The effect of blocking layer of Al_2O_3 on thermal stability and electrical properties of HfO_2 dielectric films deposited on SiGe layer

摘要

HfO_2 dielectric films with a blocking layer (BL) of Al_2O_3 on Si_(0.8)Ge_(0.2) were treated with rapid thermal annealing process. The effect of BL on thermal stability and electrical properties was reported. X-ray pho-toelectron spectroscopy suggested that BL could suppress the further growth of the interfacial layer composed of SiO_x and GeO_x, and lead to the decomposition of GeO_x and the saturation of O vacancy in SiO_x structure. High-resolution transmission electron microscopy indicated that BL would keep HfO_2 amorphous after annealed treatment. Electrical measurements indicated that there was no stretch-out in capacitance-voltage curves, the accumulation region was flat, and leakage current was reduced for the sample with BL.