V. I. Rakhlin

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.

Characterization of some trimethyl(organylamino)silanes—precursors for preparation of silicon carbonitride films

A series of aminosilanes has been synthesized by the reaction of carboxylic acid di(organyl)amides with trimethyliodsilane. A purification method providing an increase in the yield of end products to 82% has been developed. The identity of the products has been confirmed using an elemental analysis and IR, UV, and 1H NMR spectroscopy. The spectral characteristics of the synthesized aminosilanes have been determined. The temperature dependences of the saturated vapor pressure have been established, and the thermodynamic characteristics of the vaporization processes have been calculated. It has been demonstrated that the aminosilanes Me3SiNEt2, Me3SiNHAll, and Me3SiNHPh are heat resistant in the temperature range 296–452 K and have a vapor pressure sufficient for their use in the processes of chemical vapor deposition of a substance, so that they can be recommended as precursors for synthesis of silicon carbonitride films.

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 aminosilane precursors for the preparation of Si-C-N films

RnSi(NEt2)4 − n aminosilanes have been synthesized by reacting the RnSiCI4 − n (R = H, CH3; n = 1, 2) organylchlorosilanes with diethylamine. Using IR, UV, and NMR (1H, 13C, and 29Si) spectroscopies and elemental analysis, we have identified the reaction products and determined their spectroscopic characteristics. Vapor pressure measurements have been used to determine the saturated vapor pressure as a function of temperature and calculate the thermodynamic characteristics of vaporization. Thermodynamic modeling of chemical vapor deposition processes has been performed with the aim of predicting the phase composition of the deposit as a function of the nature of the precursor and process conditions.

Acyl iodides in organic synthesis. Reactions with morpholine, piperidine, and N-hydrocarbylpiperidines

Acyl iodides RCOI (R = Me, Ph) reacted with morpholine and piperidine to give the corresponding N-acyl derivatives and morpholine or piperidine hydroiodides. Reactions of acyl iodides with N-methyl- and N-ethylpiperidines involved cleavage of the exocyclic R-N bond with formation of N-acylpiperidine and alkyl iodide and were accompanied (to insignificant extent) by cleavage of the endocyclic N-C bond, leading to N-alkyl-N-(5-iodopentyl)acylamides. In the reaction of acetyl iodide with N-phenylpiperidine, the main process was cleavage of just endocyclic N-C bond to produce N-(5-iodopentyl)-N-phenylacetamide and its dehydroiodination product, N-(pent-4-en-1-yl)-N-phenylacetamide. Analogous reaction with benzoyl iodide afforded N-(5-iodopentyl)-N-phenylbenzamide in a poor yield.

Films based on the phases in the Si-C-N System: Part 1. Synthesis and characterization of bis(trimethylsilyl)ethylamine as a precursor

The characterization of bis(trimethylsilyl)ethylamine was carried out using a combination of IR, UV, 1H, 13C, 29Si, and 15N NMR spectroscopy, as well as elemental analysis. The spectral characteristics of the compound were determined. The temperature dependence of the saturated vapor pressure was established by tensimetric studies, and the thermodynamic characteristics of vaporization were calculated. Thermodynamic simulation of the chemical vapor deposition was performed and was used as a basis for predicting the composition of the deposited phase complexes depending on the type of reagent and the process conditions.

Migration of trimethylsilyl group in the reaction of sodium bis(trimethylsilyl)amide with bromobenzene

The reaction of sodium bis(trimethylsilyl)amide with bromobenzene gave a mixture of N,N-bis-(trimethylsilyl)aniline and N,2-bis(trimethylsilyl)aniline, the latter being a rearrangement product formed via 1,3-migration of trimethylsilyl group from the nitrogen atom to the ortho-carbon atom in the benzene ring.

Et3GeN(SiMe3)2 and Et3SnN(SiMe3)2: New precursors for chemical vapor deposition processes

We have synthesized the germanium- and tin-containing organosilicon compounds Et3GeN(SiMe3)2 and Et3SnN(SiMe3)2 as new precursors for the preparation of materials by chemical vapor deposition. The compounds were characterized by NMR, IR and UV spectroscopies and thermal analysis. Using vapor pressure measurements, we obtained temperature dependences of their saturated vapor pressure. We assessed their thermal stability and calculated the thermodynamic characteristics of vaporization of the organosilicon compounds.

N -bromohexamethyldisilazane: Investigation of properties and thermodynamic simulation of precipitation of thin-layer structures from the vapor phase

N-Bromohexamethyldisilazane has been characterized using an elemental analysis and IR, UV, 1H NMR, 13C NMR, and 29Si NMR spectroscopy. The spectral characteristics of the compound have been determined and the saturated vapor pressure has been measured. The thermodynamic simulation of the chemical vapor deposition (CVD) of silicon carbonitride films in the Si-C-N-Br-H system has been performed at low pressures (13.30 and 1.33 Pa) over a wide temperature range (from 400 to 1200 K) with the use of initial gas mixtures of N-bromohexamethyldisilazane with hydrogen and ammonia. The possibility of preparing films of different compositions has been demonstrated and the optimum conditions for deposition of silicon carbonitride coatings of the general composition SiCxNy have been established.

Reaction of sodium bis(trimethylsilyl)amide with bromotoluenes

Isomeric bromotoluenes react with sodium bis(trimethylsilyl)amide through intermediate methylbenzynes, yielding N,N-bis(trimethylsilyl)toluidines and rearrangement products, N,2-bis(trimethylsilyl)toluidines. The formation of the latter is a rare example of 1,3-migration of silyl group from nitrogen atom to aromatic carbon atom. The rearrangement is favored by increased solvent polarity and elevated temperature. The observed product ratio can be rationalized by DFT quantum chemical calculations.