High performance MTJ element for conventional MRAM and for STT-RAM and a method for making the same

US8749003B2 · kind B2 · utility

Assignee

• Headway Technologies, Inc. · US

Inventors

• Cheng T. Horng · San Jose, US
• Ru-Ying Tong · Los Gatos, US
• Chyu-Jiuh Tomg · Pleasanton, US
• Witold Kula · Gilroy, US

Key dates

• Filing date: Feb 11, 2013
• Grant date: Jun 10, 2014
• Expiry date: Feb 11, 2033

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10B61/22
• WIPO field: Micro-structural and nano-technology
• WIPO sector: Chemistry

Abstract

A STT-RAM MTJ that minimizes spin-transfer magnetization switching current (Jc) is disclosed. The MTJ has a MgO tunnel barrier layer formed with a natural oxidation process to achieve a low RA (10 ohm-um2) and a Fe or Fe/CoFeB/Fe free layer which provides a lower intrinsic damping constant than a CoFeB free layer. A Fe, FeB, or Fe/CoFeB/Fe free layer when formed with a MgO tunnel barrier (radical oxidation process) and a CoFeB AP1 pinned layer in a MRAM MTJ stack annealed at 360° C. provides a high dR/R (TMR)>100% and a substantial improvement in read margin with a TMR/Rp_cov=20. High speed measurement of 100 nm×200 nm oval STT-RAM MTJs has shown a Jc0 for switching a Fe free layer is one half that for switching an amorphous Co40Fe40B20 free layer. A Fe/CoFeB/Fe free layer configuration allows the Hc value to be increased for STT-RAM applications.