Remote plasma enhanced CVD deposition of silicon nitride and oxide for gate insulators in (In, Ga)As FET devices

Abstract

We have deposited silicon nitride (Si3N4) and silicon oxide (SiO2) thin films using remote plasma enhanced chemical vapor deposition (RPECVD). We have characterized the chemical composition of the films by infrared absorption (IR), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and Rutherford backscattering (RBS), and have studied the electrical properties in metal insulator semiconductor (MIS) device configurations. We have configured the deposition system and adjusted gas flow rates in order to minimize: (a) O contamination in the Si3N4 films; and (b) OH groups in the SiO2 films. This paper describes the deposition apparatus and the process, and presents a phenomenological model for the plasma phase and surface reactions involved. We have combined both types of insulators in a trilayer dielectric that has been used as a gate insulator for (In,Ga)As insulated gate field effect transistors (IGFET’s). We have found that the electrical properties of these devices are superior to devices utilizing single layer SiO2 or Si3N4 gate insulators.