Aleksander M. Wrobel

Oligomeric Products in Plasma=Polymerized Organosilicones

Abstract Plasma polymers were deposited from a number of methylsilazane and methylsiloxane monomers of linear and cyclic structure. The oligomeric phase evolved from the polymers by a mild thermal treatment was analyzed using gas chromatography/mass spectrometry combined techniques. The oligomeric phase was found to be composed of the low-molecular-weight products with the weight being mostly no higher than two monomer units. The results suggested that the oligomers might be formed in the gas phase and then they diffuse to the surface of the growing polymer film. The structure of the oligomeric products indicated that their formation must proceed via the Si-N and Si-O bonds fission in silazane and siloxane monomers, respectively. An ionic nature of the primary active species involved in this process was assumed owing to the high susceptibility of these bonds toward heterolytic fission. The postulated ionic mechanism, considered to account for the formation of the observed oligomers, seems to be more reaso...

Remote hydrogen–nitrogen plasma chemical vapor deposition from a tetramethyldisilazane source. Part 1. Mechanism of the process, structure and surface morphology of deposited amorphous hydrogenated silicon carbonitride filmsElectronic supplementary information (ESI) available: deconvoluted emission and IR spectra of a-Si–N–C–H films. See http://www.rsc.org/suppdata/jm/b2/b211415c/

Amorphous hydrogenated silicon carbonitride films were produced by remote plasma chemical vapor deposition (RP-CVD) from 1,1,3,3-tetramethyldisilazane (TMDSN) as the single-source compound using a H2–N2 upstream-gas-mixture for plasma generation. The reactivity of particular TMDSN bonds in the RP-CVD initiation step has been examined using a hexamethyldisilazane model compound in the deposition experiments. The active species contributing to RP-CVD were identified by optical emission spectroscopic analysis of the plasma region. The films were examined using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The effect of N2 content in the H2–N2 upstream-gas-mixture on plasma generation of the active species, growth rate, chemical structure, and surface morphology of the resulting films is reported.

Remote hydrogen plasma chemical vapor deposition using an organopentasilane cluster as a novel film‐forming precursor: Mechanism of the activation step

The remote hydrogen plasma chemical vapor deposition (CVD) using tetrakis(trimethylsilyl)silane (TMSS) as a source compound has been examined in terms of the mechanism of the activation step. The deposition experiments performed for different configurations of the afterglow tube (straight, with a light trap, and with a hydrogen‐radical annihilator) prove that the TMSS molecules are exclusively activated by the reactions with the hydrogen radicals. The determined temperature dependence of the film deposition rate suggests that the examined remote hydrogen plasma CVD is a nonthermally activated process. Susceptibility of particular bonds in TMSS molecule to the activation step has been characterized using suitable model source compounds. Mechanisms of the most important elementary reactions contributing to the activation step have been proposed.

Silicon nitride film growth by remote plasma CVD using Tris(dimethylamino)silane

Abstract Silicon nitride (SiN x ) films were prepared using an organosilicon monomer, Trisdimethyl-aminosilane ((Me 2 N) 3 SiH: TDMAS) by a remote plasma CVD. Plasma was generated by a mixture of hydrogen and nitrogen gases while the monomer was introduced into the downstream. Deposition of SiN x films were initiated by hydrogen radicals since no film deposition was observed in the absence of hydrogen radicals. The deposited films were contaminated with a small amount of carbon atoms for the substrate temperature over 400°C. It is proposed that at the initial step, Si–N or N–C bonds of the monomer are broken by hydrogen radicals. Furthermore, N atoms in the films are assumed to be originated from the plasma.

Mechanism of the Initiation Step in Atomic Hydrogen-Induced CVD of Amorphous Hydrogenated Silicon–Carbon Films from Single-Source Precursors

A number of alkylsilanes and alkylcarbosilanes of widely different molecular structure are characterized in terms of their ability to form amorphous hydrogenated silicon–carbon (a-Si:C:H) films in atomic hydrogen-induced chemical vapor deposition (AHCVD). The compounds containing only Si–C and C–H bonds in the molecular skeleton appear to be inactive, while those with Si–Si or Si–H bonds are capable of a-Si:C:H film formation. The reactivity of the latter group of compounds is characterized by determining the AHCVD′s rate constants. For most of the investigated source compounds AHCVD was found to be a non-thermally activated process. Based upon the values of the rate constant and the identified low-molecular-weight and oligomeric products of AHCVD, a mechanism of the initiation step, as well as the nature of resulting film-forming precursor are proposed.

Mechanical and Tribological Properties of Thin Remote Microwave Plasma CVD a-Si:N:C Films from a Single-Source Precursor

Silicon carbonitride (a-Si:N:C) films produced by remote plasma chemical vapor deposition (RP-CVD) were investigated. Tetramethyldisilazane as a single-source precursor and (H2+N2) upstream gas mixture for plasma generation were used. The influence of the upstream gas composition on the structure, density, mechanical and tribological properties of the films deposited on p-type Si (001) wafers (both heated—Ts=300°C and unheated—Ts=30°C) are reported. The H2 RP-CVD process was found to result in the formation of outstanding low friction (μ≈0.04) and high hardness (H=27-31 GPa) a-Si:N:C films exhibiting promisingly high H/E values.

Mechanism of Amorphous Silica Film Formation from Tetraethoxysilane in Atomic Oxygen‐Induced Chemical Vapor Deposition

Atomic oxygen-induced chemical vapor deposition (AOCVD), using tetraethoxysilane (TEOS) as single-source compound, was investigated to get insight into the mechanism of silica film growth. In particular, an effort was made to elucidate the chemical nature of silica film-forming precursors. AOCVD, selected as a model process suitable for mechanistic study, has been examined in terms of the effects of atomic oxygen concentration, of the contents of the ground and excited state oxygen atoms in atomic oxygen fraction, and of thermal activation. The growth rate of silica film does not depend on the composition of the atomic oxygen fraction, but is proportional to the total concentration of atomic oxygen fed into the CVD reactor. In the light of the apparent activation energy (E a ) values calculated from the Arrhenius plots of the substrate temperature dependencies of film growth rate, the mechanism of AOCVD is related to the concentration of atomic oxygen. The near zero E a value found at low concentration of atomic oxygen (1.5 × 10 1 cm -3 ) implies that AOCVD is not a thermally activated process; diffusion of the precursors from the gas phase to the substrate seems to be the ratelimiting factor of AOCVD under these conditions. Apparently negative E a values observed for high concentrations of atomic oxygen(≥9.7 × 10 14 cm -3 ) indicate that the adsorption of the precursors onto the growth surface is the main factor controlling the rate of AOCVD. Reaction products of the gas-phase conversion of TEOS, investigated by high-resolution gas chromatography/mass spectrometry, revealed the presence of linear and cyclic siloxane oligomers, containing the -(EtO) 2 SiO- repeating unit. The structure O identified oligomers, results of the study of TEOS reactions with atomic oxygen, the structure of the deposited film, chemiluminescence spectra of the gas-phase products in the CVD reactor, and the results of step coverage tests, point to diethoxysilanone (a high reactivity intermediate) and hexaethoxydisiloxane (a high surface mobility, low reactivity intermediate) as the major precursors of silica film growth.

Experiments and analyses of SiC thin film deposition from organo-silicon by a remote plasma method

Abstract The remote plasma enhanced chemical vapor depositions (RPECVD) using organo-silicon as source compounds have been examined in terms of the mechanism of the activation steps and film formation. The deposition experiments were performed for different configurations of the radical transportation tube (straight, with a light trap, and a radical trap) to prove how the source materials are effective for the film formation. In the SiC film formation, it is shown that hydrogen radicals act on the Si Si bonds or Si H bonds of the source materials, but Si C bonds in the source will not be broken by the hydrogen radicals because of its high binding energy. As a practical application, SiC film coatings on the plastic are examined using electron cyclotron resonance (ECR) plasma system. These SiC coatings provide many advantages for the development of scratch resistivity and UV degradation resistivity for plastic materials.

Preparation and Characterization of Copper Films Deposited in Hydrogen Remote Plasma by Copper(II) Acetylacetonate

High purity and low resistive copper films are in high demand for ultralarge scale integrated process technology. By remote plasma-enhanced chemical vapor deposition, high purity Cu films can be prepared using copper(II) acetylacetonate [Cu(acac) 2 ] as a source material. Depositions were carried out with three types of flow tubes in order to study the reaction steps of the film formation. It is found that Cu films could be deposited only upon reaction of atomic hydrogen (H * ), but not with ultraviolet radiation. Hydrogen remote plasma method makes Cu films damage free from ion impacts and free from contaminants of carbon, oxygen, and others. The resistivities of Cu film measured are about 1.8 μΩ cm which is close to the intrinsic value (1.72 μΩ cm) of bulk copper

Structure-property relationships of amorphous hydrogenated silicon-carbon films produced by atomic hydrogen-induced CVD from a single-source precursor

Amorphous hydrogenated silicon-carbon (a-Si:C:H) films were produced by atomic hydrogen-induced (AH) CVD using hexamethyldisilane (HMDS) as a single-source precursor. Radio frequency (rf) hydrogen plasma was the source of atomic hydrogen. The effect of substrate temperature (T s ) on the chemical structure, composition, surface morphology, mechanical properties (dynamic hardness, total stress), and optical properties (refractive index, optical bandgap) of a-Si:C:H film has been examined. Fourier transform infrared (FTIR) spectroscopy and Auger electron spectroscopy (AES) data revealed a drastic drop in hydrogen content in the film, and a rise of the atomic concentration ratio Si/C with increasing T s , thus accounting for the elimination of organic moieties from the film and the formation of a Si-carbidic structure. In the light of scanning electron microscopy (SEM) and atomic force microscopy (AFM) examinations, the films were found to be morphologically homogeneous materials with a maximum size of surface roughness not exceeding 2 nm at T s = 300 °C. Both hardness and stress (tensile in nature) are strongly affected by the film composition, their values increasing with rising atomic ratio Si/C. The investigated optical properties of a-Si:C:H film, i.e., refractive index (n) and optical bandgap (E 0 ). can be controlled by the atomic ratio Si/C for a wide range of values: n = 1.58-2.02 and E 0 = 2.3-3.2 eV.