Bipolar Transistor

A method for fabricating a bipolar transistor (BT), the method comprising:

• providing a semiconductor body including a collector region and a base region arranged on top of the collector region, the collector region being doped with dopants of a second doping type and the base region being doped with dopants of a first doping type;
• forming insulating spacers on top of the base region;
• after forming the spacers, forming a first semiconductor layer on top of the base region, so that the spacers enclose the first semiconductor layer;
• after forming the first semiconductor layer, forming a second semiconductor layer, which is doped with dopants of the second doping type, on top of the first semiconductor layer, the second layer being more heavily doped than the first semiconductor layer;
• and
• applying elevated temperatures to the semiconductor body so that dopants diffuse out of the second semiconductor layer into the first semiconductor layer thereby forming an emitter region of the BT in the first and second semiconductor layers.

A method for fabricating a bipolar transistor (BT), the method comprising:

• providing a semiconductor body including a collector region and a base region arranged on top of the collector region, the collector region being doped with dopants of a second doping type and the base region being doped with dopants of a first doping type;
• forming insulating spacers on top of the base region;
• depositing a first semiconductor layer on top of the base region such that the first semiconductor layer is laterally enclosed by the spacers;
• depositing a second semiconductor layer, which is doped with dopants of the second doping type, on top of the first semiconductor layer;
• and
• applying elevated temperatures to the semiconductor body so that dopants diffuse out of the second semiconductor layer into the first semiconductor layer thereby forming an emitter region of the BT in the first and second semiconductor layers.