Lateral bipolar junction transistor (BJT) on a silicon-on-insulator (SOI) substrate

A bipolar transistor device comprising:

• a substrate including a semiconductor layer overlying an insulating layer;
• a transistor base comprising a base region in the semiconductor layer doped with a first conductivity type dopant at a first dopant concentration;
• a transistor emitter comprising an emitter region doped with a second conductivity type dopant and located adjacent one side of the base region;
• a transistor collector comprising a collector region doped with the second conductivity type dopant and located adjacent an opposite side of the base region;
• and
• an epitaxial semiconductor material base contact region having a bottom surface in contact with a top surface of the base region;
• a replacement metal gate over and in electrical contact with said epitaxial semiconductor material base contact region;
• sidewall spacers including an oxide layer in contact with a side surface of the epitaxial semiconductor material base contact region, side surfaces of the replacement metal gate and the top surface of the base region;
• and
• wherein said epitaxial semiconductor material base contact region is doped with the first conductivity type dopant at a second dopant concentration greater than the first dopant concentration.

A method, comprising:

• epitaxially growing an epitaxial semiconductor layer from a top surface of a semiconductor layer overlying an insulating layer, said semiconductor layer doped with a first conductivity type dopant at a first dopant concentration, and said epitaxial semiconductor layer doped with the first conductivity type dopant at a second dopant concentration greater than the first dopant concentration;
• depositing a sacrificial gate material over the epitaxial semiconductor layer;
• patterning the sacrificial gate material and epitaxial semiconductor layer to define a gate stack having side surfaces and further having a bottom surface in contact with a transistor base comprising a base region of the semiconductor layer;
• forming sidewall spacers in contact with the side surfaces of the gate stack a top surface of the semiconductor layer;
• forming a transistor emitter comprising an emitter region doped with a second conductivity type dopant and located adjacent one side of the base region;
• forming a transistor collector comprising a collector region doped with the second conductivity type dopant and located adjacent an opposite side of the base region;
• replacing the sacrificial gate material of the gate stack with a replacement metal gate structure.