Semiconductor device structures with backside contacts for improved heat dissipation and reduced parasitic resistance

A method for forming a device structure, comprising:

• forming a precursor structure that comprises:
• (a) a substrate that has a front surface and a back surface, (b) at least one bipolar junction transistor (BJT) that comprises at least a collector that is located in the substrate and a base that is located over and directly on the collector, and an emitter that is located over and directly on the base (c) a collector metal contact located over the front surface of the substrate and is laterally offset from, and not directly electrically connected to, the collector, and (d) a second conductive contact located over the front surface of the substrate that is electrically connected to the base;
• and
• forming a conductive metal path in said precursor structure to electrically connect the collector with the collector metal contact, wherein the conductive metal path extends:
• (1) from directly on the collector through the substrate to the back surface of the substrate, (2) across the back surface of the substrate, and (3) from the back surface of the substrate through the substrate to the collector metal contact on the front surface of the substrate.