Effects of H2 High-pressure Annealing on HfO2/Al2O3/In0.53Ga0.47As Capacitors: Chemical Composition and Electrical Characteristics

We studied the impact of H-2 pressure during post-metallization annealing on the chemical composition of a HfO2/Al2O3 gate stack on a HCl wet-cleaned In0.53Ga0.47As substrate by comparing the forming gas annealing (at atmospheric pressure with a H-2 partial pressure of 0.04 bar) and H-2 high-pressure annealing (H-2-HPA at 30 bar) methods. In addition, the effectiveness of H-2-HPA on the passivation of the interface states was compared for both p-and n-type In0.53Ga0.47As substrates. The decomposition of the interface oxide and the subsequent out-diffusion of In and Ga atoms toward the high-k film became more significant with increasing H-2 pressure. Moreover, the increase in the H-2 pressure significantly improved the capacitance. voltage characteristics, and its effect was more pronounced on the p-type In0.53Ga0.47As substrate. However, the H-2-HPA induced an increase in the leakage current, probably because of the out-diffusion and incorporation of In/Ga atoms within the high-k stack.