Mask Pattern Correction for EUV Flare Compensation
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Solution Overview
Problem
In EUV lithography for semiconductor manufacturing, the use of reflection optical systems due to optical absorption and refractive index issues leads to surface roughness on mirrors, causing flare that degrades pattern accuracy and consistency, especially as flare varies with pattern density, resulting in blurred and dimensionally incorrect patterns.
Innovation Solution
A method for correcting mask patterns by calculating a correction amount for reference flare values through simulation, correlating this with change amounts based on flare differences, and applying these corrections to create a mask pattern that accounts for flare variations, thereby improving pattern accuracy and consistency across different positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reflection optical system is used in EUV lithography, then the pattern resolution is improved, but surface roughness on mirrors causes flare that degrades pattern accuracy
Solution Approach 1:
The patent applies preliminary action by calculating and applying flare correction amounts to the mask pattern before the actual lithography process. The correction amounts are determined through simulation of flare effects on various pattern types, and these corrections are pre-applied to the mask data so that the final pattern transferred to the wafer achieves the desired accuracy despite mirror surface roughness causing flare during exposure.
2Productivity
If conventional mask pattern correction is performed without considering flare, then the correction process is simple and fast, but the finished dimension varies depending on pattern arrangement position
Solution Approach 1:
The patent performs preliminary calculation of flare correction amounts for various pattern types through simulation, and stores these correction values in a lookup table. During actual mask pattern correction, the appropriate correction amount is retrieved from the table based on the pattern type, avoiding repeated complex simulations while ensuring dimensional consistency across different pattern arrangements.
Solution Approach 2:
The patent changes the mask pattern parameters (line width, space) based on the calculated flare correction amounts. By adjusting these parameters according to the pattern type and surrounding pattern density, the correction compensates for flare effects and achieves consistent finished dimensions across different positions on the wafer.
3Manufacturing precision
If repeated simulations are performed for flare correction, then the correction accuracy is improved, but the processing time increases significantly
Solution Approach 1:
The patent performs the computationally intensive simulation work in advance by calculating flare correction amounts for representative pattern types and storing these results in a lookup table. This preliminary action allows the actual correction process to simply retrieve pre-calculated values, achieving high correction accuracy without the need for repeated time-consuming simulations during production.
Solution Approach 2:
The patent creates a lookup table that copies the results of complex flare simulations into a readily accessible format. Instead of performing full simulations for every pattern, the system uses the pre-stored correction data from the lookup table, which replicates the effects of repeated simulations while dramatically reducing processing time.
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 enables high-speed and high-accuracy mask pattern correction, reducing the need for repeated simulations and improving pattern fidelity by directly addressing flare-induced inaccuracies, thus enhancing the precision of semiconductor device manufacturing.
Implementation Method 1
a reflection optical system such as a mirror has to be used
Implementation Method 2
this roughness irregularly reflects the lithography light emitted on the mirror surface and the scattered light falls on a not-intended region on the resist surface of a wafer
Data Source
AI summary
In the method of correcting a mask pattern according to the embodiments, a mask pattern correction amount for a reference flare value is calculated as a reference mask correction amount, for every type of patterns within the layout, and a change amount of the mask pattern correction amount corresponding to the change amount of the flare value is calculated as the change amount information. A mask pattern corresponding to the flare value of the pattern is created based on the reference mask correction amount and the change amount information corresponding to the pattern, extracted from the information having the pattern, the reference mask correction amount, and the change amount information correlated with each other, and based on a difference between the flare value of the pattern and the reference flare value.