Device isolation technology by liquid phase deposition

Abstract

A new method of forming device isolation regions on a silicon substrate is provided. This method comprises the following steps: a pad oxide layer is formed on the silicon substrate; a silicon nitride layer is formed on the pad oxide layer; portions of the silicon nitride and pad oxide layers not covered by a mask pattern are etched through and into the silicon substrate so as to provide a plurality of wide and narrow trenches within the silicon substrate that will form the device isolation regions; silicon nitride spacers are formed on the sidewalls of the trenches; a thin oxide layer is grown on all exposed surfaces of the substrate by using thermal oxidation; a first liquid phase deposition oxide layer is formed on the thin oxide layer and is densified by a thermal process to form cracks therein; the silicon nitride layer and silicon nitride spacers are removed through the cracks, wherein the first liquid phase deposition oxide layer over the silicon nitride layer and silicon nitride spacers are also lift-off; the pad oxide layer is then removed; and a second liquid phase deposition oxide layer is formed on the first liquid phase deposition oxide layer so as to fill the trenches.