Structural and electrical properties of yttria-stabilized zirconia films with controlled Y content heteroepitaxially grown on Si by reactive sputtering

Yttria-stabilized zirconia (YSZ) films with controlled Y content were heteroepitaxially grown on (100) Si substrates by dc magnetron sputtering using Y and Zr metallic targets. Y content was controlled by in-situ position control of high-density-plasma region. It is found that the deposited films of the thickness of 100 nm with the Y content between 2.3 and 19.7 at.% have the (100) cubic YSZ structure directly on (100) Si, while that with the Y content of 1.2 at.% has the (100) monoclinic (ZrO2)1−x(Y2O3)x structure on (100) Si with a (100) cubic YSZ intermediate layer. The monoclinic structure is found to be changed from the cubic structure during the cooling process after the deposition. On the other hand, the films of the thickness of 10 nm with the Y content between 1.2 and 19.7 at.% have the (100) YSZ cubic structure on (100) Si regardless of the Y content. Both the hysteresis width in capacitance–voltage (C–V) characteristics due to the ion drift and the leakage current are small for the film of the thickness of 100 nm with the Y content of 1.2 at.% compared with those with the Y content between 2.3 and 19.7 at.%. On the other hand, the opposite properties are observed for the films of 10 nm thickness.