Radiation Properties of Silicon Metal-Oxide-Semiconductor Structures with Zinc-Doped Oxides

Abstract

In this paper we present the results of investigation of radiation-induced effects in metal-oxide-semiconductor (MOS) structures with oxides doped with moderate amounts of zinc during the oxide growth. It is shown through secondary ion mass spectroscopy (SIMS) analysis that zinc, when present in the oxidation ambient, is effectively incorporated into the oxide matrix. Electrophysical parameters of the modified MOS structures are similar to those of the reference ones. On the other hand, radiation sensitivity of zinc-doped structures is significantly affected. While observing an enhanced radiation-induced positive charge buildup, we have found that the Si-SiO2 interface and the near-surface silicon region were significantly hardened in these structures. The observed effects strongly depend on the amount of zinc incorporated in the oxide. It is also shown that postirradiation low-temperature annealing can result in the improvement of the oxide and the Si-SiO2 interface characteristics. The main parameters characterizing the system, namely, the oxide charge, the density of interface states, and the minority carrier generation lifetime, are improved after the irradiation-then-annealing treatment compared to those of simply postmetallization-annealed MOS structures. A simple model to explain the observed radiation-induced ordering effect is also presented.