Boron out-diffused surface strap process

US5185294A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Chung H. Lam · Williston, US
• Jerome B. Lasky · South Burlington, US
• Craig M. Hill · Warrenton, US
• James S. Nakos · Saint Johnsbury Center, US
• Steven J. Holmes · Colchester, US
• Stephen F. Geissler · Underhill, US
• David K. Lord · Colchester, US

Key dates

• Filing date: Nov 22, 1991
• Grant date: Feb 9, 1993
• Expiry date: Nov 22, 2011

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L21/76895
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

The invention provides a method for electrically connecting a polysilicon-filled trench to a diffusion region in a semiconductor device, wherein the trench and diffusion region are separated by a dielectric. The method provides for formation of a strap or bridge contact by utilizing a diffusion barrier layer which prevents diffusion into an overlying polysilicon layer when a subsequent boron out-diffusion step is performed. Selective etching is then utilized to remove the polysilicon layer where no boron has diffused, leaving a polysilicon strap connecting the trench and diffusion region.