Method of Low-Temperature Conversion of Pehydropolysilazane into Amorphous SiOx in Aqueous Solutions

We investigated low-temperature SiOx conversion methods for the spin-coated perhydropolysilazane (a diluted dibutyl-ether solution) films prepared on (100) Si substrates under different curing schemes. From the Fourier transform-infrared (FTIR) spectroscopy and refractive index (RI) measurements, conversion to high-density SiOx was observed for the curing methods of dipping the coatings into various aqueous solutions such as H2O2, NH4OH, and deionized water with or without 405-nm ultraviolet irradiation at near room temperature. The SiOx films cured in H2O2 solution at 80 ?C for 10 min exhibited a high conversion efficiency for the SiOx network, as observed from FTIR spectra, RI measurement (?1.46), O/Si stoichiometry (?1.5), surface smoothness (roughness <1.1 nm), and mechanical property (nanoindenter elastic modulus ?42 GPa), which are comparable to those of the conventional chemical-vapor-deposited SiOx films.