FTIR Analysis of Oxidized Tungsten and Tungsten Diboride Nanolayers

Abstract

Tungsten (W) and tungsten diboride (WB₂) materials can be used to fabricate electron emission layers in field emission microelectronic devices. The characterization and quality assurance of synthesized films is crucial for the good performance of the devices. W and WB₂ nanofilms with a thickness of 150 nm and 200 nm were deposited on the Si-SiO₂ substrate by the magnetron sputtering technique. The synthesized layers were thermally treated in a thermal analysis device under various gas flow conditions (varying Ar; N₂; synthetic air; air with O₂, N₂, and moisture (further in this text – laboratory air)) and after oxidation, FTIR (Fourier transform infrared spectrometry) spectra were registered. FTIR spectra of the as-deposited layers showed weak peaks related to Si-O and Si-O-Si bonds from the substrate and considered for the analysis of the layers. Several new peaks occur in the spectra of the thermally treated layers. Of the oxidation layers, new peaks related to nanolayers, were observed W-O bonds, it is noticeable that the spectra vary with each other with signal intensity and offsets. In each experimental environment with various gas flow conditions, there were W=O bonds observed, also in every environment except in laboratory air with the flow, B-O bond was detected for about 1300 – 1350 cm^-1 range. It was shown that thermal oxidation of W and WB₂ layers can be applied for the analysis of W and WB₂ layers on SiO₂ substrate by forming W and B oxides using treatment in high temperature and detection of their bonds by FTIR.