Isolated tri-gate transistor fabricated on bulk substrate

A method of forming an isolated semiconductor body comprising:

• patterning a bulk substrate to form a fin structure;
• depositing an insulating material around the fin structure;
• recessing the insulating material a first time to expose a first portion of the fin structure;
• depositing a protective nitride cap over the first portion of the fin structure;
• recessing the insulating material a second time to expose a second portion of the fin structure below the protective nitride cap;
• thermally oxidizing the second portion of the fin structure, thereby isolating the first portion of the fin structure from the bulk substrate;
• and
• removing the nitride cap.

An apparatus comprising:

• a bulk substrate;
• a semiconductor body formed by patterning a fin structure from the bulk substrate;
• and
• an oxide layer isolating the semiconductor body from the bulk substrate, wherein the oxide layer is formed by thermally oxidizing a portion of the fin structure patterned from the bulk substrate.