Method of passivating pn-junction in a semiconductor device

Abstract

The surface termination of a p-n junction of a semiconductor device is passivated with semi-insulating material which is deposited on a thin layer of insulating material formed at the bared semiconductor surface by a chemical conversion treatment at a temperature above room temperature. The layer may be formed by oxidizing the semiconductor material of the body for example in dry oxygen between 300.degree. C. and 500.degree. C. or in an oxidizing liquid containing for example hydrogen peroxide or nitric acid at for example 80.degree. C. The layer is sufficiently thin to permit conduction (e.g. by tunnelling) between the semi-insulating material and the surface but thick enough to reduce said conduction so that when the junction is reverse-biased leakage current flows further along the semi-insulating material before flowing out to the surface across the layer. This increases the spread of the junction depletion layer along the surface thereby permitting a high breakdown voltage even with a high resistivity for the material. The thin layer can also act as a barrier against gettering of lifetime-killers (e.g. gold) from the semiconductor body by the semi-insulating material. The semi-insulating material may be based on amorphous or polycrystalline silicon or a chalcogenide.

Dependencies are inferred from the claim text.