Patent ID: 6995068

Claim:
A method of forming a varactor device on a semiconductor substrate, comprising the steps of: forming a buried layer in said semiconductor substrate, said semiconductor substrate having a first conductivity type and said buried layer having a second conductivity type; providing an epitaxial layer situated in said semiconductor substrate, said epitaxial layer having said first conductivity type, wherein said epitaxial layer is situated over said buried layer; providing an isolation structure on said semiconductor substrate, said isolation structure defining an implant region, said implant region being situated over said epitaxial layer; selecting a first peak dopant concentration and a first implant energy such that at least one of capacitance, leakage current, and tuning range of the varactor device is optimized; forming a first implant in said epitaxial layer using said first implant energy, said first implant having said first peak dopant concentration and said first conductivity type, wherein said first implant extends into said epitaxial layer a first distance, and wherein said first implant is situated over said buried layer; forming a second implant in said epitaxial layer using a second implant energy, said second implant having a second peak dopant concentration and said first conductivity type, wherein said second implant extends into said epitaxial layer a second distance, wherein said second distance is greater than said first distance, wherein said second implant is situated over said buried layer, and wherein said second peak dopant concentration has a depth that is greater than a depth of said first peak dopant concentration.