Soi lateral bipolar junction transistor having a wide band gap emitter contact

Abstract

A lateral heterojunction bipolar transistor is formed on a semiconductor-on-insulator substrate including a top semiconductor portion of a first semiconductor material having a first band gap and a doping of a first conductivity type. A stack of an extrinsic base and a base cap is formed such that the stack straddles over the top semiconductor portion. A dielectric spacer is formed around the stack. Ion implantation of dopants of a second conductivity type is performed to dope regions of the top semiconductor portion that are not masked by the stack and the dielectric spacer, thereby forming an emitter region and a collector region. A second semiconductor material having a second band gap greater than the first band gap and having a doping of the second conductivity type is selectively deposited on the emitter region and the collector region to form an emitter contact region and a collector contact region, respectively.

1 . A semiconductor structure comprising a bipolar junction transistor (BJT), wherein said BJT comprises:
 a base region comprising a first portion of a first semiconductor material having a first band gap and having a doping of a first conductivity type;   an emitter region comprising a second portion of said first semiconductor material, having a doping of a second conductivity type that is the opposite of said first conductivity type, and laterally contacting said base region; and   an emitter contact region comprising a portion of a second semiconductor material having a second band gap that is greater than said first band gap, having a doping of said second conductivity type, contacting said emitter region, and not in physical contact with said base region.   
     
     
         2 . The semiconductor structure of  claim 1 , wherein said BJT further comprises a collector region comprising a third portion of said first semiconductor material, and having a doping of said second conductivity type, laterally contacting said base region, and spaced from said emitter region by said base region. 
     
     
         3 . The semiconductor structure of  claim 2 , wherein said BJT further comprises a collector contact region comprising another portion of said second semiconductor material, having a doping of said second conductivity type, and contacting said collector region. 
     
     
         4 . A semiconductor structure comprising a bipolar junction transistor (BJT), wherein said BJT comprises:
 a base region comprising a first portion of a first semiconductor material having a first band gap and having a doping of a first conductivity type;   an emitter region comprising a second portion of said first semiconductor material, having a doping of a second conductivity type that is the opposite of said first conductivity type, and laterally contacting said base region;   an emitter contact region comprising a portion of a second semiconductor material having a second band gap that is greater than said first band gap, having a doping of said second conductivity type, and contacting said emitter region; and   a collector region comprising a third portion of said first semiconductor material, and having a doping of said second conductivity type, laterally contacting said base region, and spaced from said emitter region by said base region,   
       wherein said emitter region and said collector region have the same dopant concentration of dopants of said second conductivity type. 
     
     
         5 . The semiconductor structure of  claim 2 , further comprising an insulator layer having a planar top surface that contacts said base region, said emitter region, and said collector region. 
     
     
         6 . A semiconductor structure comprising a bipolar junction transistor (BJT), wherein said BJT comprises:
 a base region comprising a first portion of a first semiconductor material having a first band gap and having a doping of a first conductivity type;   an emitter region comprising a second portion of said first semiconductor material, having a doping of a second conductivity type that is the opposite of said first conductivity type, and laterally contacting said base region;   an emitter contact region comprising a portion of a second semiconductor material having a second band gap that is greater than said first band gap, having a doping of said second conductivity type, and contacting said emitter region; and   an extrinsic base region comprising an extrinsic base semiconductor material, vertically contacting said base region, and having a doping of said first conductivity type.   
     
     
         7 . The semiconductor structure of  claim 6 , further comprising a dielectric spacer laterally contacting sidewalls of said extrinsic base region. 
     
     
         8 . The semiconductor structure of  claim 7 , wherein said emitter contact region is in contact with an outer sidewall of said dielectric spacer. 
     
     
         9 . The semiconductor structure of  claim 7 , wherein a bottom surface of said dielectric spacer is in contact with a top surface of said emitter region and a top surface of said base region. 
     
     
         10 . The semiconductor structure of  claim 9 , wherein said top surface of said emitter region and said top surface of said base region are substantially coplanar. 
     
     
         11 . The semiconductor structure of  claim 6 , wherein an interface between said base region and said extrinsic base region is substantially coplanar with a top surface of said emitter region. 
     
     
         12 . The semiconductor structure of  claim 6 , wherein an interface between said base region and said extrinsic base region is located above a plane of a top surface of said emitter region. 
     
     
         13 . The semiconductor structure of  claim 7 , wherein said dielectric spacer is in contact with said base region, said emitter region, said emitter contact region, a collector region contacting said base region and comprising a third portion of said first semiconductor material and having a doping of said second conductivity type, and a collector contact region contacting said collector region and comprising another portion of said second semiconductor material and having a doping of said second conductivity type. 
     
     
         14 . The semiconductor structure of  claim 1 , further comprising an insulator layer having a planar top surface that contacts said base region and said emitter region. 
     
     
         15 . The semiconductor structure of  claim 14 , further comprising a handle substrate that contacts a planar bottom surface of said insulator layer. 
     
     
         16 .- 25 . (canceled) 
     
     
         26 . The semiconductor structure of  claim 1 , further comprising an emitter-side metal semiconductor alloy region in physical contact with said emitter contact region and not in physical contact with said emitter region. 
     
     
         27 . The semiconductor structure of  claim 1 , further comprising an extrinsic base region comprising an extrinsic base semiconductor material, vertically contacting said base region, and having a doping of said first conductivity type. 
     
     
         28 . The semiconductor structure of  claim 27 , further comprising a dielectric spacer laterally contacting sidewalls of said extrinsic base region. 
     
     
         29 . The semiconductor structure of  claim 4 , further comprising a collector contact region comprising another portion of said second semiconductor material, having a doping of said second conductivity type, and contacting said collector region. 
     
     
         30 . The semiconductor structure of  claim 6 , wherein said emitter contact region is not in physical contact with said base region.