Back side dopant activation in field stop IGBT

A field stop insulated gate bipolar transistor (IGBT) fabricated without back-side laser dopant activation or any process temperatures over 450° C. after fabrication of front-side IGBT structures provides activated injection regions with controlled dopant concentrations. Injection regions may be formed on or in a substrate by epitaxial growth or ion implants and diffusion before growth of N field stop and drift layers and front-side fabrication of IGBT active cells. Back-side material removal can expose the injection region(s) for electrical connection to back-side metal. Alternatively, after front-side fabrication of IGBT active cells, back-side material removal can expose the field stop layer (or injection regions) and sputtering using a silicon target with a well-controlled doping concentration can form hole or electron injection regions with well-controlled doping concentration.