SrTiO3-based sensors for in situ monitoring of trace levels of oxygen

Abstract

Semiconductive dielectric SrTiO3 thin films are promising candidates for the in situ monitoring of trace levels of oxygen in semiconductor manufacturing processes. Highly sensitive oxygen sensors were prepared by atomic-layer deposition (AlD) or pulsed-laser deposition (PlD) of SrTiO 3; however, there was a problem with AlD-SrTiO3 that surface defects, such as SrO surface segregation with a minor contribution from SrO2, affected the detection below an oxygen concentration [P O2/(PO2 + PHe)] of 1.1 × 10 -12, causing the reversion of AlD-SrTiO3 to a slightly high-resistance state. The coverage of the segregated surface of SrO and SrO2 on the AlD-SrTiO3 was considerably higher than that observed on the PlD-SrTiO3 surface, however, the reversion could be markedly suppressed by the additional thermal treatment, probably owing to gathering small SrO-based surface islands (building-up of bigger islands), resulting in the exposure of clean surfaces. ©2010 The Ceramic Society of Japan. All rights reserved.