Crystallization control of sputtered Ta2O5 thin films by substrate bias

This letter reports that, by applying a bias to Si substrates, crystalline tantalum pentoxide (Ta2O5) thin films were fabricated at low substrate temperatures. At 620 °C, it was found that the thin films as-prepared are amorphous without the bias and of high crystallinity with the bias over −100 V. Based on the present data, it is concluded that the crystallinity of the thin films is improved with increasing bias. Furthermore, when the bias was increased to −200 V, partially crystallized films could be attained at temperatures as low as 400 °C. The bias effect on the crystallization is attributed to the interaction of positive ions in the plasma with the growing surface.