Field stop IGBT with grown injection region

A method for manufacturing of a vertical Insulated Gate Bipolar Transistor (IGBT) structure, comprising:

• growing an injection region of a first conductivity type on a front side of a semiconductor substrate;
• growing a field stop layer of a second conductivity type on the injection region;
• growing a drift region of the second conductivity type on the field stop layer;
• forming a plurality of IGBT active cells in and on the drift region;
• removing material from a back side of the semiconductor substrate to expose a bottom of the injection region after forming the IGBT active cells;
• and
• depositing a back-side metal contacting the bottom of the injection region;
• wherein growing the drift region comprises:
• growing a transition segment of the drift region just above the field stop layer, the transition segment having a first doping concentration lower than a doping concentration of the field stop layer;
• and growing a high voltage segment of the drift region above the transition segment, the high voltage segment having a second doping concentration lower than the first doping concentration, the high voltage segment supporting high voltage blocking.