METHODS OF FABRICATING A SI BJT, AND CORRESPONDING DEVICES

A method of manufacturing a Si BJT device is disclosed comprising prior processing steps; formation of a protective oxide layer over an active area of the Si BJT device; deposition of a dielectric layer, and a layer stack comprising SiGe, on the protective oxide; etching the dielectric layer, and the layer stack comprising SiGe, thereby removing them from the active area of the Si BJT; deposition of a polysilicon layer, and a further dielectric layer, across the device; etching the polysilicon base, and the further dielectric layer thereby removing it from the active area; implanting, through the protective oxide layer, a p-type dopant into the active area; etching the protective oxide layer, thereby removing it, and leaving voids under the dielectric layer; thermally treating the Si BJT device, thereby filling in voids under the polysilicon base; and subsequent processing steps. Corresponding devices are also disclosed.