WO2018125196A1 - Spin transfer torque memory devices having heusler magnetic tunnel junctions - Google Patents

Spin transfer torque memory devices having heusler magnetic tunnel junctions Download PDF

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Publication number
WO2018125196A1
WO2018125196A1 PCT/US2016/069433 US2016069433W WO2018125196A1 WO 2018125196 A1 WO2018125196 A1 WO 2018125196A1 US 2016069433 W US2016069433 W US 2016069433W WO 2018125196 A1 WO2018125196 A1 WO 2018125196A1
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WIPO (PCT)
Prior art keywords
heusler alloy
magnetic layer
alloy layer
layer
semiconducting
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PCT/US2016/069433
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French (fr)
Inventor
Brian Doyle
Kaan OGUZ
Charles Kuo
Kevin O'brien
Mark Doczy
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Intel Corporation
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Application filed by Intel Corporation filed Critical Intel Corporation
Priority to PCT/US2016/069433 priority Critical patent/WO2018125196A1/en
Publication of WO2018125196A1 publication Critical patent/WO2018125196A1/en

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
    • H10B61/20—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices comprising components having three or more electrodes, e.g. transistors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/01—Manufacture or treatment
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/10—Magnetoresistive devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/80—Constructional details
    • H10N50/85—Magnetic active materials

Definitions

  • Embodiments of the present description generally relate to the field of microelectronic devices, and, more particularly, to spin transfer torque memory devices.
  • Spin devices such as spin logic and spin memory, can enable a new class of logic and architectures for microelectronic components. Thus, there is an ongoing drive to improve the design and efficiency of these spin devices.
  • FIG. la is a schematic diagram illustrating a spin transfer torque memory device in accordance with an embodiment of the present description.
  • FIG. lb is a schematic diagram illustrating a spin transfer torque memory device in accordance with another embodiment of the present description.
  • FIG. 2a is a side view schematic illustrating a magnetic tunnel junction with a free magnetic layer having a magnetic orientation anti-parallel to a fixed magnetic layer in accordance with an embodiment of the present description.
  • FIG. 2b is a side view schematic illustrating a magnetic tunnel junction with a free magnetic layer having a magnetic orientation parallel to a fixed magnetic layer in accordance with an embodiment of the present description.
  • FIG. 3 is a side view schematic of a spin transfer torque element.
  • FIG. 4 is a side view schematic of a spin transfer torque element including a magnetic tunnel junction having free and fixed Heusler magnetic layers.
  • FIGs. 5-14 are side view schematics of aspin transfer torque element magnetic including a tunnel junctions having a fixed magnetic layer comprising at least one of a Heusler alloy layer a semiconducting Heusler alloy layer, free magnetic layers comprising a semiconducting Heusler alloy layer, and a metal spacer between the fixed magnetic layer and the free magnetic layer in accordance with various embodiments of the present description.
  • FIG. 15 is a flow diagram of a process of fabricating a magnetic tunnel junction in accordance with an embodiment of the present description.
  • FIG. 16 illustrates a computing device in accordance with one implementation of the present description.
  • over, “to”, “between” and “on” as used herein may refer to a relative position of one layer with respect to other layers.
  • One layer “over” or “on” another layer or bonded “to” another layer may be directly in contact with the other layer or may have one or more intervening layers.
  • One layer “between” layers may be directly in contact with the layers or may have one or more intervening layers.
  • Embodiments of the present description relate to the fabrication of spin transfer torque memory devices, wherein a magnetic tunnel junction of the spin transfer torque memory device is formed with a fixed magnetic layer comprising at least one of Heusler alloy layer and a semiconducting Heusler alloy layer, a free Heusler magnetic layer comprising a semiconducting Heusler alloy layer, and a metal spacer between the fixed magnetic layer and the free magnetic layer.
  • the free magnetic layer may comprise both a semiconducting Heusler alloy layer and a Heusler alloy layer.
  • FIG. la shows a schematic of a microelectronic device, illustrated as a spin transfer torque memory device 100 which includes a spin transfer torque element 110.
  • the spin transfer torque element 110 may comprise a top cap/contact or free magnetic layer electrode 120 with a free magnetic layer 130 adjacent the free magnetic layer electrode 120, a bottom cap or fixed magnetic layer electrode 160 adjacent a pinned or fixed magnetic layer 150, and a tunnel barrier layer 140 disposed between the free magnetic layer 130 and the fixed magnetic layer 150.
  • a dielectric material 145 may be formed adjacent the fixed magnetic layer electrode 160, the fixed magnetic layer 150, and the tunnel barrier layer 140.
  • the free magnetic layer electrode 120 may be electrically connected to a bit line 182.
  • the fixed magnetic layer electrode 160 may be connected to a transistor 180.
  • the transistor 180 may be connected to a word line 184 and a signal line 186 in a manner that will be understood to those skilled in the art.
  • the spin transfer torque memory device 100 may further include additional read and write circuitry (not shown), a sense amplifier (not shown), a bit line reference (not shown), and the like, as will be understood by those skilled in the art, for the operation of the spin transfer torque memory device 100. It is understood that a plurality of the spin transfer torque memory devices 100 may be operably connected to one another to form a memory array (not shown), wherein the memory array can be incorporated into a non-volatile memory device.
  • the portion of the spin transfer torque element 110 comprising the free magnetic layer 130, the tunnel barrier layer 140, and the fixed magnetic layer 150 is known as a magnetic tunnel junction 170.
  • the spin transfer torque memory device 100 may have a reverse orientation, wherein the free magnetic layer electrode 120 may be electrically connected to the transistor 180 and the fixed magnetic layer electrode 160 may be connected to the bit line 182.
  • the magnetic tunnel junction 170 functions essentially as a resistor, where the resistance of an electrical path through the magnetic tunnel junction 170 may exist in two resistive states, either "high” or “low”, depending on the direction or orientation of magnetization in the free magnetic layer 130 and in the fixed magnetic layer 150.
  • FIG. 2a illustrates a high resistive state, wherein direction of
  • FIG. 2b illustrates a low resistive state, wherein direction of magnetization in the free magnetic layer 130 and the fixed magnetic layer 150 are substantially aligned or parallel with one another. This is illustrated with arrows 172 in the free magnetic layer 130 and with arrows 174 in the fixed magnetic layer 150 aligned the same direction pointing from upward.
  • the terms “low” and “high” with regard to the resistive state of the magnetic tunnel junction 170 are relative to one another.
  • the high resistive state is merely a detectibly higher resistance than the low resistive state, and vice versa.
  • the low and high resistive states can represent different bits of information (i.e. a "0" or a "1").
  • the direction of magnetization in the free magnetic layer 130 may be switched through a process call spin transfer torque ("STT") using a spin-polarized current.
  • An electrical current is generally unpolarized (e.g. consisting of about 50% spin-up and about 50% spin-down electrons).
  • a spin polarized current is one with a great number of electrons of either spin-up or spin-down, which may be generated by passing a current through the fixed magnetic layer 150.
  • the electrons of the spin polarized current from the fixed magnetic layer 150 tunnel through the tunnel barrier layer 140 and transfers its spin angular momentum to the free magnetic layer 130, wherein to free magnetic layer 130 will orient its magnetic direction from anti-parallel, as shown in FIG. 2a, to that of the fixed magnetic layer 150 or parallel, as shown in FIG. 2b.
  • the free magnetic layer 130 may be returned to its origin orientation, shown in FIG. 2a, by reversing the current.
  • the magnetic tunnel junction 170 may store a single bit of information ("0" or
  • the spin transfer torque memory device 100 of FIG. la and lb is non-volatile.
  • the free magnetic layer 130 and the fixed magnetic layer 150 may comprise a ferromagnetic layer, such as a cobalt/iron/boron (CoFeB) alloy, and the tunnel barrier layer 140 may comprise an insulative oxide layer, such as magnesium oxide (MgO).
  • CoFeB free magnetic layer 130 and the CoFeB fixed magnetic layer 150 are magnetically polarized in the same direction, the spins conduct through the insulative MgO tunnel barrier layer 140.
  • MgO magnesium oxide
  • the insulative MgO tunnel barrier layer 140 acts so as to block the spin-down minority carriers, and the resistance of the magnetic tunnel junction 170 increases, as will be understood to those skilled in the art.
  • the free magnetic layer and the fixed magnetic layer may formed from Heusler alloys (also called "Heusler half-metals”), which are labeled as free Heusler magnetic layer 130 H and fixed Heusler magnetic layer 150 H .
  • Heusler alloys are ferromagnetic metal alloys based on a Heusler phase, which are intermetallics having a specific composition and face-centered cubic crystal structure. Heusler alloys possess ferromagnetic properties dues to a double-exchange mechanism between neighboring magnetic ions.
  • Heusler alloys may include, but are not limited to type XYZ alloys, where X may be cobalt, manganese, iron, and the like, where Y may be vanadium, chromium , titanium, iron, and the like, and wherein Z may be aluminum, gallium, indium, silicon, germanium, tin, phosphorous, antimony, and the like.
  • Heusler alloys such as Co 2 FeAl, Co 2 FeGe, Co 2 FeSi, Co 2 MnAL Co 2 MnGa, Co 2 MnGe, Co 2 MnSL Co 2 Ga, Cu 2 MnAi, Cu 2 MnIn, Cu 2 MnSn, Ni 2 MnAl, Ni?MnIn, Ni 2 MnSb, Ni 2 MnGa, Ni 2 MnSn, Pd 2 MnAl, Pd 2 MnIn, Pd?MnSb, and
  • the free Heusler magnetic layer 130 H and the fixed Heusler magnetic layer 150 H are both spin-up, the magnetic tunnel junction 170 is conductive and charge passes through unimpeded. If the free Heusler magnetic layer 130 H is switched into the spin-down configuration, then the magnetic tunnel junction 170 is resistive and little or no current passes through. However, as the free Heusler magnetic layer 13 OH, the fixed Heusler magnetic layer 150 H , and the metal spacer 140 M are metals, the resistance state is still very conductive, the resistances required do not match the spin transfer torque memory cell 100 (see FIGs. la and lb) requirements.
  • the resistance state of the magnetic tunnel junction 170 needs to match or be be greater than the resistance of the transistor 180 (typically about lkQ-lOkQ).
  • the MgO tunnel barrier layer 140 of FIG. 3 instead of the metal spacer 140M, to increase the resistance and to also act as a second spin filter to further enhance the tunnel magneto-resistance ratio, such as a configuration will not be effective because of lattice mismatch between the Heusler magnetic layers 130 H and 150 H and the magnesium oxide.
  • the Heusler magnetic layers 130 H and 150 H must have a good crystalline structure to be effective and formation of such layers abutting a lattice mismatch material may not result in poor crystalline structure one or both Heusler magnetic layers 130 H and 150 H .
  • FIG. 5 illustrates the spin transfer torque element 1 10 according to one embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 1 10 may have the fixed magnetic layer 150 H formed from a Heusler alloy, as previously discussed, the free magnetic layer (labeled as " 130 S H") may be formed from a semiconducting Heusler alloy, and the metal spacer 140 M may be between the fixed magnetic layer 130 H and the free magnetic layer 130SH- Semiconducting Heusler alloys are material whose conductivity varies between that of a metal and that of an insulator, having resistivities which vary between about 10 "3 Q.m to 10 4 Q.m.
  • Semiconducting Heusler alloys possess these semiconducting properties due to the fact that these materials have a band gap at the Fermi level, while in metallic Heuslers alloys, the Fermi level is situated above the band gap in the conductive band of the material.
  • Such Heusler alloys may include, but are not limited to NiMnSb, CoTiSb, NiTiSn, NiYSb, CoYSb, and NiTii -x xSn (where M is either Sc or V and where 0 ⁇ x ⁇ 0.2), wherein Ni is nickel, Mn is manganese, Sb is antimony, Co is cobalt, Ti is titanium, Sn is tin, Y is yttrium, Sc is scandium, and V is vanadium).
  • the use of a semiconducting Heusler alloy in the free magnetic layer increases the resistance state of the magnetic tunnel junction 170 to match more closely match or be greater than the resistance of the transistor 180 (i.e. allowing it to be read by a sense amp (not shown)).
  • the metal spacer 140 M decouples the fixed magnetic layer (e.g. element 15 OH) from the free magnetic layer (e.g. element 130SH).
  • the metal space 140 M allows the weaker free magnetic layer 130 S H to be switched without being pinned by the stronger magnet in the fixed magnetic layer 150 H .
  • the metal spacer 140 M may be any appropriate metal or metal alloy which is capable of decoupling the free magnetic layer (e.g. element 130 S H) from the fixed magnetic layer (e.g. element 150 H ).
  • FIG. 6 illustrates the spin transfer torque element 110 according to another embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer formed from the semiconducting Heusler alloys (labeled as " 150SH") > the free magnetic layer 130SH may also be formed from the semiconducting Heusler alloys, and the metal spacer 140 M may be between the fixed magnetic layer 150SH and the free magnetic layer 130SH-
  • the resistance of the fixed magnetic layer 150SH should not be so high as to result in a diminished resistance ratio when the free magnetic layer 130SH is switched, as will be understood to those skilled in the art.
  • FIG. 7 illustrates the spin transfer torque element 110 according to one embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150 H formed from a Heusler alloy, the metal spacer 140 M may be on the fixed magnetic layer 150 H , and the free magnetic layer (labeled as " 130SHC") may be a composite of a semiconducting Heusler alloy layer 132 on the metal spacer 140 M and a Heusler alloy layer 134 on the semiconducting Heusler alloy layer 132.
  • FIG. 8 illustrates the spin transfer torque element 110 according to another embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150SH formed from the
  • semiconducting Heusler alloys and the free magnetic layer 130 S HC may be a composite of a semiconducting Heusler alloy layer 132 on the metal spacer 140 M and a Heusler alloy layer 134 on the semiconducting Heusler alloy layer 132.
  • FIG. 9 illustrates the spin transfer torque element 110 according to one embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150 H formed from a Heusler alloy, the metal spacer 140 M may be on the fixed magnetic layer 150 H , and the free magnetic layer 130SHC may be a composite of the Heusler alloy layer 134 on the metal spacer 140 M and the semiconducting Heusler alloy layer 132 on the Heusler alloy layer 134.
  • FIG. 10 illustrates the spin transfer torque element 110 according to another embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150SH formed from the
  • the semiconducting Heusler alloys, and the free magnetic layer 130SHC may be a composite of the Heusler alloy layer 134 on the metal spacer 140 M and the semiconducting Heusler alloy layer 132 on the Heusler alloy layer 134.
  • the semiconducting Heusler alloy layer 132 on the Heusler alloy layer 134 may allow for adjusting the resistance of the free magnetic layer 130SHC by adjusting the thicknesses and materials used, as will be understood to those skilled in the art. Furthermore, the
  • a metal coupler 136 may be placed between the semiconducting Heusler alloy layer 132 and the Heusler alloy layer 134, as discussed below with regard to the embodiments described in FIGs. 11-14.
  • FIG. 11 illustrates the spin transfer torque element 110 according to one embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150 H formed from a Heusler alloy, the metal spacer 140 M may be on the fixed magnetic layer 150 H , and the free magnetic layer (labeled as " 130SHCC") may be a composite of a semiconducting Heusler alloy layer 132 on the metal spacer 140M, the metal coupler 136 on the semiconducting Heusler alloy layer 132, and the Heusler alloy layer 134 on the metal coupler 136.
  • 130SHCC free magnetic layer
  • FIG. 12 illustrates the spin transfer torque element 110 according to another embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150SH formed from the
  • semiconducting Heusler alloys and the free magnetic layer 130SHCC may comprise the semiconducting Heusler alloy layer 132 on the metal spacer 140 M , the metal coupler 136 on the semiconducting Heusler alloy layer 132, and the Heusler alloy layer 134 on the metal coupler 136.
  • FIG. 13 illustrates the spin transfer torque element 110 according to still another embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150 H formed from a Heusler alloy, the metal spacer 140 M may be on the fixed magnetic layer 150 H , and the free magnetic layer 130SHCC may comprise the Heusler alloy layer 134 on the metal spacer 140M, a metal coupler 136 on the Heusler alloy layer 134, and the semiconducting Heusler alloy layer 132 on the metal coupler 136.
  • FIG. 14 illustrates the spin transfer torque element 110 according to a further embodiment of the present description.
  • the magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150SH formed from the
  • the semiconducting Heusler alloys, and the free magnetic layer 130SHCC may comprise the Heusler alloy layer 134 on the metal spacer 140M, a metal coupler 136 on the Heusler alloy layer 134, and the semiconducting Heusler alloy layer 132 on the metal coupler 136.
  • the metal coupler 136 may be any appropriate metal or metal alloy which can couple the semiconducting Heusler alloy layer 132 to the Heusler alloy layer 134.
  • the metal coupler 136 may comprise ruthenium. When ruthenium is utilized as the metal coupler 136, it may couple the semiconducting Heusler alloy layer 132 to the
  • Heusler alloy layer 134 either ferromagnetically or anti-ferromagnetically depending on the thickness of the metal coupler 136, as will be understood to those skilled in the art.
  • the steps for fabrication may include standard microelectronic fabrication processes such as lithography, etch, thin films deposition, planarization (such as chemical mechanical polishing (CMP)), diffusion, metrology, the use of sacrificial layers, the use of etch stop layers, the use of planarization stop layers, and/or any other associated action with microelectronic component fabrication.
  • standard microelectronic fabrication processes such as lithography, etch, thin films deposition, planarization (such as chemical mechanical polishing (CMP)), diffusion, metrology, the use of sacrificial layers, the use of etch stop layers, the use of planarization stop layers, and/or any other associated action with microelectronic component fabrication.
  • CMP chemical mechanical polishing
  • FIG. 15 is a flow chart of a process 200 of fabricating a magnetic tunnel junction according to an embodiment of the present description.
  • a fixed magnetic layer comprising at least one of a Heusler alloy layer and a semiconducting Heusler layer may be formed.
  • a free magnetic layer comprising a semiconducting Heusler alloy layer may be formed, as set forth in block 204.
  • a metal spacer may be formed between the fixed magnetic layer and the fixed magnetic layer.
  • FIG. 16 illustrates a computing device 300 in accordance with one implementation of the present description.
  • the computing device 300 houses a board 302.
  • the board 302 may include a number of components, including but not limited to a processor 304, at least one communication chip 306A, 306B, volatile memory 308, (e.g., DRAM), non-volatile memory 310 (e.g., ROM), flash memory 312, a graphics processor or CPU 314, a digital signal processor (not shown), a crypto processor (not shown), a chipset 316, an antenna, a display (touchscreen display), a touchscreen controller, a battery, an audio codec (not shown), a video codec (not shown), a power amplifier (AMP), a global positioning system (GPS) device, a compass, an accelerometer (not shown), a gyroscope (not shown), a speaker (not shown), a camera, and a mass storage device (not shown) (such as hard disk drive, compact disk (CD), digital versatile disk
  • components may be physically and electrically coupled to the board 302.
  • At least one of the microelectronic components may be a part of the processor 304.
  • the communication chip(s) 306 A, 306B enable wireless communications for the transfer of data to and from the computing device 300.
  • the term "wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not.
  • the communication chip(s) 306 A, 306B may implement any of a number of wireless standards or protocols, including but not limited to Wi-Fi (IEEE 802.11 family), WiMAX
  • the computing device 300 may include a plurality of communication chips 306 A, 306B.
  • a first communication chip 306 A may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and a second communication chip 306B may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others.
  • processor may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory.
  • Any of the microelectronic components within the computing device 300 may include a magnetic tunnel junction, including a fixed Heusler magnetic layer comprising at least one of a Heusler alloy layer and a semiconducting Heusler alloy layer, a free magnetic layer comprising a semiconducting Heusler alloy layer, and a metal spacer between the fixed magnetic layer and the free magnetic layer, as described above.
  • the computing device 300 may be a laptop, a netbook, a notebook, an ultrabook, a smartphone, a tablet, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder.
  • the computing device 300 may be any other electronic device that processes data.
  • Example 1 is an integrated circuit structure, comprising a magnetic tunnel junction, including a fixed magnetic layer comprising at least one of Heusler alloy layer and a semiconducting Heusler alloy layer, a free Heusler magnetic layer comprising a semiconducting Heusler alloy layer; and a metal spacer between the fixed magnetic layer and the free magnetic layer.
  • Example 2 the subject matter of Example 1 can optionally include the free magnetic layer comprising a semiconducting Heusler alloy layer on the metal spacer and a Heusler alloy layer on the semiconducting Heusler alloy layer.
  • Example 3 the subject matter of Example 2 can optionally include a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
  • Example 4 the subject matter of Example 3 can optionally include the metal coupler comprising ruthenium.
  • Example 5 the subject matter of Example 1 can optionally include the free magnetic layer comprising a Heusler alloy layer on the metal spacer and a semiconducting Heusler alloy layer on the Heusler alloy layer.
  • Example 6 the subject matter of Example 5 can optionally include a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
  • Example 7 the subject matter of Example 6 can optionally include the metal coupler comprising ruthenium.
  • Example 8 the subject matter of any of Examples 1 to 7 can optionally include a free magnetic layer electrode abutting the free Heusler magnetic layer and a fixed magnetic layer electrode abutting the fixed Heusler magnetic layer.
  • Example 9 the subject matter of Example 8 can optionally include the fixed magnetic layer electrode electrically connected to a bit line, and a transistor electrically connected to the free magnetic layer electrode, a source line, and a word line.
  • Example 10 the subject matter of Example 8 can optionally include the free magnetic layer electrode electrically connected to a bit line, and a transistor electrically connected to the fixed magnetic layer electrode, a source line, and a word line.
  • Example 11 is a method of forming a microelectronic device, comprising forming a magnetic tunnel junction, including: forming a fixed magnetic layer, wherein the fixed magnetic layer comprises at least one of a Heusler alloy layer and a semiconducting Heusler alloy layer; forming a free magnetic layer, wherein the free magnetic layer comprises a semiconducting Heusler alloy layer; and forming a metal spacer between the fixed magnetic layer and the free magnetic layer.
  • Example 12 the subject matter of Example 11 can optionally include forming the free magnetic layer comprising forming a semiconducting Heusler alloy layer on the metal spacer and forming a Heusler alloy layer on the semiconducting Heusler alloy layer.
  • Example 13 the subject matter of Example 12 can optionally include forming a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
  • Example 14 the subject matter of Example 13 can optionally include forming the metal coupler comprising forming a ruthenium coupler.
  • Example 15 the subject matter of Example 11 can optionally include forming the free magnetic layer comprising forming a Heusler alloy layer on the metal spacer and forming a semiconducting Heusler alloy layer on the Heusler alloy layer.
  • Example 16 the subject matter of Example 15 can optionally include forming a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
  • Example 17 the subject matter of Example 16 can optionally include forming the metal coupler comprising forming a ruthenium coupler.
  • Example 18 the subject matter of any of Examples 11 to 17 can optionally include forming a free magnetic layer electrode abutting the free Heusler magnetic layer and forming a fixed magnetic layer electrode abutting the fixed Heusler magnetic layer.
  • Example 19 the subject matter of Example 18 can optionally include forming the fixed magnetic layer electrode electrically connected to a bit line, and forming a transistor electrically connected to the free magnetic layer electrode, a source line, and a word line.
  • Example 20 the subject matter of Example 18 can optionally include forming the free magnetic layer electrode electrically connected to a bit line, and forming a transistor electrically connected to the fixed magnetic layer electrode, a source line, and a word line.
  • Example 21 is an electronic system, comprising a board; and a microelectronic device attached to the board, wherein the microelectronic device includes a spin transfer torque memory device having a magnetic tunnel junction, including a fixed magnetic layer comprising at least one of Heusler alloy layer and a semiconducting Heusler alloy layer, a free Heusler magnetic layer comprising a semiconducting Heusler alloy layer; and a metal spacer between the fixed magnetic layer and the free magnetic layer.
  • a spin transfer torque memory device having a magnetic tunnel junction, including a fixed magnetic layer comprising at least one of Heusler alloy layer and a semiconducting Heusler alloy layer, a free Heusler magnetic layer comprising a semiconducting Heusler alloy layer; and a metal spacer between the fixed magnetic layer and the free magnetic layer.
  • Example 22 the subject matter of Example 21 can optionally include the free magnetic layer comprising a semiconducting Heusler alloy layer on the metal spacer and a Heusler alloy layer on the semiconducting Heusler alloy layer.
  • Example 23 the subject matter of Example 22 can optionally include a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
  • Example 24 the subject matter of Example 23 can optionally include the metal coupler comprising ruthenium.
  • Example 25 the subject matter of Example 21 can optionally include the free magnetic layer comprising a Heusler alloy layer on the metal spacer and a semiconducting Heusler alloy layer on the Heusler alloy layer.
  • Example 26 the subject matter of Example 25 can optionally include a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
  • Example 27 the subject matter of Example 26 can optionally include the metal coupler comprising ruthenium.
  • Example 28 the subject matter of any of Examples 21 to 27 can optionally include a free magnetic layer electrode abutting the free Heusler magnetic layer and a fixed magnetic layer electrode abutting the fixed Heusler magnetic layer.
  • Example 29 the subject matter of Example 28 can optionally include the fixed magnetic layer electrode electrically connected to a bit line, and a transistor electrically connected to the free magnetic layer electrode, a source line, and a word line.
  • Example 30 the subject matter of Example 28 can optionally include the free magnetic layer electrode electrically connected to a bit line, and a transistor electrically connected to the fixed magnetic layer electrode, a source line, and a word line.

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Abstract

A spin transfer torque memory device may be fabricated with a magnetic tunnel junction within the spin transfer torque memory device having a fixed magnetic layer comprising at least one of Heusler alloy layer and a semiconducting Heusler alloy layer, a free Heusler magnetic layer comprising a semiconducting Heusler alloy layer, and a metal spacer between the fixed magnetic layer and the free magnetic layer. In further embodiments, the free magnetic layer may comprise both a semiconducting Heusler alloy layer and a Heusler alloy layer.

Description

SPIN TRANSFER TORQUE MEMORY DEVICES
HAVING HEUSLER MAGNETIC TUNNEL JUNCTIONS
BACKGROUND OF THE INVENTION
Embodiments of the present description generally relate to the field of microelectronic devices, and, more particularly, to spin transfer torque memory devices.
BACKGROUND
Higher performance, lower cost, increased miniaturization of integrated circuit components, and greater packaging density of integrated circuits are ongoing goals of the microelectronic industry for the fabrication of microelectronic logic and memory devices. Spin devices, such as spin logic and spin memory, can enable a new class of logic and architectures for microelectronic components. Thus, there is an ongoing drive to improve the design and efficiency of these spin devices.
BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. It is understood that the accompanying drawings depict only several embodiments in accordance with the present disclosure and are, therefore, not to be considered limiting of its scope. The disclosure will be described with additional specificity and detail through use of the accompanying drawings, such that the advantages of the present disclosure can be more readily ascertained, in which:
FIG. la is a schematic diagram illustrating a spin transfer torque memory device in accordance with an embodiment of the present description.
FIG. lb is a schematic diagram illustrating a spin transfer torque memory device in accordance with another embodiment of the present description. FIG. 2a is a side view schematic illustrating a magnetic tunnel junction with a free magnetic layer having a magnetic orientation anti-parallel to a fixed magnetic layer in accordance with an embodiment of the present description.
FIG. 2b is a side view schematic illustrating a magnetic tunnel junction with a free magnetic layer having a magnetic orientation parallel to a fixed magnetic layer in accordance with an embodiment of the present description.
FIG. 3 is a side view schematic of a spin transfer torque element.
FIG. 4 is a side view schematic of a spin transfer torque element including a magnetic tunnel junction having free and fixed Heusler magnetic layers.
FIGs. 5-14 are side view schematics of aspin transfer torque element magnetic including a tunnel junctions having a fixed magnetic layer comprising at least one of a Heusler alloy layer a semiconducting Heusler alloy layer, free magnetic layers comprising a semiconducting Heusler alloy layer, and a metal spacer between the fixed magnetic layer and the free magnetic layer in accordance with various embodiments of the present description.
FIG. 15 is a flow diagram of a process of fabricating a magnetic tunnel junction in accordance with an embodiment of the present description.
FIG. 16 illustrates a computing device in accordance with one implementation of the present description.
DETAILED DESCRIPTION
In the following detailed description, reference is made to the accompanying drawings that show, by way of illustration, specific embodiments in which the claimed subject matter may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the subject matter. It is to be understood that the various embodiments, although different, are not necessarily mutually exclusive. For example, a particular feature, structure, or characteristic described herein, in connection with one embodiment, may be implemented within other embodiments without departing from the spirit and scope of the claimed subject matter. References within this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation encompassed within the present description. Therefore, the use of the phrase "one embodiment" or "in an embodiment" does not necessarily refer to the same embodiment. In addition, it is to be understood that the location or arrangement of individual elements within each disclosed embodiment may be modified without departing from the spirit and scope of the claimed subject matter. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the subject matter is defined only by the appended claims, appropriately interpreted, along with the full range of equivalents to which the appended claims are entitled. In the drawings, like numerals refer to the same or similar elements or functionality throughout the several views, and that elements depicted therein are not necessarily to scale with one another, rather individual elements may be enlarged or reduced in order to more easily comprehend the elements in the context of the present description.
The terms "over", "to", "between" and "on" as used herein may refer to a relative position of one layer with respect to other layers. One layer "over" or "on" another layer or bonded "to" another layer may be directly in contact with the other layer or may have one or more intervening layers. One layer "between" layers may be directly in contact with the layers or may have one or more intervening layers.
Embodiments of the present description relate to the fabrication of spin transfer torque memory devices, wherein a magnetic tunnel junction of the spin transfer torque memory device is formed with a fixed magnetic layer comprising at least one of Heusler alloy layer and a semiconducting Heusler alloy layer, a free Heusler magnetic layer comprising a semiconducting Heusler alloy layer, and a metal spacer between the fixed magnetic layer and the free magnetic layer. In further embodiments, the free magnetic layer may comprise both a semiconducting Heusler alloy layer and a Heusler alloy layer.
FIG. la shows a schematic of a microelectronic device, illustrated as a spin transfer torque memory device 100 which includes a spin transfer torque element 110. The spin transfer torque element 110 may comprise a top cap/contact or free magnetic layer electrode 120 with a free magnetic layer 130 adjacent the free magnetic layer electrode 120, a bottom cap or fixed magnetic layer electrode 160 adjacent a pinned or fixed magnetic layer 150, and a tunnel barrier layer 140 disposed between the free magnetic layer 130 and the fixed magnetic layer 150. A dielectric material 145 may be formed adjacent the fixed magnetic layer electrode 160, the fixed magnetic layer 150, and the tunnel barrier layer 140. The free magnetic layer electrode 120 may be electrically connected to a bit line 182. The fixed magnetic layer electrode 160 may be connected to a transistor 180. The transistor 180 may be connected to a word line 184 and a signal line 186 in a manner that will be understood to those skilled in the art. The spin transfer torque memory device 100 may further include additional read and write circuitry (not shown), a sense amplifier (not shown), a bit line reference (not shown), and the like, as will be understood by those skilled in the art, for the operation of the spin transfer torque memory device 100. It is understood that a plurality of the spin transfer torque memory devices 100 may be operably connected to one another to form a memory array (not shown), wherein the memory array can be incorporated into a non-volatile memory device.
The portion of the spin transfer torque element 110 comprising the free magnetic layer 130, the tunnel barrier layer 140, and the fixed magnetic layer 150 is known as a magnetic tunnel junction 170.
As shown in FIG. lb, the spin transfer torque memory device 100 may have a reverse orientation, wherein the free magnetic layer electrode 120 may be electrically connected to the transistor 180 and the fixed magnetic layer electrode 160 may be connected to the bit line 182.
Referring to FIGs. 2a and 2b, the magnetic tunnel junction 170 functions essentially as a resistor, where the resistance of an electrical path through the magnetic tunnel junction 170 may exist in two resistive states, either "high" or "low", depending on the direction or orientation of magnetization in the free magnetic layer 130 and in the fixed magnetic layer 150. FIG. 2a illustrates a high resistive state, wherein direction of
magnetization in the free magnetic layer 130 and the fixed magnetic layer 150 are
substantially opposed or anti -parallel with one another. This is illustrated with arrows 172 in the free magnetic layer 130 pointing downward and with arrows 174 in the fixed magnetic layer 150 aligned in opposition pointing upward. FIG. 2b illustrates a low resistive state, wherein direction of magnetization in the free magnetic layer 130 and the fixed magnetic layer 150 are substantially aligned or parallel with one another. This is illustrated with arrows 172 in the free magnetic layer 130 and with arrows 174 in the fixed magnetic layer 150 aligned the same direction pointing from upward.
It is understood that the terms "low" and "high" with regard to the resistive state of the magnetic tunnel junction 170 are relative to one another. In other words, the high resistive state is merely a detectibly higher resistance than the low resistive state, and vice versa. Thus, with a detectible difference in resistance, the low and high resistive states can represent different bits of information (i.e. a "0" or a "1").
The direction of magnetization in the free magnetic layer 130 may be switched through a process call spin transfer torque ("STT") using a spin-polarized current. An electrical current is generally unpolarized (e.g. consisting of about 50% spin-up and about 50% spin-down electrons). A spin polarized current is one with a great number of electrons of either spin-up or spin-down, which may be generated by passing a current through the fixed magnetic layer 150. The electrons of the spin polarized current from the fixed magnetic layer 150 tunnel through the tunnel barrier layer 140 and transfers its spin angular momentum to the free magnetic layer 130, wherein to free magnetic layer 130 will orient its magnetic direction from anti-parallel, as shown in FIG. 2a, to that of the fixed magnetic layer 150 or parallel, as shown in FIG. 2b. The free magnetic layer 130 may be returned to its origin orientation, shown in FIG. 2a, by reversing the current.
Thus, the magnetic tunnel junction 170 may store a single bit of information ("0" or
"1") by its state of magnetization. The information stored in the magnetic tunnel
junction 170 is sensed by driving a current through the magnetic tunnel junction 170. The free magnetic layer 130 does not require power to retain its magnetic orientations; thus, the state of the magnetic tunnel junction 170 is preserved when power to the device is removed. Therefore, the spin transfer torque memory device 100 of FIG. la and lb is non-volatile.
In one embodiment of the spin transfer torque element 110, as shown in FIG. 3, the free magnetic layer 130 and the fixed magnetic layer 150 may comprise a ferromagnetic layer, such as a cobalt/iron/boron (CoFeB) alloy, and the tunnel barrier layer 140 may comprise an insulative oxide layer, such as magnesium oxide (MgO). Thus, when the CoFeB free magnetic layer 130 and the CoFeB fixed magnetic layer 150 are magnetically polarized in the same direction, the spins conduct through the insulative MgO tunnel barrier layer 140. It is understood that other layer could be incorporated into the magnetic tunnel junction 170, such as an antiferromagnetic layer between the CoFeB fixed magnetic layer 150 and the fixed magnetic layer electrode 160. When the CoFeB free magnetic layer 130 and the CoFeB fixed magnetic layer 150 are magnetically polarized in opposite directions, the insulative MgO tunnel barrier layer 140 acts so as to block the spin-down minority carriers, and the resistance of the magnetic tunnel junction 170 increases, as will be understood to those skilled in the art.
In order to improve the performance of the of the spin transfer torque element 1 10 as shown in FIG. 4, the free magnetic layer and the fixed magnetic layer may formed from Heusler alloys (also called "Heusler half-metals"), which are labeled as free Heusler magnetic layer 130H and fixed Heusler magnetic layer 150H. Heusler alloys are ferromagnetic metal alloys based on a Heusler phase, which are intermetallics having a specific composition and face-centered cubic crystal structure. Heusler alloys possess ferromagnetic properties dues to a double-exchange mechanism between neighboring magnetic ions. Such Heusler alloys may include, but are not limited to type XYZ alloys, where X may be cobalt, manganese, iron, and the like, where Y may be vanadium, chromium , titanium, iron, and the like, and wherein Z may be aluminum, gallium, indium, silicon, germanium, tin, phosphorous, antimony, and the like. These may include common Heusler alloys such as Co2FeAl, Co2FeGe, Co2FeSi, Co2MnAL Co2MnGa, Co2MnGe, Co2MnSL Co2 Ga, Cu2MnAi, Cu2MnIn, Cu2MnSn, Ni2MnAl, Ni?MnIn, Ni2MnSb, Ni2MnGa, Ni2MnSn, Pd2MnAl, Pd2MnIn, Pd?MnSb, and
Pd2MnSn (wherein Al is aluminum, Co is cobalt, Cu is copper, Fe is iron, Ga is gallium, Ge is germanium, In is indium, Mn is manganese, Ni is nickel, Pd is palladium, Sb is antimony, Si is silicon, and Sn is tin). As will be understood to those skilled in the art, such Heusler alloys act as their own filter, because, depending on their spin state, they can be highly metallic or much less metallic (assuming "spin-up" to be the conducting state and "spin- down" to be the insulating state). As the Heusler alloy acts as its own spin filter, the insulative MgO tunnel barrier layer 140 of FIG. 3 can be replaced by a metal spacer 140M, as shown in FIG. 4. In the conducting phase, the free Heusler magnetic layer 130H and the fixed Heusler magnetic layer 150H are both spin-up, the magnetic tunnel junction 170 is conductive and charge passes through unimpeded. If the free Heusler magnetic layer 130H is switched into the spin-down configuration, then the magnetic tunnel junction 170 is resistive and little or no current passes through. However, as the free Heusler magnetic layer 13 OH, the fixed Heusler magnetic layer 150H, and the metal spacer 140M are metals, the resistance state is still very conductive, the resistances required do not match the spin transfer torque memory cell 100 (see FIGs. la and lb) requirements. In other words, the resistance state of the magnetic tunnel junction 170 needs to match or be be greater than the resistance of the transistor 180 (typically about lkQ-lOkQ). Although it is conceivable to re-insert the MgO tunnel barrier layer 140 of FIG. 3, instead of the metal spacer 140M, to increase the resistance and to also act as a second spin filter to further enhance the tunnel magneto-resistance ratio, such as a configuration will not be effective because of lattice mismatch between the Heusler magnetic layers 130H and 150H and the magnesium oxide. As will be understood to those skilled in the art, the Heusler magnetic layers 130H and 150H must have a good crystalline structure to be effective and formation of such layers abutting a lattice mismatch material may not result in poor crystalline structure one or both Heusler magnetic layers 130H and 150H.
FIG. 5 illustrates the spin transfer torque element 1 10 according to one embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 1 10 may have the fixed magnetic layer 150H formed from a Heusler alloy, as previously discussed, the free magnetic layer (labeled as " 130SH") may be formed from a semiconducting Heusler alloy, and the metal spacer 140M may be between the fixed magnetic layer 130H and the free magnetic layer 130SH- Semiconducting Heusler alloys are material whose conductivity varies between that of a metal and that of an insulator, having resistivities which vary between about 10"3 Q.m to 104 Q.m. Semiconducting Heusler alloys possess these semiconducting properties due to the fact that these materials have a band gap at the Fermi level, while in metallic Heuslers alloys, the Fermi level is situated above the band gap in the conductive band of the material. Such Heusler alloys may include, but are not limited to NiMnSb, CoTiSb, NiTiSn, NiYSb, CoYSb, and NiTii-x xSn (where M is either Sc or V and where 0<x<0.2), wherein Ni is nickel, Mn is manganese, Sb is antimony, Co is cobalt, Ti is titanium, Sn is tin, Y is yttrium, Sc is scandium, and V is vanadium).
As will be understood to those skilled in the art, the use of a semiconducting Heusler alloy in the free magnetic layer (e.g. element 130SH) increases the resistance state of the magnetic tunnel junction 170 to match more closely match or be greater than the resistance of the transistor 180 (i.e. allowing it to be read by a sense amp (not shown)).
As will be further understood to those skilled in the art, the metal spacer 140M decouples the fixed magnetic layer (e.g. element 15 OH) from the free magnetic layer (e.g. element 130SH). When the free magnetic layer 130SH switches, the metal space 140M allows the weaker free magnetic layer 130SH to be switched without being pinned by the stronger magnet in the fixed magnetic layer 150H. This applies to all embodiments of the present description. The metal spacer 140M may be any appropriate metal or metal alloy which is capable of decoupling the free magnetic layer (e.g. element 130SH) from the fixed magnetic layer (e.g. element 150H).
FIG. 6 illustrates the spin transfer torque element 110 according to another embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer formed from the semiconducting Heusler alloys (labeled as " 150SH")> the free magnetic layer 130SH may also be formed from the semiconducting Heusler alloys, and the metal spacer 140M may be between the fixed magnetic layer 150SH and the free magnetic layer 130SH- However, with regard to using a semiconducting Heusler alloy in the fixed magnetic layer 150SH, the resistance of the fixed magnetic layer 150SH should not be so high as to result in a diminished resistance ratio when the free magnetic layer 130SH is switched, as will be understood to those skilled in the art.
FIG. 7 illustrates the spin transfer torque element 110 according to one embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150H formed from a Heusler alloy, the metal spacer 140M may be on the fixed magnetic layer 150H, and the free magnetic layer (labeled as " 130SHC") may be a composite of a semiconducting Heusler alloy layer 132 on the metal spacer 140M and a Heusler alloy layer 134 on the semiconducting Heusler alloy layer 132.
FIG. 8 illustrates the spin transfer torque element 110 according to another embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150SH formed from the
semiconducting Heusler alloys, and the free magnetic layer 130SHC may be a composite of a semiconducting Heusler alloy layer 132 on the metal spacer 140M and a Heusler alloy layer 134 on the semiconducting Heusler alloy layer 132.
FIG. 9 illustrates the spin transfer torque element 110 according to one embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150H formed from a Heusler alloy, the metal spacer 140M may be on the fixed magnetic layer 150H, and the free magnetic layer 130SHC may be a composite of the Heusler alloy layer 134 on the metal spacer 140M and the semiconducting Heusler alloy layer 132 on the Heusler alloy layer 134. FIG. 10 illustrates the spin transfer torque element 110 according to another embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150SH formed from the
semiconducting Heusler alloys, and the free magnetic layer 130SHC may be a composite of the Heusler alloy layer 134 on the metal spacer 140M and the semiconducting Heusler alloy layer 132 on the Heusler alloy layer 134.
With regard to the embodiments illustrated in FIGs. 7-10, the use of the
semiconducting Heusler alloy layer 132 on the Heusler alloy layer 134 may allow for adjusting the resistance of the free magnetic layer 130SHC by adjusting the thicknesses and materials used, as will be understood to those skilled in the art. Furthermore, the
semiconducting Heusler alloy layer 132 and the Heusler alloy layer 134 should be coupled to one another, such both layers switch when the free magnetic layer 130SHC is switch. To improve the coupling, a metal coupler 136 may be placed between the semiconducting Heusler alloy layer 132 and the Heusler alloy layer 134, as discussed below with regard to the embodiments described in FIGs. 11-14.
FIG. 11 illustrates the spin transfer torque element 110 according to one embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150H formed from a Heusler alloy, the metal spacer 140M may be on the fixed magnetic layer 150H, and the free magnetic layer (labeled as " 130SHCC") may be a composite of a semiconducting Heusler alloy layer 132 on the metal spacer 140M, the metal coupler 136 on the semiconducting Heusler alloy layer 132, and the Heusler alloy layer 134 on the metal coupler 136.
FIG. 12 illustrates the spin transfer torque element 110 according to another embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150SH formed from the
semiconducting Heusler alloys, and the free magnetic layer 130SHCC may comprise the semiconducting Heusler alloy layer 132 on the metal spacer 140M, the metal coupler 136 on the semiconducting Heusler alloy layer 132, and the Heusler alloy layer 134 on the metal coupler 136.
FIG. 13 illustrates the spin transfer torque element 110 according to still another embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150H formed from a Heusler alloy, the metal spacer 140M may be on the fixed magnetic layer 150H, and the free magnetic layer 130SHCC may comprise the Heusler alloy layer 134 on the metal spacer 140M, a metal coupler 136 on the Heusler alloy layer 134, and the semiconducting Heusler alloy layer 132 on the metal coupler 136.
FIG. 14 illustrates the spin transfer torque element 110 according to a further embodiment of the present description. The magnetic tunnel junction 170 of the spin transfer torque element 110 may have the fixed magnetic layer 150SH formed from the
semiconducting Heusler alloys, and the free magnetic layer 130SHCC may comprise the Heusler alloy layer 134 on the metal spacer 140M, a metal coupler 136 on the Heusler alloy layer 134, and the semiconducting Heusler alloy layer 132 on the metal coupler 136.
The metal coupler 136 may be any appropriate metal or metal alloy which can couple the semiconducting Heusler alloy layer 132 to the Heusler alloy layer 134. In one embodiment, the metal coupler 136 may comprise ruthenium. When ruthenium is utilized as the metal coupler 136, it may couple the semiconducting Heusler alloy layer 132 to the
Heusler alloy layer 134 either ferromagnetically or anti-ferromagnetically depending on the thickness of the metal coupler 136, as will be understood to those skilled in the art.
Although the precise methods of fabricating the magnetic tunnel junction 170 of FIGs. 5-14 has not been described herein, it is understood that the steps for fabrication may include standard microelectronic fabrication processes such as lithography, etch, thin films deposition, planarization (such as chemical mechanical polishing (CMP)), diffusion, metrology, the use of sacrificial layers, the use of etch stop layers, the use of planarization stop layers, and/or any other associated action with microelectronic component fabrication.
FIG. 15 is a flow chart of a process 200 of fabricating a magnetic tunnel junction according to an embodiment of the present description. As set forth in block 202, a fixed magnetic layer comprising at least one of a Heusler alloy layer and a semiconducting Heusler layer may be formed. A free magnetic layer comprising a semiconducting Heusler alloy layer may be formed, as set forth in block 204. As set forth in block 206, a metal spacer may be formed between the fixed magnetic layer and the fixed magnetic layer.
FIG. 16 illustrates a computing device 300 in accordance with one implementation of the present description. The computing device 300 houses a board 302. The board 302 may include a number of components, including but not limited to a processor 304, at least one communication chip 306A, 306B, volatile memory 308, (e.g., DRAM), non-volatile memory 310 (e.g., ROM), flash memory 312, a graphics processor or CPU 314, a digital signal processor (not shown), a crypto processor (not shown), a chipset 316, an antenna, a display (touchscreen display), a touchscreen controller, a battery, an audio codec (not shown), a video codec (not shown), a power amplifier (AMP), a global positioning system (GPS) device, a compass, an accelerometer (not shown), a gyroscope (not shown), a speaker (not shown), a camera, and a mass storage device (not shown) (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth). Any of the microelectronic
components may be physically and electrically coupled to the board 302. In some
implementations, at least one of the microelectronic components may be a part of the processor 304.
The communication chip(s) 306 A, 306B enable wireless communications for the transfer of data to and from the computing device 300. The term "wireless" and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. The communication chip(s) 306 A, 306B may implement any of a number of wireless standards or protocols, including but not limited to Wi-Fi (IEEE 802.11 family), WiMAX
(IEEE 802.16 family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well as any other wireless protocols that are designated as 3G, 4G, 5G, and beyond. The computing device 300 may include a plurality of communication chips 306 A, 306B. For instance, a first communication chip 306 A may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and a second communication chip 306B may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others.
The term "processor" may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. Any of the microelectronic components within the computing device 300 may include a magnetic tunnel junction, including a fixed Heusler magnetic layer comprising at least one of a Heusler alloy layer and a semiconducting Heusler alloy layer, a free magnetic layer comprising a semiconducting Heusler alloy layer, and a metal spacer between the fixed magnetic layer and the free magnetic layer, as described above.
In various implementations, the computing device 300 may be a laptop, a netbook, a notebook, an ultrabook, a smartphone, a tablet, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder. In further implementations, the computing device 300 may be any other electronic device that processes data.
It is understood that the subject matter of the present description is not necessarily limited to specific applications illustrated in the figures. The subject matter may be applied to other microelectronic device and assembly applications, as well as any appropriate transistor application, as will be understood to those skilled in the art.
The following examples pertain to further embodiments, wherein Example 1 is an integrated circuit structure, comprising a magnetic tunnel junction, including a fixed magnetic layer comprising at least one of Heusler alloy layer and a semiconducting Heusler alloy layer, a free Heusler magnetic layer comprising a semiconducting Heusler alloy layer; and a metal spacer between the fixed magnetic layer and the free magnetic layer.
In Example 2, the subject matter of Example 1 can optionally include the free magnetic layer comprising a semiconducting Heusler alloy layer on the metal spacer and a Heusler alloy layer on the semiconducting Heusler alloy layer.
In Example 3, the subject matter of Example 2 can optionally include a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
In Example 4, the subject matter of Example 3 can optionally include the metal coupler comprising ruthenium.
In Example 5, the subject matter of Example 1 can optionally include the free magnetic layer comprising a Heusler alloy layer on the metal spacer and a semiconducting Heusler alloy layer on the Heusler alloy layer. In Example 6, the subject matter of Example 5 can optionally include a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
In Example 7, the subject matter of Example 6 can optionally include the metal coupler comprising ruthenium.
In Example 8, the subject matter of any of Examples 1 to 7 can optionally include a free magnetic layer electrode abutting the free Heusler magnetic layer and a fixed magnetic layer electrode abutting the fixed Heusler magnetic layer.
In Example 9, the subject matter of Example 8 can optionally include the fixed magnetic layer electrode electrically connected to a bit line, and a transistor electrically connected to the free magnetic layer electrode, a source line, and a word line.
In Example 10, the subject matter of Example 8 can optionally include the free magnetic layer electrode electrically connected to a bit line, and a transistor electrically connected to the fixed magnetic layer electrode, a source line, and a word line.
The following examples pertain to further embodiments, wherein Example 11 is a method of forming a microelectronic device, comprising forming a magnetic tunnel junction, including: forming a fixed magnetic layer, wherein the fixed magnetic layer comprises at least one of a Heusler alloy layer and a semiconducting Heusler alloy layer; forming a free magnetic layer, wherein the free magnetic layer comprises a semiconducting Heusler alloy layer; and forming a metal spacer between the fixed magnetic layer and the free magnetic layer.
In Example 12, the subject matter of Example 11 can optionally include forming the free magnetic layer comprising forming a semiconducting Heusler alloy layer on the metal spacer and forming a Heusler alloy layer on the semiconducting Heusler alloy layer.
In Example 13, the subject matter of Example 12 can optionally include forming a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
In Example 14, the subject matter of Example 13 can optionally include forming the metal coupler comprising forming a ruthenium coupler.
In Example 15, the subject matter of Example 11 can optionally include forming the free magnetic layer comprising forming a Heusler alloy layer on the metal spacer and forming a semiconducting Heusler alloy layer on the Heusler alloy layer. In Example 16, the subject matter of Example 15 can optionally include forming a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
In Example 17, the subject matter of Example 16 can optionally include forming the metal coupler comprising forming a ruthenium coupler.
In Example 18, the subject matter of any of Examples 11 to 17 can optionally include forming a free magnetic layer electrode abutting the free Heusler magnetic layer and forming a fixed magnetic layer electrode abutting the fixed Heusler magnetic layer.
In Example 19, the subject matter of Example 18 can optionally include forming the fixed magnetic layer electrode electrically connected to a bit line, and forming a transistor electrically connected to the free magnetic layer electrode, a source line, and a word line.
In Example 20, the subject matter of Example 18 can optionally include forming the free magnetic layer electrode electrically connected to a bit line, and forming a transistor electrically connected to the fixed magnetic layer electrode, a source line, and a word line.
The following examples pertain to further embodiments, wherein Example 21 is an electronic system, comprising a board; and a microelectronic device attached to the board, wherein the microelectronic device includes a spin transfer torque memory device having a magnetic tunnel junction, including a fixed magnetic layer comprising at least one of Heusler alloy layer and a semiconducting Heusler alloy layer, a free Heusler magnetic layer comprising a semiconducting Heusler alloy layer; and a metal spacer between the fixed magnetic layer and the free magnetic layer.
In Example 22, the subject matter of Example 21 can optionally include the free magnetic layer comprising a semiconducting Heusler alloy layer on the metal spacer and a Heusler alloy layer on the semiconducting Heusler alloy layer.
In Example 23, the subject matter of Example 22 can optionally include a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
In Example 24, the subject matter of Example 23 can optionally include the metal coupler comprising ruthenium.
In Example 25, the subject matter of Example 21 can optionally include the free magnetic layer comprising a Heusler alloy layer on the metal spacer and a semiconducting Heusler alloy layer on the Heusler alloy layer. In Example 26, the subject matter of Example 25 can optionally include a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
In Example 27, the subject matter of Example 26 can optionally include the metal coupler comprising ruthenium.
In Example 28, the subject matter of any of Examples 21 to 27 can optionally include a free magnetic layer electrode abutting the free Heusler magnetic layer and a fixed magnetic layer electrode abutting the fixed Heusler magnetic layer.
In Example 29, the subject matter of Example 28 can optionally include the fixed magnetic layer electrode electrically connected to a bit line, and a transistor electrically connected to the free magnetic layer electrode, a source line, and a word line.
In Example 30, the subject matter of Example 28 can optionally include the free magnetic layer electrode electrically connected to a bit line, and a transistor electrically connected to the fixed magnetic layer electrode, a source line, and a word line.
Having thus described in detail embodiments of the present description, it is understood that the present description defined by the appended claims is not to be limited by particular details set forth in the above description, as many apparent variations thereof are possible without departing from the spirit or scope thereof.

Claims

CLAIMS What is claimed is:
1. An integrated circuit (IC) structure, comprising:
a magnetic tunnel junction, including:
a fixed magnetic layer comprising at least one of a Heusler alloy layer and a semiconducting Heusler alloy layer;
a free magnetic layer comprising a semiconducting Heusler alloy layer; and a metal spacer between the fixed magnetic layer and the free magnetic layer.
2. The integrated circuit structure of claim 1, wherein the free magnetic layer comprises a semiconducting Heusler alloy layer on the metal spacer and a Heusler alloy layer on the semiconducting Heusler alloy layer.
3. The integrated circuit structure of claim 2, further comprising a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
4. The integrated circuit structure of claim 3, wherein the metal coupler comprises ruthenium.
5. The integrated circuit structure of claim 1, wherein the free magnetic layer comprises a Heusler alloy layer on the metal spacer and a semiconducting Heusler alloy layer on the Heusler alloy layer.
6. The integrated circuit structure of claim 5, further comprising a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
7. The integrated circuit structure of claim 6, wherein the metal coupler comprises ruthenium
8. The integrated circuit structure of any of claims 1 to 7, further comprising: the fixed magnetic layer electrically connected to a bit line; and
a transistor electrically connected to the free magnetic layer, a source line, and a word line.
9. The integrated circuit structure of any of claims 1 to 7, further comprising:
the free magnetic layer electrically connected to a bit line; and
a transistor electrically connected to the fixed magnetic layer, a source line, and a word line.
10. A method of forming a microelectronic device, comprising:
forming a magnetic tunnel junction, including:
forming a fixed magnetic layer, wherein the fixed magnetic layer comprises at least one of a Heusler alloy layer and a semiconducting Heusler alloy layer;
forming a free magnetic layer, wherein the free magnetic layer comprises a
semiconducting Heusler alloy layer; and
forming a metal spacer between the fixed magnetic layer and the free magnetic layer.
11. The method of claim 10, wherein forming the free magnetic layer comprises forming a semiconducting Heusler alloy layer on the metal spacer and forming a Heusler alloy layer on the semiconducting Heusler alloy layer.
12. The method of claim 11, further comprising forming a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
13. The method of claim 12, wherein forming the metal coupler comprises forming a ruthenium coupler.
14. The method of claim 10, wherein forming the free magnetic layer comprises forming a Heusler alloy layer on the metal spacer and forming a semiconducting Heusler alloy layer on the Heusler alloy layer.
15. The method of claim 14, further comprising forming a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
16. The method of claim 15, wherein forming the metal coupler comprises forming a ruthenium spacer.
17. The method of any of claims 10 to 16, further comprising:
electrically connecting the fixed magnetic layer electrode to a bit line; and
electrically connecting a transistor to the free magnetic layer electrode, a source line, and a word line.
18. The method of any of claims 10 to 16, further comprising:
electrically connecting the free magnetic layer electrode to a bit line; and
electrically connecting a transistor to the fixed magnetic layer electrode, a source line, and a word line.
19. An electronic system, comprising:
a board; and
a microelectronic device attached to the board, wherein the microelectronic device includes a spin transfer torque memory device having a magnetic tunnel junction, including:
a fixed magnetic layer comprising at least one of a Heusler alloy layer and a
semiconducting Heusler alloy layer;
a free magnetic layer comprising a semiconducting Heusler alloy layer; and a metal spacer between the fixed magnetic layer and the free magnetic layer.
20. The electronic system of claim 19, wherein the free magnetic layer comprises a semiconducting Heusler alloy layer on the metal spacer and a Heusler alloy layer on the semiconducting Heusler alloy layer.
21. The electronic system of claim 20, further comprising a metal coupler between the semiconducting Heusler alloy layer and the Heusler alloy layer.
22. The electronic system of claim 21, wherein the metal coupler comprises ruthenium
23. The electronic system of claim 19, wherein the free magnetic layer comprises a Heusler alloy layer on the metal spacer and a semiconducting Heusler alloy layer on the Heusler alloy layer.
24. The electronic system of claim 23, further comprising a metal coupler between the Heusler alloy layer and the semiconducting Heusler alloy layer.
25. The electronic system of claim 24, wherein the metal coupler comprises ruthenium.
PCT/US2016/069433 2016-12-30 2016-12-30 Spin transfer torque memory devices having heusler magnetic tunnel junctions WO2018125196A1 (en)

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