High thermal stability by doping of oxide capping layer for spin torque transfer (STT) magnetic random access memory (MRAM) applications

US10522744B2 · kind B2 · utility

Assignee

• TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD. · TW

Inventors

• Guenole Jan · San Jose, US
• Jodi Mari Iwata · Redwood City, US
• Ru-Ying Tong · Los Gatos, US
• Huanlong Liu · New York, US
• Yuan-Jen Lee · Fremont, US
• Jian Zhu · Pittsburgh, US

Key dates

• Filing date: Oct 10, 2017
• Grant date: Dec 31, 2019
• Expiry date: Oct 10, 2037

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10N50/85

Abstract

A magnetic tunnel junction (MTJ) is disclosed wherein a free layer (FL) interfaces with a metal oxide (Mox) layer and a tunnel barrier layer to produce interfacial perpendicular magnetic anisotropy (PMA). The Mox layer has a non-stoichiometric oxidation state to minimize parasitic resistance, and comprises a dopant to fill vacant lattice sites thereby blocking oxygen diffusion through the Mox layer to preserve interfacial PMA and high thermal stability at process temperatures up to 400° C. Various methods of forming the doped Mox layer include deposition of the M layer in a reactive environment of O2 and dopant species in gas form, exposing a metal oxide layer to dopant species in gas form, and ion implanting the dopant. In another embodiment, where the dopant is N, a metal nitride layer is formed on a metal oxide layer, and then an anneal step drives nitrogen into vacant sites in the metal oxide lattice.