Lithography Stage Height Map Compensation
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving high-resolution patterning during lithography processes due to substrate warping and height variations, which can result in poorer pattern quality and increased complexity in manufacturing next-generation ICs with smaller geometries.
Innovation Solution
A lithography system that adjusts the vertical position and tilt of the substrate stage based on a height map or height zones to maintain the illuminated surface at or near the focal plane, combined with the use of exposure shields to control the exposure dose, allowing for improved patterning across substrates with varying heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography processes are used on substrates with height variations, then manufacturing process simplicity is maintained, but patterning quality deteriorates due to substrate warping and height variations
Solution Approach 1:
A height map of the substrate is generated before the lithography process to identify height variations and warping. Based on this preliminary information, the substrate stage is pre-configured with multiple height zones and corresponding vertical positions, allowing the system to proactively compensate for height variations during patterning without adding complex real-time adjustments
Solution Approach 2:
The substrate surface is divided into multiple height zones based on the generated height map. Each height zone is assigned a specific vertical position that corresponds to the focal plane of the projection optics. This segmentation allows different regions of the substrate to be processed at appropriate heights, maintaining patterning quality across the entire substrate while using standard lithography equipment
2Manufacturing precision
If the substrate stage vertical position is adjusted for each location, then patterning quality is improved, but manufacturing time increases
Solution Approach 1:
The height map is generated and height zones are predetermined before the lithography process begins. This preliminary preparation allows the system to quickly reference pre-calculated vertical positions for different substrate regions during scanning, eliminating the need for complex real-time height measurements and adjustments while maintaining high patterning quality
Solution Approach 2:
The substrate stage is configured to dynamically adjust its vertical position based on the predetermined height zones during the scanning process. As the substrate moves through the focal region, the stage automatically transitions between different vertical positions corresponding to different height zones, ensuring continuous focal plane alignment without manual intervention or complex control algorithms
Data Source
AI summary
A method includes placing a substrate on a stage of a lithography system, measuring a first height of the substrate at a first location on the substrate, measuring a second height of the substrate at a second location on the substrate, and performing a lithographic patterning process on the substrate, comprising directing a patterned beam of radiation at the substrate, moving the stage laterally to align the first location of the substrate with the patterned beam, moving the stage vertically to a first vertical position, the first vertical position based on the first height, moving the stage laterally to align the second location of the substrate with the patterned beam, and moving the stage vertically to a second vertical position, the second vertical position based on the second height.