G. Soto

Plasma enhanced chemical vapor deposition of SiO 2 films at low temperatures using SiCl 4 and O 2

Silicon dioxide films have been deposited by Plasma-Enhanced Chemical Vapor Deposition (PECVD) technique using SiCl4 and O2 as reactive materials. Infra-red transmittance, Auger electron spectroscopy analysis, ellipsometry, electrical, and chemical etch measurements have been used to characterize these films. It is possible to obtain good quality oxides at a substrate temperature of 200° C using a low flow of reactant gases. High flow of reactant gases results in highly non-homogeneous porous films. The best oxide films obtained show destructive breakdown at electrical fields above 4 MV/cm and a fixed charge density of the order of 2.6 × 1011 charges/cm2.

SiO2 prepared by remote plasma-enhanced chemical vapor deposition using SiCl4 and O2 at substrate temperatures of less than 200 °C

Silicon dioxide films have been prepared by the remote plasma-enhanced chemical vapor deposition technique using SiCl4 and O2 as source materials. The structural quality of the films was analyzed by infrared transmittance, ellipsometry, Auger electron spectroscopy and chemical etch rate measurements. The electrical integrity was analyzed by I-V and C-V measurements performed in metal-oxide-semiconductor structures prepared using the deposited oxides. Good-quality oxides have been obtained at substrate temperatures in the range of 100 to 150 °C. At lower temperatures (25 and 50 °C) oxide films with good insulating qualities are obtained but the level of interface states is large. The deposition rate is only slightly dependent on the substrate temperature. The chemical etch rate is similar to that obtained for oxides prepared at higher temperatures. Destructive breakdown is in the range from 6.7 to 8.9 MV cm−1. Fixed charge densities are in the range from 5 X 1010 to 5.2 X 1011 charges cm−2.

Preparation of cubic boron nitride films by plasma-enhanced chemical vapour deposition of BF3, N2 and H2 gas mixtures

Abstract Boron nitride thin films were prepared by plasma-enhanced chemical vapour deposition (PECVD) of BF 3 , H 2 and N 2 gas mixtures. Fourier transform IR (FTIR) spectroscopy and X-ray analysis reveal that the films deposited on crystalline substrates show signs of cubic and hexagonal phases present within the atomic network. The index of refraction and the film thickness were determined by ellipsometry. The deposition rate increases with temperature and saturates at high plasma powers. Values of n are in the range 1.63–1.77, and the optical gap varies from 5.0 to 5.6 eV depending on the preparation conditions (the presence of contaminants also alters this property). The ratio of N 2 to H 2 in the flow affects the properties of the films.

Optical properties of boron nitride thin films

Abstract Boron nitride thin films were deposited onto crystalline silicon and alkali halide substrates by plasma-enhanced chemical vapour deposition of BF3, N2, H2 and Ar gas mixtures. Films were prepared on both powered and grounded electrodes of the capacitatively coupled system. The deposits were analysed by ellipsometry. Fourier transform IR spectroscopy and UV spectroscopy to determine their optical properties. The relative composition was determined using nuclear reactions induced by 1 MeV deuteron bombardment and Auger spectroscopy. Ion bombardment during growth was found to affect the optical properties of the material, since films prepared with low flows of argon and those placed on the live electrode have smaller refractive indices, larger IR absorption peaks for the cubic phase, and wider optical gaps.