Abstract

We have investigated the effects of in-situ post-oxidation (PO) of a sputtered MgO barrier in a double-MgO-barrier magnetic tunnel junction (MTJ) and found that the short error rate was significantly reduced, the magnetoresistance (MR) ratio was increased approximately 18%, and the endurance lifetime was extend. In addition, we found that the distribution of breakdown number (a measure of endurance) exhibits trimodal characteristics, which indicates competition between extrinsic and intrinsic failures. This improvement in reliability might be related to the suppression of Fe and Co diffusion to the MgO barrier, as revealed by electron energy-loss spectroscopy (EELS) analysis.

Highlights

  • Reliability enhancement due to in-situ post-oxidation of sputtered MgO barrier in double MgO barrier magnetic tunnel junction

  • To realize practical devices using high density STT-MRAM built with perpendicular magnetic anisotropy (PMA)-magnetic tunnel junctions (MTJs), further reductions of MTJ size and power consumption are required

  • The MgO film is deposited using RF-sputtering; sputtered MgO film contains a large number of oxygen vacancy defects (F center), which contribute to the leakage current of MTJs.[3]

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Summary

Introduction

Reliability enhancement due to in-situ post-oxidation of sputtered MgO barrier in double MgO barrier magnetic tunnel junction. Chikako Yoshida,a Hideyuki Noshiro, Yuichi Yamazaki, and Toshihiro Sugii Fujitsu Laboratories Ltd., 10-1 Morinosato-Wakamiya, Atsugi 243-0197, Japan (Received 18 March 2017; accepted 29 May 2017; published online 5 June 2017) We fabricated a double-MgO-barrier MTJ with PMA and investigated the influence of PO effects on electric properties and endurance characteristics.

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