HIGH-TEMPERATURE-ANNEALING EFFECTS ON THE ELECTRICAL-PROPERTIES OF RF-SPUTTERED SNO2 THIN-FILMS FOR MICROELECTRONIC SENSORS

The sheet resistivity rho(s) of thin SnO2 films for microelectronic se nsors and the contact resistivity rho(c) of single layer (Ti, W, Cr) a nd double layer (TiAl, TAu, WAl, WAu, CrAl, CrAl) metal systems to the SnO2 films are investigated. The thin films are RF sputtered and anne aled at temperatures 200-800 degrees C. rho(s) and rho(c) are estimate d separately using a specific resistor-like thin film structure suppli ed with four contacts, corresponding measuring procedure and computati on on the basis of the Transmission Line Model for planar contacts. Sh eet resistivity in the range of 2-5 x 10(3) ohm/square is observed aft er annealing of the thin films at 200 degrees C. After annealing at hi gher temperatures (up to 400 degrees C) rho(s) increases with more tha n three orders of magnitude. Annealing temperatures in the range of 60 0-800 degrees C yield rho(s) similar to 10(4) ohm/square. and very fee ble dependence of rho(s) on the temperature. Strong influence of the c ontacts deposition process on rho(s) is observed for the high resistiv ity thin films (obtained after annealing above 200 degrees C and up to 400 degrees C). Behaviour of the contact resistivity rho(c) similar t o that of rho(s) is observed. Copyright (C) 1996 Elsevier Science Ltd