Patent ID: 6387769
Filing Date: 2002-05-14
Classification: H01L

Abstract:
A method of producing a Schottky varicap (25) using the following steps:(a) providing an epitaxial layer (12) on a semiconductor substrate (1), the epitaxial layer (12) having an upper surface and being of a first conductivity type; (b) providing an insulating layer, and patterning the insulating layer to provide an insulating film on a predetermined area of said surface of said epitaxial layer (12), said insulating film comprising an oxide film (4) contacting the epitaxial film (12) on said predetermined area and a silicon nitride film (5) above the oxide film (4); (c) depositing a polysilicon layer (6) of a second conductivity type; (d) applying a first high temperature step to diffuse a guard ring (10) of said second conductivity type into the epitaxial layer (12) around said first predetermined area; (e) removing a predetermined portion of said polysilicon layer (6) to expose said first silicon nitride film (5); (f) implanting atoms through at least said first oxide film (4) to provide said epitaxial layer with a predetermined varicap doping profile; (g) applying a second high temperature step to anneal and activate said varicap doping profile; (h) removing said first oxide film (4) to provide an exposed area of said upper surface of said epitaxial layer (12) with the predetermined varicap doping profile; (i) providing a Schottky electrode (17) on said exposed area.