No abstract

The behavior of the partial pressure of SiF4, a byproduct in fluorine-based plasma etching, has been measured in real-time using a method based on Laser　Absorption Spectroscopy (LAS). The partial pressure of SiF4 is highly correlated　with the etch rate of SiO2 (R2 = 0.999). Etch endpoints were clearly observed　from the signal transitions, whose period indicate the etch rate uniformity. In　addition, integrating the partial pressure of SiF4 with respect to time is correlated　with the number of Si atoms etched regardless of the composition of the etched materials. Specifically, Si, SiO2 and Si3N4 were examined in this work. Based on　the strong relationship between the measured SiF4 partial pressure and the　etching profiles, real-time monitoring by LAS is useful for the prediction of etch　profiles.