Method to form a nonmagnetic cap for the NiFe(free) MTJ stack to enhance dR/R

US7528457B2 · kind B2 · utility

Assignee

• MagIC Technologies, Inc. · US

Inventors

• Cheng T. Horng · San Jose, US
• Hui-Chuan Wang · Pleasanton, US
• Min Li · Dublin, US
• Ru-Ying Tong · Los Gatos, US
• Tong Zhao · Eden Prairie, US
• Yimin Guo · San Jose, US

Key dates

• Filing date: Apr 14, 2006
• Grant date: May 5, 2009
• Expiry date: Nov 9, 2026

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10N50/10

Abstract

An MTJ in an MRAM array or TMR read head is disclosed in which a capping layer has a bilayer configuration with a non-magnetic NiFeX inner layer on a NiFe free layer and a Ta layer on the NiFeX layer to improve dR/R and minimize magnetostriction. Optionally, a trilayer configuration may be employed where the Ta layer is sandwiched between an inner NiFeX layer and an outer Ru layer. The X component in NiFeX is preferably an element having an oxidation potential greater than Ni or Fe such as Mg, Hf, Zr, Nb, or Ta. NiFeX is preferably formed by co-sputtering a NiFe target with an X target at a forward power of about 200 W and 50 W, respectively. In an MRAM structure, the Mg content in NiFeMg may be increased to >50 atomic % to improve the gettering power of removing oxygen from the free layer.