Method of forming a hyperabrupt interface in a GaAs substrate

Abstract

A method of fabricating improved semiconductor devices, such as FET's, wh require or are improved by a hyperabrupt interface between the active channel and the underlying insulating region. A substrate, such as GaAs, is polished and then implanted with light ions, such as protons, to amorphize the crystal structure down to a certain depth determined by the ion-beam accelerating voltage and the ion fluence level. The crystal is damaged but not amorphized below the lowest amorphization depth. The interface between the amorphized and the non-amorphized, but damaged, regions is a relatively narrow region which will become a hyperabrupt junction. The substrate is then implanted with donor ions, such as Si, in accordance with the requirements of the device to be fabricated and under conditions which provide a retrograde donor ion concentration profile with depth. An annealing/donor activating step is now performed at a relatively low temperature (600.degree. C. or less) to avoid breaking down the hyperabrupt interface.

Dependencies are inferred from the claim text.