Patent ID: 7005686
Filing Date: 2006-02-28
Classification: H01L

Abstract:
1. A silicon controlled rectifier for directing electrostatic discharge current between an input pad and a ground rail, said rectifier comprising: a semiconductor substrate with a first conductivity type and having an upper surface; a first region in said semiconductor substrate at said upper surface, wherein said first region has a second conductivity type; a second region in said semiconductor substrate at said upper surface, wherein said second region has said first conductivity type and is electrically connected to said input pad; a third region in said semiconductor substrate at said upper surface, wherein said third region has said second conductivity type and is electrically connected to said ground rail; a fourth region in said semiconductor substrate at said upper surface, wherein said fourth region has said first conductivity type; a first well in said semiconductor substrate at said upper surface, wherein said first well has said second conductivity type and wherein said first region and said second region are in said first well; and, a second well in said semiconductor substrate at said upper surface, wherein said third region is in said second well, wherein said second well extends to a same depth as said first well, wherein said second well has said second conductivity type and wherein said discharge current flows from said first well around a lower surface of said second well to said fourth region prior to said rectifier turning on.