Dielectric separation type semiconductor device, e.g. silicon on insulator diode, comprises first auxiliary dielectric layer having portion junctioned to second main surface of primary dielectric layer

摘要

A dielectric separation type semiconductor device (100) comprises a first auxiliary dielectric layer disposed immediately below a second semiconductor layer, and having at least a portion junctioned to a second main surface of a primary dielectric layer (3). A dielectric separation type semiconductor device comprises: a primary dielectric layer disposed adjacent to a whole region of a first main surface of a semiconductor substrate; a first conductivity type first semiconductor layer (2) of a low impurity concentration disposed on a surface of the primary dielectric layer, in opposition to the semiconductor substrate, so that the primary dielectric layer is sandwiched between the first conductivity type first semiconductor layer and semiconductor substrate; a first conductivity type second semiconductor layer of a high impurity concentration formed selectively on the surface of the first semiconductor layer; a second conductivity type third semiconductor layer of a high impurity concentration disposed to surround an outer peripheral edge of the first semiconductor layer with a distance; a ring-like insulation film (9, 11) disposed to surround an outer peripheral edge of the third semiconductor layer; a first main electrode (6, 7) disposed in contact with a surface of the second semiconductor layer; a sheet-like back-surface electrode (8) disposed adjacent to a second main surface of the semiconductor substrate, on a side opposite to the first main surface of the semiconductor substrate; and a first auxiliary dielectric layer disposed immediately below the second semiconductor layer, and having at least a portion junctioned to a second main surface of the primary dielectric layer. An Independent claim is also included for a method of manufacturing a dielectric separation type semiconductor device in the form of a high-voltage-rated lateral array type semiconductor device implemented in a dielectric-isolated substrate and having a first main electrode and a second main electrode, which is formed to surround the first main electrode, and including a semiconductor substrate disposed on a back surface side of the dielectric-isolated substrate to serve as a pedestal (base), comprising removing the semiconductor substrate by etching with potassium hydroxide within a region, which covers the first main electrode and extends over an area of a size not less than40% of a distance between the first and second main electrodes; forming a first buried insulation film in the region; and forming a second buried insulation in the region immediately below the first buried insulation film in contact with it.