Yu. M. Rumyantsev

Growth of PbS and CdS thin films by low-pressure chemical vapour deposition using dithiocarbamates

Abstract Thin films of cadmium and lead sulphides grown by chemical vapour deposition (CVD) and remote plasma enhanced chemical vapour deposition (RPECVD) using dithiocarbamates as precursors were prepared on fused silica, sapphire, (111)Si and (111)InP substrates. These films were deposited in the temperature range 473–873 K. It was established that the activation energy of the CVD process is 191.5±1.5 kJ mol −1 . The structure of polycrystalline films was halenide for PbS and wurtzite for CdS. It was also found that r.f.-plasma activation of the gas phase decreases remarkably the growth temperature and orders the film structure. RPECVD sulphide films had a high degree of preferred orientation.

Use of hexamethylcyclotrisilazane for preparation of transparent films of complex compositions

This paper reports on the results of the thermodynamic modeling of chemical vapor deposition of SiCxNy silicon carbonitride films with the use of the volatile organosilicon compound hexamethylcyclotrisilazane (HMCTS) over a wide temperature range 300–1300 K at low pressures of 10−2−10 Torr. It is demonstrated that there are ranges of conditions under which the gas phase is in equilibrium with a mixture of solid phases SiC + Si3N4 + C with the total composition represented in the form of the ternary compound SiCxNy. Transparent silicon carbonitride films of different compositions are experimentally obtained under conditions in the above range through plasma-enhanced chemical vapor deposition at a pressure of 5 × 10−2 Torr and temperatures of 373–1023 K with the use of the initial gaseous mixture of hexamethylcyclotrisilazane and helium. The chemical and phase compositions of the films are determined and their properties are investigated using ellipsometry, IR and Raman spectroscopy, spectrophotometry, energy-dispersive spectroscopy, and synchrotron X-ray powder diffraction. It is shown that the films synthesized at low temperatures of 373–573 K contain a considerable amount of hydrogen. The results obtained ftom atomic-force and scanning electron microscopy indicate that the films involve nanograins.

Chemical Composition of Boron Carbonitride Films Grown by Plasma-Enhanced Chemical Vapor Deposition from Trimethylamineborane

Boron carbonitride and boron nitride films were grown by plasma-enhanced chemical vapor deposition using trimethylamineborane and its mixtures with ammonia, hydrogen, or helium. The effects of the starting-mixture composition and substrate temperature on the chemical composition of the deposits was studied by ellipsometry, scanning microscopy, IR spectroscopy, Raman scattering, and x-ray photoelectron spectroscopy. The results indicate that the initial composition of the gas mixture, the nature of the activation gas, and substrate temperature play a key role in determining the deposition kinetics and the physicochemical properties of the deposits. Depending on these process parameters, one can obtain h-BN, h-BN + B4C, or BCxNy films.

Synthesis of silicon carbonitride dielectric films with improved optical and mechanical properties from tetramethyldisilazane

Films of silicon carbonitride have been obtained by the plasma chemical decomposition of a gaseous mixture of helium and a volatile organic silicon compound 1,1,3,3-tetramethyldisilazane (TMDS) in the temperature range of 373–973 K. The modeling of the processes of deposition from a gaseous mixture (TMDS + He) in the temperature range of 300–1300 K and pressures of Ptotal0 = 10−2–10 Torr has shown that it is possible to vary the equilibrium composition of the condensed phase depending on the synthesis temperature and the initial gaseous mixture composition. The chemical and phase compositions, as well as physicochemical and functional properties, of the films obtained in the range of 373–973 K have been studied using a complex of modern techniques, including Fourier transformed infrared (FTIR) Raman, X-ray photoelectron (XPS) and energy-dispersive spectroscopy (EDS), scanning electron (SEM) and atomic-force microscopy (AFM), X-ray diffraction using synchrotron radiation (XRD-SR), ellipsometry, and spectrophotometry. The electrophysical parameters are determined using the C-V and I-V characteristics, and the microhardness and Young’s modulus are determined by the nanoindentation method. It is established that the chemical composition of low-temperature (373–673 K) films of silicon carbonitride corresponds to a gross formula of SiCxNyOz: H, while that of high-temperature films corresponds to SiCxNy. The presence of nanocrystals with the phase composition close to the standard phase α-Si3N4 is detected in the films. It is shown that all of the films are perfect dielectrics (k = 3.8–6.4, ρ = 2.2 × 1010−1.3 × 1011 Ohm · cm), possess high transparency (∼98%) in a wide spectral range of 280–2500 nm, and have a high microhardness (3.8–36 GPa) and Young’s momentum (125–190 GPa).

Tris(diethylamino)silane—A New Precursor Compound for Obtaining Layers of Silicon Carbonitride

Silicon carbonitride layers have been obtained by chemical deposition from the gas phase with thermal (LPCVD) and plasma (PECVD) activation of the gas mixture of helium with the new volatile siliconorganic compound tris(diethylamino)silane (Et2N)3SiH (TDEAS) in the temperature region 373–1173 K. Thermodynamic simulation of the deposition processes from the gas mixture (TDEAS + He) in the temperature interval 300–1300 K and pressure interval Ptot0 from 1 × 10−2 to 10 mm Hg has revealed the possibility of varying the equilibrium composition of the condensed phase depending on the synthesis temperature and the composition of the initial gas mixture. Physicochemical and functional properties of obtained layers were studied by complex of modern methods. It has been established that the chemical composition of the silicon carbonitride layers obtained by the PECVD method, depending on the deposition conditions, approaches that of silicon oxynitride or nitride, and the composition of those obtained by the LPCVD method approaches that of silicon carbide. The presence of nanocrystals with a phase composition close to the standard α-Si3N4 phase and of carbon inclusions has been found in the layers.

Plasma enhanced chemical deposition of nanocrystalline silicon carbonitride films from trimethyl(phenylamino)silane

Synthetic process for nanocrystalline silicon carbonitride films was developed using plasma-chemical decomposition of a new organosilicon reagent, namely, trimethyl(phenylamino)silane Me3SiNHPh. Synthesis was carried out from the gaseous mixtures, such as Me3SiNHPh + He, Me3SiNHPh + N2, and Me3SiNHPh + NH3, in a reactor in the wide temperature range (473–973 K) under the low pressure (4–5 × 10−2 Torr). Polished wafers of Si(100), Ge(111), and silica glass were used as substrates. Dependences of the chemical and phase compositions, the surface morphology, and the silicon carbonitride optical properties on the process temperature were studied using FTIR and Raman spectroscopy, energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), scanning electron microscopy (SEM), ellipsometry, and spectrophotometry.

Properties of BCxNy films grown by plasma-enhanced chemical vapor deposition from N-trimethylborazine-nitrogen mixtures

Boron carbonitride films of various compositions have been grown by plasma-enhanced chemical vapor deposition using N-trimethylborazine as a single-source precursor and nitrogen as a plasma gas and an additional nitrogen source. Experiments were performed at various deposition temperatures and rf powers. The films were characterized by ellipsometry, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, IR and Raman spectroscopies, synchrotron X-ray diffraction, energy dispersive X-ray microanalysis, and spectrophotometry. The results demonstrate that, under the conditions of this study, the growth kinetics and physicochemical properties of boron carbonitride layers are influenced by both the substrate temperature and rf power. Conditions are found for producing boron carbonitride films transparent in the UV through visible spectral region.

PECVD synthesis of hexagonal boron nitride nanowalls from a borazine + ammonia mixture

Hexagonal boron nitride nanowalls have been grown by plasma-enhanced chemical vapor deposition (PECVD) from a mixture of borazine (B3N3H6) and ammonia. As the deposition temperature increases from 100 to 700°C, the structure of the films changes from amorphous to nanocrystalline, made up of three-dimensional nanowalls normal to the substrate. The ability to produce nanowalls depends on film growth conditions. We have examined the effect of synthesis temperature on the elemental composition and surface morphology of the films. The structure of the nanowalls has been determined by transmission electron microscopy, and the presence of a transition layer between the h-BN film and Si(100) substrate has been demonstrated. The lowest temperature at which nanowalls can be grown by PECVD is 300°C. The films have high transmission in a wide spectral range (350–3200 nm). Their parameters suggest that the nanostructures in question can find application in microelectronics, optics, and catalysis.

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.

X-ray photoelectron and auger spectroscopic study of the chemical composition of BC x N y films

X-ray photoelectron and Auger spectroscopy are used to investigate the chemical composition of BCxNy films synthesized by PECVD from different initial gas mixtures in the temperature range 473–723 K. Main principles and features of the film formation are found. It is shown that the chemical composition of BCxNy films significantly depends on the synthesis parameters, which enables targeted control of their physical properties. The obtained data are discussed.