SIO2-TA2O5 SPUTTERING YIELDS - SIMULATED AND EXPERIMENTAL RESULTS

To improve the coating of mirrors, we have modelized the sputtering of binary oxide targets using the TRIM code. Firstly, we have proposed a method to calculate TRIM input parameters using on the one hand the t hermodynamic cycle and on the other hand Malherbe's results. Secondly, an iterative processing has been provided for oxide steady targets ca used by ionic bombardment. Thirdly, we have exposed a model to get exp erimental sputtering yields. Fourthly, for the (Ar-SiO2) pair, we have determined that the steady target is a silica one. A good agreement b etween simulated and experimental yields versus ion incident angle has been found. For the (Ar-Ta2O5) pair, we have to introduce the prefere ntial sputtering concept to explain the discrepancy between simulation and experiment. In this case, the steady target is tantalum monoxide. For the (Ar-Ta(+O-2)) pair, tantalum sputtered by argon ions in a rea ctive oxygen atmosphere, we have to take into account a new concept of oxidation stimulated by an ion beam. We have supposed that the tantal um target becomes a Ta2O5 one in a reactive oxygen atmosphere. Then, t he subsequent mechanism is similar to that of the previous pair. We ha ve obtained a steady target of tantalum monoxide too. Comparison betwe en simulated and experimental sputtering yields versus ion incident an gle has given a very good agreement. By simulation, we have found that the tantalum monoxide target has a thickness of at least 1.5 nm. Thes e results are compatible with those of Malherbe and Taglauer.