Effects of H High-pressure Annealing on HfO/AlO/InGaAs Capacitors: Chemical Composition and Electrical Characteristics.

We studied the impact of H pressure during post-metallization annealing on the chemical composition of a HfO/AlO gate stack on a HCl wet-cleaned InGaAs substrate by comparing the forming gas annealing (at atmospheric pressure with a H partial pressure of 0.04 bar) and H high-pressure annealing (H-HPA at 30 bar) methods. In addition, the effectiveness of H-HPA on the passivation of the interface states was compared for both p- and n-type InGaAs 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 pressure. Moreover, the increase in the H pressure significantly improved the capacitance‒voltage characteristics, and its effect was more pronounced on the p-type InGaAs substrate. However, the H-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.