Composite hard mask for the etching of nanometer size magnetic multilayer based device

US7696551B2 · kind B2 · utility

Assignee

• MagIC Technologies, Inc. · US

Inventors

• Rongfu Xiao · Dublin, US
• Chyu-Jiuh Torng · Pleasanton, US
• Tom Zhang · Saratoga, US
• Witold Kula · Gilroy, US
• Adam Yu Zhang · Dagu, CN

Key dates

• Filing date: Sep 20, 2007
• Grant date: Apr 13, 2010
• Expiry date: Oct 10, 2028

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/24736

Abstract

A composite hard mask is disclosed that enables sub-100 nm sized MTJ cells to be formed for advanced devices such as spin torque MRAMs. The hard mask has a lower non-magnetic metallic layer such as Ru to magnetically isolate an overlying middle metallic spacer such as MnPt from an underlying free layer. The middle metallic spacer provides a height margin during subsequent processing to avoid shorting between a bit line and the MTJ cell in the final device. An upper conductive layer may be made of Ta and is thin enough to allow a MTJ pattern in a thin overlying photoresist layer to be transferred through the Ta during a fluorocarbon etch without consuming all of the photoresist. The MTJ pattern is transferred through the remaining hard mask layers and underlying MTJ stack of layers with a second etch step using a C, H, and O etch gas composition.