Novel Oxygen-based Dry Strip Process Reducing NOx Emissions During Photoresist Removal

Industrial interest in NOx emissions from dry strip process using O2/N2 downstream plasma has been significantly increased. In this article, we compared strip performances and NOx emissions for recipes with different total gas flow rate and nitrogen ratio. When total gas flow rate and nitrogen ratio are lowered, NOx emissions were reduced and strip performances, such as strip rate, within-wafer uniformity, wafer-to-wafer uniformity, were achieved. For both qualitative and quantitative analysis, an optical emission spectroscope on the chamber and a portable gas analyzer on the dry pump were used, respectively. The results of both analyzes were well matched to demonstrate NOx emissions from the various recipes. In conclusion, > 12.3 μ/min of strip rate, < 5.1% of within-wafer uniformity, 1.4% of wafer-to-wafer uniformity, and 3,414 of NOx emissions can be achieved from the newly proposed recipe.