Germanium oxynitride (GeOxNy) as a back interface passivation layer for Germanium-on-insulator substrates

Abstract

This paper describes the development of a GeOxNy surface passivation of germanium, which is mandatory for microelectronics germanium-on-insulator (GeOI) substrate fabrication. Indeed, germanium surface reactivity in ambient atmosphere requires the development of Ge surface passivation in order to provide an electrically acceptable interface between the active layer and the buried oxide (BOX) of GeOI substrates. In this paper, GeOI substrates with a passivation interlayer between the Ge film and the BOX were fabricated using the Smart Cut™ technology. Plasma treatments produced a germanium oxynitride (GeOxNy) passivation interlayer with a nitrogen concentration up to 40% and thickness of 3nm. Electrical activity in such GeOI active layer was investigated with pseudo-metal-oxide-semiconductor field effect transistor measurements. Electron mobility reaches a value of 670cm2V−1s−1, notably higher than those typically reported on nonpassivated GeOI structures.