Insulators obtained by electron cyclotron resonance plasmas on Si or GaAs

Abstract

Silicon oxynitride (SiO x N y ) and nitride (SiN x ) insulators have been deposited or grown (with or without silane in the gas mixture, respectively) by electron cyclotron resonance (ECR) plasmas on Si and/or GaAs substrates at room temperature (20 °C) and low pressures (up to 10 mTorr). Chemical bonding characteristics of the SiO x N y and SiN x films were evaluated using Fourier transform infrared spectrometry (FTIR). The profile measurements determined the film thickness, the deposition (or oxidation) rate and the etch rates in buffered HF (BHF). The refractive indexes and the thicknesses were determined by ellipsometry. The effective interface charge densities were determined by capacitance–voltage (C–V) measurements. With these processes and analyses, different films were obtained and optimized. Suitable gate insulators for metal–insulator–semiconductor (MIS) devices with low interface charge densities were developed: (a) SiN x films deposited by ECR-chemical vapor deposition (ECR-PECVD) on GaAs substrates; (b) SiO x N y insulators obtained by low-energy molecular nitrogen ion ( 28N 2 +) implantation (energy of 5 keV and dose of 1×10 15/cm 2) in Si substrates prior to high-density O 2 ECR plasma oxidation; and (c) SiO x N y insulators grown (without silane in the gas mixture) by O 2/N 2/Ar ECR plasma “oxynitridation.” Furthermore, some SiN x films also present very good masking characteristics for local oxidation of silicon process.