Patent ID: 7824967
Filing Date: 2010-11-02
Classification: H01L

Abstract:
1. A method for the fabrication of a monolithically integrated light-activated thyristor, comprising: positioning a lightly-doped n-type semiconductor wafer between two p-type layers, a base layer and an anode layer, wherein the base layer is lightly doped and the anode layer is heavily doped; forming an n-type emitter layer on top of the p-type base layer, by coating the top surface of the p-type base layer with a masking layer and photolithographically removing portions of the masking layer to form a plurality of cathode shorts and gate contacts; forming a p-type doping zone in the emitter layer by introducing a second masking pattern covering the top surface of the emitter layer; forming a n-type doping zone within the p-type doping zone by introducing via a masking pattern a n-type doping zone on top of the p-type doping zone to form a PN junction that acts as a switching diode; depositing an insulating layer that is transparent to light over the top surface of the semiconductor body; forming an anode electrode coupled to a bottom surface; opening portions of the insulating layer to form the cathode and gate electrodes, wherein the n-type emitter layer and the p-type zone of the switching diode are electrically shorted by the cathode, and wherein the insulating layer is transparent to light; forming optical apertures, a first aperture being an optical opening of the cathode electrode over the emitter layer, a second aperture being an optical opening over the junction area of the embedded switching diode; and linking the gate and the diode cathode contact by first masking the top surface with a pattern and interconnecting with subsequent metallization over the insulation layer, such that a floating gate comprised of the interconnect, the gate, and the diode cathode is kept floating and diverts the thyristor current when the embedded switching diode is shorted by light.