Patent ID: 8633113
Filing Date: 2014-01-21
Classification: H01L

Abstract:
1. A method for fabricating a bottom oxide layer in a trench, the method comprising: forming the trench in a semiconductor substrate; depositing an oxide layer to partially fill a field area and the trench, wherein said oxide layer has oxide overhang portions; removing the oxide overhang portions of the deposited oxide layer by wet etching of the oxide overhang portions and a circumferential wall of the trench using chemical compound comprising hydrofluoric acid; forming a bottom anti-reflective coating (BARC) layer to cover the oxide layer in the field area and the trench; removing the BARC layer from the field area, while retaining a predetermined thickness of the BARC layer in the trench by performing dry plasma etching of the BARC layer using a high BARC-to-oxide selectivity; removing the oxide layer from the field area; and removing the BARC layer and oxide layer in the trench to obtain a predetermined thickness of the bottom oxide layer.