Patent ID: 6720233
Filing Date: 2004-04-13
Classification: H01L

Abstract:
A method of producing a trench insulation in a silicon substrate, said silicon substrate having a first main surface and a second main surface, comprising the following steps;a) depositing a first silicon-oxide layer, a first silicon nitride layer, and a second silicon-oxide layer in this order on the first main surface of the silicon substrate; b) structuring the first silicon-oxide layer, the first silicon nitride layer, and the second silicon-oxide layer so as to define a mask for a subsequent formation of a trench; c) etching a trench in the silicon substrate making use of said mask; d) filling said trench by a local oxidation of silicon (â€œLOCOSâ€ ) process by subjecting the structure formed by step (a) to (c) to an oxidation in a thermal oxidation process for growing on the trench walls silicon oxide layers until the silicon oxide layers grown on the trench wall contact each other, thereby completely filling the trench with a silicon oxide; e) conforming deposition of a first polysilicon layer on the second silicon-oxide layer and on the oxide-filled trench; f) removing said first polysilicon layer in such a way that a polysilicon cover remains on said oxide-filled trench; and g) removing the second silicon-oxide layer.