Effect of sputtering-gas pressure on properties of silicon nitride films produced by helicon plasma sputtering

Silicon nitride films were deposited by helicon plasma enhanced radio frequ ency (rf) reactive sputtering. This technique was shown to produce films wi th low hydrogen and oxygen content at very low sputtering-gas pressure, wit h improved deposition rate compared with conventional rf reactive sputterin g. Stoichiometric Si3N4 film with extremely low hydrogen content (<1%) and oxygen content (<1%) was obtained at the Ar/N-2 partial pressure ratio of 1 .5, and total sputtering-gas pressure of less than 0.1 Pa. The influence of sputtering-gas pressure on the mechanical, chemical, optical and compositi onal properties of the films was investigated by stress and chemical etch r ate measurements, infrared absorption spectroscopy, ultraviolet-visible spe ctroscopy, and Rutherford backscattering spectrometry (RBS). These studies revealed that when keeping all other deposition conditions the same, reduci ng the sputtering-gas pressure, can effectively reduce the film contaminati on of H and O, and increase the film density. (C) 2001 Elsevier Science B.V . All rights reserved.