Avalanche Technology, Inc.

Hitachi Global Storage Technologies Netherlands B.v.

Western Digital (fremont), Inc.

Hgst Netherlands, B.v.

Read Rite Corporation

Jing Zhang

Yiming Huai

Kimihiro Satoh

Yuchen Zhou

Rajiv Yadav Ranjan

Roger Klas Malmhall

Dong Ha Jung

Hongxin Yang

Ebrahim Abedifard

Parviz Keshtbod

Zihui Wang

Bing K Yen

Yong Shen

Xiaojie Hao

Mike Wang

Ioan Tudosa

Heng Gong

Jinqiu Zhang

Xiaobin Wang

Benjamin P Chen

Youping Deng

Terry Farren

Wen-Chien David Hsiao

Aron Pentek

Yingjian Chen

Thomas Young Chang

Kroum Stanimirov Stoev

Yimin Hsu

Francis H Liu

Honglin Zhu

Marcos Moises Lederman

Xinjiang Shen

Amritpal Singh Rana

Wenjie Chen

Ningjia Zhu

Lifan Chen

Bogdan M Simion

Thomas Roucoux

Yong Sheng

Mathew Gibbons

Aparna C Vadde

Bernardo Sardinha

Yiming Hual

Ebrahim Abedlfard

A spin-transfer torque magnetic random access memory (STTMRAM) element employed to store a state based on the magnetic orientation of a free layer, the STTMRAM element is made of a first perpendicular free layer (PFL) including a first perpendicular enhancement layer (PEL). The first PFL is formed on top of a seed layer. The STTMRAM element further includes a barrier layer formed on top of the first PFL and a second perpendicular reference layer (PRL) that has a second PEL. The second PRL is formed on top of the barrier layer. The STTMRAM element further includes a capping layer that is formed on top of the second PRL.

Memory system having thermally stable perpendicular magneto tunnel junction (MTJ) and a method of manufacturing same

The present invention is directed to a memory cell that includes a magnetic tunnel junction (MTJ) memory element and a two-terminal selector element coupled in series. The MTJ memory element includes a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween. The magnetic reference layer structure includes one or more magnetic reference layers having a first invariable magnetization direction substantially perpendicular to layer planes thereof. The two-terminal selector element includes a first inert electrode and a second inert electrode with a volatile switching layer interposed therebetween; a first active electrode formed adjacent to the first inert electrode; and a second active electrode formed adjacent to the second inert electrode. The volatile switching layer includes at least one conductor layer interleaved with insulating layers.

Magnetic memory cell including two-terminal selector device

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 and a two-terminal selector element coupled in series. The MTJ memory element includes a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween. The magnetic reference layer structure includes one or more magnetic reference layers having a first invariable magnetization direction substantially perpendicular to layer planes thereof. The two-terminal selector element includes a first inert electrode and a second inert electrode with a volatile switching layer interposed therebetween; a first active electrode formed adjacent to the first inert electrode; and a second active electrode formed adjacent to the second inert electrode. The volatile switching layer includes a plurality of metal-rich particles or clusters embedded in a matrix or at least one conductor layer interleaved with insulating layers.

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 manufacturing a memory cell that includes a magnetic memory element electrically connected to a two-terminal selector. The method includes the steps of depositing a selector film stack on a substrate; depositing a magnetic memory element film stack on top of the selector film stack; etching the magnetic memory element film stack with an etch mask formed thereon to remove at least an insulating tunnel junction layer in the magnetic memory element film stack not covered by the etch mask, thereby forming a magnetic memory element pillar; depositing a first conforming dielectric layer over the magnetic memory element pillar, including a sidewall thereof, and surrounding surface; etching a portion of the first conforming dielectric layer covering the surrounding surface to form a first protective sleeve around at least the insulating tunnel junction layer of the magnetic memory element pillar; and etching the selector film stack using the etch mask and the first protective sleeve as a composite mask to form a memory cell pillar.

Method for manufacturing magnetic memory cells

The present invention is directed to a method for manufacturing a memory cell that includes a magnetic memory element electrically connected to a two-terminal selector. The method includes the steps of depositing a magnetic memory element film stack on a substrate; depositing a selector film stack on top of the magnetic memory element film stack; etching the selector film stack with an etch mask formed thereon to remove at least a switching layer in the selector film stack not covered by the etch mask, thereby forming a selector pillar; depositing a first conforming dielectric layer over the selector pillar and surrounding surface; etching a portion of the first conforming dielectric layer covering the surrounding surface to form a first protective sleeve around at least the switching layer of the selector pillar; and etching the magnetic memory element film stack using the etch mask and the first protective sleeve as a composite mask to form a memory cell pillar.

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

A spin-transfer torque magnetic random access memory (STTMRAM) element includes a composite fixed layer formed on top of a substrate and a tunnel layer formed upon the fixed layer and a composite free layer formed upon the tunnel barrier layer. The magnetization direction of each of the composite free layer and fixed layer being substantially perpendicular to the plane of the substrate. The composite layers are made of multiple repeats of a bilayer unit which consists of a non-magnetic insulating layer and magnetic layer with thicknesses adjusted in a range that makes the magnetization having a preferred direction perpendicular to film plane.

Spin-transfer torque magnetic random access memory with perpendicular magnetic anisotropy multilayers

The present invention is directed to a spin transfer torque magnetic random access memory (STTMRAM) element comprising a composite free layer including one or more stacks of a bilayer unit that comprises an insulator layer and a magnetic layer with the magnetic layer having a variable magnetization direction substantially perpendicular to a layer plane thereof; a magnetic pinned layer having a first fixed magnetization direction substantially perpendicular to a layer plane thereof; a tunnel barrier layer formed between the composite free layer and the magnetic pinned layer; and a magnetic fixed layer coupled to the magnetic pinned layer through an anti-ferromagnetic coupling layer. The magnetic fixed layer has a second fixed magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to the first fixed magnetization direction.

A memory device comprises a semiconductor substrate having a plurality of parallel trenches therein, a memory region formed in the substrate including an array of memory cells having a plurality of vertical selection transistors with respective channels formed in trench sidewalls, a plurality of buried source electrodes in trench bottoms, a plurality of paired gate electrodes formed on paired trench sidewalls, a first and second stitch region disposed adjacent the memory region along a trench direction including a first and second row of gate contacts, respectively, and a row of source contacts disposed in the first or second stitch region with each of the source contacts coupled to a respective one of the source electrodes. One of each pair of the gate electrodes is coupled to a respective one of the first row of gate contacts and the other one of each pair of gate electrodes is coupled to a respective one of the second row of gate contacts.

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Fabrication methods using Ion Beam Etching (IBE) for MRAM cell memory elements are described. In embodiments of the invention the top electrode and MTJ main body are etched with one mask using reactive etching such as RIE or magnetized inductively coupled plasma (MICP) for improved selectivity, then the bottom electrode is etched using IBE as specified in various alternative embodiments which include selection of incident angles, wafer rotational rate profiles and optional passivation layer deposited prior to the IBE. The IBE according to the invention etches the bottom electrode without the need for an additional mask by using the layer stack created by the first etching phase as the mask. This makes the bottom electrode self-aligned to MTJ. The IBE also achieves MTJ sidewall cleaning without the need for an additional step.

MTJ stack and bottom electrode patterning process with ion beam etching using a single mask

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Los Altos, CA, United States of America

Jing Zhang