Mask Pattern Arrangement for Lens Mura Reduction
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Solution Overview
Problem
The precision bias in lenses of exposure apparatuses used in semiconductor manufacturing leads to lens mura, resulting in non-uniformity of exposure light and critical dimension variations, which decreases product quality and yield.
Innovation Solution
The method involves arranging mask patterns with different corresponding positions relative to the lenses, ensuring each mask pattern has unique distances from lens overlapping sections, thereby altering the position of lens mura on the photoresist layer and blurring its effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mask patterns are arranged with the same corresponding position relative to lenses, then the exposure process is simple and consistent, but lens mura occurs and critical dimension variations increase
Solution Approach 1:
The patent applies asymmetry by intentionally arranging mask patterns at different corresponding positions relative to the lenses. Specifically, the mask pattern is positioned at different distances from the lens overlapping section for different masks, creating an asymmetric arrangement that prevents lens mura and critical dimension variations while maintaining exposure process feasibility
2Area of stationary object
If multiple lenses are combined for large mask sizes, then the exposure coverage is sufficient, but lens overlapping sections cause non-uniform exposure light
Solution Approach 1:
The patent applies local quality by adjusting the position of mask patterns relative to lens overlapping sections for different masks. Each mask pattern is positioned at a specific distance from its corresponding lens overlapping section, creating locally optimized exposure conditions that compensate for lens variations and ensure uniform exposure light across the entire mask area
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 effectively reduces lens mura by ensuring each lens mura is formed in a different position on the photoresist layer, improving the uniformity of exposure and maintaining stable critical dimensions, thus enhancing product quality and yield.
Implementation Method 1
The light passes through a mask and a projection lens to project on a photoresist of a semiconductor wafer or a glass substrate
Data Source
AI summary
A method of arranging mask patterns, which includes a first mask has a first mask pattern, a second mask has a second mask pattern. The distance between the first mask boundary and the first mask pattern boundary is different form the distance between the second mask boundary and the second mask pattern boundary.