V. R. Shayapov

Films of hydrogenated silicon oxycarbonitride. Part I. Chemical and phase composition

The method of preparation of hydrogenated silicon oxycarbonitride films with variable composition SiCxNyOz: H by the plasma chemical vapor decomposition of a volatile organosilicon compound, 1,1,1,3,3,3-hexamethyldisilazane (enhanced to IUPAC, bis(trimethylsilyl)amine) in a gas phase containing nitrogen and oxygen in the temperature range of 373–973 K has been developed. It has been shown that nitrogen and oxygen provide the decrease in carbon content in films due to gas-phase reaction giving volatile products (CN)2, CH4, CO, and H2(H). The obtained SiCxNyOz: H films are nanocomposite, in the amorphous part of which the nanocrystals are distributed, which belong to the determined phases of the Si-C-N system, namely, α-Si3N4, α-Si3 − xCxN4, and graphite.

Mechanical properties and density of BCxNy films grown by low-pressure chemical vapor deposition from triethylamine borane

Boron carbonitride (BCxNy) films of different compositions have been grown by low-pressure chemical vapor deposition using triethylamine borane as a single-source precursor and ammonia as an additional nitrogen source. Experiments were performed at various initial vapor compositions. The resultant films have been characterized by ellipsometry, IR spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, nanoindentation, and surface acoustic wave spectroscopy. The mechanical properties of the films are shown to correlate with their density and chemical composition. With increasing initial ammonia partial pressure in the vapor phase, the elemental composition of the films moves away from boron carbide, approaching boron nitride, which is accompanied by a reduction in the Young’s modulus, hardness, and density of the films.

Features of determination of thickness of dielectric films obtained in searching experiments

The approach to determination of the thickness and the refractive indices of dielectric films obtained in searching experiments is discussed. Experiments of this kind often exhibit unpredictable values of thickness and refractive indices of films. Nondestructive noncontact methods of spectrophotometry and ellipsometry not involving preliminary preparation of samples are applied. The approach to determination of the thickness and the refractive indices of films is illustrated by means of samples of silicon carbonitride films obtained on silicon substrates by plasma-chemical decomposition of gas-phase trimethyl(phenylamino)silane.

Hydrogenated silicon oxycarbonitride films. Part II. Physicochemical and functional properties

The optical, and electrophysical characteristics of hydrogenated silicon oxycarbonitride films synthesized by the plasma enhanced chemical vapor decomposition of the mixtures of 1,1,1,3,3,3-hexamethyldisilazane with oxygen and nitrogen in the temperature range of 373–973 K have been studied. It has been shown that the obtained films are highly transparent (transmittance is ∼92–99%) in the UV, visible, and IR ranges of the spectrum; they have refractive indices in the range of 1.43–2.25, a low reflection coefficient of visible light (nearly 3%), and low dielectric permittivity.

Optical and mechanical properties of films obtained by plasma decomposition of hexamethyldisilazane

Films of SiCxNyHz composition are obtained by chemical deposition from the vapor phase via the activation of high-frequency discharge plasma (PECVD). The organosilicon compound hexamethyldisilazane, which contains all the atoms needed for the formation of films, is used as our initial material. Physicochemical properties of the films are studied by spectroscopy of surface acoustic waves, measuring the bending of a film-substrate system, ellipsometry, and infrared spectroscopy. Important features of the films’ structure are established. It is shown that at temperatures of deposition below 400°C, films contain chemical bonds of an organic nature, have very low values of density and the Young modulus, and exhibit high levels of elasticity, indicating their polymer-like structure. It is established that at higher temperatures of deposition, films are inorganic composite materials.

Structure and elemental composition of transparent nanocomposite silicon oxycarbonitride films

Based on thermodynamic simulation on the deposition of condensed phases with the complex composition in the Si–C–N–O–H system in a wide temperature range, using initial gas mixtures of 1,1,3,3-tetramethyldisilazane (HSi(CH3)2)2NH (TMDS), TMDS with a variable mixture of oxygen and nitrogen (O2+xN2), a method is developed to obtain SiCxNyOz:H nanocomposite films by the plasma chemical decomposition of this gas mixture in the temperature range of 373-973 K. By FTIR and energy dispersive X-ray spectroscopy the structure of chemical bonds and the elemental composition of the obtained silicon oxycarbonitride films are studied. The in situ composition of the initial gas phase in PECVD processes is examined by optical emission spectroscopy.

Chemical Composition of an Inductively Coupled Hexamethyldisilazane-Argon Plasma and Properties of Films Grown in this Plasma

The simplest components (atoms, diatomic molecules, and simple free radicals) of an inductively coupled rf plasma in a hexamethyldisilazane–argon mixture have been identified by optical emission spectroscopy. We have studied the influence of process conditions (plasma power and hexamethyldisilazane concentration in the mixture) on the intensity of lines and bands corresponding to these components and the corresponding changes in the composition and physicochemical properties of SiCxNyHz films grown in this plasma.

Structural defects in SiC x N y H z films obtained by plasma-enhanced chemical deposition from hexamethyldisilazane vapor

By electron paramagnetic resonance spectroscopy the paramagnetic centers are investigated in SiCxNyHz films obtained by plasma-enhanced chemical deposition from hexamethyldisilazane vapor. It is found that the films contain dangling bonds broken at carbon atoms, their concentration considerably increasing with an increase in the deposition temperature. By Raman spectroscopy a deposition temperature range is determined within which the films contain carbon clusters. Similarity in the properties of the films synthesized at high deposition temperatures and the films initially deposited at low temperatures and then annealed is established. The results of the study are interpreted with the use of the known data on the film composition and structure and also the representations described in the literature.

Synthesis and Properties of Thin Films Formed by Vapor Deposition from Tetramethylsilane in a Radio-Frequency Inductively Coupled Plasma Discharge

Thin films of hydrogenated silicon carbide (SiCx:H) and carbonitride (SiCxNy:H) are synthesized in a reactor with inductively coupled RF plasma with the introduction of tetramethylsilane vapors and additive gases—argon and/or nitrogen. The process is carried out at different synthesis temperatures, plasma power, and partial pressure of tetramethylsilane and additive gases in the reactor. The dependences on the synthesis conditions of the films’ growth rate, chemical composition, and properties such as the light transmission coefficient, refractive index, optical band gap, and dielectric constant are obtained. The weak dependence of the films’ composition and properties on the preset synthesis conditions is a characteristic feature of the studied process within the investigated range of conditions. The possible reasons of this phenomenon and the results of in situ studies of the gas phase composition in the plasma are examined.

Temperature dependences of the optical properties and the phase composition of vanadium dioxide films obtained by chemical vapor deposition

By low pressure chemical vapor deposition single-phase vanadium dioxide films containing monoclinic phase M1from vanadyl acetylacetonate vapor are obtained on monocrystalline silicon Si(100) substrates. Changes in the phase composition of the films on heating to 90 °C are studied by X-ray diffraction. It is found that in the temperature range 60-70 °C the monoclinic phase passes into tetragonal R. At higher temperatures only the tetragonal phase is observed. By reflection spectrophotometry and ellipsometry the temperature dependences of the optical properties of the films exhibiting hysteresis are determined. At wavelengths less than 600 nm the reflection spectra are almost insensitive to temperature variation. After the linear normalization the reflection and extinction coefficients are well consistent with changes in the phase composition.