Patent ID: 8158522

Claim:
A method of forming a deep trench in a substrate, the method comprising: providing a substrate with a patterned film disposed thereon, the patterned film comprising a trench having a first width and a pair of sidewalls, the trench exposing the top surface of the substrate; forming a material layer over the patterned film and conformal with the trench, wherein forming the material layer comprises forming a polymer layer using a gaseous composition comprising an amount of C 4 F 8 source gas approximately in the range of 100-500 sccm and an amount of helium and/or argon carrier gas approximately in the range of 0-500 sccm, the gaseous composition having a pressure approximately in the range of 10-200 mTorr, the gaseous composition biased approximately in the range of 0-150 Watts, and the gaseous composition having a source power applied thereto approximately in the range of 1000-5000 Watts; etching the material layer to form sidewall spacers along the pair of sidewalls of the trench, the sidewall spacers reducing the first width of the trench to a second width; and etching the substrate to form a deep trench in the substrate, the deep trench undercutting at least a portion of the sidewall spacers.