Local atomic structure in thin films of silicon nitride and silicon diimide produced by remote plasma-enhanced chemical-vapor deposition

Abstract

We have grown thin films of silicon nitride by remote plasma-enhanced chemical-vapor deposition and have studied the chemical bonding by infrared absorption, x-ray photoelectron spectroscopy, Rutherford backscattering, and Auger-electron spectroscopy. Films were grown using two different gases as the source of nitrogen, ${\mathrm{N}}_{2}$ and ${\mathrm{NH}}_{3}$. We have found that films grown from ${\mathrm{N}}_{2}$ and deposited at substrate temperatures in excess of 350 \ifmmode^\circ\else\textdegree\fi{}C have a composition corresponding to stoichiometric ${\mathrm{Si}}_{3}$${\mathrm{N}}_{4}$, whereas films deposited from ${\mathrm{NH}}_{3}$ require substrate temperatures in excess of about 500 \ifmmode^\circ\else\textdegree\fi{}C to eliminate bonded H and yield the same stoichiometric composition. In contrast films grown from ${\mathrm{NH}}_{3}$ at temperatures in the range of 50 to 100 \ifmmode^\circ\else\textdegree\fi{}C have a chemical composition corresponding to silicon diimide, Si(NH${)}_{2}$. Films grown from ${\mathrm{NH}}_{3}$ at intermediate substrate temperatures are solid solutions of ${\mathrm{Si}}_{3}$${\mathrm{N}}_{4}$ and Si(NH${)}_{2}$.