JP2007057849A - Pattern inspection method, exposure mask, and pattern inspection program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern inspection method for efficiently performing lithography rule check on a design pattern after optical proximity correction. <P>SOLUTION: The method includes: a first step (S01 to S03) of subjecting a cell pattern preliminarily registered in a cell library to optical proximity correction (OPC) subjecting the pattern after the OPC to lithography rule checking (LRC) and registering a cell having the pattern passing the LRC in a data base; a second step (S05, S06) of identifying a cell from a design pattern after OPC, the cell which is equal to a cell registered in the data base by referring to the data base; a third step (S07, S08) of extracting an object pattern for the LRC from the design pattern after OPC based on the outer shape of the identified cell; and a fourth step (S09) of subjecting the object pattern for LRC to LRC. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pattern inspection method, an exposure mask, and a pattern inspection program, and more particularly to a pattern inspection method, an exposure mask, and a pattern inspection program that are suitable for performing a lithography rule check efficiently.

In recent years, the progress of semiconductor manufacturing technology is very remarkable. For example, semiconductor devices having a minimum processing dimension of 0.13 μm are mass-produced.
Such miniaturization is realized by dramatic progress in fine pattern formation techniques such as a mask process technique, an optical lithography technique, and an etching technique.

  If the pattern size is sufficiently large, draw the planar shape of the LSI pattern you want to form on the wafer as a design pattern, create a mask pattern that is faithful to the design pattern, and transfer the mask pattern onto the wafer by the projection optical system. Then, by etching the base, a pattern almost as designed can be formed on the wafer.

  However, as the pattern becomes finer, it has become difficult to faithfully form the pattern in each process, and a problem has arisen that the final finished dimension does not match the design pattern.

  In particular, in the lithography and etching processes that are the most important for achieving microfabrication, other pattern layout environments arranged around the pattern to be formed greatly affect the dimensional accuracy of the pattern.

  Therefore, in order to reduce these effects, optical proximity correction (OPC) technology that adds an auxiliary pattern to the design pattern in advance so that the dimension after processing becomes a desired dimension is for device manufacturing. It is an indispensable technique (see, for example, Patent Document 1).

  The optical proximity effect correction method disclosed in Patent Document 1 divides a mask pattern specified by design pattern data into limited areas A to C, and uses the correction result registered in the reference database RB to limit the mask pattern. An OPC addition pattern for the limited area B is generated by generating an OPC additional pattern for the area A and applying a rule-based OPC for the limited area B, and the OPC additional pattern and the limited area for these limited areas A and B The original mask pattern of C is synthesized.

  The optical proximity effect correction is performed under the most stable conditions of the exposure apparatus, but there are always variations in actual exposure conditions.

  As a result, even if the exposure conditions vary in the obtained pattern after the optical proximity effect correction, it is not guaranteed whether the processed pattern dimensions are within a desired range.

  Therefore, it is necessary to perform a lithography rule check (LRC: Lithography Rule Check) for verifying whether or not the processed pattern dimension is within a desired range by separately correcting the optical proximity effect under different exposure conditions.

However, in the conventional lithography rule check, there is a problem that a long inspection time is required to perform the optical proximity effect correction a plurality of times by changing the exposure conditions for all design patterns.
Japanese Patent Laying-Open No. 2005-49403 (page 7, FIG. 1)

  The present invention provides a pattern inspection method for efficiently performing a lithography rule check on a design pattern after optical proximity effect correction.

  A pattern inspection method according to an aspect of the present invention is a pattern inspection method for performing a lithography rule check on a design pattern after optical proximity effect correction, and the optical proximity to a cell pattern registered in a cell library in advance. A first step of performing an effect correction, performing a lithography rule check on the pattern after the optical proximity correction, and registering a cell having a pattern that has passed the lithography rule check in a database; and referring to the database A second step of specifying a cell equal to a cell registered in the database from the design pattern after the optical proximity effect correction, and the design after the optical proximity effect correction based on the outer shape of the specified cell. A third step of extracting a lithography rule check target pattern from the pattern; It is characterized by comprising a fourth step of performing lithography rule check, the relative source chromatography rule checked pattern.

  The exposure mask of one embodiment of the present invention performs optical proximity effect correction on a cell pattern registered in advance in a cell library with respect to a design pattern after optical proximity effect correction, and the optical proximity effect corrected A lithography rule check is performed on the pattern, and a cell having a pattern that passes the lithography rule check is registered in the database, and the design pattern after optical proximity correction is registered in the database with reference to the database. A cell that is equal to the cell being identified, a step of extracting a lithography rule check target pattern from the design pattern after the optical proximity effect correction based on the outer shape of the specified cell, and the lithography rule check target A process to perform lithography rule check on patterns When, is characterized in that it is formed a mask pattern pattern inspection has been performed with.

  A pattern inspection program according to an aspect of the present invention is a pattern inspection program for performing a lithography rule check on a design pattern after optical proximity effect correction, and the optical proximity effect is applied to a cell pattern registered in a cell library. Performing a correction, performing a lithography rule check on the pattern after the optical proximity correction, a first function of registering a cell having a pattern that has passed the lithography rule check in a database, and referring to the database, Based on the second function for specifying a cell equal to the cell registered in the database from the design pattern after the optical proximity effect correction, and the design pattern after the optical proximity effect correction based on the outer shape of the specified cell Function to extract lithography rule check target pattern from image It is characterized by comprising a fourth function of performing lithography rule check on the lithographic rule check target pattern.

  According to the present invention, a pattern inspection method for efficiently performing a lithography rule check on a design pattern after optical proximity effect correction is obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing a pattern inspection method according to an embodiment of the present invention.
As shown in FIG. 1, the pattern inspection method of this embodiment performs optical proximity effect correction on a cell pattern registered in the cell library in advance, and performs lithography rule check on the pattern after optical proximity effect correction. And a first step (steps S01 to S03) of registering in the database a cell having a pattern that has passed the lithography rule check.

  Further, referring to the database, based on the second step (steps S05 and S06) for specifying a cell equal to the cell registered in the database from the design pattern after the optical proximity effect correction, and the outer shape of the specified cell A third step (steps S07 and S08) of extracting a lithography rule check target pattern from the design pattern after the optical proximity effect correction, and a fourth step of performing a lithography rule check on the lithography rule check target pattern (step S09) And).

  That is, the cell pattern data registered in the cell library is read, and the optical proximity correction is performed on the pattern of each cell under the most stable condition (best condition) of the exposure apparatus (step S01).

  Next, with respect to the cell pattern after the optical proximity effect correction, for example, a condition in which the exposure amount is maximized within an exposure amount variation range of the exposure apparatus (over condition) and a condition in which the exposure amount is minimized (under condition) Then, the optical proximity effect is corrected, and a lithography rule check is performed to verify whether or not the processed pattern dimensions are within a desired range even if the exposure amount varies (step S02).

Next, the result of the lithography rule check is determined (step S03), and a cell in which the processed pattern dimension falls within a desired range is registered as a certified cell in the certified cell database in a file format as shown in FIG. Yes in step S03).
On the other hand, cells that do not fall within the desired range are registered in the non-certified cell database as non-certified cells (No in step S03).

  Next, the optical proximity effect correction is performed on the design pattern under the most stable condition (best condition) of the exposure apparatus (step S05).

  Next, refer to the certified cell database, identify the cell that is equal to the cell registered in the database from the design pattern after the optical proximity effect correction, extract the cell outline of the identified cell, and place it inside the cell outline The certified pattern is used as a certified cell pattern, and a pattern arranged outside the cell outer shape is extracted as a non-certified cell pattern (step S06).

  That is, as shown in FIG. 3, for example, when there are 3 × 3 certified cells 10a to 10i equal to the cells registered in the database in the design pattern after the optical proximity effect correction, the certified cells 10a to 10i are mutually connected. A rectangle composed of non-adjacent sides is extracted as the outer shape 11 of the certified cell.

  Seventeen patterns arranged inside the outer shape 11 of the certified cell are extracted as the patterns 12 of the certified cells 10a to 10i, and patterns arranged outside the cell outer shape 11 are extracted as the pattern 14 of the non-certified cell 13. . The pattern 14 is a lithography rule check target pattern.

  Next, a pattern in the influence range of the optical proximity effect correction is extracted as a lithography rule check target pattern from the pattern of the non-certified cell, and a pattern not in the influence range of the optical proximity effect correction is extracted as a reference pattern (step S07).

  That is, as shown in FIG. 4, the range 20 of the optical proximity effect correction from the pattern 14 of the non-certified cell 13, for example, the pattern 21 of the certified cell 10 a and the certified cell 10 b of which the distance L from the pattern 14 is 1 μm. The pattern 22 is extracted as a lithography rule check target pattern, and the other patterns of the certified cells 10 a to 10 i are extracted as the reference pattern 23.

  Next, only the reference pattern in the influence range of the optical proximity effect correction is left from the reference pattern 23, and the other reference patterns are deleted (step S08).

  That is, as shown in FIG. 5, the pattern 31 of the certified cell 10a and the pattern 32 of the certified cell 10b are within the range 30 of the optical proximity effect correction from the reference pattern 23, for example, the distance L from the patterns 21 and 22 is 1 μm. Only the four patterns 33 and 34 of the certified cell 10c remain as reference patterns, and the other reference patterns are deleted.

  Next, for the lithography rule check target pattern, for example, the optical proximity effect under the condition that the exposure amount is maximum (over condition) and the condition that the exposure amount is minimum (under condition) within the exposure amount variation range of the exposure apparatus. Correction is performed, and a lithography rule check is performed to verify whether the processed pattern dimensions are within a desired range even if the exposure amount varies (step S09).

  For example, the lithography rule check is performed on the pattern 14 of the non-certified cell 13 with reference to the lithography rule check target patterns 21 and 22.

  The lithography rule check target pattern 21 is subjected to a lithography rule check with reference to the lithography rule check target patterns 14 and 22 and the reference patterns 31 and 32.

  The lithography rule check target pattern 22 is subjected to a lithography rule check with reference to the lithography rule check target patterns 14 and 21 and the reference patterns 31 to 34.

  Therefore, as shown in FIG. 6, in the pattern 41 after the optical proximity effect correction that passed the lithography rule check with respect to the design pattern 40, the processed pattern 42 under the best exposure condition, for example, the exposure amount is an over condition Any of the pattern 43 after processing and the pattern 44 after processing under the under condition can be within the allowable range δ (for example, 5 nm) of the pattern.

  As a result, the design pattern after optical proximity effect correction is classified into certified cells and non-certified cells, and the lithography rule check is performed only for the non-certified cell pattern and the lithography rule check target pattern that is affected by the optical proximity effect correction. Can be done.

  FIG. 7 is a view showing an exposure film mask on which a mask pattern subjected to the pattern inspection of this embodiment is formed.

  As shown in FIG. 7, the exposure film mask 50 has a logic circuit pattern 52, a memory pattern 53, a decoder pattern 54, and an I / O pattern 55 formed on a mask base 51, for example, quartz glass.

  For the logic circuit pattern 52, the memory pattern 53, the decoder pattern 54, and the I / O pattern 55, the optical proximity effect correction is performed on the pattern of the cell registered in advance in the cell library for each design pattern, A process of performing a lithography rule check on the pattern after the optical proximity effect correction, registering a cell having a pattern that has passed the lithography rule check in a database, and a design pattern after the optical proximity effect correction with reference to the database A step of identifying a cell equal to a cell registered in the database from the step of extracting a lithography rule check target pattern from the design pattern after the optical proximity correction based on the outer shape of the identified cell; The lithography rule check target Through a step of performing lithography rule check against over emissions, pattern inspection is applied.

  FIG. 8 is a block diagram showing the configuration of a pattern inspection system for realizing the pattern inspection of this embodiment.

  As shown in FIG. 8, the pattern inspection system 60 of this embodiment includes a cell library storage unit 61 that stores general-purpose cell patterns, and a design pattern storage unit 62 that stores design patterns to be inspected. A program storage unit 63 for storing a program for extracting an optical proximity effect correction calculation, a lithography rule check calculation, a certified cell, a rule check inspection target pattern, a reference pattern, and the like.

  Furthermore, a certified cell storage unit 64 that stores a certified cell that has passed the lithography rule check, a post-OPC pattern storage unit 65 that stores a pattern after optical proximity correction, and a lithography rule check target pattern and a reference pattern are stored. An LRC pattern storage unit 66 and a process control unit 67 having means for executing a series of processes necessary for pattern inspection are configured.

  Further, the output device 69 is configured to output a processing result via the input / output control unit 68, and the input device 70 is configured to input an instruction to the processing control unit 67.

  The cell library storage unit 61, the design pattern storage unit 62, the program storage unit 63, the certified cell storage unit 64, the post-OPC pattern storage unit 65, and the LRC pattern storage unit 66 are partially configured by a main storage device inside the computer. Alternatively, a storage device such as a semiconductor memory, a magnetic disk, a magnetic tape, or an optical disk connected to the computer may be used.

  The processing control unit 67 constitutes a part of a central processing unit of a computer system, and is executed by a centralized processing system or a distributed processing system computer system.

  Cell pattern data for general use is input from the cell library storage unit 61 to the processing control unit 67.

  The processing control unit 67 includes a certified cell registration unit 71 that registers, in the certified cell storage unit 64, cell pattern data that has passed the lithography rule check in advance, an optical proximity effect correction unit 72 that performs optical proximity effect correction processing, and lithography. An LRC target pattern extraction unit 73 that extracts a rule check target and an LRC unit 74 that executes a lithography rule check are included.

  The authorized cell registration unit 71, the optical proximity effect correction unit 72, the LRC target pattern extraction unit 73, and the LRC unit 74 are stored in advance in the program storage unit 63 as software, and the central processing unit of the computer system according to the procedure However, it may be executed by dedicated hardware.

  As described above, in this embodiment, the design pattern after the optical proximity effect correction is classified into the certified cell and the non-certified cell, and the lithography rule check target related to the influence range of the non-certified cell pattern and the optical proximity effect correction is used. The lithography rule check can be performed only on the pattern.

  As a result, the lithography rule check can be efficiently performed on the design pattern after the optical proximity effect correction. Therefore, the time required for the lithography rule check can be shortened.

  A semiconductor integrated device having a large number of certified cells can perform the lithography rule check more efficiently. For example, when the ratio of the area occupied by the certified cell to the chip area is about 60%, the time required for the lithography rule check is the conventional time. It could be shortened to about 1/2.

  Here, the case where the lithography rule check is efficiently performed and the lithography rule check time is shortened has been described. However, if there is no problem even if the lithography rule check time is not shortened, the lithography is performed with finer exposure conditions. You may do a rule check. According to this, there is an advantage that optical proximity effect correction with higher accuracy can be performed.

  Furthermore, although the case where the cell outer shape 11 of the certified cell is rectangular by the 3 × 3 aggregated certified cells 10a to 10i has been described, the same applies regardless of whether the outer shape of the certified cell is other than a rectangle or a single certified cell. Can be implemented.

The flowchart which shows the pattern inspection method which concerns on the Example of this invention. The file which shows the authorization cell which concerns on the Example of this invention. The figure which shows the external shape of the authorization cell which concerns on the Example of this invention. The figure which shows the lithography rule check object pattern and reference pattern which concern on the Example of this invention. The figure which shows the narrowing-down result of the reference pattern based on the Example of this invention. The figure which shows the lithography rule check result which concerns on the Example of this invention. The figure which shows typically the mask for exposure which concerns on the Example of this invention. The figure which shows the structure of the pattern inspection system which concerns on the Example of this invention.

Explanation of symbols

10a to 10i Certified cell 11 Outline of certified cell 12 Pattern in outline of certified cell 13 Non-certified cell 14 Pattern of non-certified cell (pattern for lithography rule check)
20, 30 Influence range of optical proximity effect correction 21, 22 Authorized cell pattern (lithographic rule check target pattern)
23, 31, 32, 33, 34 Reference pattern 40 Design pattern 41 Design pattern after correction of optical proximity effect (mask pattern)
42 Pattern after processing (best conditions)
43 Pattern after processing (over condition)
44 Pattern after processing (under condition)
50 Exposure Mask 51 Mask Base 52 Logic Circuit Pattern 53 Memory Pattern 54 Decoder Pattern 55 I / O Pattern 60 Pattern Inspection System 61 Cell Library Storage Unit 62 Design Pattern Storage Unit 63 Program Storage Unit 64 Certified Cell Storage Unit 65 Pattern after OPC Storage unit 66 LRC pattern storage unit 67 Processing control unit 68 Input / output control unit 69 Output device 70 Input device 71 Authorized cell registration unit 72 Optical proximity effect correction unit 73 LRC target pattern extraction unit 74 LRC unit δ Pattern tolerance

Claims (5)

A pattern inspection method for performing a lithography rule check on a design pattern after optical proximity correction,
An optical proximity effect correction is performed on a cell pattern registered in advance in the cell library, a lithography rule check is performed on the pattern after the optical proximity effect correction, and a cell having a pattern that passes the lithography rule check is obtained. A first step of registering in the database;
A second step of referring to the database and identifying a cell equal to a cell registered in the database from the design pattern after the optical proximity effect correction;
A third step of extracting a lithography rule check target pattern from the design pattern after the optical proximity effect correction based on the identified outer shape of the cell;
A fourth step of performing a lithography rule check on the lithography rule check target pattern;
A pattern inspection method comprising:   In the third step, the pattern arranged outside the outer shape of the cell and the pattern arranged inside the outer shape of the cell and applied to the influence range of the optical proximity effect on the pattern are the lithography. The pattern inspection method according to claim 1, wherein the pattern is extracted as a rule check target pattern.   In the fourth step, the lithography rule check is performed by using, as a reference pattern, a pattern in the influence range of the optical proximity effect on the lithography rule check target pattern from a pattern excluding the lithography rule check target pattern. The pattern inspection method according to claim 1, wherein: For the design pattern after optical proximity correction,
An optical proximity effect correction is performed on a cell pattern registered in the cell library in advance, a lithography rule check is performed on the pattern after the optical proximity effect correction, and a cell having a pattern that passes the lithography rule check is obtained. Registering in the database;
Referring to the database, identifying a cell equal to a cell registered in the database from a design pattern after optical proximity correction, and
Extracting a lithography rule check target pattern from the design pattern after the optical proximity effect correction based on the identified outer shape of the cell;
Performing a lithography rule check on the lithography rule check target pattern;
A mask for exposure, wherein a mask pattern subjected to pattern inspection is formed. A pattern inspection program for performing a lithography rule check on a design pattern after optical proximity correction,
An optical proximity effect correction is performed on the cell pattern registered in the cell library, a lithography rule check is performed on the pattern after the optical proximity effect correction, and a cell having a pattern that passes the lithography rule check is stored in a database. A first function to register with
A second function of referring to the database and identifying a cell equal to a cell registered in the database from the design pattern after the optical proximity effect correction;
A third function of extracting a lithography rule check target pattern from the design pattern after the optical proximity effect correction based on the identified outer shape of the cell;
A fourth function of performing a lithography rule check on the lithography rule check target pattern;
A pattern inspection program comprising:

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