Electrical Properties of SiGe MOS Capacitors with Ultrathin ALD Hafnium Dioxide

Ultra thin HfO2 high-k gate dielectric has been deposited directly on Si0.81Ge0.19 by the atomic layer deposition (ALD) process. HfO2 layers were characterized by grazing incidence x-ray diffraction (GIXRD) to examine crystallinity. In this work it is shown that MIS capacitors annealed in N2 ambient show better electrical properties than the samples annealed in O2 and mixed gas ambient (O2 and N2) and without annealing. Furthermore, trapping and detrapping behavior of charge carriers in N2 annealed ultrathin HfO2 gate dielectrics during constant current stress (CCS) and constant voltage stress (CVS) has been investigated in detail.