Silicon nitride films deposited at substrate temperatures < 100 degrees C in a permanent magnet electron cyclotron resonance plasma

Deposition of silicon nitride at low temperatures by plasma-enhanced chemic al vapor deposition requires an efficient source of activated precursors an d high-current, low-energy ion assist. We report the deposition of silicon nitride at substrate temperatures <100 degrees C using a permanent magnet e lectron cyclotron resonance plasma reactor capable of generating uniform pl asmas over 300 mm diameters. The effects of gas mixture, silane flow, press ure, and microwave power on the film deposition rate, composition and bondi ng, index of refraction, stress, and etch rate in buffered oxide etch solut ion are reported. The N-2/SiH4 flow ratio and microwave power both influenc e the film index and hydrogen content and bonding. For a SiH4 flow of 30 se em and N-2/SiH4 similar to 0.75, hydrogen is equally distributed between Si -H and N-H sites and total hydrogen content is minimized. At a deposition r ate of 500-600 Angstrom/min, a threshold in microwave power of similar to 1 100 W exists, above which films with buffered oxide etch rates <150 Angstro m/min result. Near the threshold microwave power compressive stress <400 MP a is observed, with increasing stress at higher microwave powers. (C) 1999 American Vacuum Society. [S0734-2101(99)05005-8].