Sacrificial collar method for improved deep trench processing

US6905944B2 · kind B2 · utility

Assignees

• International Business Machines Corporation · US
• Infineon Technologies AG · DE

Inventors

• Michael P. Chudzik · Beacon, US
• Irene McStay · Hopewell Junction, US
• Helmut Tews · Poughkeepsie, US
• Porshia Wrschka · Danbury, US

Key dates

• Filing date: May 8, 2003
• Grant date: Jun 14, 2005
• Expiry date: May 8, 2023

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10B12/0387

Abstract

A method for fabricating a deep trench etched into a semiconductor substrate is provided by the present invention. The trench is divided into an upper portion and a lower portion and the method allows for the lower portion to be processed differently from the upper portion. After the trench is etched into the semiconductor substrate, a nitride layer is formed over a sidewall of the trench. A layer of oxide is then formed over the nitride layer. A filler material is then deposited and recessed to cover the oxide layer in the lower portion of the trench, followed by the removal of the oxide layer from the upper portion of the trench above the filler material. Once the oxide layer is removed from the upper portion of the trench, the filler material can also be removed, while allowing the oxide layer and the nitride layer to remain in the lower portion of the trench. Silicon is selectively deposited on the exposed nitride layer in the upper portion of the trench. The oxide layer and the nitride layer is then removed from the lower portion. Finally, the lower portion of the trench is processed selectively to nitride, e.g. by one or more capacitor forming processes, and then the upper po…