Patent ID: 8461015

Claim:
A method for forming a shallow trench isolation (STI) structure, comprising: (a) providing a semiconductor substrate; (b) forming a trench in the substrate, the trench having a first sidewall and a second sidewall opposite the first sidewall, the first and second sidewalls extending down to a bottom portion of the trench; (c) depositing an insulating material to conformally line surfaces of the first and second sidewalls and the bottom portion of the trench; (d) etching back the insulating material proximate the top portions of the trench and the bottom portion of the trench; (e) depositing successively the insulating material to line the surfaces of the first and the second sidewalls and the bottom portion of the trench at a rate that is sufficient to allow a first protruding insulating material deposited on the first sidewall and a second protruding insulating material deposited on the second sidewall to approach theretogether; (f) repeating steps (d) and (e) to have the first protruding insulating material and the second protruding insulating material abut, thereby forming a void proximate the bottom portion of the trench.