Structure and composition studies for silicon nitride thin films deposited by single ion bean sputter deposition

Abstract

Silicon nitride films were deposited on Al/glass, NaCl, KBr, and silicon substrates by single ion beam sputter deposition. Films were prepared at various N 2 + ion beam voltages over the range from 500 to 1200 V. The resulting films were characterized by using secondary ion mass spectrometry, Fourier transform infrared spectroscopy, transmission electron microscopy, and transmission electron diffraction. The stoichiometry of these silicon nitride films was controlled by adjusting the ion beam voltage. Films deposited under conditions of ion beam voltage below about 700 V were nitrogen rich while films made with beam voltages in excess of 900 V were silicon rich. The film structure changed with the substrate temperature from amorphous at room temperature to nanocrystalline/amorphous at 300 °C. The lowest occupied (LO) phonon band for stoichiometric Si 3N 4 was approximately 1124 cm −1 and the stoichiometry of thin silicon nitride films could be assessed with the LO phonon position. © 1997 Elsevier Science S.A.