18 March 2015 DUV ArF light source automated gas optimization for enhanced repeatability and availability
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The need for repeatable, reliable, and faster DUV ArF light source gas optimizations drove the development of Automated Gas Optimization (AGO). These automate the manual gas optimization procedure previously used to select the laser chamber gas pressures and in addition, bandwidth actuation settings, to deliver consistent performance and long gas lives, while maintaining stability and bounds on laser inputs. Manual gas optimization procedure requires at least two refills and an on-site visit by service personnel that can take over an hour to complete. This results in inconsistent light source performance, and sometimes unscheduled downtime. The key to AGO technology is the real-time estimation and monitoring of the laser’s gas and bandwidth states, and automatic adjustment of gas pressure and bandwidth actuators until the states reach their specified targets, thus creating a closed loop. AGO executes on every refill, typically complete in less than 5 minutes, and collect performance data to allow long-term trending. They include built-in safety features and flexibility to allow future upgrades of light source features or performance tuning. Deployed in many lasers in the field, AGO has proved to be a dependable automation, yielding repeatable, fast, and reliable optimizations and valuable long-term trending data used to assess chamber performance
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Tanuj Aggarwal, Tanuj Aggarwal, Kevin O'Brien, Kevin O'Brien, } "DUV ArF light source automated gas optimization for enhanced repeatability and availability", Proc. SPIE 9426, Optical Microlithography XXVIII, 942624 (18 March 2015); doi: 10.1117/12.2085815; https://doi.org/10.1117/12.2085815

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