a‐SiC:H Films by Remote Hydrogen Microwave Plasma CVD From Ethylsilane Precursors^**

Abstract

Amorphous, hydrogenated, silicon carbide (a-SiC:H) films are deposited in the remote hydrogen microwave plasma (RP-CVD) process using diethylsilane as a single-source precursor. The effect of substrate temperature (T S ) on the kinetics of RP-CVD, chemical composition, structure, surface morphology, and properties (density, refractive index, and extinction coefficient) of the resulting a-SiC:H films is investigated. The T S dependence of film growth rate implies that RP-CVD is an adsorption-controlled process. The increase of T S from 30°C to 350°C causes the elimination of organic moieties from the film and the formation of a SiÀC network structure. The relationships between the content of SiÀC bonds, represented by the relative integrated intensity of the SiÀC IR band, and the film properties are determined. The number of SiÀC bonds is found to be a key parameter in the control of the examined film properties. The films deposited at T S ¼ 350°C appear to be very dense materials exhibiting small surface roughness and high refractive index. The results of the present study are compared with those reported for a-SiC:H films produced by RP-CVD from a triethylsilane precursor.

Thin a‐SiC:H Films Formed by Remote Hydrogen Microwave Plasma CVD using Dimethylsilane and Trimethylsilane Precursors

“…The same effect of T S on surface morphology as revealed by the R rms data for DMS and TrMS films (Fig. b) has also been observed for a‐SiC:H films formed by RPCVD from the hexamethyldisilane (HMDS), (dimethylsilyl)(trimethylsilyl)methane (DTMSM), and diethylsilane (DES) precursors where the rise in T S from 30 °C to 400 °C caused a drop in surface roughness in the ranges 2.1 nm ≥ R rms ≥ 1.5 nm, 1.7 nm ≥ R rms ≥ 0.8 nm, and 2.1 nm ≥ R rms ≥ 0.9 nm . We have observed the opposite trend for the surface morphology of a‐SiC:H films formed by RPCVD from the triethylsilane (TrES) and bis(dimethylsilyl)ethane (BDMSE)precursors.…”

“…b) has also been observed for a‐SiC:H films formed by RPCVD from the hexamethyldisilane (HMDS), (dimethylsilyl)(trimethylsilyl)methane (DTMSM), and diethylsilane (DES) precursors where the rise in T S from 30 °C to 400 °C caused a drop in surface roughness in the ranges 2.1 nm ≥ R rms ≥ 1.5 nm, 1.7 nm ≥ R rms ≥ 0.8 nm, and 2.1 nm ≥ R rms ≥ 0.9 nm . We have observed the opposite trend for the surface morphology of a‐SiC:H films formed by RPCVD from the triethylsilane (TrES) and bis(dimethylsilyl)ethane (BDMSE)precursors. Their surface roughness increased with increasing T S from a mean value R rms = 0.9 nm for T S = 30–150 °C to a mean value R rms = 1.7 nm for T S = 250–400 °C, and from R rms = 0.9 nm at T S = 100 °C to a constant value R rms = 1.7 nm for T S = 200–350 °C .…”

“…We have observed the opposite trend for the surface morphology of a‐SiC:H films formed by RPCVD from the triethylsilane (TrES) and bis(dimethylsilyl)ethane (BDMSE)precursors. Their surface roughness increased with increasing T S from a mean value R rms = 0.9 nm for T S = 30–150 °C to a mean value R rms = 1.7 nm for T S = 250–400 °C, and from R rms = 0.9 nm at T S = 100 °C to a constant value R rms = 1.7 nm for T S = 200–350 °C . This opposite effect of T S on R rms may result from a different surface mobility of film‐forming species produced from these precursors.…”

Silicon Oxycarbide Films Produced by Remote Microwave Hydrogen Plasma CVD using a Tetramethyldisiloxane Precursor: Growth Kinetics, Structure, Surface Morphology, and Properties

“…A zero values of α we have observed in a wide range of wavelength ( λ = 400–1000 nm) for a‐SiC:H films formed by RP‐CVD from diethylsilane precursor …”

“…Referring to the PL intensity plot in Figure b, a sharp increase of I PL observed with rising T S from 30 °C to 200 °C may result from rising content of structural defects (capable of photoluminescence) formed during film growth. This process is associated with the formation of SiOx segments . A marked drop of I PL with T S rising from 200 °C to 350 °C may be ascribed to the elimination of such structural defects in favor of the formation of Si–C crosslinks or even SiC phase separation in silicon oxycarbide network…”