INFLUENCE OF STOICHIOMETRY AND HYDROGEN BONDING ON THE INSULATING PROPERTIES OF PECVD SILICON NITRIDE.

The aim of this work is to describe in some detail the bonding in a ternary alloy such as Si//xN//yH//z (y greater than 10 at %, z greater than 5 at %) in order to understand better the electronical behaviors observed in present samples as well as the general corresponding trends reported in the literature. In particular authors check published empirical laws for some optical parameters against their own experimental data. For this purpose, a set of one micron-thick amorphous hydrogenated Silicon Nitride samples were prepared at 320 degree C by the 50 kH//z glow discharge of a NH//3/H//2/SiH//4 mixture, in a capacitive geometry. The NH//3/SiH//4 ratio was varied between 0. 2 and 20. The total H and N profiles and mean contents were obtained from SIMS analysis and ERD, and their different bonding sites have been studied by IR transmission spectroscopy. The electronical properties of the films were investigated through optical absorption, dark conductivity and photoconductivity.