Patent ID: 6838731

Claim:
A microwave transistor structure having a step drain region comprising: a substrate having a top surface; a silicon semiconductor material of a first conductivity type, said silicon semiconductor material having a first dopant concentration and a top surface; said silicon semiconductor material overlaying said top surface of said semiconductor substrate; a conductive gate overlying and insulated from said top surface of said silicon semiconductor material; at least one horizontal drain extension region formed completely within said silicon semiconductor material, said horizontal drain extension region being of a second conductivity type and having a horizontal drain extension dopant concentration; a step drain region formed in said silicon semiconductor material; said step drain region contacting said horizontal drain extension region; a body region formed in said silicon semiconductor material, said body region being of said first conductivity type and having a body region dopant concentration, said body region dopant concentration being equal or greater than said first dopant concentration, said body region having a first end underlying said conductive gate, any remaining portion of said silicon semiconductor material underlying said gate being of said first conductivity type; a source region formed in said silicon semiconductor material, said source region being of said second conductivity type and having a source region dopant concentration, said source region being located within said body region; a shield plate region formed on said top surface of said silicon semiconductor material over a portion of said horizontal drain extension region, said shield plate being adjacent and parallel to said horizontal drain extension region; said shield plate being adjacent and parallel to said conductive gate region; a bottom of said shield plate extending above said top surface of said silicon semiconductor material, said bottom surface of said shield separated from said top surface of said silicon semiconductor material by a shield plate distance, said shield plate being insulated from said top surface of said silicon semiconductor material; and a conductive plug region.