Microstructure and corrosion resistance of room-temperature RF sputtered Ta2O5 thin films

The connection between the chemical corrosion resistance and the microstruc ture of the Ta2O5 thin films prepared at room temperature by a RF magnetron sputtering technique on Si substrates has been investigated. We find that the microstructure of the films changes with different RF sputtering power, and is responsible for the degradation of the corrosion resistance in HF s olutions. The deposited films are amorphous and porous when the RF power is low. A preferred orientation toward (200) beta-Ta2O5 can be observed when the RF power is increased to 150 W. In addition, the films deposited under this condition are dense and are consequently more resistant to the attack of chemicals. At an RF power of 300 W the corrosion resistance of the films declines due to an increase of the exposed pore surface to the HF solution .