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

Abstract

We investigated low-temperature SiO x 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 SiO x was observed for the curing methods of dipping the coatings into various aqueous solutions such as H 2 O 2 , NH 4 OH, and deionized water with or without 405-nm ultraviolet irradiation at near room temperature. The SiO x films cured in H 2 O 2 solution at 80 °C for 10 min exhibited a high conversion efficiency for the SiO x 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 SiO x films.