Magnetic element with perpendicular magnetic anisotropy for high coercivity after high temperature annealing

Abstract

A magnetic tunnel junction (MTJ) is disclosed wherein a free layer has an interface with a tunnel barrier and a second interface with a metal oxide layer to promote perpendicular magnetic anisotropy (PMA) therein. A diffusion barrier is formed on a side of the metal oxide layer opposite the second interface to prevent non-magnetic metals in a hard mask or electrode from migrating to the second interface and degrading free layer PMA. A second diffusion barrier may be formed between a second electrode and a reference layer. The diffusion barrier may be a single layer of SiN, TiN, TaN, Mo, or CoFeX where X is Zr, P, B, or Ta, or is a multilayer such as CoFeX / Mo wherein CoFeX contacts the metal oxide layer and Mo adjoins a hard mask. As a result, coercivity is maintained or increased in the MTJ after annealing at 400 DEG C for 30 minutes.

Description

technical field [0001] This application relates to the following cases: U.S. Patent Publication No. 8,946,834; U.S. Patent Publication No. 9,006,704; and U.S. Patent Publication No. 2015 / 0008547, all assigned to a common assignee and incorporated herein by reference incorporated in this article. [0002] The present invention relates to magnetic devices utilizing magnetic tunneling junctions (MTJs) with perpendicular magnetic anisotropy (PMA), and in particular, relates to inserting a diffusion barrier layer between a capping layer and a top electrode to facilitate the annealing The coercive force (Hc) of the MTJ stack is maintained thereafter or during high temperature semiconductor steps of about 400°C. Background technique [0003] Magnetic random access memory (MRAM) has a read function based on the tunneling magnetoresistance (TMR) effect in an MTJ stack, wherein a tunneling barrier layer is formed between a free layer and a reference layer. While the reference layer ...

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Problems solved by technology

[0018] One problem caused by high temperature annealing around 400°C is that the hard mask material diffuses into the MTJ

Current technology fails to provide high Hc and thermal stability in a free layer with PMA characteristics that will withstand high temperature processing up to at least 400°C, which is required in semiconductor manufacturing methods

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