Reduction of Barrier Resistance X Area (RA) Product and Protection of Perpendicular Magnetic Anisotropy (PMA) for Magnetic Device Applications

摘要

A method of forming a MTJ with a tunnel barrier having a high tunneling magnetoresistance ratio, and low resistance x area value is disclosed. The method preserves perpendicular magnetic anisotropy in bottom and top magnetic layers that adjoin bottom and top surfaces of the tunnel barrier. A key feature is a passive oxidation step of a first Mg layer that is deposited on the bottom magnetic layer wherein a maximum oxygen pressure is 10−5 torr. A bottom portion of the first Mg layer remains unoxidized thereby protecting the bottom magnetic layer from substantial oxidation during subsequent oxidation and anneal processes that are employed to complete the fabrication of the tunnel barrier and MTJ. An uppermost Mg layer may be formed as the top layer in the tunnel barrier stack before a top magnetic layer is deposited.

主权项

1. A method of forming a magnetic tunnel junction (MTJ) stack of layers including a tunnel barrier layer between two magnetic layers, comprising:
(a) providing a bottom magnetic layer with perpendicular magnetic anisotropy (PMA); (b) depositing a first metal layer that forms a bottom magnetic layer/first metal layer interface; (c) performing a first passive oxidation process with a maximum oxygen pressure of about 10−5 torr, the first passive oxidation process oxidizes an upper portion of the first metal layer while a bottom portion of the first metal layer along the bottom magnetic layer/first metal layer interface remains unoxidized; (d) forming one or more metal or metal oxide layers on the oxidized portion of the first metal layer wherein steps (b)-(d) form a tunnel barrier layer; and (e) depositing a top magnetic layer on a top surface of the tunnel barrier layer.