Avalanche Technology, Inc.

Lexar Media, Inc.

Cirrus Logic Inc.

Other

Lexar Microsystems, Inc.

Lexa Media, Inc.

Avalanche Technologies, Inc.

Parviz Keshtbod

Rajiv Yadav Ranjan

Ebrahim Abedifard

Roger Klas Malmhall

Mahmud M Assar

Petro Estakhri

Kimihiro Satoh

Yiming Huai

Jing Zhang

Siamack Nemazie

Yuchen Zhou

Roger Klaus Malmhall

Mehdi Asnaashari

Zihui Wang

Bing K Yen

Huadong Gan

Xiaobin Wang

Dong Ha Jung

Ravishankar Tadepalli

Mahmood Mozaffari

Ngon Van Le

The present invention is directed to a method for programming a memory cell that includes a transistor and a memory element coupled in series between a first conductive line and a second conductive line. The method includes the steps of applying a voltage across the memory cell with the voltage being sufficiently high to enable switching of the memory element from initial resistance state to target resistance state; determining the initial resistance state of the memory element; comparing the initial resistance state with the target resistance state; and if the initial resistance state and the target resistance state are same, concluding that the memory element is already in the target resistance state and terminating programming process; otherwise, continually monitoring the voltage until a change in the voltage is detected and then concluding that the memory element has switched to the target resistance state and terminating the programming process.

Power-efficient programming of magnetic memory

The present invention is directed to a method for programming a memory cell that includes a two-terminal selector and a memory element coupled in series between a first conductive line and a second conductive line. The method includes the steps of applying a voltage across the memory cell with the voltage being sufficiently high to enable switching of the memory element from initial resistance state to target resistance state; determining the initial resistance state of the memory element; comparing the initial resistance state with the target resistance state; and if the initial resistance state and the target resistance state are same, concluding that the memory element is already in the target resistance state and terminating programming process; otherwise, continually monitoring the voltage until a change in the voltage is detected and then concluding that the memory element has switched to the target resistance state and terminating the programming process.

The present invention is directed to a magnetic memory device comprising a memory array structure that includes a first memory array comprising a first plurality of memory cells and a second memory array comprising a second plurality of memory cells. Each memory cell of the first and second plurality of magnetic memory cells includes a magnetic memory element and a two-terminal selector coupled in series. The memory array structure further includes a first multiplexer coupled to a third plurality of first conductive lines with each line connected to a respective column of the first plurality of memory cells; a second multiplexer coupled to a fourth plurality of first conductive lines with each line connected to a respective column of the second plurality of memory cells; a sense amplifier, whose input is connected to the output of the first multiplexer and the output of the second multiplexer; and one or more latches coupled to the sense amplifier.

Magnetic memory emulating dynamic random access memory (DRAM)

The present invention is directed to a spin-orbitronics device including an array of MTJs with each of the MTJs coupled to a respective one of a plurality of selection transistors; a plurality of transverse polarizing lines with each of the transverse polarizing lines coupled to a row of the MTJs along a first direction; a plurality of word lines with each of the word lines coupled to gates of a row of the selection transistors along a second direction; and a plurality of source lines with each of the source lines coupled to a row of the selection transistors along a direction substantially perpendicular to the second direction. Each MTJ includes a magnetic comparison layer structure having a pseudo-invariable magnetization direction, which is configured to switch between two stable states by passing a comparison current through one of the plurality of transverse polarizing lines formed adjacent to the magnetic comparison layer structure.

Spin-orbitronics device and applications thereof

A non-volatile memory system includes a first circuit and a second circuit both coupled to a magnetoresistance tunnel junction (MTJ) cell to substantially reduce the level of current flowing through the MTJ with rise in temperature, as experienced by the MTJ. The first circuit is operable to adjust a slope of a curve representing current as a function of temperature and the second circuit is operable to adjust a value of the current level through the MTJ to maintain current constant or to reduce current when the temperature increases. This way sufficient current is provided for the MTJ at different temperatures to prevent write failure, over programming, MTJ damage and waste of current.

Method and apparatus for adjustment of current through a magnetoresistive tunnel junction (MTJ) based on temperature fluctuations

The present invention is directed to a method for programming a magnetic tunnel junction (MTJ) coupled to a transistor having a gate, a source, and a drain. The method includes the steps of setting a voltage of a source line to a first voltage, the source line being coupled to one of the source and drain of the transistor, the other one of the source and drain of the transistor being coupled to one end of the MTJ; setting a voltage of a bit line to zero, the bit line being coupled to the other end of the MTJ; setting a voltage of a word line coupled to the gate of the transistor to a second voltage that is higher than the first voltage; and programming the MTJ from a first resistance state to a second resistance state by driving a current through the MTJ from the source line to the bit line.

Programming of magnetic random access memory (MRAM) by boosting gate voltage

A method of programming an MTJ includes selecting the MTJ and an access transistor coupled thereto. The gate of the selected access transistor is coupled to a selected word line (WL), which is raised to a first voltage, Vdd, and is then allowed to float. The first voltage and a second voltage, Vx, are respectively applied to a selected bit line (BL) coupled to the selected MTJ and a selected source line (SL) coupled to the selected access transistor, thereby driving a switching current through the selected MTJ from the selected BL to SL. Alternatively, the switching current may be reversed by applying 0 V and Vdd to the selected BL and SL, respectively. Moreover, the second voltage is applied to other BLs not coupled to the selected MTJ and the first voltage is applied to other SLs not coupled to the selected access transistor, thereby boosting the voltage of the floating WL to above the first voltage.

A method of programming a voltage-controlled magnetoresistive tunnel junction (MTJ) includes applying a programming voltage pulse (Vp), reading the voltage-controlled MTJ, and determining if the voltage-controlled MTJ is programmed to a desired state and if not, changing the Vp and repeating the applying and reading steps until the voltage-controlled MTJ is programmed to the desired state.

Pulse programming techniques for voltage-controlled magnetoresistive tunnel junction (MTJ)

Fast programming of magnetic random access memory (MRAM)

The present invention is directed to a spin-orbitronics device including a magnetic comparison layer structure having a pseudo-invariable magnetization direction; a magnetic free layer structure whose variable magnetization direction can be switched by a switching current passing between the magnetic comparison layer structure and the magnetic free layer structure; an insulating tunnel junction layer interposed between the magnetic comparison layer structure and the magnetic free layer structure; and a non-magnetic transverse polarizing layer formed adjacent to the magnetic comparison layer structure. The pseudo-invariable magnetization direction of the magnetic comparison layer structure may be switched by passing a comparison current through the transverse polarizing layer along a direction that is substantially parallel to a layer plane of the transverse polarizing layer. The pseudo-invariable magnetization direction of the magnetic comparison layer structure is not switched by the switching current. The variable magnetization direction of the magnetic free layer structure is not switched by the comparison current.

A non-volatile memory system includes a first circuit and a second circuit both coupled to a magnetoresistance tunnel junction (MTJ) cell to substantially reduce the level of current flowing through the MTJ with rise in temperature, as experienced by the MTJ. The first circuit is operable to adjust a slope of a curve representing current as a function of temperature and the second circuit is operable to adjust a value of the current level through the MTJ to maintain current constant or to reduce current when the temperature increases. This way sufficient current is provided for the MTJ at different temperatures, to prevent write failure, over programming, MTJ damage and waste of current.

A method of programming an MTJ includes selecting an MTJ that is coupled to an access transistor at the drain of the access transistor. The gate of the access transistor is coupled to a selected word line (WL), the selected WL being substantially at a first voltage, Vdd; whereas the WLs that are not coupled to the MTJ are left to float. A second voltage, Vx, is applied to the unselected bit lines (BLs) and further applied to a source line (SL), the SL being coupled to the source of the access transistor. A third voltage, Vdd or 0 Volts, is applied to a selected BL, the selected BL being coupled the MTJ. The first voltage is applied to a SL, the SL being coupled to the source of the access transistor thereby causing the WL to boot above the first voltage.

The present invention is directed to a multi-state current-switching magnetic memory element configured to store a state by current flowing therethrough to switch the state including two or more magnetic tunneling junctions (MTJs) coupled in parallel between a top electrode and a bottom electrode. Each MTJ includes a free layer with a switchable magnetic orientation perpendicular to a layer plane thereof, a fixed layer with a fixed magnetic orientation perpendicular to a layer plane thereof, and a barrier layer interposed between the free layer and the fixed layer. The magnetic memory element is operable to store more than one bit of information.

High capacity low cost multi-state magnetic memory

A method of programming a MTJ includes selecting a MTJ that is coupled to an access transistor at the drain of the access transistor. The gate of the access transistor is coupled to a selected word line (WL), the selected WL is substantially at a first voltage, Vdd; whereas the WLs that are not coupled to the MTJ are left to float. A second voltage, Vx, is applied to the unselected bit lines (BLs) and further applied to a source line (SL), the SL being coupled to the source of the access transistor. A third voltage, Vdd or 0 Volts, is applied to a selected BL, the selected BL is coupled the MTJ. The first voltage is applied to a SL, the SL is coupled to the source of the access transistor thereby causing the WL to boot above the first voltage.

The present invention is directed to a multi-state current-switching magnetic memory element configured to store a state by current flowing therethrough to switch the state. The magnetic memory element includes a stack of two or more magnetic tunneling junctions (MTJs) with each MTJ including a free layer with a switchable magnetic orientation perpendicular to a layer plane thereof, a barrier layer, and a fixed layer with a fixed magnetic orientation perpendicular to a layer plane thereof. Each MTJ is separated from other MTJs in the stack by at least an isolation layer. The stack of MTJs may store more than one bit of information. The free layer of each MTJ has a switching current threshold different from free layers of other MTJs in the stack.

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Los Altos Hills, CA, United States of America

Parviz Keshtbod