Transistors with multiple emitters, and transistors with substantially square base emitter junctions

A transistor comprising:

• a first region of a first conductivity type, said first region having a top surface;
• a second region of a second conductivity type opposite said first conductivity type, said second region contacting said top surface of said first region, said second region having a contiguous top surface S1 which has a boundary;
• a first conductive metal-containing region overlying and contacting said second region;
• and
• a third region of said first conductivity type, said third region comprising a contiguous first portion overlying said surface S1, said first portion comprising semiconductor material deposited over said second region, said first portion forming a junction with said surface S1 such that the junction extends from said boundary of said top surface S1 inside said top surface S1 and terminates inside said top surface S1,
• wherein:
• said first conductive metal-containing region is spaced from said first portion, and said first conductive metal-containing region encloses said junction within said surface S1;
• said third region is a contiguous region;
• said transistor further comprises a fourth region of said first conductivity type, said fourth region being spaced from said third region, said fourth region comprising a contiguous portion which comprises semiconductor material deposited over said second region, said portion of said fourth region forming a junction with said surface S1 which junction extends from said boundary of said surface S1 inside said surface S1 and terminates inside said surface S1;
• and
• said first conductive metal-containing region is spaced from said portion of said fourth region, and said first conductive metal containing region runs adjacent to an entire lateral boundary within said surface S1 of said junction of said portion of said fourth region.

A transistor comprising:

• a collector region of a first conductivity type;
• a base region of a second conductivity type over the collector region;
• a plurality of emitter regions of the first conductivity type over a portion of the base region, each emitter region including:
• a first portion;
• and
• a second portion deposited over the first portion, the second portion providing impurities to the first portion by diffusion;
• insulating spacers adjacent to each emitter region;
• and
• a conducting non-semiconductor material adjacent to and self-aligned with the spacers for making a contact to a portion of the base region not overlaid by any emitter region,
• wherein each emitter region has three sides surrounded by the spacers and the conducting material, and each emitter region is isolated from the conducting material by the spacers, and
• wherein the transistor further comprises a semiconductor base contact region for electrically contacting the base region, wherein the semiconductor base contact region contacts the conducting material and does not extend between the adjacent emitter regions, allowing the emitter regions to be brought closer to each other and the base region size and the overall transistor size to be reduced.