Dynamic Slit Width Control for Overlay Deviation Correction
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Solution Overview
Problem
Conventional light-exposure methods face challenges in accurately correcting overlay deviations during the light-exposure process, often requiring a trade-off between slit width and scanning speed, which affects the precision and efficiency of the patterning process.
Innovation Solution
A method and apparatus that dynamically adjust the slit width based on overlay deviation data, using a correction plot to set optimal slit widths and scanning speeds at different coordinate positions, allowing for precise correction of overlay deviations while maintaining desired light-exposure amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the slit width is reduced to correct overlay deviation, then the manufacturing precision is improved, but the scanning speed decreases
Solution Approach 1:
The patent divides the shot region into multiple regions based on overlay deviation magnitude, and assigns different slit widths to different regions. This segmentation allows the system to use narrow slits only where needed for correction while maintaining wide slits in other areas, thus preserving overall scanning speed while achieving precise overlay correction where required.
Solution Approach 2:
The patent implements local quality by setting different slit widths at different coordinate positions within the shot region according to the overlay deviation distribution. Areas with significant overlay deviations receive narrower slits for precise correction, while areas with minimal deviations maintain wider slits for high-speed exposure, optimizing both precision and efficiency locally.
2Productivity
If the slit width is increased to maintain scanning speed, then the productivity is improved, but the overlay correction accuracy deteriorates
Solution Approach 1:
The patent segments the exposure field into regions requiring high precision and regions where speed is prioritized, based on overlay deviation analysis. This allows the system to maintain high productivity overall by using wide slits in most areas while concentrating narrow slit correction only in specific regions needing overlay adjustment.
Solution Approach 2:
The system applies local quality by dynamically adjusting slit width at each coordinate position according to the overlay deviation magnitude. This ensures that productivity is maintained in regions where precision requirements are lower, while overlay correction accuracy is enhanced in regions where deviations exceed acceptable thresholds.
3Manufacturing precision
If the slit width is uniformly reduced across the entire shot region, then the overlay deviation is corrected, but the light-exposure amount becomes insufficient in some areas
Solution Approach 1:
The patent applies local quality by setting slit widths on a per-coordinate-position basis according to overlay deviation characteristics. This ensures that each region receives the appropriate light-exposure amount tailored to its specific overlay correction needs, preventing both under-exposure and over-correction that would result from uniform slit width reduction.
Data Source
AI summary
According to one embodiment, a correction plot in which a slit width is set different depending on overlay deviation in a shot region is generated. Then, a light-exposure scanning speed defined by a relative speed between a photomask stage with a photomask mounted thereon and a stage with a processing object mounted thereon is set, to obtain a desired light-exposure amount at each coordinate position, in accordance with the slit width in the correction plot. Then, a light-exposure process is performed, while controlling the slit width of a light-exposure slit, the photomask stage, and the stage, in accordance with the correction plot and the light-exposure scanning speed.