Self-aligned and robust IGBT devices

A method of forming a vertical insulated gate bipolar transistor (IGBT) device, comprising:

• providing a semiconductor substrate of n conductivity type having a front side and a backside;
• forming column structures of p conductivity type fully surrounding an active region in the front side of the semiconductor substrate, forming each column structure including:
• forming a column trench in the front side of the semiconductor substrate, the trench including trench side walls and a trench floor,
• forming dielectric spacers on the trench side walls,
• forming a column deep region extending downwardly from the trench floor by applying dopants of p conductivity type into the semiconductor substrate through the trench floor,
• filling the trench with poly silicon of p conductivity type which is in contact with the column deep region;
• and
• depositing an oxide layer including silicon oxide onto the front side of the semiconductor substrate including the column trenches filled with the poly silicon;
• planarizing the oxide layer;
• depositing an etch stop layer including silicon nitride on the oxide layer;
• applying a photomask on the etch stop layer;
• and
• forming a plurality of metal-oxide-semiconductor field-effect transistor (MOSFET) cells in the active region fully surrounded by the column structures,
• wherein the substrate of n conductivity type is common to the plurality of MOSFET cells formed in the active area, and
• wherein the column structures are substantially deeper than the MOSFET cells to protect the cells from high voltage.