Method of forming a bi-directional diode and structure therefor
View Patent ↗In one embodiment, a bi-directional diode structure is formed to have a substantially symmetrical current-voltage characteristic.
1. A method of forming a bi-directional diode comprising:
forming a first doped region overlying a semiconductor region of a first conductivity type and a first doping concentration wherein the first doped region has a second conductivity type and a second doping concentration;
forming a second doped region of the first conductivity type within the first doped region;
forming a third doped region of the first conductivity type within the first doped region and spaced a first distance from the second doped region and having a third doping concentration wherein a differential doping concentration between the first doped region and the third doped region is greater than a differential doping concentration between the first doped region and the semiconductor region; and
reducing a recombination lifetime of carriers within the first doped region subsequently to forming the second and third doped regions.
2. The method of claim 1 wherein forming the first doped region includes forming the first doping concentration and the second doping concentration to have a differential doping concentration that is less than a differential doping concentration between the second and third doping concentrations.
3. The method of claim 2 wherein forming the second doped region includes forming the second doped region with the first conductivity type and a fourth doping concentration wherein a differential doping concentration between the second and fourth doping concentrations is greater than the differential doping concentration between the first and second doping concentrations.
4. The method of claim 3 wherein forming the third doped region includes forming the third doped region with an inner periphery that surrounds a periphery of the second doped region.
5. The method of claim 1 wherein forming the third doped region includes forming the third doped region no greater than about twenty five microns from the second doped region.
6. The method of claim 1 wherein reducing the carrier recombination lifetime within the first doped region includes irradiating the bi-directional diode with one of particle bombardment, an electron beam, a proton beam, a neutron beam, or gamma particles prior to assembling the bi-directional diode into a semiconductor package.
7. The method of claim 6 wherein irradiating the bi-directional diode includes irradiating the bi-directional diode at a dose of no less than 32 Kgy.
8. A method of forming a diode comprising:
providing a semiconductor substrate of a first conductivity type and a first doping concentration and having a surface;
forming a semiconductor region overlying at least a portion of the semiconductor substrate wherein the semiconductor region has a second conductivity type and a second doping concentration that is less than the first doping concentration;
forming a first diode within the semiconductor region including forming a first doped region within the semiconductor region and having a third doping concentration that forms a differential doping concentration with the semiconductor region that is greater than a differential doping concentration between the semiconductor substrate and the semiconductor region; and
reducing a carrier recombination lifetime within the first portion of semiconductor region.
9. The method of claim 8 further including forming a second diode in the semiconductor region and spaced a first distance from the first diode wherein a first portion of the semiconductor region forms a drift region for current flow between the first diode and the second diode; and wherein forming the first diode and forming the second diode includes forming a second portion of the semiconductor region underlying the first diode and having a thickness no greater than about twenty five microns, and forming a third portion of the semiconductor region underlying the first diode and having a thickness no greater than about twenty five microns.
10. A method of forming a diode comprising:
providing a semiconductor substrate of a first conductivity type and a first doping concentration and having a surface;
forming a semiconductor region overlying at least a portion of the semiconductor substrate wherein the semiconductor region has a second conductivity type and a second doping concentration that is less than the first doping concentration;
forming a first diode within the semiconductor region;
forming a second diode in the semiconductor region and spaced a first distance from the first diode wherein a first portion of the semiconductor region forms a drift region for current flow between the first diode and the second diode; and wherein forming the first diode and the second diode includes forming a first doped region within the semiconductor region and having the first conductivity type and a third doping concentration that is less than the second doping concentration, and forming a second doped region within the semiconductor region and having the first conductivity type and the third doping concentration; and
reducing a carrier recombination lifetime within the first portion of semiconductor region.