Lithography Alignment Method for Stress-Induced Position Gaps
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Solution Overview
Problem
The accuracy of alignment in photolithography processes is compromised by position gaps resulting from stress on the pattern at the alignment destination, which existing technologies fail to adequately address.
Innovation Solution
An alignment method that calculates position gaps in a device area based on applied stress and corrects exposure conditions in the lithography process using a system comprising a surface shape measurement device, stress calculation unit, position gap calculation unit, and correction value calculation unit to set control parameters for the patterning device, ensuring accurate alignment despite stress-induced position gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stress is applied to the device area during lithography, then productivity can be increased through faster processing, but position gaps occur that degrade alignment accuracy
Solution Approach 1:
The patent calculates position gaps based on stress distribution before the lithography process begins. By pre-determining the magnitude and direction of position gaps caused by stress, the system can compensate for these gaps in advance by adjusting the writing positions of the patterning device, thereby maintaining alignment accuracy even when stress-induced position gaps occur during high-speed processing
Solution Approach 2:
The patent modifies exposure conditions (such as writing positions and scanning parameters) based on calculated position gap data. By changing these parameters in response to predicted stress effects, the system compensates for alignment errors while maintaining high productivity during the lithography process
2Manufacturing precision
If stress compensation calculations are performed for the entire device area, then alignment accuracy is improved, but calculation time and system complexity increase
Solution Approach 1:
The patent divides the device area into multiple regions and calculates position gaps for each region separately based on local stress characteristics. This localized approach allows the system to achieve accurate compensation throughout the entire device area while reducing the overall calculation complexity compared to treating the entire area as a single unit
Solution Approach 2:
The patent segments the stress calculation and compensation process into distinct components: stress distribution calculation, position gap calculation, and exposure condition correction. This segmentation allows each component to be optimized independently and facilitates efficient implementation of the overall compensation system
Data Source
AI summary
According to one embodiment, an alignment method includes calculating a position gap of a predetermined point in a device area of a wafer based on a stress applied to the device area, and correcting an exposure condition in a lithography process of the device area based on the position gap of the predetermined point.