Magic Technologies, Inc.

Headway Technologies, Incorporated

Chyu-Jinh Torng

Ru-Ying Tong

Cheng Tzong Horng

Witold Kula

Liubo Hong

Rongfu Xiao

Tom Zhong

Wei Cao

Wai-Ming Johnson Kan

Terry Kin Ting Ko

A multi-layered bottom electrode for an MTJ device on a silicon nitride substrate is described. It comprises a bilayer of alpha tantalum on ruthenium which in turn lies on a nickel chrome layer over a second tantalum layer.

Bottom electrode for MRAM device

Formation of a bottom electrode for an MTJ device on a silicon nitride substrate is facilitated by including a protective coating that is partly consumed during etching of the alpha tantalum portion of said bottom electrode. Adhesion to SiN is enhanced by using a TaN/NiCr bilayer as 'glue'.

Process to fabricate bottom electrode for  MRAM device

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.

Bottom electrode for MRAM device and method to fabricate it

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Pleasanton, CA, United States of America

Chyu-Jinh Torng