EUV Mask Flare Correction Using Segmented Point Spread Functions
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Solution Overview
Problem
The extreme ultraviolet (EUV) lithography process faces challenges in correcting critical dimension (CD) errors due to flare, which is exacerbated by the high light absorption of most materials in the EUV domain, requiring innovative methods to manage flare effects across different influence ranges during semiconductor device manufacturing.
Innovation Solution
A method involving the measurement and calculation of point spread functions (PSFs) of flare, which are then used to correct flare effects by dividing the influence range into short-range and long-range categories, allowing for specific correction operations and dose adjustments to minimize distortion in the EUV lithography process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single correction operation is used for all flare ranges, then the correction process is simple, but the manufacturing precision of critical dimensions deteriorates
Solution Approach 1:
The patent segments the flare correction process into two distinct operations: short-range flare correction and long-range flare correction. Each correction targets a specific distance range from the pattern, allowing precise control of critical dimensions while maintaining manageable process complexity through specialized correction algorithms for each range.
2Manufacturing precision
If different correction operations are applied for short-range and long-range flare, then the manufacturing precision improves, but the device complexity increases
Solution Approach 1:
The patent applies local quality by using different correction strategies tailored to specific spatial ranges. Short-range flare correction focuses on immediate pattern vicinity with one algorithm, while long-range flare correction addresses distant regions with another algorithm, optimizing each correction for its specific spatial characteristics and improving overall pattern accuracy.
3Reliability
If flare correction is performed without dividing influence ranges, then the process is straightforward, but the reliability of CD correction deteriorates
Solution Approach 1:
The patent enhances correction reliability by segmenting the influence range into short-range and long-range zones, each with dedicated correction algorithms. This segmentation ensures that each algorithm optimizes for its specific range characteristics, improving the overall reliability of critical dimension correction compared to a single undifferentiated correction approach.
Data Source
AI summary
A method of correcting flare includes measuring flare of a test pattern, calculating point spread functions (PSFs) of the flare as a function of distance, and correcting the flare using corresponding PSFs for an influence range of the flare. The influence range is divided into a first range less than a predetermined distance and a second range equal to or greater than the predetermined distance, and corresponding PSFs are separately applied to the first and second ranges to correct the flare.