Process flow for thick isolation collar with reduced length

US6605838B1 · kind B1 · utility

Assignees

• International Business Machines Corporation · US
• Infineon Technologies North America Corp. · US

Inventors

• Jack A. Mandelman · Stormville, US
• Rama Divakaruni · Ossining, US
• Gerd Fehlauer · Unterhaching, DE
• Stephan Kudelka · Radeberg, DE
• Uwe Schroeder · Fishkill, US
• Helmut Tews · Poughkeepsie, US

Key dates

• Filing date: Sep 30, 2002
• Grant date: Aug 12, 2003
• Expiry date: Sep 30, 2022

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10B12/0383

Abstract

A trench capacitor memory cell structure is provided with includes a vertical collar region that suppresses current leakage of an adjacent vertical parasitic transistor that exists between the vertical MOSFET and the underlying trench capacitor. The vertical collar isolation, which has a vertical length of about 0.50 &mgr;m or less, includes a first portion that is present partially outside the trench and a second portion that is present inside the trench. The first portion of the collar oxide is thicker than said second portion oxide thereby reducing parasitic current leakage.