Method for a controlled bottle trench for a dram storage node

US6190988A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Toshiharu Furukawa · South Burlington, US
• Mark C. Hakey · Saint Albans, US
• Steven J. Holmes · Colchester, US
• David V. Horak · South Burlington, US
• William H. Ma · Wappingers Falls, US
• James M. Never · South Burlington, US

Key dates

• Filing date: May 28, 1998
• Grant date: Feb 20, 2001
• Expiry date: May 28, 2018

Classification

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

Abstract

A bottle-shaped trench capacitor with a buried plate is formed in a controlled etch process. The bottle-shape is fabricated by etching deep trenches from a layered substrate, using the layers as a mask, and covering the side walls of the substrate with protective oxide and nitride layers. With the side walls covered, deep trench etching is then resumed, and a lower trench portion, below the protective layers of the side wall are formed. By diffusing a first dopant in the lower portion of the deep trench region, using the side wall protective layers as a mask, an etch stop is established for a wet etch process at the p/n junction established by the first dopant. The width of the lower trench portion is regulated by the time and temperature of the diffusion. Removing the doped material and applying a second dopant to the lower trench portion establishes a continuous buried plate region between trenches. A capacitor is formed by applying an insulating layer to the trench and filling with a conductor.