Composite hard mask with upper sacrificial dielectric layer for the patterning and etching of nanometer size MRAM devices

US8722543B2 · kind B2 · utility

Assignee

• Headway Technologies, Inc. · US

Inventors

• Rodolfo P. Belen · San Francisco, US
• Rongfu Xiao · Dublin, US
• Tom Zhong · Saratoga, US
• Witold Kula · Gilroy, US
• Chyu-Jiuh Torng · Pleasanton, US

Key dates

• Filing date: Jul 30, 2010
• Grant date: May 13, 2014
• Expiry date: Mar 1, 2031

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/31678

Abstract

A composite hard mask is disclosed that prevents build up of metal etch residue in a MRAM device during etch processes that define an MTJ shape. As a result, MTJ shape integrity is substantially improved. The hard mask has a lower non-magnetic spacer, a middle conductive layer, and an upper sacrificial dielectric layer. The non-magnetic spacer serves as an etch stop during a pattern transfer with fluorocarbon plasma through the conductive layer. A photoresist pattern is transferred through the dielectric layer with a first fluorocarbon etch. Then the photoresist is removed and a second fluorocarbon etch transfers the pattern through the conductive layer. The dielectric layer protects the top surface of the conductive layer during the second fluorocarbon etch and during a substantial portion of a third RIE step with a gas comprised of C, H, and O that transfers the pattern through the underlying MTJ layers.