Silicon nitride deposited by inductively coupled plasma using dichlorosilane and ammonia

Abstract

Silicon nitride films were deposited at low temperature (350°C and pressure of 60 mTorr), on silicon substrates, using an inductively coupled plasma chemical vapour deposition system. Different ammonia to dichlorosilane flow ratios (1.4–9.5) and RF powers (25 and 50 W) were adopted for comparison. Deposition rates of the order of 2.6–12.3 nm min −1 and refractive indexes ranging from 1.710 to 1.818 were determined by ellipsometry. Fourier transformed infrared spectra revealed the presence of SiN breathing and stretching modes, Si–NH–Si bending mode and NH stretching mode. The dielectric constant (4.5–5.8), dielectric breakdown electric field (0.36 MV/mm) and conductivity (3×10 −12 (Ω cm) −1) were determined by capacitance–voltage and current–voltage measurements. The films present low compressive total stress but when increasing the concentration of the nitrogen in the film the total stress tends to become tensile.