Avalanche Technology, Inc.

Hongxin Yang

Jing Zhang

Bing K Yen

Kimihiro Satoh

Xiaobin Wang

Xiaojie Hao

Dong Ha Jung

Zihui Wang

Zhiqiang Wei

The present invention is directed to a magnetic memory cell including a magnetic tunnel junction (MTJ) memory element and a two-terminal bidirectional selector coupled in series between two conductive lines. The MTJ memory element includes a magnetic free layer, a magnetic reference layer, and an insulating tunnel junction layer interposed therebetween. The two-terminal bidirectional selector includes bottom and top electrodes, first and third volatile switching layers interposed between the bottom and top electrodes, and a second volatile switching layer interposed between the first and third volatile switching layers. The bottom and top electrodes each independently include one of titanium nitride or iridium. The first and third volatile switching layers each include tantalum oxide and silver. The second volatile switching layer includes hafnium oxide and has a higher electrical resistance than the first and third volatile switching layers.

Bidirectional selector device for memory applications

The present invention is directed to a memory cell array comprising an array of magnetic memory elements arranged in rows and columns; a plurality of electrodes, each of which is formed adjacent to a respective one of the array of magnetic memory elements; a plurality of first conductive lines, each of which is connected to a respective row of the array of magnetic memory elements along a row direction; and a plurality of composite lines. Each composite line includes a volatile switching layer connected to a respective column of the plurality of electrodes along a column direction; an electrode layer formed adjacent to the volatile switching layer; and a second conductive line formed adjacent to the electrode layer. The dimension of the volatile switching layer may be substantially larger than the size of the magnetic memory element along the row direction.

Magnetic memory array incorporating selectors and method for manufacturing the 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

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 memory device including a magnetic memory element; a horizontal conductive line disposed above the magnetic memory element; a bottom electrode formed beneath the magnetic memory element and having a top, first and second sides that are opposite to each other; a first vertical conductive line formed adjacent to the first side of the bottom electrode with a first volatile switching layer and a first electrode layer interposed therebetween; and a second vertical conductive line formed adjacent to the second side of the bottom electrode with a second volatile switching layer and a second electrode layer interposed therebetween. The magnetic memory element is electrically connected to the horizontal conductive line at one end and to the bottom electrode at the other end.

Magnetic memory incorporating dual selectors

The present invention is directed to a memory device that includes an array of memory cells. Each of the memory cells includes a memory element connected to a two-terminal selector element. The two-terminal selector element includes a first electrode and a second electrode with a switching layer interposed therebetween. The switching layer includes a plurality of metal-rich clusters embedded in a nominally insulating matrix. One or more conductive paths are formed in the switching layer when an applied voltage to the memory cell exceeds a threshold level. Each of the memory cells may further include an intermediate electrode interposed between the memory element and the two-terminal selector element. The two-terminal selector element may further include a third electrode formed between the first electrode and the switching layer, and a fourth electrode formed between the second electrode and the switching layer.

Selector device incorporating conductive clusters 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

The present invention is directed to a memory device including a memory cell coupled to two wiring lines at two ends thereof. The memory cell includes a memory element, which includes a magnetic free layer and a magnetic reference layer with a tunnel junction layer interposed therebetween, and a bi-directional two-terminal selector element having multiple threshold voltages coupled to the memory element in series. The magnetic free layer has a variable magnetization direction substantially perpendicular to a layer plane thereof and the magnetic reference layer has a fixed magnetization direction substantially perpendicular to a layer plane thereof. In an embodiment, the bi-directional two-terminal selector element includes two selector devices with each selector device including two electrodes with a switching layer interposed therebetween. In another embodiment, the bi-directional two-terminal selector element includes a selector device incorporating therein two switching layers.

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Newark, CA, United States of America

Hongxin Yang