Methods for roughening and volume expansion of trench sidewalls to form high capacitance trench cell for high density dram applications

US5877061A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Scott D. Halle · Slingerlands, US
• ChorngLii Hwang · Wappingers Falls, US
• K. Paul Muller · Wappingers Falls, US

Key dates

• Filing date: Feb 25, 1997
• Grant date: Mar 2, 1999
• Expiry date: Feb 25, 2017

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S438/964

Abstract

Trench cells with increased storage capacity are prepared with roughened sidewalls using a layer of grainy polysilicon or hemispherical grain polysilicon. The top collar region of the trench is protected with oxide while the lower portion of the trench coated with polysilicon or hemispherical grain polysilicon is etched isotropically. The trench structure created has roughened sidewalls for increased volume of storage.