A STUDY OF AMORPHOUS HYDROGENATED SILICON-NITRIDE FILMS PRODUCED IN THE PLASMA OF A HIGH-FREQUENCY DISCHARGE

A study has been carried out of a-SiNx:H films produced by deposition from a silane+nitrogen mixture in the plasma of a 55-MHz glow discharg e. It was found that, as compared with the 13.56-MHz discharge, a lowe r concentration of nitrogen was required to ensure that the electronic properties of the films were appreciably influenced by nitrogen. A va riation was observed in the electronic properties of these films as th e nitrogen concentration X=[N]/[Si] in the gas mixture was varied. Inf rared spectroscopy has shown that hydrogen bonds preferentially to sil icon. In films with X<8, nitrogen appears to behave as an impurity, fo rming chemical bonds with the silicon lattice, whereas a wide-bandgap alloy of the type a-SiNx:H is formed for X>8. (C) 1996 American Instit ute of Physics.