Silicon Dioxide Films Fabricated by Electron Cyclotron Resonant Microwave Plasmas

Abstract

High-quality silicon dioxide films were deposited on a silicon < 100 > substrate from an electron cyclotron resonant microwave plasma under the following conditions: substrate temperatures of 150 to 320°C, flow rates of 1.0 seem of 10% SiH4 in Ar and 5.0 seem of O2, 5 W (0.16 W/cm2) absorbed power, and at a pressure of 0.3 Pa. Films were determined to be stoichiometric, of high density, good bonding properties, and most importantly of excellent electrical integrity. A minimum deposition temperature required for good electrical properties appears to be about 285°C for the deposition conditions used in this study. Above this temperature the silicon dioxide films exhibited electrical strength characteristics similar to those found for thermally grown silicon dioxide films. More specifically, Fowler-Nordheim electron injection and destructive breakdown occurred at ≤ 5 and 9 MV/cm, respectively, in metal-oxide-semiconductor devices for oxides deposited at 320°C. Films deposited under optimal conditions had IR spectra nearly identical to those of thermally grown silicon oxides and index of refraction of 1.456, as measured by ellipsometry. We conclude that using an ECR microwave plasma, SiO2 films with physical and electronic properties comparable to thermally grown oxides can be deposited at low temperature (350°C) and low pressure (0.1 Pa). © 1990 IEEE