Deep trench capacitor with buried plate electrode and isolation collar

US7122437B2 · kind B2 · utility

Assignees

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

Inventors

• Thomas W. Dyer · Pleasant Valley, US
• Chun-Yung Sung · Poughkeepsie, US
• Ravikumar Ramachandran · Beacon, US
• Ramachandra Divakaruni · Ossining, US
• Carl Radens · Lagrangeville, US

Key dates

• Filing date: Dec 19, 2003
• Grant date: Oct 17, 2006
• Expiry date: Dec 25, 2023

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D1/665

Abstract

A deep trench capacitor used in a trench DRAM includes a buried plate and an isolation collar. The deep trench is bottle-shaped, and the isolation collar is formed in upper portion of the wider region of the bottle-shaped trench. The buried plate surrounds the lower portion of the wider part of the bottle-shaped trench, and hemispherical grain polysilicon lines the walls of at least the lower portion of the wider part of the trench. A nitride liner layer lines the inner walls of the oxide collar and prevents diffusion of dopant through the oxide collar into the substrate when the HSG polysilicon and the doped buried plate are formed. The buried plate region is self-aligned to the isolation collar. The depth of the top of the wider part of the bottle shape and the bottom depth of the isolation collar are determined by successive resist deposition and recessing steps.