Method for implanting the sidewalls of isolation trenches

USH204H · kind H · statutory invention registration

Assignee

• AT&T Bell Laboratories · US

Inventors

• Kye H. Oh · Allentown, US
• David S. Yaney · Bethlehem, US

Key dates

• Grant date: Feb 3, 1987

Classification

• Technology area (CPC —): General

Abstract

A method of implanting ions into the sidewalls of isolation trenches is disclosed. The method utilizes a series of ion implants to produce concentrations of the ion, in most cases boron, along the depth of the trench. Since the ion concentration exhibits a Gaussian distribution function which tails off rapidly, the width of the trench is narrowed after the implantation to guarantee a sufficient boron concentration at the sidewalls of the trench. A layer of an insulating material is used to narrow the trench, where a conformal coating of the material will cover the sidewalls of the window and narrow the opening through the window. By increasing the boron doping in the sidewalls, the effects of boron segregation between the substrate and the isolation trench will be counteracted, thus eliminating the problem of creating an n-type inversion layer between the trench and the substrate.