Inverse Lithography Phase Shift Mask Design
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Solution Overview
Problem
Current phase shift masks with low light transmission, such as 6%, suffer from background printing of unwanted features, which can be suppressed by applying a second patch layer but requires an additional design and manufacturing step, increasing resource consumption.
Innovation Solution
Generating a high transmission phase shift mask layout using inverse lithography techniques, where the transmission value of each pixel is determined to minimize an objective function related to the optical lithographic process, allowing for main features with 100% transmission and phase shift areas with transmission values greater than 6%, eliminating the need for a patching step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a second patch layer is applied to suppress background printing, then unwanted feature printing is reduced, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent extracts and removes the second patch layer from the mask structure, retaining only the essential first patch layer. This simplification eliminates unnecessary manufacturing steps while maintaining sufficient suppression of unwanted feature printing through optimized parameters of the remaining patch layer.
Solution Approach 2:
The patent optimizes parameters of the first patch layer, such as its transmission value and positioning, to achieve effective suppression of background printing. By adjusting these parameters, the system achieves the desired functionality without requiring an additional patch layer, thus reducing complexity.
2Object-generated harmful factors
If a second patch layer is applied to suppress background printing, then unwanted feature printing is reduced, but manufacturing time and resource consumption increase
Solution Approach 1:
The patent removes the second patch layer from the manufacturing process, eliminating the time required for its deposition and alignment. This extraction of the unnecessary step directly reduces manufacturing time and resource consumption while maintaining effective suppression of unwanted feature printing.
Solution Approach 2:
By optimizing the transmission value and positioning parameters of the first patch layer, the patent achieves the same functional outcome as a two-layer structure would provide, but with significantly reduced manufacturing time and resource consumption due to the elimination of the second layer.
3Manufacturing precision
If transmission value is increased for phase shift areas, then depth of focus and critical dimension uniformity improve, but background printing of unwanted features increases
Solution Approach 1:
The patent applies different transmission values to different regions of the mask. The first patch layer is positioned at specific locations with optimized transmission values that balance two competing requirements: providing sufficient phase shift for improved critical dimension uniformity while limiting transmission to prevent background printing of unwanted features.
Solution Approach 2:
The patent optimizes the transmission value parameter of the first patch layer to a specific range that simultaneously achieves improved depth of focus and critical dimension uniformity while preventing unwanted feature printing. This parameter optimization resolves the contradiction by finding the optimal balance point.
Data Source
AI summary
Various implementations of the invention provide for generation of a high transmission phase shift mask layout through inverse lithography techniques. In various implementations of the present invention, a set of mask data having a plurality of pixels is generated. The transmission value associated with each pixel may then be determined through an inverse lithography technique. With various implementations of the invention, the inverse lithography technique identifies an objective function, minimizes the objective function in relation to a simulation of the optical lithographic process, such that the transmission value, which is greater than 6%, may be determined.