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 deg. 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 deg. C. The bias effect on the crystallization is attributed to the interaction of positive ions in the plasma with the growing surface