H-2 High Pressure Annealed Y-Doped ZrO2 Gate Dielectric With an EOT of 0.57 nm for Ge MOSFETs

Abstract

We report on the impact of H-2 high pressure annealing (H-2-HPA) on a Y-doped ZrO2 (Y-ZrO2)/GeOx/Ge gate stack. In this paper, compared to conventional forming gas annealing (FGA), the H-2-HPA increased the k-value of the Y-doped ZrO2 gate dielectric to as high as 47.8 by enhancing the crystallization of the Y-ZrO2. This process can achieve an aggressively scaled equivalent oxide thickness (EOT) of 0.57 nm with an extremely low gate leakage current (J(g)) of 4.5 x 10(-6)A/cm(2). In addition, the H-2-HPA effectively passivated the dangling bonds and reduced the interface trap density (D-it) to as low as 3.4 x 10(11)eV(-1)cm(-2). The Ge pMOSFETs of the Y-ZrO2 with H-2-HPA led to a similar to 70% improvement in the effective hole mobility compared to the counterpart device with the conventional FGA. The device with H-2-HPA also showed an improved subthreshold swing (SS) value of 93 mV/dec compared to that with the FGA (135 mV/dec).