Analysis of the oxygen contamination present in SiNx films deposited by electron cyclotron resonance

Abstract

Silicon nitride (SiNx:H) films are deposited by the electron cyclotron resonance method at different microwave powers and nitrogen to silane gas flow ratio (R). Auger electron spectroscopy (AES), infrared (IR) absorption, and refractive index (n) measurements are used to determine deposition conditions resulting in oxygen contamination of the films as well as those conditions that result in good quality films without oxygen incorporation. Oxygen contamination of the films is produced at high microwave powers and R ratios as shown by the oxygen content determined by AES and different features in the IR spectra: the shift to higher frequencies for the positions of the Si–N and Si–H peaks, the presence of the N–H bending mode, and the broadening of the Si–N peak with its frequency. Low n values confirm the oxygen incorporation into the films, as they decrease when the oxygen content increases. The characteristic dependence of the oxygen presence in the films with the deposition conditions indicate that the oxygen source is the sputtering of the quartz liner located inside the plasma source.