Avalanche Technology, Inc.

Xiaojie Hao

Zihui Wang

Yiming Huai

Yuchen Zhou

Huadong Gan

Xiaobin Wang

Bing K Yen

Jing Zhang

Rajiv Yadav Ranjan

Hongxin Yang

Ebrahim Abedifard

Kimihiro Satoh

Pengfa Xu

Longqian Hu

The present invention is directed to a magnetic memory element including a magnetic free layer structure incorporating three magnetic free layers separated by two perpendicular enhancement layers (PELs) and having a variable magnetization direction substantially perpendicular to layer planes thereof; an insulating tunnel junction layer formed adjacent to the magnetic free layer structure; a first magnetic reference layer formed adjacent to the insulating tunnel junction layer opposite the magnetic free layer structure; a second magnetic reference layer separated from the first magnetic reference layer by a third perpendicular enhancement layer; an anti-ferromagnetic coupling layer formed adjacent to the second magnetic reference layer; and a magnetic fixed layer formed adjacent to the anti-ferromagnetic coupling layer. The first and second magnetic reference layers have a first invariable magnetization direction substantially perpendicular to layer planes thereof. The magnetic fixed layer has a second invariable magnetization direction substantially opposite to the first invariable magnetization direction.

Magnetic memory element incorporating perpendicular enhancement layer

An STTMRAM element includes a magnetic tunnel junction (MTJ) having a perpendicular magnetic orientation. The MTJ includes a barrier layer, a free layer formed on top of the barrier layer and having a magnetic orientation that is perpendicular and switchable relative to the magnetic orientation of the fixed layer. The magnetic orientation of the free layer switches when electrical current flows through the STTMRAM element. A switching-enhancing layer (SEL), separated from the free layer by a spacer layer, is formed on top of the free layer and has an in-plane magnetic orientation and generates magneto-static fields onto the free layer, causing the magnetic moments of the outer edges of the free layer to tilt with an in-plane component while minimally disturbing the magnetic moment at the center of the free layer to ease the switching of the free layer and to reduce the threshold voltage/current.

Perpendicular magnetic tunnel junction (pMTJ) with in-plane magneto-static switching-enhancing layer

The present invention is directed to a memory cell that includes a magnetic tunnel junction (MTJ) memory element, which has a low resistance state and a high resistance state, and a two-terminal selector coupled to the MTJ memory element in series. The MTJ memory element includes a magnetic free layer and a magnetic reference layer with an insulating tunnel junction layer interposed therebetween. The two-terminal selector has an insulative state and a conductive state. The two-terminal selector in the conductive state has substantially lower resistance when switching the MTJ memory element from the low to high resistance state than from the high to low resistance state. The voltages applied to the memory cell to respectively switch the MTJ memory element from the low to high resistance state and from the high to low resistance state may be substantially same.

Selector device having asymmetric conductance for memory applications

The present invention is directed to a method for sensing the resistance state of a memory cell that includes an MTJ memory element coupled to a two-terminal selector element in series. The method includes the steps of raising a cell voltage across the memory cell above a threshold voltage for the selector element to become conductive; decreasing the cell voltage to a first sensing voltage and measuring a first sensing current passing through the memory cell, the selector element being nominally conductive irrespective of the resistance state of the MTJ memory element at the first sensing voltage; and further decreasing the cell voltage to a second sensing voltage and measuring a second sensing current, the selector element being nominally conductive if the MTJ memory element is in the low resistance state or nominally insulative if the MTJ memory element is in the high resistance state at the second sensing voltage.

Method for sensing memory element coupled to selector device

The present invention is directed to a magnetic memory element including a magnetic free layer structure having a variable magnetization direction perpendicular to a layer plane thereof; an insulating tunnel junction layer formed adjacent to the magnetic free layer structure; a first magnetic reference layer comprising cobalt, iron, and boron formed adjacent to the insulating tunnel junction layer; a second magnetic reference layer comprising cobalt separated from the first magnetic reference layer by a molybdenum layer; an iridium layer formed adjacent to the second magnetic reference layer; and a magnetic fixed layer structure formed adjacent to the iridium layer. The magnetic free layer structure includes a first and a second magnetic free layers with a perpendicular enhancement layer interposed therebetween. The first and second magnetic reference layers have a first invariable magnetization direction perpendicular to layer planes thereof. The magnetic fixed layer structure has a second invariable magnetization direction opposite to the first invariable magnetization direction.

Magnetic memory element with iridium anti-ferromagnetic coupling layer

The present invention is directed to an MTJ memory element, which includes a magnetic free layer structure having a variable magnetization direction perpendicular to a layer plane thereof; a tunnel junction layer formed adjacent to the magnetic free layer structure; a magnetic reference layer structure formed adjacent to the tunnel junction layer and having a first invariable magnetization direction perpendicular to a layer plane thereof; an anti-ferromagnetic coupling layer formed adjacent to the magnetic reference layer structure; and a magnetic fixed layer structure formed adjacent to the anti-ferromagnetic coupling layer and having a second invariable magnetization direction that is perpendicular to a layer plane thereof and is opposite to the first invariable magnetization direction. The magnetic fixed layer structure includes multiple stacks of a trilayer unit structure, which includes three layers of different materials with at least one of the three layers of different materials being magnetic.

Perpendicular magnetic fixed layer with high anisotropy

The present invention is directed to an MRAM device comprising a plurality of MTJ memory elements. Each of the memory elements includes a magnetic free layer and a first magnetic reference layer with an insulating tunnel junction layer interposed therebetween; a second magnetic reference layer formed adjacent to the first magnetic reference layer opposite the insulating tunnel junction layer; an anti-ferromagnetic coupling layer formed adjacent to the second magnetic reference layer opposite the first magnetic reference layer; and a magnetic fixed layer formed adjacent to the anti-ferromagnetic coupling layer. The magnetic free layer has a variable magnetization direction substantially perpendicular to the layer plane thereof. The first and second magnetic reference layers have a first fixed magnetization direction substantially perpendicular to the layer planes thereof. The magnetic fixed layer has a second fixed magnetization direction that is substantially perpendicular to the layer plane thereof and is substantially opposite to the first fixed magnetization direction.

Magnetic random access memory with ultrathin reference layer

The present invention is directed to an MTJ memory element including a magnetic free layer structure which includes one or more magnetic free layers that have a same variable magnetization direction substantially perpendicular to layer planes thereof; an insulating tunnel junction layer formed adjacent to the magnetic free layer structure; a magnetic reference layer structure comprising a first magnetic reference layer formed adjacent to the insulating tunnel junction layer and a second magnetic reference layer separated therefrom by a perpendicular enhancement layer with the first and second magnetic reference layers having a first fixed magnetization direction substantially perpendicular to layer planes thereof; an anti-ferromagnetic coupling layer formed adjacent to the second magnetic reference layer opposite the perpendicular enhancement layer; and a magnetic fixed layer comprising first and second magnetic fixed sublayers with the second magnetic fixed sublayer formed adjacent to the anti-ferromagnetic coupling layer opposite the second magnetic reference layer.

Magnetic memory element with composite fixed layer

The present invention is directed to an MTJ memory element including a magnetic free layer structure which comprises one or more magnetic free layers that have a same variable magnetization direction substantially perpendicular to layer planes thereof; an insulating tunnel junction layer formed adjacent to the magnetic free layer structure; a magnetic reference layer structure comprising a first magnetic reference layer formed adjacent to the insulating tunnel junction layer and a second magnetic reference layer separated therefrom by a perpendicular enhancement layer with the first and second magnetic reference layers having a first fixed magnetization direction substantially perpendicular to layer planes thereof; an anti-ferromagnetic coupling layer formed adjacent to the second magnetic reference layer opposite the perpendicular enhancement layer; and a magnetic fixed layer comprising first and second magnetic fixed sublayers with the second magnetic fixed sublayer formed adjacent to the anti-ferromagnetic coupling layer opposite the second magnetic reference layer.

Magnetic random access memory with tri-layer reference layer

MRAM devices that are switched by unipolar electron flow are described. Embodiments use arrays of cells that include a diode or transistor with a pMTJ. The switching between the high and low resistance states of the pMTJ is achieved by electron flow in the same direction, i.e. a unipolar flow. Embodiments of the invention include methods of operating unipolar MRAM devices that include a read step after a write step to verify the operation. Embodiments also include methods of operating unipolar MRAM devices that include an iterative stepped-voltage write process that includes a plurality of write-read steps that begin with a selected voltage for the write pulse for the first iteration and gradually increase the voltage for the write pulse for the next iteration until a successful read operation occurs.

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Fremont, CA, United States of America

Xiaojie Hao