Magnetic random access memory with switable switching assist layer

Abstract

A perpendicular spin-transfer torque magnetic random access memory (STTMRAM) element is configured to store a state when electrical current is applied thereto. The perpendicular STTMRAM element includes a magnetization layer having a first free layer and a second free layer, separated by a non-magnetic separation layer (NMSL). The direction of magnetization of the first and second free layers each is in-plane prior to the application of electrical current and after the application of electrical current, the direction of magnetization of the second free layer becomes substantially titled out-of-plane and the direction of magnetization of the first free layer switches. Upon electrical current being discontinued, the direction of magnetization of the second free layer remains in a direction that is substantially opposite to that of the first free layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of previously-filed U.S. patent application Ser. No. 13 / 035,857, filed on Feb. 25, 2011, by Zhou et al., and entitled “Magnetic Latch Magnetic Random Access Memory (MRAM), which claims priority from previously-filed U.S. Provisional Application No. 61 / 391,263, filed on Oct. 8, 2010, by Huai et al. and entitled “Magnetic Latch Magnetic Random Access Memory (MRAM)”.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a spin-transfer torque (STT) magnetic random access memory (MRAM), and, more particularly, to an STTMRAM element having magnetic tunnel junctions (MTJs) with a multi-layered free layer.[0004]2. Description of the Prior Art[0005]Magnetic random access memory (MRAM) is a type of non-volatile memory in which magnetization of magnetic layers in MTJs switches between parallel (corresponding to a low resistance state) and anti-parallel (correspondi...

AI Technical Summary

Benefits of technology

The present invention relates to a spin-transfer torque magnetic random access memory (STTMRAM) element that can store a state when electrical current is applied. The element includes a fixed layer with a magnetization pinned in the plane of the layer, a barrier layer, a junction layer, and a magnetization layer. A perpendicular reference layer is also included. The direction of magnetization of the first and second free layers acts on each other through anti-parallel coupling. The element can switch between a parallel and anti-parallel magnetic orientation. The invention also includes various embodiments of the element with different layers and thicknesses, as well as different switching processes. The technical effects of the invention include improved switching stability, reduced power consumption, and increased data storage capacity.

Problems solved by technology

The main hurdles associated with field-switched-MRAM are its more complex cell architecture with high write current (currently in the order of milliamps (mA)) and poor scalability attributed to the process used to manufacture these devices.

That is, these devices cannot scale beyond 65 nanometer (nm) process node.

The poor scalability of such devices is intrinsic to the field writing methods.

However, the problem with the element 10 as well as other prior art STTMRAM elements is that the level of electric current required to switch the magnetization orientation of FL 1 between parallel and anti-parallel relative to that of RL 3 is still higher than a typical semiconductor CMOS structure can provide, therefore making prior art STTMRAMs' applicability to storage systems not practical.

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