Papers by Author: Mei Sheng Zhou

Abstract: Tetramethylammonium hydroxide (TMAH) is a common etchant for Sigma shape formation in IC manufacturing. The impact of oxygen dissolved in TMAH solution on process was studied in this paper. A novel O2 gas injector was developed to improve the process stabilization by control of the oxygen concentration in TMAH solution

Abstract: Megasonic cleaning using de-gassed water (less than 2ppm N2, O2, CO2) in a 300mm batch immersion tool often does not give optimal particle performance, with particle streaks and clusters added onto the wafer, and low particle removal efficiency (PRE). When water was re-gasified with N2, the resultant stable cavitation activity reduced particle adders and increased PRE. With N2 concentration increased to just above 5ppm, number of particle adders decreased by three folds. Optimal particle performance could be obtained by operating at an N2 level close to saturation.