Surface cleaning for enhanced adhesion to packaging surfaces: Effect of oxygen and ammonia plasma

The effects of direct plasma chemistries on carbon removal from silicon nitride (SiNx) and oxynitride (SiOxNy) surfaces have been studied by in-situ x-ray photoelectron spectroscopy (XPS) and ex-situ contact angle measurements. The data indicate that O2 and NH3 capacitively coupled plasmas are effective at removing adventitious carbon from silicon nitride (SiNx) and Si oxynitride (SiOxNy) surfaces. O2 plasma treatment results in the formation of a silica overlayer. In contrast, the exposure to NH3 plasma results in negligible additional oxidation of the SiNx or SiOxNy surface. Ex-situ contact angle measurements show that SiNx and SiOxNy surfaces exposed to oxygen plasma are initially more hydrophilic than surfaces exposed to NH3 plasma, indicating that the O2 plasma-induced SiO2 overlayer is highly reactive toward ambient. At longer ambient exposures (≳10 h), however, surfaces treated by either O2 or NH3 plasma exhibit similar steady state contact angles, correlated with rapid uptake of adventitious carbo...