UV Laser Photolysis of Disiloxanes for Chemical Vapor Deposition of Nano-Textured Silicones

Abstract

Gas-phase photolysis of methyldisiloxanes [(CH3) n H3 - n Si]2O (n = 1−3) has been achieved for the first time through absorption of ArF laser radiation at 193 nm and has been shown to yield C1−C2 hydrocarbons (major volatile products), methylsilanes (minor volatile products), and solid methylsilicones with their H(Si) content and Si/O ratio reflecting those of the parent compounds. The identified volatile and solid products are compatible with a number of reactions occurring within less than 1 ms in a narrow region of the gaseous sample maintained at room temperature. These reactions are discussed. The solid deposited materials were characterized by FTIR, NMR, UV, and XP spectroscopy, electron microscopy, and thermal gravimetry. They were revealed to contain all possible SiC x H y O z (x + y + z = 4) compositions, to possess nanometer-sized texture, and to be thermally more stable than linear poly(dialkylsiloxanes).

UV laser deposition of nanostructured Si/C/O/N/H from disilazane precursors and evolution to silicon oxycarbonitride

“…This is in agreement with the observed evolution of the hydrocarbons. We note that the observed thermal behaviour of the deposits, resembling that of crosslinked polysiloxanes 1 and laser-fabricated polyoxocarbosilanes 24,28 suggests that the annealed materials can be best described as a highly crosslinked Si/C/N/O structure.…”

Evidence of ionic film deposition from single‐filament dielectric barrier discharges in Ar–HMDSO mixtures

“…The alternative dissociation channel (), resulting in the formation of the trimethylsilyl radical, Me 3 Si, and dimethylsilanone, Me 2 Si═O, was postulated to explain the product formation during photolysis of HMDSO using an ArF laser (193 nm, 6.4 eV), which was assumed to proceed via photodissociation of the precursor into and . [ 64 ] Similar to the multiphoton IR laser photolysis of HMDSO, substantial redistribution (or “scrambling”) of the substituents on silicon atoms takes place, along with the formation of Si–H as well as Si–CH 2 –Si moieties. [ 65 ] The same is observed upon pyrolysis of a gel obtained by cohydrolysis of dimethyldiethoxysilane and tetraethoxysilane.…”

An innovative GC-MS, NMR and ESR combined, gas-phase investigation during chemical vapor deposition of silicon oxynitrides films from tris(dimethylsilyl)amine

“…As suggested by Pola et al, 46 siloxane molecules can disproportionate into a silanone and a radical species when given enough energy, with the radical species participating in the polymerization of other siloxane molecules. Following this proposition, compound 3 is assumed to yield Si_int°, H° and a dimethylsilanone through Equation (7).…”