Multiple internal reflection IR spectroscopy of CVD SiO2, SiOxNyand SiO3N4films

Thin 200-500 Å films of chemically-vapor-deposited (CVD) SiO2, SiOxNyand Si3N4are technologically important dielectric materials in integrated circuits. Si3N4, for example, is used as a gate dielectric in non-volatile MNOS memory devices (1), and as an encapsulating layer for GaAs devices against surface damage during post-implant anneals (2). The processing and annealing conditions of CVD Si3N4can significantly alter the physical and chemical properties of the film which ultimately will have a pronounced effect on the performance of the device. A very sensitive tool for chemically analyzing these thin CVD films is by multiple internal reflection IR spectroscopy (MIR). The various active vibrational modes associated with Si, O, N and H can be detected. CVD Si3N4films have been characterized from MIR spectra, ellipsometry, etch rate, and conductivity. The influence of the Si3N4film properties on the performance of the MNOS memory devices will be discussed briefly.