Coherence Map Generation for Mask Data Simplification
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Solution Overview
Problem
Existing high-resolution exposure methods for forming fine contact hole patterns are complex and time-consuming due to the need for calculating transmission cross coefficients and eigenfunctions to derive an interference map, which complicates the mask data generation process.
Innovation Solution
A method that generates mask data by Fourier-transforming the effective light source to create a coherence map, allowing for the arrangement of auxiliary patterns in regions with high coherence, thereby simplifying the calculation and shortening the mask data generation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmission cross coefficient and eigenfunction calculation is performed to derive interference map, then auxiliary pattern arrangement accuracy is improved, but mask data generation time increases
Solution Approach 1:
The patent extracts only the essential coherence information from the full TCC calculation by directly computing the coherence map from the illumination light source distribution. This avoids the time-consuming eigenfunction decomposition while retaining the necessary information for auxiliary pattern placement, thus reducing calculation time while maintaining arrangement accuracy.
Solution Approach 2:
The patent performs preliminary calculation of the coherence map based on the illumination light source distribution before auxiliary pattern arrangement. This pre-computed coherence map provides the necessary guidance for auxiliary pattern placement without requiring subsequent TCC and eigenfunction calculations, thereby streamlining the overall process and reducing total generation time.
2Manufacturing precision
If TCC and eigenfunction calculation is performed, then imaging characteristics are optimized, but calculation complexity increases
Solution Approach 1:
The patent extracts only the coherence information necessary for auxiliary pattern arrangement from the complete TCC calculation process. By directly computing the coherence map from the illumination light source distribution without full eigenfunction decomposition, it reduces calculation complexity while maintaining the essential imaging characteristics needed for accurate micropattern formation.
3Reliability
If auxiliary pattern is inserted based on interference map, then contact hole pattern exposure is improved, but mask data generation process becomes more complex
Solution Approach 1:
The patent extracts the essential coherence information needed for reliable contact hole pattern exposure directly from the illumination light source distribution. This approach maintains exposure reliability by properly positioning auxiliary patterns while avoiding the complex TCC and eigenfunction calculations, thus simplifying the mask data generation process.
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 enables accurate micropattern formation by improving imaging characteristics and reducing the complexity of the mask data generation process, resulting in faster data generation times without the need for complex calculations.
Implementation Method 1
Fourier-transforming a function indicating an effective light source to generate a coherence 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, an arrangement step of arranging a main pattern at an origin of the coherence map and arranging an auxiliary pattern in a region where a coherence with respect to the origin is not less than a set value, and a data generation step of generating mask data including the main pattern and the auxiliary pattern, which are arranged in the arrangement step.