Patent ID: 8039386

Claim:
A method of forming a through silicon via (TSV), the method comprising: forming a hard mask over a semiconductor substrate, wherein the hard mask has a mask opening; forming a via opening in the semiconductor substrate using the hard mask, wherein: the via opening comprises a bottom and sidewalls; a portion of the hard mask overhangs the via opening; and a polymer comprising silicon, carbon, and fluorine is formed along at least a portion of the bottom of the via opening; performing a first wet clean to remove a first portion of the polymer and form a first carbon containing oxide along portions of the sidewalls by pulling silicon and carbon from the substrate; performing a first ash process to modify the first carbon containing oxide and to remove a second portion of the polymer; performing a first wet etch process to remove the modified first carbon containing oxide and a third portion of the polymer; performing a second ash process to form a second carbon containing oxide along at least a portion of the sidewalls by pulling silicon and carbon from the semiconductor substrate; performing a second wet etch process to remove the second carbon containing oxide and a fourth portion of the polymer; and performing a third ash process to form a third carbon containing oxide along portions of the sidewalls by pulling silicon and carbon from the substrate and removing any remaining portions of the polymer.