Patent ID: 6696344
Filing Date: 2004-02-24
Classification: H01L

Abstract:
A method for forming a bottle-shaped trench, comprising:providing a semiconductor substrate having a pad stack layer thereon and a trench in a predetermined position; forming a first dielectric layer conformally on the pad stack layer and the sidewalls of the trench; filling the lower portion of the trench with a sacrificial layer; removing the first dielectric layer on the pad stack layer and the upper sidewalls of the trench; removing the sacrificial layer and leaving the first dielectric layer located on the lower sidewalls of the trench; forming a second dielectric layer conformally on the pad stack layer, the upper sidewalls of the trench and filling the lower portion of the trench to fully close the opening of the first dielectric layer; forming a protection layer conformally on the second dielectric layer; recessing the protection layer so that only the protection layer located on the upper sidewalls of the trench remains to form a sidewall protection layer; removing the second dielectric layer located at the bottom of the trench to form an opening; using the sidewall protection layer as a mask to remove the first dielectric layer and the second dielectric layer located at the lower portion of the trench to expose the lower sidewalls of the trench; and removing the lower sidewalls of the trench to form a bottle-shaped trench by wet stripping.