PHYSICAL-ELECTRICAL PROPERTIES OF SILICON-NITRIDE DEPOSITED BY PECVD ON III-V SEMICONDUCTORS

Silicon nitride films have been produced from SiH4 and NH3 by reactive plasma deposition. This paper describes the effect of deposition parameters, i.e., substrate temperature T (100°–350°C), RF power (20–150W), and gas ratio (1–19), on various film properties deposited on III–V semiconductor substrate. A parameter working range has been identified suitable for III–V technology, that is Ts = 300°C, RF power P = 20W, and ammonia/silane ratio R = 4–9. Under these conditions films have been made with a Si/N ratio of 0.7–1 and a refractive index of 1.9–2. Electrical resistivity greater than 1012 Ω cm at a field of 2 MV/cm, breakdown strength of 3–9 MV/cm at a current of 1 pA, and a dielectric constant of 7 were observed. The density of interface states for the silicon nitride/InGaAs system was evaluated at 5–1012 cm−2 eV−1 Si-H and N-H bonds per unit area, evaluated by IR measurements, were very low, especially after an annealing procedure. Excellent step coverage and good adhesion were obtained for ridge and mushroom structure lasers. Finally, a RF power of 50W gives silicon nitride layers particularly stable with temperatures. © 1990, The Electrochemical Society, Inc. All rights reserved.