Title

High-power impulse magnetron sputter deposition of TiBx thin films: Effects of pressure and growth temperature

Document Type

Article

Publication Date

11-1-2019

Abstract

© 2019 Elsevier Ltd Titanium boride, TiBx, thin films are grown in pure Ar discharges by high-power impulse magnetron sputtering (HiPIMS) from a compound TiB2 target. Film compositions are determined by time-of-flight elastic recoil detection analysis and Rutherford backscattering spectrometry as a function of deposition temperature (Ts = 25–900 °C) and Ar pressure (pAr = 0.67–2.67 Pa, 5–20 mTorr). For reference, films are also grown by direct current magnetron sputtering (dcMS) under similar conditions. The HiPIMS waveform, average target power PT, and resulting film compositions are strongly dependent not only on pAr, but also on Ts. At high pressures the effect of varying Ts on PT is minimal, while at lower pAr the effect of Ts is more pronounced, due to substrate-temperature-induced gas rarefaction. Films grown by HiPIMS at 0.67 Pa are understoichiometric, with B/Ti = 1.4–1.5, while at 2.67 Pa, B/Ti decreases from 2.4 to 1.4 as Ts increases from 25 to 900 °C. dcMS-deposited films are overstoichiometric (B/Ti ≃ 3) when grown at low pressures, and near-stoichiometric (B/Ti ≃ 1.9–2.2) for higher pAr. All experimental results are explained by differences in the ionization potentials of sputtered Ti and B atoms, together with pAr- and Ts -dependent gas-phase scattering.

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