Method For Providing Semiconductors Having Self-Aligned Ion Implant

A process for forming a foundation element for semiconductor devices comprising the steps of:

• a) providing a wafer of single-crystal wide hand gap material serving as a substrate;
• b) growing a first epitaxial layer of p-type wide band gap material on said substrate with a p doping density less than about 2×1017 cm−3;
• c) growing a first epitaxial layer of n-type wide band gap material on top of said first epitaxial layer of p-type wide band gap material with n-type wide band gap material epilayer having a predetermined doping density, which exceeds twice said p doping density of said first epitaxial layer of p-type wide band gap material and with a preselected n-type epilayer thickness, wherein said n-type epilayer doping density and said n-type epilayer thickness are selected to provide a desired junction field effect transistor threshold voltage;
• d) growing a first epitaxial layer of a highly conductive p+ type wide band gap material of p+ thickness which is about less than said preselected n-type eiplayer thickness, said first epitaxial layer of p+ type wide band gap material having a p+ doping density selected to be greater than twice said n-type epilayer doping density of wide band gap material, said growing of said first epitaxial p+ type wide band gap material being on top of said first epitaxial layer of n-type wide band gap material;
• e) depositing and patterning a first masking layer of a predetermined thickness on top of said first epitaxial layer of highly conductive p+ type material so as to form a first element of a p+ gate region;
• f) etching so as to (1) remove all of said first epitaxial layer of said highly conductive p+ type wide band gap material, except for a portion laying under said first masking layer so as to form a second element of said p+ gate region with said second element of said p+ gate region having a top surface, said etching also (2) removing a portion of the top surface of said epitaxial layer of said first epitaxial layer of n-type wide band gap material so as to form an exposed n-type wide band gap material surface, said etching also leaving a portion laying under said second element of said p+ gate region that forms a third element of said p+ gate region, wherein said first, second and third elements form said p+ gate region;
• g) performing a self-aligned implant of n-type dopant into a self-aligned implant region that is provided by a union of both of said exposed n-type wide band gap material surface and said first element of said p+ gate region, said self-aligned implant having a region abutting said p+ gate regions and. extending outward therefrom, said self-aligned implant of n-type dopant having a (1) first peak doping (2) first peak depth, and (3) first straggle into the said p+ gate region, said self-aligned implant further having (4) a second peak doping (5) a second peak depth, and (6) a peak straggle into said n-type epitaxial layer of n-type wide band gap material beneath said exposed n-type wide band gap material surface, wherein:
• the sum of said first peak depth plus said first straggle is less than the sum of said p+ thicknesses of the highly conductive p+ type wide band gap material and said first masking layer predetermined thickness;
• said first peak doping being less than 50% of the said p+ doping density of the said highly conductive first epitaxial layer of highly conductive p+ type wide band gap material;
• said second peak doping being greater than twice the said n-type epilayer doping density of said first layer of n-type wide band gap material;
• h) depositing and patterning a second masking layer having a predetermined thickness on (1) said p+ gate region and (2) said nitrogen-implant region abutting said p+ gate region and extending outward therefrom,
• i) etching so as to form a n-channel mesa by progressively removing said p+ type, n-type and p-type wide band gap materials to a depth that removes all of the said first epitaxial layer of p+ type wide band gap material and first epitaxial layer n-type wide band gap material except in predetermined regions beneath said first masking layer and said second masking layer.