The effect of blocking layer of Al2O3 on thermal stability and electrical properties of HfO2 dielectric films deposited on SiGe layer

HfO2 dielectric films with a blocking layer (BL) of Al2O3 on Si0.8Ge0.2 were treated with rapid thermal annealing process. The effect of BL on thermal stability and electrical properties was reported. X-ray photoelectron spectroscopy suggested that BL could suppress the further growth of the interfacial layer composed of SiOx and GeOx, and lead to the decomposition of GeOx and the saturation of O vacancy in SiOx structure. High-resolution transmission electron microscopy indicated that BL would keep HfO2 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.