Electrical properties of sputter deposited SrTiO3 gate dielectrics

We report the electrical properties of gate dielectric SrTiO3 (STO) thin films on Si substrates grown by radio-frequency magnetron sputtering. The interfacial layer between STO and Si degrades the performance of the gate dielectric. We used SiON as a sacrificial layer for incorporating nitrogen into Si substrate surface, which can retard the formation of interfacial layer during the high temperature growth of STO gate dielectric. The polycrystalline STO film grown on nitrogen incorporated Si substrate exhibited lower leakage current due to better interfacial properties and higher dielectric constant. The repeated spike heating technique was also employed to deposit polycrystalline STO film for improving the thermal uniformity of the wafer, which leads to lower gate leakage current. The processing parameters including working pressure, oxygen mass ratio and plasma power also show obvious effect on the electrical properties of the films.