Physical and optical properties of an antireflective layer based on SiOxNy

Abstract

SiO x N y based materials were deposited at low substrate temperature (300 °C) and low pressure (0.6 Torr) in a plasma enhanced chemical vapor deposition reactor. The precursor gases were nitrous oxide (N2O) and silane (SiH4); the ratio of the two-gas concentration N2O/SiH4=α was a critical determinant of film structure and composition. An extensive analysis of SiOxNy based materials was carried out using Fourier transform infrared, and Rutherford backscattering, and Auger and ellipsometric spectroscopies. The two-phase structure of this material was deduced. This structure favors a high silicon film concentration and provides a sufficiently absorbing layer at photolithographic wavelengths (365, 248, and 193 nm). Thanks to its optical and physical properties silicon oxynitride constitutes a good antireflective layer for photolithographic applications.