Silicon-on-insulator vertical array DRAM cell with self-aligned buried strap

US6426252B1 · kind B1 · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Carl Radens · Lagrangeville, US
• Gary B. Bronner · Stormville, US
• Tze-Chiang Chen · Yorktown Heights, US
• Bijan Davari · Mahopac, US
• Jack A. Mandelman · Stormville, US
• Dan Moy · Bethel, US
• Devendra K. Sadana · Pleasantville, US
• Ghavam G. Shahidi · Pound Ridge, US
• Scott R. Stiffler · Hopewell Junction, US

Key dates

• Filing date: Oct 25, 1999
• Grant date: Jul 30, 2002
• Expiry date: Oct 25, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D86/201

Abstract

A silicon on insulator (SOI) dynamic random access memory (DRAM) cell, array and method of manufacture. The memory cell includes a vertical access transistor above a trench storage capacitor in a layered wafer. A buried oxide (BOX) layer formed in a silicon wafer isolates an SOI layer from a silicon substrate. Deep trenches are etched through the upper surface SOI layer, the BOX layer and into the substrate. Each trench capacitor is formed in the substrate and, the access transistor is formed on a sidewall of the SOI layer. Recesses are formed in the BOX layer at the SOI layer. A polysilicon strap recessed in the BOX layer connects each polysilicon storage capacitor plate to a self-aligned contact at the source of the access transistor. Dopant is implanted into the wafer to define device regions. Access transistor gates are formed along the SOI layer sidewalls. Shallow trenches are formed and filled with insulating material to isolate cells from adjacent cells. Wordlines and bitlines are formed to complete the memory array.