In situ x-ray photoelectron spectroscopy analysis of SiOxFy passivation layer obtained in a SF6/O2 cryoetching process

The oxyfluorinated silicon passivation layer created during various cryoetching processes is of interest in order to improve high aspect ratio profiles. In this work, the desorption of a SiOxFy layer obtained in an overpassivating SF6/O2 regime was investigated during the wafer warm-up from the cryogenic temperature to room temperature. An in situ x-ray photoelectron spectroscopy (XPS) device is used in order to probe the top-surface layer and understand the desorption mechanism. A new mechanism can be proposed using the evolution of fluorine, oxygen, silicon, and carbon contributions evidenced by XPS.