Formation of silica coating films from spin-on polysilazane at room temperature and their stability in hot water

Abstract

Spin-coating was conducted on single-crystal silicon substrates using a xylene solution of perhydropolysilazane (PHPS) to obtain 0.14-μm-thick PHPS films. The PHPS films obtained were suspended over various acidic and basic solutions at room temperature so that they were exposed to the vapors from the solutions. PHPS-to-silica film conversion was studied by infrared absorption spectroscopy, and the stability of the exposed films in hot water was examined by soaking the films in 80 °C water. The as-deposited PHPS films were found to be dissolved in water. When the PHPS films were suspended over water, the films were partially converted into silica, but the resultant film had low stability in hot water. Higher degrees of PHPS-to-silica conversion and higher stabilities in hot water were found on exposing the PHPS films to basic or acidic vapors. Exposure to highly basic vapors from aqueous solutions of ammonia and ethylamine was significantly effective in PHPS-to-silica film conversion, which provided silica thin films with high stability in hot water.

Characterization of gas barrier silica coatings prepared from perhydropolysilazane films by vacuum ultraviolet irradiation

“…15) Kozuka and co-workers, on the other hand, converted PHPS coatings into silica coatings by exposure to vapor from an aqueous ammonia solution at room temperature. 16) 19) Recently, irradiation of vacuum ultraviolet (VUV) light has been utilized for PHPS-to-silica convertion. 20 …”

Silica film coating method for veneering resin composite

“…Coatings produced by depositing silica are widely used to create gas barriers, chemical corrosion resistance, electrical isolation, mechanical hardness, and various optical features 5,[7][8][9] . Silica coating of steel and plastic materials with silicon alkoxides, such as tetraethylorthosilicate (TEOS: Si(OC2H5)4), has been shown to improve corrosion-resistance and heatresistance of the base materials 10,11) .…”

Formation of Micro and Mesoporous Amorphous Silica-Based Materials from Single Source Precursors

“…R2: Room temperature oxidation followed by heat treatment in air [32] Polymer precursor was converted to amorphous silica-based hybrid by exposing the polymer precursor to vapour from aqueous ammonia (NH 3 ) according to the procedure reported by Kubo et al [28,29]. In this process, 15 mL of aqueous NH 3 was placed in a 200 mL beaker with a slightly open lid and the polymer precursor (ca.…”

“…The PHPS contains many reactive Si-H and N-H groups which can react with chemical modifiers to yield novel ternary or quaternary Si-based non-oxide ceramics [24][25][26][27]. In addition, compared with polysiloxanes often used as a precursor for silica, PHPS can be easily oxidized at low temperatures to yield pure silica in high ceramic yield due to the weight gain as shown in the following equation [28][29][30].…”