the density calculation area setting means 213 in the design pattern SP so as to move from the center DC to the end of the density calculation area DA. Move to the position.

  FIG. 7 is a plan view showing the density calculation area DA moved by the design pattern SP in the embodiment according to the present invention.

  In the present embodiment, as shown in FIGS. 7A and 7B, the density calculation area moving means 215 is arranged so that the danger pattern candidate DK extends along the longitudinal direction y extending in a line shape. The density calculation area DA is moved from the center coordinate position CP in the direction D1 and in the downward direction D2 opposite to the upward direction D1. Further, here, the density calculation area DA set by the density calculation area setting means 213 is set to the density calculation area moving means so as to correspond to a distance twice the minimum value of the space distance in the plurality of patterns. 215 moves. That is, as shown in FIGS. 7A and 7B, the density calculation area is set so that the distance from the center in the extending direction y is twice the pattern width WP corresponding to the minimum design rule. Move the center of DA.

  Next, as shown in FIG. 3, the second pattern density PD2 is calculated (S61).

  Here, the second pattern density calculation means 216 calculates the second pattern density PD2. Specifically, in the density calculation area DA moved to a plurality of positions by the density calculation area moving means 215, each density having the pattern P is set as the second pattern density PD2, and the second pattern density calculating means. 216 calculates. That is, as shown in FIG. 7A, the ratio of the area of the pattern existing in the density calculation area DA moved upward is calculated, and the density moved downward as shown in FIG. 7B. By calculating the ratio of the area of the pattern existing in the calculation area DA, the second pattern density PD2 at each position is obtained.

  Next, as shown in FIG. 3, the pattern density ratio PDR is calculated (S71).

  Here, the pattern density ratio calculation means 217 calculates the pattern density ratio PDR. Specifically, the ratio between the first pattern density PD1 calculated by the first pattern density calculation unit 214 and the second pattern density PD2 calculated by the second pattern density calculation unit 216 is expressed as follows: For each position of the density calculation area DA moved by the density calculation area moving means 215, the pattern density ratio calculating means 217 calculates the pattern density ratio PDR. That is, as shown in FIG. 7A, the pattern density ratio PDR with the second pattern density PD2 in the density calculation area DA moved upward is calculated, and downward as shown in FIG. 7B. The pattern density ratio PDR with the second pattern density PD2 in the moved density calculation area DA is calculated.

  Next, as shown in FIG. 3, the danger pattern DP is determined (S81).

  Here, based on the pattern density ratio PDR calculated by the pattern density ratio calculating unit 217, the dangerous pattern determining unit 218 determines whether or not the dangerous pattern candidate DK is the dangerous pattern DP. For example, when at least one of the pattern density ratios PDR calculated by the pattern density ratio calculating unit 217 is equal to or greater than a predetermined threshold, the dangerous pattern candidate DK is determined as the dangerous pattern DP by the dangerous pattern candidate DK. to decide. In the present embodiment, the second pattern density PD2 in the density calculation area DA moved upward as shown in FIG. 7A, or the density moved downward as shown in FIG. 7B. When one of the pattern density ratios PDR between the second pattern density PD2 in the calculation area DA and the first pattern density PD1 calculated by the first pattern density calculation unit 214 is, for example, 2 or more Further, the risk pattern candidate DK is determined as the risk pattern DP. That is, when the first pattern density PD1 is greater than or equal to 2 times or less than 1/2 times the second pattern density PD2 in the density calculation area DA that has been moved upward, or the density calculation that has been moved downward. When the first pattern density PD1 is not less than 2 times or not more than 1/2 times the second pattern density PD2 in the area DA, the danger pattern candidate DK is determined and extracted as the danger pattern DP. And the image which shows the extraction result of this danger pattern DP is produced | generated, and the display apparatus 31 displays the image which shows the extraction result on a screen.

  As described above, according to the present embodiment, a portion where the pattern width is equal to or smaller than the reference value and the space distance between the patterns is changed is extracted as the dangerous pattern candidate DK in the plurality of patterns constituting the design pattern SP. . Thereafter, in the density calculation area DA set so as to include the dangerous pattern candidates DK extracted in the design pattern SP, the density at which the pattern exists is calculated as the first pattern density PD1. The density calculation area DA is moved around the center coordinate position CP of the danger pattern candidate DK, and the density at which the pattern exists in the moved density calculation area DA is calculated as the second pattern density PD2. Then, based on the pattern density ratio PDR between the first pattern density PD1 and the second pattern density PD2, it is determined whether or not the dangerous pattern candidate DK is a dangerous pattern DP. That is, based on the difference between the first pattern density PD1 in the region including the dangerous pattern candidate DK and the second pattern density PD2 in the surrounding area, the dangerous pattern candidate DK is a dangerous pattern DP with a low process margin. It is determined whether or not there is a danger pattern DP. As described above, since the danger pattern DP is extracted using only the information about the design pattern SP without performing OPC and optical simulation in this embodiment, the presence or absence of the danger pattern DP is fed back to the designer. Can be shortened. Therefore, this embodiment can improve work efficiency.

  In the present embodiment, the density calculation area DA is set as a design pattern so as to be divided by a width twice as large as the minimum value of the space width in a plurality of patterns, and the density calculation area DA is set as the space. Move so as to correspond to a distance twice as large as the minimum width. For this reason, since this embodiment can extract effectively the dangerous pattern DP from which a pattern density changes large in a narrow range, it can improve work efficiency.

  In the present embodiment, the center DC of the density calculation area DA is defined from the center coordinate position CP of the danger pattern candidate DK upward and downward along the extending direction y in which the danger pattern candidate DK extends. Moving. Then, the pattern density ratio PDR at each moving position is calculated. For this reason, this embodiment can obtain | require the ratio of a change of pattern density effectively, and since it can shorten calculation time, it can improve working efficiency.

  In the above embodiment, step S11 corresponds to the first step of the present invention. In the above embodiment, step S21 corresponds to the second step of the present invention. In the present embodiment, step S31 corresponds to the third step of the present invention. In the above embodiment, step S41 corresponds to the fourth step of the present invention. In the present embodiment, step S51 corresponds to the fifth step of the present invention. In the above embodiment, step S61 corresponds to the sixth step of the present invention. In the present embodiment, step S71 corresponds to the seventh step of the present invention. In the above embodiment, step S81 corresponds to the eighth step of the present invention.

  Moreover, when implementing this invention, it is not limited to said embodiment, A various deformation | transformation form is employable.

  For example, in the above-described embodiment, the center DC of the density calculation area DA is set to the center coordinate position CP of the danger pattern candidate DK above and below along the extending direction y in which the danger pattern candidate DK extends. Although the case of moving from is shown, it is not limited to this. For example, the center DC of the density calculation area DA may be moved from the center coordinate position CP of the danger pattern candidate DK in the right direction and the left direction in addition to the upper direction and the lower direction. Moreover, you may move to the direction which inclines with respect to this extending direction. In this case, the danger pattern DP can be extracted with higher accuracy.

  Further, for example, in the above-described embodiment, the case of the danger pattern candidate DK whose longitudinal direction extends in the vertical direction has been described, but the present invention can also be applied to the case where the longitudinal direction of the danger pattern candidate DK extends in the horizontal direction. Thus, the effects of the present invention can be achieved by performing each operation in the same manner as in the above embodiment. For example, the center DC of the density calculation area DA is moved from the center coordinate position CP of the danger pattern candidate DK to the right side and the left side along the horizontal direction x in which the danger pattern candidate DK extends to correspond to each position. The pattern density ratio to be calculated is calculated.

  Further, the layout information of the danger pattern extracted in the present embodiment may be stored, and the danger pattern may be extracted from the design pattern using the stored danger pattern layout information. Further, by incorporating it in an automatic placement and routing tool, it is possible to prevent a dangerous pattern from occurring in automatic placement and routing. In addition, for the extracted dangerous pattern, the model when the process fluctuates is adopted for the extracted dangerous pattern, and the ideal process condition model is adopted for the other pattern, and the OPC is performed. You may comprise. As a result, it is possible to obtain a correction result that is not easily affected by process variations.

FIG. 1 is a block diagram showing a danger pattern extraction device 1 in an embodiment according to the present invention. FIG. 2 is a block diagram showing the central processing unit 21 in the embodiment according to the present invention. FIG. 3 is a flowchart showing the operation of the danger pattern extraction apparatus 1 in the embodiment according to the present invention. FIG. 4 is a plan view showing the danger pattern candidates DK extracted by the design pattern SP in the embodiment according to the present invention. FIG. 5 is a plan view showing the center coordinate position CP calculated by the danger pattern candidate DK in the embodiment according to the present invention. FIG. 6 is a plan view showing the density calculation area DA set by the design pattern SP in the embodiment according to the present invention. FIG. 7 is a plan view showing the density calculation area DA moved by the design pattern SP in the embodiment according to the present invention.

Explanation of symbols

1 ... Danger pattern extraction device,
11 ... Input device,
21 ... Central processing unit,
31 ... display device,
211 ... Danger pattern candidate extraction means,
212 ... Center coordinate position calculation means,
213 ... Density calculation area setting means,
214 ... 1st pattern density calculation means,
215 ... Density calculation area moving means,
216 ... second pattern density calculating means,
217 ... Pattern density ratio calculation means,
218 ... Danger pattern judgment means

Claims (7)

In a design pattern in which a plurality of patterns are arranged with a space between them, a dangerous pattern extraction method for extracting a pattern with a small process margin as a dangerous pattern,
A first step of extracting, from the plurality of patterns, dangerous pattern candidates that are candidates for the dangerous pattern based on the width of the pattern and the distance of the space;
A second step of calculating a coordinate position corresponding to the center in the risk pattern candidate extracted in the first step as a central coordinate position;
After forming the density calculation area by partitioning the design pattern so as to include the dangerous pattern candidates extracted in the first step in the design pattern, the center coordinate position calculated in the second step is A third step of setting the density calculation area in the design pattern so that the center of the density calculation area corresponds;
A fourth step of calculating a density at which the pattern exists as a first pattern density in the density calculation area set in the design pattern in the third step;
The center of the density calculation area set in the third step is around the center coordinate position of the risk pattern candidate calculated in the second step, and the center set in the third step A fifth step of moving the density calculation area set in the third step to a plurality of positions in the design pattern so as to move from the center of the density calculation area to the end of the density calculation area. When,
A sixth step of calculating each density at which the pattern exists as a second pattern density in the density calculation area moved to a plurality of positions in the fifth step;
The ratio of the first pattern density calculated in the fourth step and the ratio of the second pattern density calculated in the sixth step is the density calculation area moved in the fifth step. A seventh step of calculating as a pattern density ratio for each position;
An eighth step of determining whether or not the risk pattern candidate is the risk pattern based on the pattern density ratio calculated in the seventh step. In the first step, a portion in which the width of the pattern in the plurality of patterns is equal to or less than a reference value and the distance of the space between the pattern and an adjacent pattern adjacent to the pattern is changed to the dangerous pattern. The risk pattern extraction method according to claim 1, wherein the danger pattern is extracted as a candidate. 3. The danger pattern according to claim 2, wherein in the third step, the density calculation area is set in the design pattern so as to be divided with a width twice as large as a minimum value of a space distance in the plural patterns. Extraction method. In the fifth step, the first step and the second direction opposite to the first direction are set in the third step so as to extend along the extending direction in which the danger pattern candidate extends. The risk pattern extraction method according to claim 3, wherein the density calculation area is moved. 5. In the fifth step, the density calculation area set in the third step is moved so as to correspond to a double distance with respect to a minimum value of a space distance in the plurality of patterns. The hazard pattern extraction method described in 1. The dangerous pattern extraction according to claim 5, wherein in the eighth step, the dangerous pattern candidate is determined to be the dangerous pattern when the pattern density ratio calculated in the seventh step is 2 or more. Method. In a design pattern in which a plurality of patterns are arranged with a space between them, a dangerous pattern extraction device that extracts a pattern with a small process margin as a dangerous pattern,
Danger pattern candidate extraction means for extracting a danger pattern candidate that is a candidate for the danger pattern from the plurality of patterns based on the width of the pattern and the distance of the space;
Center coordinate position calculating means for calculating a coordinate position corresponding to the center as the center coordinate position in the danger pattern candidate extracted by the danger pattern candidate extracting means;
After forming the density calculation area by partitioning the design pattern so as to include the risk pattern candidate extracted by the risk pattern candidate extraction unit in the design pattern, the calculated by the central coordinate position calculation unit A density calculation area setting unit that sets the density calculation area in the design pattern so that the center of the density calculation area corresponds to a center coordinate position;
In the density calculation area set in the design pattern by the density calculation area setting means, a first pattern density calculation means for calculating a density at which the pattern exists as a first pattern density;
The center of the density calculation area set by the density calculation area setting means is around the center coordinate position of the danger pattern candidate calculated by the center coordinate position calculation means, and the center of the density calculation area Density calculation area moving means for moving the density calculation area set by the density calculation area setting means to a plurality of positions in the design pattern so as to move from the density calculation area to the end of the density calculation area. ,
In the density calculation area moved to a plurality of positions by the density calculation area moving means, a second pattern density calculating means for calculating each density at which the pattern exists as a second pattern density;
The ratio of the first pattern density calculated by the first pattern density calculation means and the second pattern density calculated by the second pattern density calculation means is set to move the density calculation area. Pattern density ratio calculation means for calculating as a pattern density ratio for each position of the density calculation area moved by means;
A dangerous pattern extraction device comprising: dangerous pattern determination means for determining whether or not the dangerous pattern candidate is the dangerous pattern based on the pattern density ratio calculated by the pattern density ratio calculation means.

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