Method of fabricating a low base-resistance bipolar transistor

A method for fabricating a bipolar transistor, comprising the steps of:

• providing a semiconductor material structure;
• forming a base layer on said semiconductor material structure having an exposed surface;
• forming an emitter contact region on said exposed surface of said base layer;
• implanting portions of said semiconductor material structure with ions to render said portions of said semiconductor material structure semi-insulating, said base layer being thereby disposed on an implanted and non-implanted portion of said semiconductor material and said emitter contact region being disposed on a non-implanted portion of said semiconductor material;
• forming a first epitaxial layer of semiconductor material over said exposed surface of said base layer in said implanted portion of said semiconductor material structure;
• forming a base contact over said first epitaxial layer of semiconductor material;
• forming a second epitaxial layer of semiconductor material over said exposed surface of said base layer prior to forming said first epitaxial layer of semiconductor material, said first epitaxial layer being wide bandgap semiconductor material.

A method for fabricating a bipolar transistor, comprising the steps of:

• providing a semiconductor material structure including:
• a subcollector layer;
• a collector layer adjacent said subcollector layer;
• a base layer adjacent said collector layer;
• an emitter layer adjacent said base layer;
• an emitter cap layer adjacent said emitter layer;
• removing portions of said emitter cap layer and said emitter layer to form an emitter mesa on said base layer, said emitter mesa comprising said emitter layer and said emitter cap layer;
• implanting ions in said semiconductor material structure in regions adjacent said emitter mesa;
• forming an epitaxial wide bandgap semiconductor layer over said implanted regions;
• forming base contact metallization over said epitaxial wide bandgap semiconductor layer;
• forming emitter contact metallization over said emitter cap layer;
• and
• forming collector contact metallization over said subcollector layer.

A method for fabricating a bipolar transistor, comprising the steps of:

• providing a semiconductor material structure including:
• a subcollector layer;
• a collector layer adjacent said subcollector layer;
• a base layer adjacent said collector layer;
• an emitter layer adjacent said base layer;
• an emitter cap layer adjacent said emitter layer;
• removing portions of said emitter cap layer and said emitter layer to form an emitter mesa on said base layer, said emitter mesa comprising said emitter layer and said emitter cap layer;
• implanting ions in said semiconductor material structure in regions adjacent said emitter mesa;
• forming a first epitaxial wide bandgap semiconductor layer over said implanted regions;
• forming emitter contact metallization over said emitter cap layer;
• forming collector contact metallization over said subcollector layer;
• and
• forming a second epitaxial semiconductor layer over said first epitaxial wide bandgap semiconductor layer, and
• then forming base contact metallization over said second epitaxial semiconductor layer.

A method for fabricating a bipolar transistor, comprising the steps of:

• providing a semiconductor material structure including:
• a subcollector layer;
• a collector layer adjacent said subcollector layer;
• a base layer adjacent said collector layer;
• an emitter layer adjacent said base layer;
• an emitter cap layer adjacent said emitter layer;
• removing portions of said emitter cap layer and said emitter layer to form an emitter mesa on said base layer, said emitter mesa comprising said emitter layer and said emitter cap layer;
• implanting ions in said semiconductor material structure in regions adjacent said emitter mesa;
• forming a first epitaxial wide bandgap semiconductor layer over said implanted regions;
• forming base contact metallization over said first epitaxial wide bandgap semiconductor layer;
• forming emitter contact metallization over said emitter cap layer;
• forming collector contact metallization over said subcollector layer;
• and
• forming a second epitaxial semiconductor layer over said implanted regions prior to forming said epitaxial wide bandgap semiconductor layer.