Computer-aided design and analysis of circuits and semiconductor – Nanotechnology related integrated circuit design
Reexamination Certificate
1998-09-29
2001-06-05
Smith, Matthew (Department: 2768)
Computer-aided design and analysis of circuits and semiconductor
Nanotechnology related integrated circuit design
C430S005000, C430S030000
Reexamination Certificate
active
06243855
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to photolithography applied to, for example, the manufacture of semiconductor integrated circuits and liquid crystal panels. The present invention relates to, in particular, a mask data design method and a mask data design apparatus for conducting automatic correction processing and to a recording medium capable of reading a computer storing mask data design procedures.
In photolithography for manufacturing a semiconductor integrated circuit, as the integration of devices mounted on a wafer is higher and a design rule is narrower, the problem of so-called an optical proximity effect attracts more attention.
The “optical proximity effect” is a phenomenon that a design pattern cannot be transferred onto a wafer with a desired shape and size. The optical proximity effect is a term originally used to mean the effect of light during transfer operation. It has now been used to generally means the effect which occurs throughout wafer process.
To attain desired device performance, it is necessary to realize the desired size and form of a design pattern on a wafer even if the optical proximity effect occurs. In recent years, optical proximity effect correction or OPC which corrects a process bias on a mask in advance, has been studied vigorously since it is considered effective to correct the optical proximity effect.
To make OPC effectively to a large-scale layout, it is required to automatically execute OPC processing on a computer. Various methods have been conventionally proposed for such automatic OPC processing. They include “OPTIMASK: An OPC algorithm for chrome and phase-shift mask design” in Proc. SPIE-Int. Soc. Opt. Eng. (USA) vol. 2440: pp. 192-206 (1995); “Optical Proximity Correction, a First Look at Manufacturability” in Proc. SPIE-Int. Soc. Opt. Eng. (USA) vol. 2,322, pp. 229-238 (1994); “Simple Method of Correcting Optical Proximity Effect for 0.35 &mgr;m Logic LSI Circuits” in Jpn. J. Appl. Phys. vol. 34 (1995), pp. 6,547-6,551, Part 1, No. 12B, December 1995; and “Fast Sparse Aerial Image Calculation for OPC” in Proc. SPIE-Int. Soc. Opt. Eng. (USA) vol. 2,621: pp. 534-545 (1995).
Mask data design using the conventional OPC method, however, employs a single correction method to all design patterns. This disadvantageously requires great time for correction calculation and, in some cases, accurate corrections cannot be made depending on the shape and arrangement of a mask pattern.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made in the above circumstances. It is therefore the first object of the present invention to provide a mask data design method capable of obtaining mask data which has been subjected to optical proximity effect correction, at high speed and high accuracy.
It is the second object of the present invention to provide a mask data design method capable of making appropriate corrections at high speed by changing correction methods in accordance with characteristics of the spatial arrangement of a pattern including a correction target segment.
It is the third object of the present invention to provide a one-dimensional rule for appropriately classifying characteristics of the spatial arrangement of a pattern.
It is the fourth object of the present invention to provide a method for dividing a noted segment into lengths suited for correction in order to make appropriate corrections in a mask data design method according to the present invention.
It is the fifth object of the present invention to provide a mask data design apparatus for realizing the above method.
It is the sixth object of the present invention to provide a recording medium which can read by a computer storing procedures for the computer to execute the above method.
To achieve the above objects, the present invention has the following aspects.
(1) According to the first aspect of the present invention, there is provided a mask data design method correcting a design pattern and using the corrected design pattern as mask data to improve fidelity of a transferred pattern, obtained by transferring onto a wafer a pattern formed on a mask based on the design pattern, to the design pattern, the method comprising the steps of:
extracting a correction target segment from the design pattern;
dividing the extracted segment into lengths suited for correction;
determining whether characteristics of spatial arrangement of a divided segment complies to a predetermined one-dimensional rule; and
classifying, if the characteristics of spatial arrangement of the divided segment complies to the predetermined one-dimensional rule, the divided segment as a one-dimensional pattern and, if not comply, classifying the divided segment as a two-dimensional pattern.
Correcting the divided segment in accordance with classified pattern types.
With this structure, it is possible to apply correction methods suited for correction target segments by correcting the correction target segments, which have been obtained by extraction, division and classification from the design pattern, in accordance with classified pattern types.
It is preferable that the characteristics of the spatial arrangement of the divided segment are dimensions of the divided segment, dimensions of an adjacent segment located within a predetermined distance S from the divided segment in perpendicular direction and positional relationship between the divided segment and the adjacent segment.
It is also preferable that, in the step of dividing the segment, while a pattern located within a predetermined distance R from a noted segment in perpendicular direction being observed, the noted segment is divided such that a length of a segment after being divided is not shorter than a predetermined length L based on an intersection between perpendicular lines drawn to the noted segment from topmost vertices of the pattern or based on the adjacency of the intersection.
It is preferable that the standards described in claims
10
through
14
are used as the one-dimensional rule.
(2) According to the second aspect of the present invention, there is provided a mask data design apparatus characterized in that, in the mask data design method described in (1) above, the step of correcting the divided segment includes the steps of: obtaining, if the characteristics of the spatial arrangement of the divided segment is classified as a one-dimensional pattern, a correction value for the divided segment by conducting one of a one-dimensional process simulation, a one-dimensional pattern transfer test and a combination of the one-dimensional process simulation and the one-dimensional pattern transfer test for a certain region including the segment; and obtaining, if the characteristics of the spatial arrangement of the divided segment is classified as a two-dimensional pattern, a correction value for the divided segment by conducting one of a two-dimensional process simulation, a two-dimensional pattern transfer test and a combination of the two-dimensional process simulation and the two-dimensional pattern transfer test for a certain region including the segment.
With this structure, it is possible to correct most of the correction target edges one-dimensionally. Due to this, if a simulator is used for calculating a correction value, it is possible to process correction value calculation at high speed and with a little volume of data. If a test is used, it is possible to easily obtain a correction value with a SEM (scanning electron microscope) or by measuring electrical characteristics. As for a pattern which cannot be one-dimensionally approximated, a correction value is obtained using a two-dimensional simulation or a test, thereby making highly accurate correction possible.
In this case, it is preferable that the step of correcting the divided segment further includes the step of, while using a database storing characteristics of spatial arrangement of segments and correction values corresponding to the segments, taking out a correction value suited for the divided segment from the database and co
Hashimoto Koji
Kobayashi Sachiko
Uno Taiga
Yamamoto Kazuko
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Smith Matthew
Thompson A. M.
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