Exposure System Aberration Correction for Focus Consistency
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Solution Overview
Problem
In semiconductor device manufacturing, substrates with varying height differences and pattern densities lead to increased defocus due to the need for different spherical aberration corrections for each pattern, resulting in inconsistent best focus across regions.
Innovation Solution
An exposure method that correlates focus sensitivity information with aberration correction values and surface height differences to calculate an appropriate aberration correction value for minimizing focus differences between patterns, using an exposure device with a control unit that measures substrate height and adjusts exposure settings accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spherical aberration is adjusted for constant height difference regions, then the difference in best focus between regions is reduced, but the amount of defocus increases when height varies for each substrate with various pattern densities
Solution Approach 1:
The patent applies local quality by dividing the substrate into multiple regions with different pattern densities and assigning different spherical aberration correction values to each region. The control unit calculates region-specific correction values based on local pattern density characteristics, allowing each region to have optimized focus conditions tailored to its specific density requirements rather than using a uniform correction value across the entire substrate.
Solution Approach 2:
The patent implements dynamics by making the spherical aberration correction value variable and adjustable based on real-time measurements. The system dynamically determines the appropriate correction value by measuring the actual focus position and pattern dimensions, then adjusting the correction value accordingly to optimize focus for different pattern densities and substrate conditions.
2Device complexity
If a single aberration correction value is used for the entire substrate, then the device complexity is reduced, but the defocus amount increases for patterns with varying heights
Solution Approach 1:
The patent applies segmentation by dividing the substrate into multiple regions based on pattern density characteristics. Each region is assigned a specific spherical aberration correction value that is optimized for its local conditions. This segmentation approach allows the system to maintain relatively simple control logic while achieving improved focus accuracy across different regions by treating them separately rather than uniformly.
Data Source
AI summary
According to an embodiment, focus sensitivity information in which focus sensitivity expressing a relation between an aberration correction value set in an exposure device and a best focus when a pattern is formed on a first substrate by exposure of the exposure device using the aberration correction value, and the pattern are correlated is input. Moreover, on the basis of the focus sensitivity information and a surface height difference of a second substrate, the aberration correction value in which best focuses for a pattern group to be formed on the second substrate by exposure satisfy a first condition is calculated. In addition, the second substrate is exposed by the exposure device using the aberration correction value satisfying the first condition.