Mask Data Generation Using Coherent Map Fourier Transform
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Solution Overview
Problem
Existing high-resolution exposure methods require complex numerical calculations for deriving interference maps, leading to long mask data generation times in multiple exposure techniques.
Innovation Solution
A computer-readable recording medium and method that generates mask data by Fourier-transforming an effective light source to create a coherent map, specifying reference vectors for removing elements at forbidden pitches, and generating new patterns, thereby simplifying the calculation process and reducing mask data generation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex numerical calculations (TCC and eigenfunction) are performed to derive interference maps, then the accuracy of micropattern formation is improved, but the mask data generation time is significantly increased
Solution Approach 1:
The patent extracts only the essential coherence information from the complex TCC calculation by performing a Fourier transform of the effective light source to generate a coherent map. This extraction approach obtains the necessary interference map data without performing the full complex numerical calculations of TCC and eigenfunctions, thereby reducing computation time while maintaining sufficient accuracy for auxiliary pattern placement
Solution Approach 2:
The patent performs preliminary calculation of the coherent map using Fourier transform before the actual mask data generation process. This preliminary action provides the necessary coherence distribution information in advance, allowing subsequent auxiliary pattern placement to proceed without requiring time-consuming TCC and eigenfunction calculations during the main processing stage
2Loss of information
If traditional interference map calculation methods are used, then comprehensive optical information is obtained, but the calculation complexity and processing time are excessive
Solution Approach 1:
The patent extracts the essential coherence distribution information from the full optical calculation by directly Fourier transforming the effective light source. This extraction obtains the necessary interference map data for auxiliary pattern placement without performing the complete complex numerical calculations of TCC and eigenfunctions, reducing computational complexity while retaining sufficient optical information
Solution Approach 2:
The patent performs only the necessary partial calculation (Fourier transform of effective light source) rather than the complete TCC and eigenfunction analysis. This partial action provides sufficient coherence information for the specific purpose of auxiliary pattern placement without the excessive computational burden of full optical information derivation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly shortens the time required to generate mask data for multiple exposure, improving efficiency without the need for calculating transmission cross coefficients or eigenfunctions, thus enhancing the speed and accuracy of micropattern formation.
Implementation Method 1
Fourier-transforming a function indicating an effective light source to generate a coherent map expressing a coherence distribution on an object plane
Data Source
AI summary
A computer-readable recording medium recording a mask data generation program, which causes a computer to generate data of a mask illuminated by illumination light and used to form a latent image on a photoresist via a projection optical system. The program causes the computer to execute a map generation step of Fourier-transforming a function indicating an effective light source to generate a coherence map expressing a coherence distribution on an object plane of the projection optical system, on which the mask is arranged, a specifying step of specifying a reference vector from an origin of the coherence map to a region where coherence is less than a reference value, a first data generation step of selecting one element from a pattern including a plurality of elements, and removing, from the pattern, an element existing at a position matching a terminal point of the reference vector arranged such that the center of the selected element serves as a starting point, to generate data of a first pattern different from the pattern, and a second data generation step of generating data of a second pattern including the element removed in generating the data of the first pattern.