JP2006292813A - Method for correcting design pattern, method for setting parameter, design pattern correcting apparatus, parameter setting apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for correcting a design pattern capable of setting parameters at appropriate values to be used for a model-base formula. <P>SOLUTION: Reference design patterns in a plurality of types are subjected to correction processes using a mathematical model in a plurality of times for the respective parameters to calculate a plurality of corrected reference design patterns on each reference design pattern of a plurality of types. Each of the plurality of corrected reference design patterns is subjected to the processes of calculating an error between the post exposure pattern and the corrected reference design pattern. Then the errors are separately summarized for each parameter to calculate an error sum for each parameter value. The value of the parameter showing the smallest error sum is selected in the parameter values with errors satisfying specified conditions in specified reference design patterns. Then the design pattern is corrected (S14, S16 and S18) by the numerical model using the selected parameter value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a design pattern correction method, a parameter setting method, a design pattern correction device, a parameter setting device, and a program for performing a model-based optical proximity effect correction on a design pattern. In particular, the present invention relates to a design pattern correction method, a parameter setting method, a design pattern correction device, a parameter setting device, and a program that can set parameters used in model-based mathematical formulas to appropriate values.

  In recent years, a layout pattern (for example, a wiring pattern) inside a semiconductor device has become finer than the wavelength of a light source used for exposure. For this reason, due to the optical proximity effect, dimensional variation or the like has occurred in the transferred pattern.

  As a technique for preventing dimensional fluctuations, there is optical proximity correction (hereinafter referred to as OPC). The OPC is designed to obtain a desired layout pattern after the transfer by preliminarily deforming the design pattern in consideration of the dimensional variation during transfer.

In OPC, there is a method (hereinafter referred to as model base) in which a pattern after transfer is calculated by simulation, and the design pattern is changed and simulation is repeated so that the calculated pattern approaches a desired pattern. The mathematical formula used for the model base has a plurality of parameters. When performing OPC on a design pattern, it is necessary to set each of a plurality of parameters included in the mathematical formula in advance to a value suitable for the design pattern (see, for example, Patent Document 1).
JP 2003-337402 A (second paragraph to sixth paragraph)

  FIG. 7 is a flowchart for explaining a parameter setting method by a conventional computer. First, the operator sets a plurality of parameter candidates for each parameter type (S100). Next, a process of performing simulation for each of the plurality of types of standard design patterns is performed for each parameter candidate combination. Then, the process of calculating the pattern error in actual exposure and the pattern error by simulation for each standard design pattern is performed for each parameter combination. Then, the sum of errors is calculated for each parameter combination (S102). Then, the combination of parameters with the smallest sum of errors is selected as a parameter suitable for the design pattern (S104).

  The standard design pattern includes a pattern that requires the highest accuracy and a pattern that requires less accuracy. However, in the above-described conventional example, the computer does not determine whether the selected parameter has sufficient accuracy for the pattern that requires the most accuracy.

For example, in the wiring pattern with the narrowest line width, when the line width of the actually formed wiring pattern is reduced, the resistance of the wiring is increased. In addition, when the width of the wiring is increased, the distance between the wirings is reduced, which may cause a short circuit.
For this reason, it is necessary to confirm whether the mathematical formula using the selected parameter has sufficient accuracy for the pattern that requires the highest accuracy.

  The present invention has been made in consideration of the above circumstances, and its purpose is to provide a design pattern correction method, a parameter setting method, and a design that can set parameters used in model-based equations to appropriate values. A pattern correction apparatus, a parameter setting apparatus, and a program are provided.

In order to solve the above problems, a design pattern correction method according to the present invention is a design pattern correction method for correcting an optical proximity effect of a design pattern inside a semiconductor device using a mathematical model having parameters,
The computer performs a plurality of corrections for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model for each of the plurality of types of standard design patterns a plurality of times with each of the values of the plurality of parameters. A step of calculating a post-standard design pattern;
A process in which the computer calculates an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern for each of the plurality of corrected standard design patterns;
A computer calculating the sum of the errors for each parameter value by aggregating the errors for each parameter value;
A step of selecting a value of the parameter with the smallest sum of the errors out of the values of the parameters in which the error in the specific standard design pattern satisfies a specific condition;
And a step of correcting the design pattern by the mathematical model using the selected value of the parameter.

  According to this design pattern correction method, the computer selects the parameter value having the smallest sum of the errors among the parameter values satisfying a specific condition by the error in the specific standard design pattern. For this reason, the parameter used for the model-based mathematical formula can be set to an appropriate value.

  In the case of a pattern that requires the highest accuracy among the plurality of standard design patterns, the step of selecting the value of the parameter includes the step of selecting the parameter so that the error in the specific standard design pattern is equal to or less than a reference value. This is a step of selecting a value. The specific standard design pattern includes, for example, a pattern in which a plurality of linear patterns are arranged in parallel to each other, and the error is, for example, an error in the width of the linear pattern.

  One of the plurality of types of standard design patterns is arranged in a direction substantially orthogonal to the first linear pattern and the first linear pattern, and an end portion is separated from the first linear pattern. The error may be an error in the width of the end of the second linear pattern. A third linear pattern; and a fourth linear pattern located on an extension of the third linear pattern and extending in the same direction as the third linear pattern. It may be an error of at least one of the width of the end of the third linear pattern and the end of the fourth linear pattern.

A parameter setting method according to the present invention is a parameter setting method for setting a parameter of the mathematical model in a mathematical model for correcting an optical proximity effect of a design pattern inside a semiconductor device,
The computer performs a plurality of corrections for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model for each of the plurality of types of standard design patterns a plurality of times with each of the values of the plurality of parameters. A step of calculating a post-standard design pattern;
A process in which the computer calculates an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern for each of the plurality of corrected standard design patterns;
A computer calculating the sum of the errors for each parameter value by aggregating the errors for each parameter value;
And a step of selecting the parameter value having the smallest sum of the errors among the parameter values satisfying a specific condition by the error in the specific standard design pattern.

A design pattern correction apparatus according to the present invention is a design pattern correction apparatus that corrects an optical proximity effect of a design pattern inside a semiconductor device using a mathematical model having parameters,
For each of a plurality of types of standard design patterns, a plurality of corrected standard designs are provided for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model a plurality of times with each of the plurality of parameter values. A corrected design pattern calculation unit for calculating a pattern;
A process of calculating an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern is performed for each of the plurality of corrected standard design patterns, and the error is set to the parameter. An error totaling unit that calculates the sum of the errors according to the value of the parameter,
A parameter selection unit that selects a value of the parameter having the smallest sum of the errors, among the values of the parameter in which the error in the specific standard design pattern satisfies a specific condition;
And a correction unit that corrects the design pattern by the mathematical model using the selected parameter value.

A parameter setting device according to the present invention is a parameter setting device for setting a parameter of the mathematical model in a mathematical model for correcting the optical proximity effect of a design pattern inside a semiconductor device,
For each of a plurality of types of standard design patterns, a plurality of corrected standard designs are provided for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model a plurality of times with each of the plurality of parameter values. A corrected design pattern calculation unit for calculating a pattern;
A process of calculating an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern is performed for each of the plurality of corrected standard design patterns, and the error is set to the parameter. An error totaling unit that calculates the sum of the errors according to the value of the parameter,
A parameter selection unit that selects a value of the parameter having the smallest sum of the errors among the parameter values satisfying a specific condition by the error in the specific standard design pattern.

A program according to the present invention is a program that is executed by a computer and corrects an optical proximity effect of a design pattern inside a semiconductor device using a mathematical model having parameters,
For each of a plurality of types of standard design patterns, a plurality of corrected standard designs are provided for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model a plurality of times with each of the plurality of parameter values. The ability to calculate patterns,
A function of calculating an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern for each of the plurality of corrected standard design patterns;
A function of calculating the sum of the errors for each parameter value by aggregating the errors for each parameter value;
A function of selecting the parameter value having the smallest sum of the errors among the parameter values satisfying a specific condition by the error in the specific standard design pattern;
A function of correcting the design pattern by the mathematical model using the value of the selected parameter.

Another program according to the present invention is a program that is executed by a computer to set parameters of the mathematical model in a mathematical model that corrects the optical proximity effect of the design pattern inside the semiconductor device,
For each of a plurality of types of standard design patterns, a plurality of corrected standard designs are provided for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model a plurality of times with each of the plurality of parameter values. The ability to calculate patterns,
A function of calculating an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern for each of the plurality of corrected standard design patterns;
A function of calculating the sum of the errors for each parameter value by aggregating the errors for each parameter value;
A function of selecting the parameter value having the smallest sum of the errors among the parameter values satisfying a specific condition by the error in the specific standard design pattern.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram for explaining the configuration of a design pattern correction apparatus according to an embodiment of the present invention. This design pattern correction apparatus is an apparatus that performs OPC on a model basis, and sets a plurality of parameters of mathematical formulas used for simulation to optimum values, and then performs OPC on the design pattern.

  The design pattern correction apparatus includes a corrected design pattern calculation unit 10, an error addition unit 20, a parameter selection unit 30, and a correction unit 40. A standard design pattern used for parameter setting and a plurality of parameter candidates are input to the post-correction design pattern calculation unit 10. The post-exposure pattern formed by actual exposure is input to the error adding unit 20. A design pattern in which OPC is performed is input to the correction unit 40. From the correction unit 40, a post-correction design pattern that is a design pattern after performing OPC is output.

  Hereinafter, the utilization method of the input data and the operation of the design pattern correction apparatus will be described in detail with reference to FIGS.

  2 and 3 are flowcharts for explaining the operation of the design pattern correction apparatus shown in FIG. First, the worker selects parameter candidates for each of a plurality of parameters and inputs them to the corrected design pattern calculation unit 10. Further, the worker inputs a plurality of standard design patterns to the corrected design pattern calculation unit 10. In addition, the operator inputs the post-exposure patterns of the plurality of standard design patterns to the error adding unit 20.

  FIG. 4 is a table for explaining an example of parameter candidate selection. In the example shown in the figure, the mathematical formula F used for the simulation has five parameters A, B, C, D, and E. For each of the five parameters, five candidates (a1 to a5, b1 to b5, c1 to c5, d1 to d5, and e1 to e5) are selected.

Each drawing in FIG. 5 is a plan view for explaining an example of a standard design pattern. The standard design pattern shown in FIG. 5A is a pattern in which a plurality of linear patterns 51 are arranged in parallel. The standard design pattern, the width W ₁ of the pattern 51 is changed by the optical proximity effect. The amount of change varies depending on the interval S _{1 of the} pattern 51 when the design value of the width W ₁ of the pattern 51 is constant. Design pattern correction apparatus according to this embodiment, as an error pattern and post exposure pattern by the simulation, see the error of the width W _1.

The standard design pattern shown in FIG. 5B includes a first linear pattern 52a and a second linear pattern 52b arranged in a direction substantially orthogonal to the first linear pattern 52a. End of the second linear pattern 52b is spaced from the first linear pattern 52a as the distance _{S 2.} The standard design pattern, the width W ₂ of the end of the second linear pattern 52b by the optical proximity effect is changed. The amount of change varies depending on the distance S ₂ when the design value of the end width W ₂ is constant. Design pattern correction apparatus according to this embodiment, as an error pattern and post exposure pattern by the simulation, see the error of the width W _2.

The standard design pattern shown in FIG. 5C is a third linear pattern 53a and a fourth linear pattern that is located on the extension of the third linear pattern 53a and extends in the same direction as the third linear pattern 53a. 53b. End of the third linear pattern 53a is spaced from the end of the fourth linear pattern 53b as the distance S _3. The standard design pattern, the third linear pattern 53a and the fourth linear pattern 53b width W ₃ of the respective end portion is changed by the optical proximity effect. The amount of change varies depending on the distance S ₃ when the design value of the end width W ₃ is constant. Design pattern correction apparatus according to this embodiment, as an error pattern and post exposure pattern by the simulation, see the error of the width W _3.

The standard design pattern 54 shown in FIG. 5D is a pattern obtained by bending a linear pattern at a substantially right angle. In the standard design pattern 54, as shown by the dotted line, the corner of the bent portion 54a is rounded by the optical proximity effect. The amount of change varies depending on the width W ₄ of the standard design pattern 54. The design pattern correction apparatus according to the present embodiment sees the error of the bent portion 54a as the error between the simulation pattern and the post-exposure pattern.

The standard design pattern 55 shown in FIG. 5 (E) extends downward in the drawing, then turns 90 ° clockwise, and extends in the horizontal direction in the drawing. Then, it is extended upward in the figure by bending 90 ° in the same direction. Also in this standard design pattern 55, as shown by a dotted line, the corner of the bent portion 55a is rounded by the optical proximity effect. The amount of change varies depending on the width W ₅ of the standard design pattern 55. The design pattern correction apparatus according to the present embodiment sees the error of the bent portion 55a as the error between the simulated pattern and the post-exposure pattern.

In actual processing, a plurality of patterns in which the line widths W _n and the intervals S _n of the examples shown in FIG. 5 are different from each other are used as standard design patterns.

  Returning to FIG. The corrected design pattern calculation unit 10 sets a combination of parameter candidates (S4). In the example shown in FIG. 4, there are 125 combinations, and any one of these is selected. The corrected design pattern calculation unit 10 performs a simulation for each of the standard design patterns using a combination of selected parameter candidates, and calculates each corrected standard design pattern (S6). . Then, the error adding unit 20 calculates the error of the corrected standard design pattern with respect to the post-exposure pattern for each of the standard design patterns (S8), and calculates the sum of the calculated errors (S10).

  The calculation of the sum of errors is performed for all parameter candidate combinations (125 patterns in the example shown in FIG. 4) (S12).

Next, as shown in FIG. 3, the parameter selection unit 30 selects a combination of parameters with the smallest sum of errors (S14). Then, a formula model using the combination of the selected parameter, the most (in illustrated in example FIG. 5 (A) pattern, narrowest pattern spacing S ₁ wire) accuracy standard design pattern required to simulate a Then, a corrected standard design pattern is calculated. Then, an error of the corrected standard design pattern with respect to the post-exposure pattern (pattern width error in the pattern shown in FIG. 5A) is calculated, and it is determined whether or not the calculated error is equal to or less than a reference value ( S16).

FIG. 6 is a graph for explaining the processing of S16 of FIG. This figure is an example of a graph showing the relationship between the pattern width W ₁ and the pattern spacing S _{1 in} the pattern shown in FIG. The solid line shows the pattern width W ₁ simulated and the dotted line represents a pattern width W ₁ by experiment. In a combination of selected parameters in S14, the error of the pattern width when the distance _{S 1} between the pattern narrowest _{(S 1} = _k 1) is, if the wider spacing _{S 1} of _(k 2, k ₃ ...) It is larger than the error and may not satisfy the reference value. When OPC is performed under such conditions and a wiring or the like is formed using a pattern after OPC, the wiring may be thinned to increase resistance. In addition, the interval between the wirings becomes narrow, and a short circuit may occur.
For this reason, the process shown in S16 is required.

  Returning to FIG. When the error calculated in S16 is equal to or less than the reference value, the parameter selection unit 30 excludes the currently selected parameter combination (S18), and again selects the parameter combination with the smallest sum of errors ( S14), the above-described processing proceeds.

  In this way, among the parameter combinations in which the error in the first design pattern is less than or equal to the reference value, the one with the smallest sum of errors is selected as the parameter combination to be actually used. Then, the operator inputs a design pattern to be actually corrected into the design pattern correction apparatus. The correction unit 40 processes the input design pattern using a mathematical model using the selected combination of parameters, and calculates a corrected design pattern (S20).

  Note that the design pattern correction apparatus according to the present embodiment is realized by installing a program having the above-described functions in a computer system. This program is installed in the computer system via a recording medium, for example. The recording medium for storing the program is, for example, a floppy disk (registered trademark), a removable disk such as a CD-ROM, a CD-R, a CD-R / W, a DVD-RAM, an MO, and a semiconductor memory, or a hard disk. Other than these may be used. Further, this program may be installed in a computer system by being downloaded through a communication line such as the Internet.

  As described above, according to the embodiment of the present invention, among the combinations of parameters in which the error in the first design pattern is less than or equal to the reference value by the design pattern correction apparatus, the one with the smallest error is the parameter that is actually used. Selected as a combination. Therefore, the parameters used in the model-based mathematical formula can be reliably set to appropriate values.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in S16 of FIG. 3, the selected parameter has only one condition to be satisfied (the error in the first design pattern is equal to or smaller than the reference value), but other conditions (for example, other standard designs) It may be confirmed whether or not the error in the pattern satisfies the second reference value or less.

The block diagram for demonstrating the structure of the design pattern correction apparatus which concerns on embodiment. The flowchart for demonstrating operation | movement of the design pattern correction | amendment apparatus shown in FIG. The flowchart for demonstrating the continuation of FIG. A table for explaining a selection example of parameter candidates. Each figure is a plan view for explaining an example of a standard design pattern. The graph for demonstrating the process of S16 of FIG. The flowchart which shows the setting method of the parameter by the conventional computer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Design pattern calculation part after correction | amendment, 20 ... Error addition part, 30 ... Parameter selection part, 40 ... Correction | amendment part, 51 ... Pattern, 52a ... 1st linear pattern, 52b ... 2nd linear pattern, 53a ... 3rd Linear pattern, 53b ... fourth linear pattern, 54, 55 ... standard design pattern, 54a, 55a ... bent portion

Claims (10)

A design pattern correction method for correcting an optical proximity effect of a design pattern inside a semiconductor device using a mathematical model having parameters,
The computer performs a plurality of corrections for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model for each of the plurality of types of standard design patterns a plurality of times with each of the values of the plurality of parameters. A step of calculating a post-standard design pattern;
A process in which the computer calculates an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern for each of the plurality of corrected standard design patterns;
A computer calculating the sum of the errors for each parameter value by aggregating the errors for each parameter value;
A step of selecting a value of the parameter with the smallest sum of the errors out of the values of the parameters in which the error in the specific standard design pattern satisfies a specific condition;
A computer correcting the design pattern by the mathematical model using the selected parameter value;
A design pattern correction method comprising: The specific standard design pattern is a pattern that requires the highest accuracy among the plurality of standard design patterns.
The design pattern correction method according to claim 1, wherein in the step of selecting the parameter value, the parameter value is selected such that the error in the specific standard design pattern is equal to or less than a reference value. The specific standard design pattern includes a pattern in which a plurality of linear patterns are arranged in parallel to each other,
The design pattern correction method according to claim 2, wherein the error is an error in the width of the linear pattern. One of the plurality of types of standard design patterns is arranged in a direction substantially orthogonal to the first linear pattern and the first linear pattern, and an end portion is separated from the first linear pattern. A linear pattern of
The design pattern correction method according to claim 1, wherein the error is an error in a width of an end portion of the second linear pattern. One of the multiple types of standard design patterns is:
A third linear pattern;
A fourth linear pattern located on an extension of the third linear pattern and extending in the same direction as the third linear pattern;
5. The design pattern correction according to claim 1, wherein the error is at least one of an end width of the third linear pattern and an end width of the fourth linear pattern. Method. In the mathematical model for correcting the optical proximity effect of the design pattern inside the semiconductor device, a parameter setting method for setting parameters of the mathematical model,
The computer performs a plurality of corrections for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model for each of the plurality of types of standard design patterns a plurality of times with each of the values of the plurality of parameters. A step of calculating a post-standard design pattern;
A process in which the computer calculates an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern for each of the plurality of corrected standard design patterns;
A computer calculating the sum of the errors for each parameter value by aggregating the errors for each parameter value;
A step of selecting a value of the parameter with the smallest sum of the errors out of the values of the parameters in which the error in the specific standard design pattern satisfies a specific condition;
A parameter setting method comprising: A design pattern correction apparatus that corrects an optical proximity effect of a design pattern inside a semiconductor device using a mathematical model having parameters,
For each of the plurality of types of standard design patterns, a plurality of corrected standard designs are provided for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model multiple times for each of the plurality of parameter values. A corrected design pattern calculation unit for calculating a pattern;
A process of calculating an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern is performed for each of the plurality of corrected standard design patterns, and the error is set to the parameter. An error totaling unit that calculates the sum of the errors according to the value of the parameter,
A parameter selection unit that selects a value of the parameter having the smallest sum of the errors, among the values of the parameter in which the error in the specific standard design pattern satisfies a specific condition;
A correction unit that corrects the design pattern by the mathematical model using the value of the selected parameter;
A design pattern correction apparatus comprising: In a mathematical model for correcting the optical proximity effect of a design pattern inside a semiconductor device, a parameter setting device for setting parameters of the mathematical model,
For each of a plurality of types of standard design patterns, a plurality of corrected standard designs are provided for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model a plurality of times with each of the plurality of parameter values. A corrected design pattern calculation unit for calculating a pattern;
A process of calculating an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern is performed for each of the plurality of corrected standard design patterns, and the error is set to the parameter. An error totaling unit that calculates the sum of the errors according to the value of the parameter,
A parameter selection unit that selects a value of the parameter having the smallest sum of the errors, among the values of the parameter in which the error in the specific standard design pattern satisfies a specific condition;
A parameter setting device comprising: A program executed by a computer for correcting the optical proximity effect of a design pattern inside a semiconductor device using a mathematical model having parameters,
For each of a plurality of types of standard design patterns, a plurality of corrected standard designs are provided for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model a plurality of times with each of the plurality of parameter values. The ability to calculate patterns,
A function of calculating an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern for each of the plurality of corrected standard design patterns;
A function of calculating the sum of the errors for each parameter value by aggregating the errors for each parameter value;
A function of selecting the parameter value having the smallest sum of the errors among the parameter values satisfying a specific condition by the error in the specific standard design pattern;
A function of correcting the design pattern by the mathematical model using the value of the selected parameter;
A program comprising: In a mathematical model that is executed by a computer and corrects an optical proximity effect of a design pattern inside a semiconductor device, a program for setting parameters of the mathematical model,
For each of a plurality of types of standard design patterns, a plurality of corrected standard designs are provided for each of the plurality of types of standard design patterns by performing correction processing using the mathematical model a plurality of times with each of the plurality of parameter values. The ability to calculate patterns,
A function of calculating an error between the post-exposure pattern formed by exposing the standard design pattern and the corrected standard design pattern for each of the plurality of corrected standard design patterns;
A function of calculating the sum of the errors for each parameter value by aggregating the errors for each parameter value;
A function of selecting the parameter value having the smallest sum of the errors among the parameter values satisfying a specific condition by the error in the specific standard design pattern;
A program comprising:

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