Electric field assisted perpendicular stt-mram

Abstract

Present invention discloses a perpendicular STT-MRAM, a method of operating, and a method of manufacturing the same and a plurality of magnetoresistive memory elements having a recording layer which has an interface interaction with an underneath dielectric functional layer. The energy switch barrier of the recording layer is reduced under an electric field applying along a perpendicular direction of the functional with a proper voltage on a digital line from a control circuitry; accordingly, the perpendicular magnetization of the recording layer is readily reversible in a low spin-transfer switching current.

Description

RELATED APPLICATIONS[0001]This application is a divisional application due to a restriction requirement on application Ser. No. 14 / 159,116. This application seeks priority to U.S. Utility patent application Ser. No. 14 / 159,116 filed on 2014 Jan. 20 and U.S. Provisional Patent Application No. 61,754,923 filed on 2013 Jan. 21; the entire contents of each of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates generally to a perpendicular spin-transfer-torque magnetic-random-access memory (MRAM) element and a method of manufacturing the same magnetoresistive element, more particularly to structures and methods of reading and programming a spin-torque magnetoresistive random access memory (MRAM) element having an electric field assisted recording.[0004]2. Description of the Related Art[0005]In recent years, magnetic random access memories (hereinafter referred to as MRAMs) using the magnetoresistive effect of f...

AI Technical Summary

Benefits of technology

[0014]An exemplary embodiment includes method of operating a perpendicular spin-transfer-torque magnetoresistive memory including a circuitry coupled to the bit line positioned adjacent to selected ones of the plurality of magnetoresistive memory elements to supply a reading current or bi-directional spin-transfer recording current, and coupled to the digital line configured to generate an electric field pointing a way from the top surface of the functional layer and accordingly to decrease the perpendicular anisotropy strength of the recording layer. Thus magnetization of a recording layer can be readily switched or reversed to the direction in accordance with a direction of a current across the MTJ stack by applying a low spin transfer current.

[0015]Another exemplary embodiment includes a recording layer consisting of one or more nonmagnetic insertion layers and magnetic sub-layers and includes method of operating a perpendicular spin-transfer-torque magnetoresistive memory including a circuitry coupled to the bit line positioned adjacent to selected ones of the plurality of magnetoresistive memory elements to supply a reading current or bi-directional spin-transfer recording current, and coupled to the digital line configured to generate an electric field pointing away from the top surface of the functional layer, decreasing the perpendicular anisotropy strength and rotating the magnetization of the bottom sub-layer in a recording layer in a film plane, accordingly generating an in-plane demag bias field acting on the top sub-layer magnetization of the recording layer. Thus a low write current is readily achieved while maintaining a high thermal stability and improving margins among reading, recording voltage and breakdown voltage.

Problems solved by technology

More, even when the tunnel barrier does not immediately break down, if recording operations are repeated, the element may still become nonfunctional such that the resistance value changes (decreases) and information readout errors increase, making the element un-recordable.

Furthermore, recording is not performed unless a sufficient voltage or sufficient spin current is applied.

Accordingly, problems with insufficient recording arise before possible tunnel barrier breaks down.

However, patterning of small MTJ element leads to increasing variability in MTJ resistance and sustaining relatively high switching current or recording voltage variation in a STT-MRAM.

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