Method for fabricating a concave bottom oxide in a trench

US6265269A · kind A · utility

Assignee

• MOSEL VITELIC INC. · TW

Inventors

• Chien-Hung Chen · Taipei, TW
• Chih-Ta Wu · Hsinchu, TW
• Ching-Shun Lin · Hsinchu, TW
• Juinn-Sheng Chen · Danei, TW

Key dates

• Filing date: Aug 6, 1999
• Grant date: Jul 24, 2001
• Expiry date: Aug 6, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D30/668

Abstract

A method for forming a concave bottom oxide layer in a trench, comprising: providing a semiconductor substrate; forming a pad oxide layer on the semiconductor substrate; forming a silicon nitride layer on the pad oxide layer; etching the silicon nitride layer, the pad oxide layer and the semiconductor substrate to form the trench in the semiconductor substrate; depositing a silicon oxide layer to refill into the trench and cover on the silicon nitride layer, wherein the silicon oxide layer has overhang portions at corners of the trench; anisotropically etching the silicon oxide layer to form a concave bottom oxide layer in the trench; etching the silicon oxide layer to remove the silicon oxide layer on the silicon nitride layer and the sidewalls of the trench; removing the silicon nitride layer and the pad oxide layer.