Thermal properties of some organosilicon precursors for chemical vapor deposition

Abstract

Five volatile organosilicon compounds: trimethyl (phenyl)silane Me 3 SiC 6 H 5 (I), trimethyl(cyclohexyl)silane Me 3 SiC 6 H 11 (II), trimethyl(phenoxy)silane Me 3 SiOC 6 H 5 (III), trimethyl(cyclohexyloxy)silane Me 3 SiOC 6 H 11 (IV), and trimethyl(allyloxy)silane Me 3 SiOC 3 H 5 (V) were synthesized, purified, and identified. Data of IR spectroscopy; gas-liquid chromatography; and 1 H NMR, 13 C NMR, 29 Si NMR analyses were used to identify and confirm the high purity of the compounds (more than 99.6 %). The thermal stability of the compounds was investigated by DTA-TG. The quantitative data on temperature dependences of the saturated vapor pressure of the compounds were obtained by static tensimetry method with glass membrane null manometer. The volatilities of compounds Me 3 SiOC 6 H 5 , Me 3 SiC 6 H 5 , Me 3 SiC 6 H 11 , Me 3 SiOC 6 H 11 were shown to be close due to the presence of large-size phenyl/cyclohexyl group. The replacement of phenyl/cyclohexyl group by allyl substituent in the molecule led to significant increase in volatility for Me 3 SiOC 3 H 5 in comparison with compounds mentioned before. The vapor pressure of all of the compounds is enough to use them as precursors in CVD processes without additional heating. The thermodynamic parameters (enthalpies and entropies) of vaporization processes for four compounds II-V were determined for the first time.

Macromonomers as a Novel Way to Investigate and Tailor Silicon-Oxycarbide-Based Materials Obtained from Polymeric Preceramic Precursors

“…Si-C bond stretching vibrations band can be seen at 825-845 cm −1 [38] and complex Si-C-Hx bending vibrations for T and D units can be found at 760-780 cm −1 and 800 cm −1 , respectively [51]. The main difference between spectra lies in bands correlated to C-H stretching vibrations at 2850-3000 cm −1 [25,[31][32][33][34][35][36][37][38][39][40][41] and Si-CH 3 bending vibrations at 1270-1285 cm −1 [25,[31][32][33][34][36][37][38][39][40][41] that are a result of different D unit amounts between samples. The barely visible bands at about 3500 cm −1 can be attributed to unreacted Si-OH groups [25,31,41,42] due to sterical limitations, while the broad band between 3000 and 3550 cm −1 can be correlated to OH stretching vibrations in ethanol (~3430 cm −1 )/water (~3380 cm −1 ) occluded in the polycondensed lattice and not removed completely by drying [25,39,41].…”

“…Vibrations of parts important In the case of both spectra, a number of bands typical for siloxanes and silsesquioxanes can be observed. These include stretching vibrations of C-H bonds at 2900-3000 cm −1 [25,[31][32][33][34][35][36][37][38][39][40][41], bending vibrations of Si-CH 3 groups at about 1270 cm −1 [25,31,[38][39][40], and a number of bands that can be attributed to symmetric bending of Si-O-Si bridges between 790 and 900 cm −1 [38][39][40] and Si-O ring with 4 Si atoms bending vibrations at 565-585 cm −1 [39]. The Si-C bond stretching vibrations band can be found at 825-845 cm −1 , its intensity enhanced by the coupling with C-H bond vibrations [38].…”

Insights on toxicity, safe handling and disposal of silica aerogels and amorphous nanoparticles

“…Lower molecular weight PDMS materials in soil can undergo two different processes: hydrolysis and evaporation. 127 Since the evaporation rate is higher than the hydrolysis rate, 128 low molecular weight PDMS tends to evaporate to atmosphere, being oxidized by hydroxyl radicals (the life time of PDMSs in atmosphere is no longer than 10-30 days). 129,130 On the other hand, high molecular weight organosilicons are not volatile and, consequently, remain in water or soil, where they eventually suffer hydrolysis.…”