Impact of Air-borne NH3 and Humidity against Wafer-to-wafer CD Variation in ArF Lithography through 45nm Technology Node

摘要

An impact of air-borne NH3 and humidity against a wafer-to-wafer (WTW) CD variation is investigated. An environmental stability of ArF resist materials is also investigated through the design of experiment (DOE) analysis, where the different resist formulations are chosen as variation factors. Assuming the most environmentally sensitive ArF resist material used in the 45nm 1:1 LS pattern imaging (worst case scenario), the WTW CD variations caused by air-borne NH3 and humidity fluctuations are estimated to be 0.10 nm and 0.29nm, respectively.