Backup Optical Environment Mixing and Matching for Lithography
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Solution Overview
Problem
In semiconductor manufacturing, the high numerical aperture (NA) scanners are expensive and often single in a factory, leading to significant throughput issues when they break down, as conventional backup scanners with lower NA compromise the resolution of the primary environment to match critical dimension behavior, resulting in suboptimal performance.
Innovation Solution
A mixing-and-matching method that modifies standard photomasks and adjusts off-axis illumination (OAI) modes of backup optical environments to replicate the critical dimension behavior of the primary environment, using a calibration database to determine appropriate mask modification factors and OAI adjustments based on design rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the NA of the primary optical environment is tuned down to a middle NA to accommodate DCD/ECD performance matching, then the backup optical environment can match the primary environment's critical dimension behavior, but the resolution of the primary optical environment deteriorates and cannot show optimal performance
Solution Approach 1:
The patent applies parameter changes by modifying the NA and OAI mode parameters of the backup optical environment to match the critical dimension behavior of the primary environment. Specifically, the backup environment's NA is adjusted and its OAI mode is configured to replicate the primary environment's imaging characteristics, enabling consistent DCD/ECD performance without compromising the primary environment's resolution capability
Solution Approach 2:
The patent implements preliminary action by pre-configuring the backup optical environment with specific NA and OAI mode settings before failure occurs. The backup scanner is prepared in advance with matched parameters so that when the primary scanner fails, the backup can immediately take over with compatible critical dimension behavior, avoiding any performance degradation
2Reliability
If a backup scanner with lower NA is used, then a backup strategy can be provided for the primary high NA scanner, but the throughput is seriously affected when the primary scanner breaks down
Solution Approach 1:
The patent uses parameter changes to adjust the backup scanner's NA and OAI mode to match the primary scanner's critical dimension behavior. This parameter optimization enables the backup scanner to achieve comparable throughput and performance characteristics, preventing serious productivity loss when switching from primary to backup scanner
Solution Approach 2:
The patent applies copying by replicating the primary optical environment's critical dimension behavior in the backup environment. By copying the imaging characteristics and optical parameters, the backup scanner can produce identical pattern fidelity and throughput performance, ensuring business continuity without significant productivity impact
Data Source
AI summary
A mixing-and-matching method for an optical environment group is disclosed in this invention. The optical environment group has at least a primary optical environment having a first numerical aperture (NA) and a first off-axis illumination (OAI) mode and at least one backup optical environment having a second NA and a second OAI mode. The method comprises steps of providing information including a first critical dimension behavior on a mask (a first MCD behavior) with respect to a design rule and a first critical dimension behavior on a developed photoresist (a first DCD behavior) obtained by using the primary optical environment with the mask and modifying the first MCD behavior to be a second MCD behavior according to the information, wherein a second DCD behavior obtained by using the backup optical environment with the modified mask having the second MCD behavior is as same as the first DCD behavior.