Silicon nitride (SiN) films had been prepared at low substrate temperature (100 degrees C) using the ion-assisted deposition (IAD) process. The films had been analyzed by the measurement of X-ray diffraction, atomic force microscopy. Fourier transform infrared spectrometry, nano indenter, and ellipsometry. The effects of N-ion current density on the surface morphology, compositional, mechanical, and infrared optical properties of SiN thin films were investigated. The results showed that the stoichiometric Si(3)N(4) thin film with desirable properties, such as continuous and smooth surface morphology, extremely low hydrogen content, mechanical strong, and low extinction coefficient, could be obtained by using the IAD technique. (C) 2010 Elsevier B.V. All rights reserved.