Radical Modification of Gate Oxide by Lateral Gettering of Electroactive Centers

Abstract

An approach to radically modifying gate dielectric by laterally gettering electroactive defects (centers) is suggested. Gettering of the ionized centers is accomplished through intentionally creating structure defects in the surface layers of the side oxide that are adjacent to the periphery of the gate oxide. The process was carried out at low temperatures, e.g., during postmetallization annealing in a hydrogen-free atmosphere. The structure defects in the side oxide capture excessive hydrogen, which otherwise produces ionized donors in the gate oxide layer. If the gate size is comparable to the hydrogen diffusion length (5–10 μm), ionized acceptor centers of concentration no more than 1011 cm–2 dominate in the gate oxide after annealing. This is apparently related to the minimization of excessive hydrogen content in the gate oxide of structures with small lateral dimensions.