Bottom electrode for MRAM device and method to fabricate it

US7838436B2 · kind B2 · utility

Assignee

• MagIC Technologies, Inc. · US

Inventors

• Rongfu Xiao · Dublin, US
• Cheng T. Horng · San Jose, US
• Ru-Ying Tong · Los Gatos, US
• Chyu-Jinh Torng · Pleasanton, US
• Tom Zhong · Saratoga, US
• Witold Kula · Gilroy, US
• Terry Kin Ting Ko · South San Francisco, US
• Wei Cao · Milpitas, US
• Wai-Ming J. Kan · San Ramon, US
• Liubo Hong · San Jose, US

Key dates

• Filing date: Sep 28, 2006
• Grant date: Nov 23, 2010
• Expiry date: Oct 9, 2028

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10N50/10
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

Formation of a bottom electrode for an MTJ device on a silicon nitride substrate is facilitated by including a layer of ruthenium near the silicon nitride surface. The ruthenium is a good electrical conductor and it responds differently from Ta and TaN to certain etchants. Adhesion to SiN is enhanced by using a TaN/NiCr bilayer as “glue”. Thus, said included layer of ruthenium may be used as an etch stop layer during the etching of Ta and/or TaN while the latter materials may be used to form a hard mask for etching the ruthenium without significant corrosion of the silicon nitride surface.