Formation process and material properties of reactive sputtered IrO2 thin films

IrO2 thin films were deposited by reactive sputtering in various O-2/(O-2 Ar) mixing ratios (OMR). The systematic study of the OMR effect on the pro perties of IrO2 thin films has been reported. It was found that the formati on of IrO2 could be classified into two classes, depending on the O-2 flow ratio. At low OMR (10-30%), the Ir target and Si substrate were not oxidize d and a high deposition rate and high crystallinity IrO2 could be obtained. On the other hand, at high OMR(> 30%), the target and Si substrate were ox idized. It resulted in a lower deposition rate of IrO2 and yielded poor str uctural properties. Moreover, the high OMR provided O atoms, incorporated i nto the IrO2 thin film. This point could be confirmed by X-ray photoelectro n spectroscopy. The excess O defects would also make the resistivity of IrO 2 increase as the samples were prepared at high OMR. The effect of substrat e temperature on the resistivity was also discussed. It was found that the resistivity of the IrO2 films decreased with an increase of the substrate t emperature and a minimum resistivity of 70 mu Omega cm was obtained as film s deposited at 600 degreesC using 10% OMR. (C) 2000 Elsevier Science S.A. A ll rights reserved.