Mask Element Sliver Resolution in Optical Proximity Correction
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Solution Overview
Problem
Current lithographic techniques face challenges in precisely reproducing mask patterns for integrated circuits due to optical effects and resolution issues, particularly with small, thin 'slivers' generated during mask fracturing, which can result in poor image reproduction on semiconductor wafers.
Innovation Solution
The method involves applying optical proximity correction (OPC) to mask elements, fracturing them into polygonal segments, and modifying segments with potentially lower resolution by adjusting their length to enhance resolution, effectively eliminating poorly resolvable 'slivers' by merging them with adjacent segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mask fracturing is performed to convert polygons into primitive shapes for mask writing, then the mask can be manufactured using standard tools, but small thin slivers are generated that cannot be properly resolved by the mask writer
Solution Approach 1:
The method performs preliminary detection of slivers before mask writing and applies length modifications to eliminate them. By identifying and correcting sliver issues in the design data before the mask writing process, the invention prevents the resolution problems that would occur during actual mask manufacturing, thus resolving the contradiction between manufacturability and precision.
2Measurement precision
If standard OPC techniques are applied to correct mask patterns, then optical proximity errors are compensated, but slivers generated by fracturing still cause resolution issues
Solution Approach 1:
The invention merges the sliver detection and correction function with the existing OPC process. By integrating sliver length modification into the OPC workflow, the method combines optical proximity correction with geometric optimization, allowing both optical errors and sliver resolution issues to be addressed simultaneously in a unified correction process.
3Manufacturing precision
If long thin slivers are created during mask fracturing, then the mask element geometry can be accurately represented, but the mask writer cannot resolve these shapes properly
Solution Approach 1:
The method changes the geometric parameters of slivers by modifying their length dimensions. Specifically, it detects slivers with lengths exceeding certain thresholds and modifies their dimensions to fall within the resolvable range of the mask writer, thereby maintaining geometric accuracy while ensuring reliable mask writing.
Data Source
AI summary
A method of designing and forming a mask used for projecting an image of an integrated circuit design. After providing a mask element corresponding to a portion of a design of an integrated circuit layout, the method includes correcting the mask element using OPC techniques, and fracturing the OPC-corrected mask element into a plurality of polygonal segments. The method then includes identifying along an edge of the mask element a polygon edge having a thickness less than that which can be normally reproduced by a mask writer, and modifying configuration of the identified mask element segment to add or subtract length to an end of the polygon to create a corrected mask element having increased resolution by the mask writer. The method then includes using an electron beam or other mask writer to form a mask having the mask element with modified configuration.