Effects of annealing conditions on humidity-sensing characteristics of SrNbxTi1-xO3 thin-film resistor on SiO 2/Si substrate

Abstract

Strontium titanate-niobate (SrNbxTi1-xO3) film deposited on SiO2/Si substrate by argon ion-beam sputtering technique is used to fabricate thin-film resistors by standard integrated-circuit technology. Effects of annealing conditions on their humidity-sensing characteristics were studied. Four cases were considered: 400 °C 20 min in N2; 400 °C 20 min, 400 °C 4 h and 600 °C 4h in O2. Experimental results showed that, as compared to the N2-annealed device, the O2-annealed devices have higher humidity sensitivity and faster response. Based on scanning electron microscope (SEM) study and adsorption-isotherm analysis, it can be concluded that oxygen annealing is helpful for grain growth, thus resulting in a higher porosity of the film. Among the four cases, 400 °C 4h in O2 is the best annealing condition, which gives rise to the highest porosity and an appropriate pore-volume distribution for improving the humidity sensitivity. © 2003 Elsevier B.V. All rights reserved.