Lithography Mask Pattern Generation Using Auxiliary Patterns
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Solution Overview
Problem
Current lithography techniques face challenges in achieving high resolution for mask patterns due to unwanted light interactions between adjacent patterns, leading to defective pattern formation, especially when the target pattern size is smaller than the light source wavelength, and existing methods either require excessive calculations or do not effectively utilize auxiliary patterns to improve resolution.
Innovation Solution
A method is introduced where auxiliary patterns are arranged outside the footprint of main patterns in a cell library, with specific rules for placement and removal to optimize light distribution and reduce optical proximity effects, allowing for higher resolution and reduced calculation complexity by selectively removing auxiliary pattern elements that interfere with the main pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If auxiliary patterns are arranged outside the footprint of main patterns to improve resolution, then light distribution is optimized and resolution is enhanced, but calculation complexity increases and pattern element interference occurs
Solution Approach 1:
The patent segments the mask pattern into main patterns and auxiliary patterns, with auxiliary patterns placed outside the footprint of main patterns. This segmentation allows independent optimization of each pattern type while managing their interactions systematically, reducing the overall calculation complexity compared to treating the entire pattern as a single unit.
Solution Approach 2:
The patent extracts auxiliary patterns from the main pattern footprint area and places them in the surrounding region. By taking out the auxiliary patterns and positioning them externally, the method optimizes light distribution for higher resolution while enabling separate calculation and optimization of auxiliary pattern placement, thereby reducing computational complexity.
2Stability of the object's composition
If auxiliary patterns are placed outside the footprint of main patterns to reduce optical proximity effects, then image consistency is improved, but harmful light interactions occur between adjacent cells
Solution Approach 1:
The patent converts the potentially harmful light interactions between adjacent cells into beneficial effects by strategically placing auxiliary patterns outside the main pattern footprint. These auxiliary patterns, when properly positioned, modify the light distribution to reduce optical proximity effects within cells while their external placement allows controlled interactions between cells that improve overall image consistency.
Solution Approach 2:
The patent applies local quality by differentiating the treatment of patterns within and between cells. Auxiliary patterns are placed outside the footprint of main patterns to create localized modifications in light distribution that improve image consistency within each cell, while the external placement allows these local modifications to positively influence adjacent cells without causing harmful interactions.
3Manufacturing precision
If full chip OPC is performed on all arranged cells, then comprehensive optical correction is achieved, but calculation time and resources become excessively large
Solution Approach 1:
The patent performs preliminary optical proximity correction on individual cells before arranging them into the full chip pattern. By conducting OPC at the cell level first, the method pre-corrects optical effects for each cell, which reduces the amount of correction needed at the full chip level, thereby significantly reducing total calculation time while maintaining comprehensive correction accuracy.
Solution Approach 2:
The patent segments the optical proximity correction process into two stages: cell-level OPC and full-chip OPC. This segmentation allows the computationally intensive correction work to be distributed and performed on smaller cell units first, reducing the overall calculation burden and time required compared to performing full-chip OPC on all cells simultaneously.
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 enhances the resolution of mask patterns by effectively managing light interactions and reducing computational load, achieving a larger lithography margin with improved focal depth and image consistency across the mask pattern.
Implementation Method 1
The projection optical system projects an image of a mask pattern onto a substrate (such as a wafer)
Implementation Method 2
The illumination optical system illuminates a mask with light from a light source
Implementation Method 3
the projection of the image of the mask pattern onto the substrate involves unwanted light interaction (interference) between adjacent patterns
Data Source
AI summary
A method for generating a pattern includes defining a footprint of a main pattern in each cell, arranging a first cell and a second cell which has an auxiliary pattern outside the footprint of the main pattern, side by side in such a manner that the auxiliary pattern outside the footprint of the second cell is present in the footprint of the main pattern of the first cell, and generating the pattern of the mask by removing a pattern element of the auxiliary pattern outside the footprint of the second cell in a portion where the pattern element of the auxiliary pattern outside the footprint of the second cell is close to or overlaps with the main pattern in the first cell of the first cell and the second cell arranged side by side.