Nitridation-induced surface donor layer in silicon

Abstract

Thin (11.4 nm) gate quality silicon dioxide films were subjected to high-temperature (850–1150 °C) rapid thermal nitridation cycles in ultrapure ammonia. Secondary-ion mass spectroscopy and neutron depth profiling results indicate a significant level of nitrogen diffusion into the silicon substrate. After stripping the dielectric layers, Schottky diode studies were performed using an electrolyte-based technique. We found, for the first time, the formation of nitridation-induced ultrathin (less than 60 nm) n-type layers at the top surface of nominally p-type silicon substrates used in the study. A nitrogen-oxygen donor complex formation mechanism is invoked to explain the presence of the ultrathin n-type layers.

Nitridation of Thin Gate or Tunnel Oxides by Nitric Oxide

“…[10][11][12][13] Several recipes, mainly consisting of annealing in NH 3 or N 2 O, have been proposed in literature. 3,5,6,[14][15][16][17] It has been shown that NH 3 nitridation incorporates in the oxide a high amount of nitrogen, resulting in a strong barrier to boron and reduction of oxygen vacancies. Nevertheless, such a process leads to generation of many hydrogen-related charge traps.…”