Bipolar transistor and method of manufacturing the same

A bipolar transistor, comprising:

• a single-crystal silicon substrate;
• a first insulating layer over the single-crystal silicon substrate;
• a first silicon layer over the first insulating layer;
• an opening extending through the first silicon layer and first insulating layer;
• an insulating sheath covering lateral walls of the opening, said insulating sheath including a lateral opening;
• in the opening, a collector region made of epitaxial silicon doped with a first conductivity type;
• in the opening, a base region made of epitaxial semiconductor material doped with a second conductivity type, said base region in contact with the collector region, wherein a side of the base region is present at the lateral opening in the insulating sheath;
• in the opening, an emitter region doped with the first conductivity type, said emitter region in contact with the base region;
• and
• a base contact made of epitaxial silicon extending through the lateral opening in the insulating sheath to connect to both the base region and first silicon layer.

A bipolar transistor, comprising:

• a semiconductor region doped with a first conductivity type in a semiconductor substrate;
• a first insulating layer over the doped semiconductor collector region;
• a first silicon layer over the first insulating layer;
• an opening extending through the first silicon layer and the first insulating layer to the semiconductor substrate;
• an insulating sheath covering lateral walls of the opening and including a lateral opening;
• a collector region made of epitaxial semiconductor material doped with the first conductivity type and located in said opening in contact with the semiconductor region;
• a base region made of epitaxial semiconductor material doped with a second conductivity type and located in said opening in contact with the collector region;
• an emitter region made of semiconductor material doped with the first conductivity type and located in said opening in contact with the base region;
• and
• a base contact region made of epitaxial semiconductor material extending through the lateral opening to connect the base region to the first silicon layer.