Vertical transistor with a body contact for back-biasing

A method of forming a substrate contact in a vertical transistor device, the method comprising:

• patterning a sacrificial layer to form an opening in the sacrificial layer, the sacrificial layer disposed on hardmask arranged on a substrate, and the substrate comprising a bulk semiconductor layer, a buried oxide layer arranged on the bulk semiconductor layer, and a semiconductor layer arranged on the buried oxide layer;
• forming oxide spacers on sidewalls of the opening in the sacrificial layer, the oxide spacers comprising a single layer that extends continuously from a top surface of the hardmask to a top surface of the sacrificial layer, the oxide spacers being substantially the same height as the sacrificial layer;
• using the oxide spacers as a pattern to etch a trench through the substrate, the trench stopping at a region within the bulk semiconductor layer;
• and
• depositing a conductive material in the trench to form the substrate contact.