Method of making bipolar transistor having amorphous silicon contact as emitter diffusion source

A method of fabricating a complementary bipolar junction transistor ("BJT") having an increased Early voltage from a semiconductor substrate, said substrate comprising a first well, a second well, and an isolation region for isolating said first well from said second well, said first well having a first conductivity and comprising a first base region and a first collector region, said second well having a second conductivity and comprising a second base region and a second collector region, said method comprising the steps of:

• forming an interlevel dielectric layer superjacent said substrate;
• removing portions of said interlevel dielectric layer such that a first segment of said substrate is exposed for accessing said first base region and a second segment of said substrate is exposed for accessing said second base region;
• forming a contact layer superjacent said interlevel dielectric layer, said contact layer comprising a material having a grain size smaller than polycrystalline silicon;
• masking said first base region with a first mask;
• implanting said contact layer with a first dopant;
• removing said first mask;
• masking said second base region with a second mask;
• implanting said contact layer with a second dopant;
• removing said second mask;
• removing portions of said contact layer to form a first and a second electrical contact for the complementary BJT;
• and
• annealing said substrate such that said first dopant diffuses into said first base region to form a first emitter region and said second dopant diffuses into said second base region to form a second emitter region, thereby increasing Early voltage of the bipolar junction transistor.