Self-aligned structure for bulk FinFET

A method of forming a FinFET device comprising, in the following order:

• forming a plurality of semiconductor fins from a bulk semiconductor substrate;
• forming an oxide layer between each of the plurality of semiconductor fins, the oxide layer extending from the bulk semiconductor substrate only part way up a sidewall of each of the semiconductor fins to cover a bottom portion of each of the semiconductor fins, a top portion of the sidewall of each of the semiconductor fins being exposed and not covered by the oxide layer;
• forming a dummy spacer on the exposed top portion of each of the semiconductor fins;
• completely stripping the oxide layer to expose the bulk semiconductor substrate and the bottom portion of each of the semiconductor fins;
• depositing a doping material to be in contact with the exposed bulk semiconductor substrate and the bottom portion of each of the semiconductor fins previously covered by the oxide layer;
• heat treating the bulk semiconductor substrate to drive in dopants from the doping material into the exposed bulk semiconductor substrate and the bottom portion of each of the semiconductor fins;
• stripping only the doping material;
• forming a second oxide layer only in contact with the exposed bulk semiconductor substrate and the bottom portion of each of the semiconductor fins previously contacted by the doping material;
• and
• stripping the dummy spacer from each of the semiconductor fins.