WO2018125243A1 - Perpendicular magnetic tunnel junction (pmtj) devices having a metal oxide layer - Google Patents

Perpendicular magnetic tunnel junction (pmtj) devices having a metal oxide layer Download PDF

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Publication number
WO2018125243A1
WO2018125243A1 PCT/US2016/069625 US2016069625W WO2018125243A1 WO 2018125243 A1 WO2018125243 A1 WO 2018125243A1 US 2016069625 W US2016069625 W US 2016069625W WO 2018125243 A1 WO2018125243 A1 WO 2018125243A1
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Prior art keywords
layer
depositing
magnetic
ferromagnetic
coupling
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PCT/US2016/069625
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French (fr)
Inventor
Md Tofizur Rahman
Christopher J. WIEGAND
Brian MAERTZ
Daniel G. OUELLETTE
Kaan OGUZ
Kevin P. O'brien
Brian S. Doyle
Mark L. Doczy
Daniel B. Bergstrom
Tahir Ghani
Oleg Golonzka
Justin S. BROCKMAN
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Intel Corporation
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Priority to PCT/US2016/069625 priority Critical patent/WO2018125243A1/en
Publication of WO2018125243A1 publication Critical patent/WO2018125243A1/en

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    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00Galvanomagnetic devices
    • H10N50/01Manufacture or treatment
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00Galvanomagnetic devices
    • H10N50/10Magnetoresistive devices
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00Galvanomagnetic devices
    • H10N50/80Constructional details
    • H10N50/85Magnetic active materials

Definitions

  • This disclosure generally relates perpendicular magnetic tunnel junction (pMTJ) devices, and more particularly, to pMTJ devices having a metal oxide layer.
  • pMTJ perpendicular magnetic tunnel junction
  • Magnetic tunnel junctions can represent electronic components comprising two ferromagnets separated by a thin insulator.
  • the insulating layer can be thin (typically a few nanometers), permitting electrons to tunnel from one ferromagnet into the other.
  • MTJs can be manufactured using thin film technology.
  • a magnetic tunnel junction with a perpendicular magnetic axis (referred herein as a perpendicular magnetic tunnel junction, pMTJ) is a type of MTJ that can be used for spintronic non-volatile magnetoresistive random access memory (MRAM).
  • MRAM spintronic non-volatile magnetoresistive random access memory
  • FIG. 1 shows a diagram of an example cross-sectional view of a perpendicular magnetic tunnel junction (pMTJ) device, in accordance with one or more example embodiments of the disclosure
  • FIG. 2 shows an example cross-sectional view of a pMTJ device, in accordance with one or more example embodiments of the disclosure
  • FIG. 3 shows an example of a diagram representing the performance parameters of example pMTJ devices fabricated on a blanket wafer, in accordance with example embodiments of the disclosure;
  • FIG. 4 shows a second example of a diagram representing the performance parameters of example pMTJ devices having critical dimension of approximately 40 nm, in accordance with example embodiments of the disclosure;
  • FIG. 5 shows an example processing flow diagram that can be used to fabricate an example pMTJ device, in accordance with one or more example embodiments of the disclosure.
  • FIG. 6 illustrates an example of a system, in accordance with one or more embodiments of the disclosure.
  • the term "horizontal” as used herein may be defined as a direction parallel to a plane or surface (for example, surface of a substrate), regardless of its orientation.
  • the term “vertical,” as used herein, may refer to a direction orthogonal to the horizontal direction as just described. Terms, such as “on,” “above,” “below,” “bottom,” “top,” “side” (as in “sidewall”), “higher,” “lower,” “upper,” “over,” and “under,” may be referenced with respect to a horizontal plane, where the horizontal plane can include an x- y plane, a x-z plane, or a y-z plane, as the case may be.
  • processing as used herein includes deposition of material or photoresist, patterning, exposure, development, etching, cleaning, ablating, polishing, and/or removal of the material or photoresist as required in formation a described structure.
  • the systems, methods, and apparatus disclosed herein can reduce the effects of damping, for example, Gilbert damping, in pMTJ devices, while maintaining the tunnel magnetoresistance (TMR) and/or the resistance area (RA) product of the pMTJ devices.
  • the Gilbert damping can be directly proportional to the switching current in pMTJ devices. Accordingly, because the systems, methods, and apparatus can reduce the Gilbert damping, the switching current can also be reduced the pMTJ devices.
  • spin pumping can refer to a process where a current of spin-polarized electrons (spin current) generated by the precession of magnetization in a ferromagnetic layer can be injected and can relax in adjacent nonmagnetic material.
  • spin current spin-polarized electrons
  • spin pumping can occur when spin current flows through a ferromagnetic layer followed by a nonmagnetic layer assembly.
  • a magnetic layer which can, alternatively or additionally be referred to as a free layer, can exist in the device.
  • the free layer can include a multilayer stack including a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer, where the non-magnetic layer can act as a coupling layer to enhance perpendicular anisotropy (PMA).
  • PMA perpendicular anisotropy
  • the damping coefficient for devices employing such a multilayer stack may be high, for example, due to the aforementioned spin pumping that can exist in the non-magnetic layer.
  • this can lead to a higher switching current in a device employing a free layer that includes a multilayer including a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer.
  • a device comprising a free layer that includes a multilayer including a first ferromagnetic layer, a non-magnetic oxide layer (for example, a metal oxide layer), and a second ferromagnetic layer can have a reduced spin pumping.
  • the non-magnetic oxide layer can be referred to as a coupling layer herein.
  • the non-magnetic oxide layer may further increase the series resistance in the device, potentially increasing the RA of the device with respect to devices having a non-magnetic layer instead of the non-magnetic oxide layer in the free layer.
  • the systems, methods, and apparatus describe non-magnetic oxide layers that can reduce Gilbert damping while not substantially increasing the RA.
  • the RA of a device can be maintained at a level to allow the resistance of the device to fall with a predetermined range, thereby permitting the device to integrate with one or more driving transistors that drive the pMTJ device.
  • the coupling layer can include a non-magnetic oxide, for example, a metal oxide, such as an oxide of tungsten, molybdenum and/or tantalum or similar metals.
  • the coupling layer comprising a metal oxide can have metal atoms that are coupled to oxygen atoms, causing less interaction between charge carriers (for example, electrons) transported through a multilayer stack that can include the first ferromagnetic layer, the coupling layer, and the second ferromagnetic layer, and thereby leading to less Gilbert damping in the device.
  • Gilbert damping in the device can be due to spin orbit coupling with the metal atoms in the coupling layer.
  • the spin orbit coupling can be reduced by the introduction of a metal oxide as the coupling layer.
  • this metal oxide serving as the coupling layer can increase the TMR and reduce the RA of the device. Accordingly, the switching current in both polarities (that is, the switching current from the top electrode to the bottom electrode, or vice versa, the switching current from the bottom electrode to the top electrode) can be reduced.
  • the metal oxide coupling layer can allow for the coersivity of the device to be reduced.
  • the reduction in coersivity can be due to a reduction in the magnetic anisotropy in the multilayer.
  • the reduction in the coersivity of the device may be due to the reduced damping, that is, the reduced Gilbert damping in the device.
  • the reduction of the magnetic anisotropy in the multilayer can be likened to a reduction in the depth of an energy well that represents the energetic transition that charge carriers (for example, electrons) overcome in transporting between the second magnetic layer and the first magnetic layer, through the coupling layer.
  • the reduction in the Gilbert damping can be likened to a reduction in a frictional force for the charge carriers to overcome in being transported from the second magnetic layer to the first magnetic layer through the coupling layer, or vice versa.
  • the thickness of the coupling layer can be one or a few atomic layers.
  • the coupling layer can have a thickness of approximately 1 angstrom to approximately 10 angstroms with example thicknesses of approximately 2 angstroms to approximately 3 angstroms.
  • the resistance of a buffer layer in the device (for example, a magnesium oxide buffer layer) and the resistance of a tunneling layer (for example, a magnesium oxide tunneling layer) in the device can dominate the resistivity of the device. Accordingly, the resistance of the coupling layer may have a reduced impact on the overall RA of the device in comparison to the resistance of the buffer layer and/or the tunneling layer.
  • the coupling layer can be deposited (that is, formed) using physical vapor deposition (PVD) and a post-deposition oxidation, for example, including flowing oxygen on the deposited coupling layer.
  • the coupling layer can comprise a metal oxide deposited (that is, formed) by a variety of techniques, including but not limited to, pulsed DC and/or Radio frequency (RF) sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), and/or PVD followed by a post oxidation step.
  • RF Radio frequency
  • the oxide coupling layers also can be formed by reactive sputtering with metals and oxygen.
  • the post-oxidation of the coupling layer may need slight optimization from batch to batch.
  • the transition metal can have different magnetic states based on the oxidation state of the transition metal; accordingly, the overall electronic properties of the device can change based on the magnetic states and/or oxidation states of the transition metal oxide.
  • This can lead to different device performance parameters in the device, for example, including but not limited to, different TMR, different RA, different damping, different switching currents, and/or different coercivities based at least in part on the magnetic states and/or oxidation states of the transition metal oxide.
  • FIG. 1 shows an example pMTJ device, in accordance with one or more example embodiments of the disclosure.
  • the device 100 can include a substrate 102.
  • the substrate 102 can be a thin slice of material such as silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide, an alloy of silicon and germanium, or indium phosphide, and/or glass.
  • the substrate 102 can serve as a heat sink for the device 100 allowing for the dissipation of heat generated by the various layers (to be discussed) in the device 100.
  • the device 100 can include a bottom electrode 104 and a top electrode 114 that may, together, sandwich an active layer 110.
  • the bottom electrode 104 can be disposed substantially on the substrate 102.
  • the bottom electrode 104 can include, for example, copper, tungsten, titanium nitride, platinum, and/or any other suitable material.
  • the top electrode 114 can include, for example, a copper, tungsten, titanium nitride, platinum, and/or any other suitable material.
  • the bottom electrode 104 can have a thickness of approximately 1 nm to approximately 150 nm with example thicknesses of approximately 5 nm to approximately 25 nm. In another embodiment the bottom electrode 104 can be deposited (that is, formed) using PVD, CVD and/or ALD. In another embodiment the top electrode 114 can have a thickness of approximately 2 nm to 100 nm with example thicknesses of approximately 5 nm to approximately 60 nm. In another embodiment the top electrode 114 can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0031] In an embodiment, the device 100 can include a synthetic antiferromagnetic (SAF) layer 106.
  • SAF synthetic antiferromagnetic
  • the SAF layer can include cobalt-platinum (Co/Pt) multilayers, cobalt- nickel (Co/Ni) multilayers, L10 alloys, suplerlattice magnets, other hard magnetic materials, and/or ruthenium, rhodium, iridium or similar metals that can generate Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions and effects.
  • RKKY can refer to a coupling mechanism of nuclear magnetic moments or localized inner d or f shell electron spins in a metal, for example, by means of an interaction through the conduction electrons.
  • the synthetic antiferromagnetic (SAF) layer 106 can have a thickness of approximately 3 nm to 20 nm with example thicknesses of approximately 5 nm to approximately 10 nm. In another embodiment the synthetic antiferromagnetic (SAF) layer 106 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the device 100 can include a reference layer 108.
  • the reference layer can include alloys of cobalt, iron, boron, and/or any transition metal and/or any transition metal oxides.
  • the reference layer 108 can have a thickness of approximately 0.5 nm to 5 nm with example thicknesses of approximately 1.5 nm to approximately 3 nm.
  • the reference layer 108 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the SAF layer 106 and the reference layer 108 serve as a p-n magnetic assembly.
  • the SAF layer 106 and/or reference layer 108 can produce an electric field during operation that can be referred to as a stray field, the stray field being non-zero in magnitude.
  • the stray field can affect a tunneling layer that is part of the active layer 110 (not shown, to be discussed in connection with FIG. 2).
  • the SAF layer 106 has magnetic anisotropy and can pin the magnetic state of the device 100.
  • the reference layer 108 has a weaker anisotropy as compared with the SAF layer 106.
  • the reference layer 108 can be at least partially anchored in terms of its antimagnetic anisotropy to the SAF layer 106.
  • the reference layer 108 can have one or more of its magnetic properties, thickness, and/or electronic properties be adjusted or preselected to result in the maximum tunnel magnetoresistance (TMR) across a tunneling layer (not shown, but a part of the active layer 110) in the device 100.
  • TMR tunnel magnetoresistance
  • HRS high resistant state
  • LRS low resistant
  • the device 100 can further include an active layer 110.
  • the active layer 110 can include the reference layer 108.
  • the active layer 110 can include a tunnel barrier, a first magnetic layer, a coupling layer, and a second ferromagnetic layer (not shown, but to be shown and described in connection with FIG. 2).
  • the active layer 110 and/or any of its constituent layers can be deposited (that is, formed) using any suitable technique, including PVD, CVD, and/or ALD.
  • the device 100 can include a buffer layer 112.
  • the buffer layer 112 can include magnesium oxide (MgO), and/or any transition metal or transition metal oxides.
  • the buffer layer 112 can have a thickness of 0.3 nm to 5 nm.
  • the buffer layer 112 can be deposited (that is, formed) using any suitable technique, including PVD, CVD, and/or ALD.
  • the device 100 can include a top electrode 114.
  • the top electrode 114 can include, for example, a copper, tungsten, titanium nitride, platinum, and/or any other suitable material.
  • the top electrode 114 can have a thickness of approximately 2 nm to 100 nm with example thicknesses of approximately 5 nm to approximately 60 nm. In another embodiment the top electrode 114 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the bottom electrode 104 and/or the top electrode 114 can serve as the anode and/or the cathode in the device 100.
  • the bottom electrode 104 can serve as a cathode in the device 100.
  • the bottom electrode 104 can serve as an anode in the device 100.
  • the top electrode 114 can serve as a cathode if it has a lower potential with respect to its neighboring layer(s) (for example, the buffer layer 112). In another embodiment, the top electrode 114 can serve as an anode if it has a higher potential with respect to its neighboring layer(s) (for example, the buffer layer 112).
  • the device 100 can be a bidirectional current-driven device, transporting current (for example, spin current) in different directions through the active layer 110. For example, the device can send current from the bottom electrode 104 to the top electrode 114 or vice versa, from the top electrode 114 to the bottom electrode 104 in the device 100.
  • the active layer 110 (which can include a tunnel barrier, a first magnetic layer, a coupling layer, and a second ferromagnetic layer, not shown) can include a switching mechanism that can serve to permit the memory functionality of the device 100.
  • the switching mechanism can operate as follows: the SAF layer 106 and/or the reference layer 108 can have a perpendicular anisotropy vector that points substantially in the positive z direction with respect to the z- axis of the device 100.
  • one or more magnetic layers in the active layer 110 can have a perpendicular anisotropy vector pointing in the positive z direction with respect to the z-axis of the device.
  • forward bias can refer to the application of a positive voltage to both the bottom electrode 104 and/or the top electrode 114, while grounding one of the electrodes, for example, the bottom electrode 104.
  • the tunneling layer 1 10 which can be a relatively thin layer relative to the other layer thicknesses, can pass current. This passage of current by the active layer 1 10 can be considered synonymous to achieving a low resistant state in the device.
  • FIG. 2 shows another example of pMTJ device, in accordance with one or more example embodiments of the disclosure.
  • the device 200 can include a substrate 202.
  • the substrate 202 can be a thin slice of material such as silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide, an alloy of silicon and germanium, or indium phosphide, and/or glass.
  • the substrate 202 can serve as a heat sink for the device 200 allowing for the dissipation of heat generated by the various layers in the device 200.
  • the device 200 can also include a bottom electrode 204.
  • the bottom electrode 204 can include, for example, copper, tungsten, titanium nitride, platinum, and/or any other suitable material.
  • the bottom electrode 204 can have a thickness of approximately 5 nm to approximately 25 nm with example thicknesses of approximately 10 nm to approximately 15 nm.
  • the bottom electrode 204 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the device 200 can further include a SAF layer 206.
  • the SAF layer can include (Co/Pt) multilayers, cobalt-nickel (Co/Ni) multilayers, L10 alloys, suplerlattice magnets, other hard magnetic materials, and/or ruthenium, rhodium, iridium or similar metals that can generate RKKY interactions and effects.
  • the SAF layer 206 can have a thickness of approximately 3 nm to approximately 20 nm with example thicknesses of approximately 5 nm to approximately 10 nm.
  • the SAF layer 206 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the device 200 can further include a reference layer 208.
  • the reference layer can include alloys of cobalt, iron, boron, and/or any transition metal and/or any transition metal oxides.
  • the reference layer 108 can have a thickness of approximately 0.5 nm to approximately 5 nm with example thicknesses of approximately 1.5 nm to approximately 3 nm.
  • the reference layer 108 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the device 200 can include a tunneling layer 210.
  • the tunneling layer 210 can include magnesium oxides (MgO), aluminum oxides (AlOx), and/or any oxides of magnesium or aluminum.
  • the tunneling layer 210 can have a thickness of approximately 0.5 nm to 5 nm with example thicknesses of approximately 1 nm to approximately 3 nm.
  • the tunneling layer 210 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the device 200 may further include a first ferromagnetic layer 212.
  • the first ferromagnetic layer 212 can include alloys of cobalt, iron, boron, and/or other magnetic materials.
  • the first ferromagnetic layer 212 can have a thickness of approximately 0.4 nm to 4 nm with example thicknesses of approximately 0.8 nm to approximately 2 nm.
  • the first ferromagnetic layer 212 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the device 200 can further include a coupling layer 214.
  • the coupling layer 214 can include tantalum, tungsten, molybdenum or other transition metals or their oxides. In another embodiment the coupling layer 214 can have a thickness of approximately 0.1 nm to 1 nm with example thicknesses of approximately 0.2 nm to approximately 0.6 nm. In another embodiment the coupling layer 214 can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0050] In an embodiment, the device 200 can include a second ferromagnetic layer 216. In one embodiment, the second ferromagnetic layer 216 can include alloys of cobalt, iron and boron and/or any other magnetic materials.
  • the second ferromagnetic layer 216 can have a thickness of approximately 0.3 nm to 3 nm with example thicknesses of approximately 0.5 nm to approximately 2 nm.
  • the tunneling layer 210 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the first ferromagnetic layer 212 and/or the second ferromagnetic layer 216 can comprise a cobalt boron iron system.
  • the first ferromagnetic layer 212 and the second ferromagnetic layer 216 can comprise the same materials. That is, for example, the cobalt boron iron system; however, they may have different thicknesses.
  • first ferromagnetic layer 212 and the second ferromagnetic layer 216 can have a different cobalt to boron ratio. In another embodiment, the first ferromagnetic layer 212 and the second ferromagnetic layer 216 can have perpendicular anisotropy and parallel or anti-parallel magnetization with respect to the reference layer 208.
  • the device 200 can further include a buffer layer 218.
  • the buffer layer 218 can include can include magnesium oxide (MgO), and/or any transition metal or transition metal oxides.
  • the tunneling layer 210 can have a thickness of approximately 0.3 nm to 5 nm with example thicknesses of approximately 0.6 nm to approximately 3 nm.
  • the tunneling layer 210 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the device 200 can include a top electrode 220.
  • the top electrode 220 can include, for example, copper, tungsten, titanium nitride, platinum, and/or any other suitable material.
  • the top electrode 220 can have a thickness of approximately 2 nm to 100 nm with example thicknesses of approximately 5 nm to approximately 60 nm.
  • the top electrode 220 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the coupling layer 214 can include a metal oxide, for example, an oxide of tungsten, molybdenum and/or tantalum.
  • the coupling layer 214 comprising a metal oxide can have metal atoms that are coupled to oxygen atoms, causing less interaction between charge carriers (for example, electrons) transported through the multilayer comprising the first ferromagnetic layer 212, the coupling layer 214 and the second ferromagnetic layer 216, and thereby leading to less Gilbert damping in the device 200.
  • charge carriers for example, electrons
  • Gilbert damping in the device 200 can be due to spin orbit coupling with metal in the coupling layer 214.
  • the spin orbit coupling can be reduced by the introduction of a metal oxide as the coupling layer 214.
  • this metal oxide serving as the coupling layer 214 can increase the TMR and reduce the RA of the device 200. Accordingly, the switching current in both polarities (that is, the switching current from the top electrode 220 to the bottom electrode 204, or vice versa, the switching current from the bottom electrode 204 to the top electrode 220) can be reduced.
  • a metal oxide coupling layer 214 can allow for the coersivity of the device 200 to be reduced.
  • the reduction in coersivity can be due to a reduction in the magnetic anisotropy in the multilayer 224 that can serve as the free layer in the device 200.
  • the reduction in the coersivity of the device 200 may be due to the reduced damping, that is, the reduced Gilbert damping in the device 200.
  • the reduction of the magnetic anisotropy in the multilayer 224 can be likened to the reduction and the depth of an energy well that represents the energetic transition that charge carriers (for example, electrons) overcome in going between the second ferromagnetic layer 216 and the first ferromagnetic layer 212 through the coupling layer 214.
  • charge carriers for example, electrons
  • the reduction in the Gilbert damping can be likened to a reduction in a frictional force for the charge carriers to overcome in being transported from the second ferromagnetic layer 216 to the first ferromagnetic layer 212 through the coupling layer 214, or vice versa.
  • the coupling layer 214 can have a thickness of approximately 1 angstrom to approximately 10 angstroms with example thicknesses of approximately 2 angstroms to approximately 3 angstroms.
  • the thickness of the coupling layer 214 can be one or a few atomic layers.
  • the resistance of the buffer layer 218 and the resistance of the tunneling layer 210 can dominate the resistivity of the system, then the resistance of the coupling layer 214 may have a reduced impact on the overall resistance area (RA) of the device 200.
  • the coupling layer 214 can be deposited (that is, formed) using PVD and a post-deposition oxidation, for example, including flowing oxygen on the deposited (that is, formed) coupling layer 214.
  • the coupling layer 214 can comprise a metal oxide deposited (that is, formed) by a variety of techniques, including but not limited to, pulsed DC and/or RF sputtering, CVD, ALD, and/or PVD followed by a post oxidation step.
  • the post-oxidation of the coupling layer 214 may need to be optimized.
  • the transition metal can have different magnetic states based on the oxidation state of the transition metal, then the overall electronic properties of the device 200 can change. This can lead to different device performance parameters of the device, for example, including but not limited to, different TMR, different RA, different damping, different switching currents, and/or different coercivities.
  • using a chromium oxide may lead to different oxidation states and/or different magnetic states that may alter the performance parameters of the device 200. Accordingly, the device may need to be optimized for a given thickness and composition of the coupling layer 214.
  • FIG. 3 shows a diagram 300 representing the performance parameters of an example pMTJ device, in accordance with one or more example embodiments of the disclosure.
  • a device structure for the performance parameters depicted in diagram 300 can be as follows: a substrate, followed by a bottom electrode, followed by an SAF layer, followed by a reference layer, followed by a tunneling layer, followed by a first ferromagnetic layer, followed by a coupling layer, followed by a second ferromagnetic layer, followed by a buffer layer, and followed by a top electrode.
  • the bottom electrode can include a copper layer that serves as a cathode.
  • the tunnel barrier layer can include a magnesium oxide.
  • the tunnel layer can be approximately 1 angstrom to approximately 2 nanometers thick.
  • the first ferromagnetic layer and the second ferromagnetic layer can include a cobalt boron iron system having different thicknesses and/or a different cobalt to boron ratio.
  • the coupling layer can include a tungsten, molybdenum, and/or tantalum oxide.
  • the thickness of the coupling layer may be approximately 2 angstroms to approximately 3 angstroms thick.
  • the buffer layer can include a magnesium oxide.
  • the top electrode can include an inert electrode, for example, a palladium, a gold, or other inert material.
  • row 302 represents various properties of the devices, for example, the type of coupling layer 303 used in the device, the TMR 306 of the device, the RA 308 of the device and the damping 310 of the device.
  • column 304 of diagram 300 shows the different types of materials that can be used as the coupling layer 303 in the devices, for example, a non-magnetic metal 312 or a non-magnetic oxide 314.
  • devices having a non-magnetic metal 312 as the coupling layer 303 show a TMR 306 of approximately 142%, a RA 308 of approximately 4.9 ⁇ - ⁇ 2 , and a damping 310 of approximately 0.016. Additionally, as represented by the data for the non-magnetic oxide 314, the TMR of the devices having a non-magnetic oxide as the coupling layer can be approximately 142%.
  • the RA 308 of the devices having a non-magnetic oxide as the coupling layer is slightly smaller at 4.7 Q ⁇ 2 with respect to the RA 308 of the non-magnetic metal 312 based devices.
  • diagram 300 represents data from a blanket wafer having the device architecture mentioned. Accordingly, diagram 300 shows the different RA and damping parameters for devices having different coupling layers (non-magnetic metal and non-magnetic oxide).
  • the data shows that the pMTJ devices having a nonmagnetic metal and the non-magnetic oxide coupling layers show comparable TMR and RA on the blanket wafer. Further, pMTJ devices having the non-magnetic oxide coupling layer show an approximately 20% damping reduction as compared to devices having a non-magnetic metal coupling layer.
  • the damping for example, Gilbert damping
  • the damping in the devices may be proportional to the switching current. Accordingly a reduction of the damping can lead to a reduction in the switching current.
  • FIG. 4 shows a diagram 400 representing the performance parameters of example pMTJ devices, in accordance with one or more example embodiments of the disclosure.
  • the diagram 400 represents the performance parameters for devices that are approximately 40 nanometers by 40 nanometers in dimensions.
  • a device structure for the devices having the performance parameters depicted in diagram 400 can be as follows: a substrate, followed by a bottom electrode, followed by an SAF layer, followed by a reference layer, followed by a tunneling layer, followed by a first ferromagnetic layer, followed by a coupling layer, followed by a second ferromagnetic layer, followed by a buffer layer, and followed by a top electrode.
  • the bottom electrode can include a copper layer that serves as a cathode.
  • the tunnel barrier layer can include a magnesium oxide.
  • the tunnel layer can be approximately 1 nm to approximately 2 nm thick.
  • the first ferromagnetic layer and the second ferromagnetic layer can include a cobalt boron iron system having different thicknesses and/or a different cobalt to boron ratio.
  • the coupling layer can include a tungsten, molybdenum, and/or tantalum oxide.
  • the thickness of the coupling layer may be approximately 2 angstroms to approximately 3 angstroms thick.
  • the buffer layer can include a magnesium oxide.
  • the top electrode can include an inert electrode, for example, a palladium, a gold, or other inert material.
  • the diagram 400 includes a first row 401 that shows the various parameters of the devices tested. The parameters include the coupling layer 402 used in the devices tested, a TMR 404 of the devices tested, a RA 406 of the devices tested, a switching current having a first polarity 408 of the devices tested, a switching current having a second polarity 410 of the devices tested, and a coercivity 412 of the devices tested.
  • the first column 403 of the diagram 400 shows the two materials used as the coupling layer, that is, the non-magnetic coupling layer 414 and the non-magnetic oxide coupling layer 416.
  • the diagram with the non-magnetic coupling layer 414 has a TMR of approximately 85% and an RA of approximately 6.5 ⁇ - ⁇ 2 , a switching current having a first polarity of approximately 150 ⁇ , a second switching current having a second polarity of approximately 100 ⁇ , and a coercivity of approximately 1250 De.
  • the device having a non-magnetic oxide coupling layer 416 shows an increased TMR of approximately 95% and a slightly increased RA of 7.5 ⁇ - ⁇ 2 , a reduced switching current having a first polarity of 80 ⁇ , a reduced second switching current having a second polarity of 35 ⁇ , and a reduced coercivity of 350 De. Consequently, the device having the non-magnetic oxide coupling layer is shown to provide a higher TMR as compared with the device having a non-magnetic coupling layer.
  • the device with the non-magnetic oxide coupling layer is shown to provide approximately 3 times the reduction in the switching current as compared with devices having a non-magnetic coupling layer.
  • the reduction in the coercivity that is, 350 De in the non-magnetic oxide coupling layer case, as compared with 1250 De in the non-magnetic coupling layer case
  • the magnetic anisotropy and/or the damping in the device can be reduced, leading to the performance data show in diagram 400.
  • the coercivity can represent the device stability, which may be a performance parameter of a pMTJ device.
  • the non-volatility of a pMTJ device may be measured in units of kT of stability. For example, for a non-volatility of 10 years, approximately 60 kT of stability may be needed in the device.
  • the RA parameter of the device can determine the resistance of the device. That is, the RA multiplied by the critical dimension defining the area of the device can provide an indication of the resistance of the device. In one embodiment, the RA may need to have a magnitude that is sufficient to produce a resistance that is in the range of the output of the driving transistor driving the device.
  • the RA may need to produce a resistance of approximately 2 kilo ohms to approximately 3 kilo ohms in order to be in the range of the output of the driving transistor.
  • a device having a critical of approximately 60 nanometers and an RA of approximately 2 kilo ohms to approximately 3 kilo ohms can work with such driving transistors.
  • the device may need a higher RA.
  • the device may need a lower RA to continue working with the driving transistors.
  • a lower RA may cause a lower TMR, which presents a challenge in the fabrication of smaller PMTJ memory devices.
  • FIG. 5 shows a diagram 500 of an example processing flow for the fabrication of example pMTJ device, in accordance with example embodiments of the disclosure.
  • a substrate can be provided.
  • the substrate can be a thin slice of material such as silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide, an alloy of silicon and germanium, or indium phosphide, and/or glass.
  • the substrate can serve as a heat sink for the device allowing for the dissipation of heat generated by the various layers in the device.
  • a first electrode that injects charge carriers into a first magnetic layer can be deposited (that is, formed) on the substrate.
  • the bottom electrode can include, for example, the bottom electrode can include copper, tungsten, titanium nitride, platinum, and/or any other suitable material.
  • the bottom electrode can have a thickness of approximately 1 nm to 150 nm with example thicknesses of approximately 5 nm to approximately 25 nm.
  • the bottom electrode can be deposited (that is, formed) using PVD, CVD and/or ALD.
  • the first magnetic layer can be deposited (that is, formed), the first magnetic layer having a first magnetic moment oriented parallel or antiparallel to a second magnetic moment of a multilayer, the multilayer comprising a first ferromagnetic layer, a coupling layer, and a second ferromagnetic layer.
  • the first magnetic layer can also be referred to as a reference layer and can include alloys of cobalt, iron and boron, any of the transition metals or transition metal oxides.
  • the first magnetic layer or reference layer can have a thickness of approximately 3 nm to 20 nm, with example thicknesses of approximately 5 nm to approximately 10 nm.
  • the first magnetic layer or reference layer can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the first magnetic layer or reference layer can be deposited (that is, formed) on a SAF layer.
  • the SAF layer and the first magnetic layer or reference layer can serve as a PIN magnetic assembly.
  • the SAF layer and/or the first magnetic layer or reference layer can produce an electric field during operation that can be referred to as a stray field, the stray field being non-zero in magnitude.
  • the stray field can affect a tunneling layer of the device.
  • the stray field from the SAF layer can determine which magnetic state of the device (for example, parallel or anti-parallel) is more stable.
  • the SAF layer can have a magnetic anisotropy and can pin the magnetic state of the device.
  • the first magnetic layer or the reference layer can have a weaker anisotropy as compared with the SAF layer.
  • the reference layer can be at least partially anchored, in terms of its antimagnetic anisotropy, to the SAF layer.
  • the first magnetic layer or the reference layer can have one or more of its magnetic properties, thickness, and/or electronic properties be adjusted or preselected to result in the maximum TMR across a tunneling layer in the device.
  • a tunneling layer that transports the charge carriers from the first magnetic layer to the multilayer, can be deposited (that is, formed) on the first magnetic layer.
  • the tunneling layer can include can include magnesium oxide (MgO), and/or any transition metal or transition metal oxides.
  • the tunneling layer 210 can have a thickness of approximately 0.5 nm to 5 nm with example thicknesses of approximately 1 nm to approximately 3 nm.
  • the tunneling layer can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the tunneling layer under forward bias, the tunneling layer, which can be a relatively thin layer relative to the other layer thicknesses, can pass current. This passage of current by the active layer can be considered synonymous to achieving a low resistant state in the device.
  • the first ferromagnetic layer can be deposited (that is, formed) on the tunneling layer.
  • the first ferromagnetic layer can comprise a cobalt boron iron system.
  • the first ferromagnetic layer can include alloys of cobalt, iron, boron, and/or other magnetic materials.
  • the first ferromagnetic layer can have a thickness of approximately 0.4 nm to 4 nm with example thicknesses of approximately 0.8 nm to approximately 2 nm.
  • the first ferromagnetic layer 212 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the coupling layer can be deposited (that is, formed) on the first ferromagnetic layer.
  • the coupling layer can include a metal oxide, for example, an oxide of tungsten, molybdenum and/or tantalum.
  • the coupling layer can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the coupling layer comprising a metal oxide can have metal atoms that are coupled to oxygen atoms, causing less interaction between charge carriers (for example, electrons) transported through the multilayer comprising the first magnetic layer, the coupling layer, and the second ferromagnetic layer, and thereby leading to less Gilbert damping in the device.
  • Gilbert damping in the device can be due to spin orbit coupling with metal in the coupling layer.
  • the spin orbit coupling can be reduced by the introduction of a metal oxide as the coupling layer.
  • this metal oxide serving as the coupling layer can increase the TMR and reduce the RA of the device. Accordingly, the switching current in both polarities (that is, the switching current from the top electrode to the bottom electrode, or vice versa, the switching current from the bottom electrode to the top electrode) can be reduced.
  • the metal oxide coupling layer can allow for the coersivity of the device to be reduced.
  • the reduction in coersivity can be due to a reduction in the magnetic anisotropy in the multilayer.
  • the reduction in the coersivity of the device may be due to the reduced damping, that is, the reduced Gilbert damping in the device.
  • the reduction of the magnetic anisotropy in the multilayer can be likened to the reduction and the depth of an energy well that represents the transition that charge carriers (for example, electrons) overcome in going between the second magnetic layer and the first magnetic layer through the coupling layer.
  • charge carriers for example, electrons
  • the reduction in the Gilbert damping can be likened to a reduction in a frictional force for the charge carriers to overcome in being transported from the second magnetic layer to the first magnetic layer through the coupling layer, or vice versa.
  • the coupling layer can have a thickness of approximately 1 angstrom to approximately 10 angstroms with example thicknesses of approximately 2 angstroms to approximately 3 angstroms.
  • the second ferromagnetic layer can be deposited (that is, formed) on the coupling layer.
  • the second ferromagnetic layer can include alloys of cobalt, iron, boron, and/or other magnetic materials.
  • the second ferromagnetic layer can have a thickness of approximately 0.4 nm to 4 nm with example thicknesses of approximately 0.8 nm to approximately 2 nm.
  • the second ferromagnetic layer 212 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • the first ferromagnetic layer and the second ferromagnetic layer can comprise the same materials. That is, for example, the cobalt boron iron system; however, they may have different thicknesses.
  • first ferromagnetic layer and the second ferromagnetic layer can have a different cobalt to boron ratio.
  • first ferromagnetic layer and the second ferromagnetic layer can have perpendicular anisotropy and parallel or anti-parallel magnetization with respect to the reference layer.
  • a second electrode can be deposited (that is, formed), the second electrode collects the charge carriers from the multilayer.
  • the second electrode can include any suitable metal; for example, copper, tungsten, titanium nitride, platinum, and/or any other suitable material.
  • the second electrode can have a thickness of approximately 2 nm to 100 nm with example thicknesses of approximately 5 nm to approximately 60 nm.
  • the second electrode can be deposited (that is, formed) using PVD, CVD, and/or ALD.
  • FIG. 6 depicts an example of a system 600 according to one or more embodiments of the disclosure.
  • the systems, methods, and apparatus disclosed herein including for example, the pMTJ devices described herein can be used in connection with system 600.
  • the pMTJ devices described herein can be used in connection with system 600 to improve the performance of system 600 or to provide memory capabilities to one or more devices of system 600.
  • system 600 includes, but is not limited to, a desktop computer, a laptop computer, a netbook, a tablet, a notebook computer, a personal digital assistant (PDA), a server, a workstation, a cellular telephone, a mobile computing device, a smart phone, an Internet appliance or any other type of computing device.
  • system 600 can include a system on a chip (SOC) system.
  • SOC system on a chip
  • system 600 includes multiple processors including processor 610 and processor N 605, where processor N 605 has logic similar or identical to the logic of processor 610.
  • processor 610 has one or more processing cores (represented here by processing core 1 612 and processing core N 612N, where 612N represents the Nth processor core inside processor 610, where N is a positive integer). More processing cores can be present (but not depicted in the diagram of FIG. 6).
  • processing core 612 includes, but is not limited to, pre-fetch logic to fetch instructions, decode logic to decode the instructions, execution logic to execute instructions, a combination thereof, or the like.
  • processor 610 has a cache memory 616 to cache instructions and/or data for system 600. Cache memory 616 may be organized into a hierarchical structure including one or more levels of cache memory.
  • processor 610 includes a memory controller (MC) 614, which is configured to perform functions that enable the processor 610 to access and communicate with memory 630 that includes a volatile memory 632 and/or a non-volatile memory 634.
  • processor 610 can be coupled with memory 630 and chipset 620.
  • Processor 610 may also be coupled to a wireless antenna 678 to communicate with any device configured to transmit and/or receive wireless signals.
  • the wireless antenna antenna 678 operates in accordance with, but is not limited to, the IEEE 802.11 standard and its related family, Home Plug AV (HPAV), Ultra Wide Band (UWB), Bluetooth, WiMax, or any form of wireless communication protocol.
  • volatile memory 632 includes, but is not limited to, Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM), and/or any other type of random access memory device.
  • Non-volatile memory 634 includes, but is not limited to, flash memory, phase change memory (PCM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or any other type of non-volatile memory device.
  • Memory device 630 stores information and instructions to be executed by processor 610. In one embodiment, memory 630 may also store temporary variables or other intermediate information while processor 610 is executing instructions.
  • chipset 620 connects with processor 610 via Point-to-Point (PtP or P-P) interface 617 and P-P interface 622.
  • PtP Point-to-Point
  • Chipset 620 enables processor 610 to connect to other elements in system 600.
  • P-P interface 617 and P-P interface 622 can operate in accordance with a PtP communication protocol, such as the Intel® QuickPath Interconnect (QPI) or the like. In other embodiments, a different interconnect may be used.
  • QPI QuickPath Interconnect
  • chipset 620 can be configured to communicate with processor 610, the processor N 605, display device 640, and other devices 672, 676, 674, 660, 662, 664, 666, 677, etc. Chipset 620 may also be coupled to the wireless antenna 678 to communicate with any device configured to transmit and/or receive wireless signals.
  • Chipset 620 connects to display device 640 via interface 626.
  • Display 640 may be, for example, a liquid crystal display (LCD), a plasma display, cathode ray tube (CRT) display, or any other form of visual display device.
  • processor 610 and chipset 620 are integrated into a single SOC.
  • chipset 620 connects to bus 650 and/or bus 655 that interconnect various elements 674, 660, 662, 664, and 666.
  • Bus 650 and bus 655 may be interconnected via a bus bridge 672.
  • chipset 620 couples with a non-volatile memory 660, a mass storage device(s) 662, a keyboard/mouse 664, and a network interface 666 via interface 624 and/or 604, smart TV 676, consumer electronics 677, etc.
  • mass storage device(s) 662 can include, but not be limited to, a solid state drive, a hard disk drive, a universal serial bus flash memory drive, or any other form of computer data storage medium.
  • network interface 666 is implemented by any type of well-known network interface standard including, but not limited to, an Ethernet interface, a universal serial bus (USB) interface, a Peripheral Component Interconnect (PCI) Express interface, a wireless interface and/or any other suitable type of interface.
  • the wireless interface operates in accordance with, but is not limited to, the IEEE 802.11 standard and its related family, Home Plug AV (HPAV), Ultra Wide Band (UWB), Bluetooth, WiMax, or any form of wireless communication protocol.
  • modules shown in FIG. 7 are depicted as separate blocks within the system 600, the functions performed by some of these blocks may be integrated within a single semiconductor circuit or may be implemented using two or more separate integrated circuits.
  • cache memory 616 is depicted as a separate block within processor 610, cache memory 616 or selected elements thereof can be incorporated into processor core 612.
  • system 600 described herein may be any suitable type of microelectronics packaging and configurations thereof, including, for example, system in a package (SiP), system on a package (SOP), package on package (PoP), interposer package, 3D stacked package, etc.
  • microelectronic components may be provided in the semiconductor packages, as described herein.
  • microcontrollers, microprocessors, baseband processors, digital signal processors, memory dies, field gate arrays, logic gate dies, passive component dies, MEMSs, surface mount devices, application specific integrated circuits, baseband processors, amplifiers, filters, combinations thereof, or the like may be packaged in the semiconductor packages, as disclosed herein.
  • the semiconductor packages (for example, the semiconductor packages described in connection with any of FIGS. 1-6), as disclosed herein, may be provided in any variety of electronic device including consumer, industrial, military, communications, infrastructural, and/or other electronic devices.
  • the devices may be used in connection with one or more processors.
  • the one or more processors may include, without limitation, a central processing unit (CPU), a digital signal processor(s) (DSP), a reduced instruction set computer (RISC), a complex instruction set computer (CISC), a microprocessor, a microcontroller, a field programmable gate array (FPGA), or any combination thereof.
  • the processors may also include one or more application specific integrated circuits (ASICs) or application specific standard products (ASSPs) for handling specific data processing functions or tasks.
  • ASICs application specific integrated circuits
  • ASSPs application specific standard products
  • the processors may be based on an Intel® Architecture system and the one or more processors and any chipset included in an electronic device may be from a family of Intel® processors and chipsets, such as the Intel® Atom® processor(s) family or Intel-64 processors (for example, Sandy Bridge®, Ivy Bridge®, Haswell®, Broadwell®, Skylake®, etc.).
  • Intel® Atom® processor(s) family or Intel-64 processors (for example, Sandy Bridge®, Ivy Bridge®, Haswell®, Broadwell®, Skylake®, etc.).
  • the devices may be used in connection with one or more additional memory chips.
  • the memory may include one or more volatile and/or non-volatile memory devices including, but not limited to, magnetic storage devices, read-only memory (ROM), random access memory (RAM), dynamic RAM (DRAM), static RAM (SRAM), synchronous dynamic RAM (SDRAM), double data rate (DDR) SDRAM (DDR-SDRAM), RAM-BUS DRAM (RDRAM), flash memory devices, electrically erasable programmable read-only memory (EEPROM), non-volatile RAM (NVRAM), universal serial bus (USB) removable memory, or combinations thereof.
  • ROM read-only memory
  • RAM random access memory
  • DRAM dynamic RAM
  • SRAM static RAM
  • SDRAM synchronous dynamic RAM
  • DDR double data rate SDRAM
  • RDRAM RAM-BUS DRAM
  • flash memory devices electrically erasable programmable read-only memory (EEPROM), non-volatile RAM (NVRAM), universal serial bus (USB) removable memory, or combinations thereof.
  • the electronic device in which the disclosed devices are used and/or provided may be a computing device.
  • a computing device may house one or more boards on which the devices may be disposed.
  • the board may include a number of components including, but not limited to, a processor and/or at least one communication chip.
  • the processor may be physically and electrically connected to the board through, for example, electrical connections of the devices.
  • the computing device may further include a plurality of communication chips. For instance, a first communication chip may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth, and a second communication chip may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, EV-DO, and others.
  • the computing device 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, a digital video recorder, combinations thereof, or the like.
  • the computing device may be any other electronic device that processes data.
  • pMTJ perpendicular magnetic tunnel junction
  • the device may comprise: a first magnetic layer having a first magnetic moment; a multilayer comprising a first ferromagnetic layer, a coupling layer, and a second ferromagnetic layer, wherein the multilayer includes a second magnetic moment perpendicular to the first magnetic moment of the first magnetic layer; a first electrode configured to inject charge carriers into the first magnetic layer; a tunneling layer configured to transport the charge carriers from the first magnetic layer to the multilayer; a second electrode configured to collect the charge carriers from the multilayer; and wherein the coupling layer comprises a non-magnetic metal oxide layer, and the coupling layer positioned between the first ferromagnetic layer and the second ferromagnetic layer.
  • the coupling layer may have a thickness of about 2 angstroms (example 2).
  • the coupling layer may comprise a transition metal oxide, a tungsten oxide, a molybdenum oxide, or a tantalum oxide (example 3).
  • the first ferromagnetic layer of the device comprising cobalt and boron having a first weight ratio and the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may be different weight ratios (example 4).
  • the first ferromagnetic layer of the device comprising cobalt and boron having a first weight ratio and the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may be the same weight ratio and wherein further, the first ferromagnetic layer has a first thickness and the second ferromagnetic layer has a second thickness, wherein the first thickness may be different than the second thickness (example 5).
  • the tunneling layer of the device may comprise a metal oxide, a magnesium oxide or an aluminum oxide (example 6).
  • the device may further comprise a synthetic antiferromagnetic (SAF) layer disposed between the first electrode and the first magnetic layer (example 7).
  • SAF synthetic antiferromagnetic
  • the SAF layer may include a cobalt layer, a platinum layer, a nickel layer, a L10 alloy layer, a suplerlattice magnet layer, a ruthenium layer, a rhodium layer, or a iridium layer (example 8).
  • a buffer layer may be disposed between the multilayer and the second electrode and the buffer layer may comprise a metal oxide (example 9).
  • any of the aforementioned examples may be used in part or in whole in connection with any other example in any combination or subcombination.
  • a method for fabricating a perpendicular magnetic tunnel junction (pMTJ) device (example 10).
  • a substrate depositing, on the substrate, a first electrode; depositing a first magnetic layer having a first magnetic moment, wherein the first electrode is configured to inject charge carriers into the first magnetic layer; depositing, on the first magnetic layer, a tunneling layer that transports the charge carriers; depositing, on the tunneling layer, a multilayer having a second magnetic moment, the second magnetic layer having a second magnetic moment is oriented parallel or antiparallel to the first magnetic moment of the first magnetic layer, wherein depositing the multilayer comprises, depositing a first ferromagnetic layer on the tunneling layer, depositing a coupling layer on the first ferromagnetic layer, depositing a second ferromagnetic layer on the coupling layer; and depositing a second electrode that collects the charge carriers from the multilayer.
  • pMTJ perpendicular magnetic tunnel junction
  • the method of depositing the couple layer may comprise depositing the coupling layer using radio frequency (RF) sputtering, pulsed DC sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD) (example 11).
  • Depositing the coupling layer may further comprise a post-deposition oxidation(example 12).
  • Depositing the coupling layer on the first ferromagnetic layer may comprise depositing the coupling layer having a thickness of 2 degrees and may comprise depositing a transition metal oxide, a tungsten oxide, a molybdenum oxide, or a tantalum oxide on the first ferromagnetic layer (example 13).
  • Depositing the first ferromagnetic layer on the tunneling layer may comprise depositing the first ferromagnetic layer comprising cobalt and boron having a first weight ratio and depositing the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may have different weight ratios (example 14).
  • Depositing the first ferromagnetic layer on the tunneling layer may comprise depositing the first ferromagnetic layer comprising cobalt and boron having a first weight ratio and depositing the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may have the same weight ratios, wherein further, the first ferromagnetic layer has a first thickness and the second ferromagnetic layer has a second thickness, wherein the first thickness may be different than the second thickness (example 15).
  • the method of depositing the tunneling layer may further comprise depositing metal oxide, a magnesium oxides or an aluminum oxide (example 16).
  • the method may further comprise depositing a synthetic antiferromagnetic (SAF) layer between the first electrode and the first magnetic layer (example 17).
  • the method may further comprise depositing a buffer layer, which may comprise depositing a metal oxide, between the multilayer and the second electrode (example 18).
  • SAF synthetic antiferromagnetic
  • a buffer layer which may comprise depositing a metal oxide, between the multilayer and the second electrode (example 18).
  • any of the aforementioned examples may be used in part or in whole in connection with any other example in any combination or subcombination.
  • the electronic device may comprise: a perpendicular magnetic tunnel junction (pMTJ) which may comprise: a first magnetic layer having a first magnetic moment; a multilayer comprising a first ferromagnetic layer, a coupling layer, and a second ferromagnetic layer, wherein the multilayer includes a second magnetic moment perpendicular to the first magnetic moment of the first magnetic layer; a first electrode configured to inject charge carriers into the first magnetic layer; a tunneling layer configured to transport the charge carriers from the first magnetic layer to the multilayer; a second electrode configured to collect the charge carriers from the multilayer; and wherein the coupling layer comprises a non-magnetic metal oxide layer, and the coupling layer positioned between the first ferromagnetic layer and the second ferromagnetic layer (example 20).
  • pMTJ perpendicular magnetic tunnel junction
  • the coupling layer may have a thickness of about 2 angstroms (example 22).
  • the coupling layer may comprise a transition metal oxide, a tungsten oxide, a molybdenum oxide, or a tantalum oxide (example 23).
  • the first ferromagnetic layer of the electronic device comprising cobalt and boron having a first weight ratio and the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may be different weight ratios (example 24).
  • the first ferromagnetic layer of the electronic device comprising cobalt and boron having a first weight ratio and the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may be the same weight ratio and wherein further, the first ferromagnetic layer has a first thickness and the second ferromagnetic layer has a second thickness, wherein the first thickness may be different than the second thickness (example 25).
  • the tunneling layer of the electronic device may comprise a metal oxide, a magnesium oxide or an aluminum oxide (example 26).
  • the electronic device may further comprise a synthetic antiferromagnetic (SAF) layer disposed between the first electrode and the first magnetic layer (example 27).
  • SAF synthetic antiferromagnetic
  • the SAF layer may include a cobalt layer, a platinum layer, a nickel layer, a L10 alloy layer, a suplerlattice magnet layer, a ruthenium layer, a rhodium layer, or a iridium layer.
  • a buffer layer may be disposed between the multilayer and the second electrode and the buffer layer may comprise a metal oxide (example 28).
  • any of the aforementioned examples may be used in part or in whole in connection with any other example in any combination or subcombination.

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Abstract

In various embodiments, the systems, methods, and apparatus disclosed herein are directed to reducing the effects of damping, for example, Gilbert damping, in perpendicular magnetic tunnel junction (pMTJ) devices, while maintaining the tunnel magnetoresistance (TMR) and/or the resistance area (RA) product of the pMTJ devices. In one embodiment, the Gilbert damping can be directly proportional to the switching current in pMTJ devices. Accordingly, because the systems, methods, and apparatus can reduce the Gilbert damping, the switching current can also be reduced the pMTJ devices. In one embodiment, a pMTJ device is disclosed, the device comprising a free layer that includes a multilayer including a first ferromagnetic layer, a non-magnetic oxide layer (for example, a metal oxide layer), and a second ferromagnetic layer can have a reduced spin pumping.

Description

PERPENDICULAR MAGNETIC TUNNEL JUNCTION (PMTJ) DEVICES HAVING A
METAL OXIDE LAYER
TECHNICAL FIELD
[0001] This disclosure generally relates perpendicular magnetic tunnel junction (pMTJ) devices, and more particularly, to pMTJ devices having a metal oxide layer.
BACKGROUND
[0002] Magnetic tunnel junctions (MTJs) can represent electronic components comprising two ferromagnets separated by a thin insulator. The insulating layer can be thin (typically a few nanometers), permitting electrons to tunnel from one ferromagnet into the other. MTJs can be manufactured using thin film technology. A magnetic tunnel junction with a perpendicular magnetic axis (referred herein as a perpendicular magnetic tunnel junction, pMTJ) is a type of MTJ that can be used for spintronic non-volatile magnetoresistive random access memory (MRAM).
BRIEF DESCRIPTION OF THE FIGURES [0003] Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
[0004] FIG. 1 shows a diagram of an example cross-sectional view of a perpendicular magnetic tunnel junction (pMTJ) device, in accordance with one or more example embodiments of the disclosure; [0005] FIG. 2 shows an example cross-sectional view of a pMTJ device, in accordance with one or more example embodiments of the disclosure;
[0006] FIG. 3 shows an example of a diagram representing the performance parameters of example pMTJ devices fabricated on a blanket wafer, in accordance with example embodiments of the disclosure; [0007] FIG. 4 shows a second example of a diagram representing the performance parameters of example pMTJ devices having critical dimension of approximately 40 nm, in accordance with example embodiments of the disclosure;
[0008] FIG. 5 shows an example processing flow diagram that can be used to fabricate an example pMTJ device, in accordance with one or more example embodiments of the disclosure; and
[0009] FIG. 6 illustrates an example of a system, in accordance with one or more embodiments of the disclosure.
DETAILED DESCRIPTION [0010] Embodiments of the disclosure are described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like, but not necessarily the same or identical, elements throughout.
[0011] The following embodiments are described in sufficient detail to enable at least those skilled in the art to understand and use the disclosure. It is to be understood that other embodiments would be evident based on the present disclosure and that process, mechanical, material, dimensional, process equipment, and parametric changes may be made without departing from the scope of the present disclosure.
[0012] In the following description, numerous specific details are given to provide a thorough understanding of various embodiments of the disclosure. However, it will be apparent that the disclosure may be practiced without these specific details. In order to avoid obscuring the present disclosure, some well-known system configurations and process steps may not be disclosed in full detail. Likewise, the drawings showing embodiments of the disclosure are semi-diagrammatic and not to scale and, particularly, some of the dimensions are for the clarity of presentation and may be exaggerated in the drawings. In addition, where multiple embodiments are disclosed and described as having some features in common, for clarity and ease of illustration, description, and comprehension thereof, similar and like features will ordinarily be described with like reference numerals even if the features are not identical.
[0013] The term "horizontal" as used herein may be defined as a direction parallel to a plane or surface (for example, surface of a substrate), regardless of its orientation. The term "vertical," as used herein, may refer to a direction orthogonal to the horizontal direction as just described. Terms, such as "on," "above," "below," "bottom," "top," "side" (as in "sidewall"), "higher," "lower," "upper," "over," and "under," may be referenced with respect to a horizontal plane, where the horizontal plane can include an x- y plane, a x-z plane, or a y-z plane, as the case may be. The term "processing" as used herein includes deposition of material or photoresist, patterning, exposure, development, etching, cleaning, ablating, polishing, and/or removal of the material or photoresist as required in formation a described structure.
[0014] In various embodiments, the systems, methods, and apparatus disclosed herein can reduce the effects of damping, for example, Gilbert damping, in pMTJ devices, while maintaining the tunnel magnetoresistance (TMR) and/or the resistance area (RA) product of the pMTJ devices. In one embodiment, the Gilbert damping can be directly proportional to the switching current in pMTJ devices. Accordingly, because the systems, methods, and apparatus can reduce the Gilbert damping, the switching current can also be reduced the pMTJ devices.
[0015] In one embodiment, spin pumping can refer to a process where a current of spin-polarized electrons (spin current) generated by the precession of magnetization in a ferromagnetic layer can be injected and can relax in adjacent nonmagnetic material. For example, spin pumping can occur when spin current flows through a ferromagnetic layer followed by a nonmagnetic layer assembly.
[0016] In some pMTJ devices, a magnetic layer, which can, alternatively or additionally be referred to as a free layer, can exist in the device. In one embodiment, the free layer can include a multilayer stack including a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer, where the non-magnetic layer can act as a coupling layer to enhance perpendicular anisotropy (PMA). However, the damping coefficient for devices employing such a multilayer stack may be high, for example, due to the aforementioned spin pumping that can exist in the non-magnetic layer. In one embodiment, this can lead to a higher switching current in a device employing a free layer that includes a multilayer including a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer. [0017] In one embodiment, a device comprising a free layer that includes a multilayer including a first ferromagnetic layer, a non-magnetic oxide layer (for example, a metal oxide layer), and a second ferromagnetic layer can have a reduced spin pumping. In one embodiment, the non-magnetic oxide layer can be referred to as a coupling layer herein. In one embodiment, the non-magnetic oxide layer may further increase the series resistance in the device, potentially increasing the RA of the device with respect to devices having a non-magnetic layer instead of the non-magnetic oxide layer in the free layer. In one embodiment, the systems, methods, and apparatus describe non-magnetic oxide layers that can reduce Gilbert damping while not substantially increasing the RA. In particular, the RA of a device can be maintained at a level to allow the resistance of the device to fall with a predetermined range, thereby permitting the device to integrate with one or more driving transistors that drive the pMTJ device.
[0018] In an embodiment, the coupling layer can include a non-magnetic oxide, for example, a metal oxide, such as an oxide of tungsten, molybdenum and/or tantalum or similar metals. In an embodiment, the coupling layer comprising a metal oxide can have metal atoms that are coupled to oxygen atoms, causing less interaction between charge carriers (for example, electrons) transported through a multilayer stack that can include the first ferromagnetic layer, the coupling layer, and the second ferromagnetic layer, and thereby leading to less Gilbert damping in the device.
[0019] In an embodiment, Gilbert damping in the device can be due to spin orbit coupling with the metal atoms in the coupling layer. In one embodiment, the spin orbit coupling can be reduced by the introduction of a metal oxide as the coupling layer. In one embodiment, this metal oxide serving as the coupling layer can increase the TMR and reduce the RA of the device. Accordingly, the switching current in both polarities (that is, the switching current from the top electrode to the bottom electrode, or vice versa, the switching current from the bottom electrode to the top electrode) can be reduced. [0020] In another embodiment, the metal oxide coupling layer can allow for the coersivity of the device to be reduced. In an embodiment, the reduction in coersivity can be due to a reduction in the magnetic anisotropy in the multilayer. In another embodiment, the reduction in the coersivity of the device may be due to the reduced damping, that is, the reduced Gilbert damping in the device.
[0021] In an embodiment, the reduction of the magnetic anisotropy in the multilayer can be likened to a reduction in the depth of an energy well that represents the energetic transition that charge carriers (for example, electrons) overcome in transporting between the second magnetic layer and the first magnetic layer, through the coupling layer. [0022] In another embodiment, the reduction in the Gilbert damping can be likened to a reduction in a frictional force for the charge carriers to overcome in being transported from the second magnetic layer to the first magnetic layer through the coupling layer, or vice versa.
[0023] In another embodiment, the thickness of the coupling layer can be one or a few atomic layers. In an embodiment, the coupling layer can have a thickness of approximately 1 angstrom to approximately 10 angstroms with example thicknesses of approximately 2 angstroms to approximately 3 angstroms.
[0024] In another embodiment, the resistance of a buffer layer in the device (for example, a magnesium oxide buffer layer) and the resistance of a tunneling layer (for example, a magnesium oxide tunneling layer) in the device can dominate the resistivity of the device. Accordingly, the resistance of the coupling layer may have a reduced impact on the overall RA of the device in comparison to the resistance of the buffer layer and/or the tunneling layer.
[0025] In an embodiment, the coupling layer can be deposited (that is, formed) using physical vapor deposition (PVD) and a post-deposition oxidation, for example, including flowing oxygen on the deposited coupling layer. In another embodiment, the coupling layer can comprise a metal oxide deposited (that is, formed) by a variety of techniques, including but not limited to, pulsed DC and/or Radio frequency (RF) sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), and/or PVD followed by a post oxidation step. In another embodiment, the oxide coupling layers also can be formed by reactive sputtering with metals and oxygen.
[0026] In one embodiment, the post-oxidation of the coupling layer may need slight optimization from batch to batch. For example, if a transition metal oxide is used as the coupling layer, the transition metal can have different magnetic states based on the oxidation state of the transition metal; accordingly, the overall electronic properties of the device can change based on the magnetic states and/or oxidation states of the transition metal oxide. This can lead to different device performance parameters in the device, for example, including but not limited to, different TMR, different RA, different damping, different switching currents, and/or different coercivities based at least in part on the magnetic states and/or oxidation states of the transition metal oxide. For example, using a chromium oxide as the coupling layer may lead to different oxidation states and/or different magnetic states that may alter the performance parameters of the device, and may need to be optimized for a given thickness and composition of the coupling layer. [0027] In various embodiments, the systems, methods, and apparatus disclosed herein can reduce the switching currents of pMTJ devices, and thereby reduce the read and/or write power consumption during operation of the device. For example, the read and/or write power consumption can be reduced in the context of a memory array employing several devices in an array. [0028] FIG. 1 shows an example pMTJ device, in accordance with one or more example embodiments of the disclosure. In one embodiment, the device 100 can include a substrate 102. In one embodiment, the substrate 102 can be a thin slice of material such as silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide, an alloy of silicon and germanium, or indium phosphide, and/or glass. In one or more embodiments, the substrate 102 can serve as a heat sink for the device 100 allowing for the dissipation of heat generated by the various layers (to be discussed) in the device 100.
[0029] In another embodiment, the device 100 can include a bottom electrode 104 and a top electrode 114 that may, together, sandwich an active layer 110. For example, the bottom electrode 104 can be disposed substantially on the substrate 102. In one embodiment the bottom electrode 104 can include, for example, copper, tungsten, titanium nitride, platinum, and/or any other suitable material. Similarly, the top electrode 114 can include, for example, a copper, tungsten, titanium nitride, platinum, and/or any other suitable material.
[0030] In another embodiment the bottom electrode 104 can have a thickness of approximately 1 nm to approximately 150 nm with example thicknesses of approximately 5 nm to approximately 25 nm. In another embodiment the bottom electrode 104 can be deposited (that is, formed) using PVD, CVD and/or ALD. In another embodiment the top electrode 114 can have a thickness of approximately 2 nm to 100 nm with example thicknesses of approximately 5 nm to approximately 60 nm. In another embodiment the top electrode 114 can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0031] In an embodiment, the device 100 can include a synthetic antiferromagnetic (SAF) layer 106. The SAF layer can include cobalt-platinum (Co/Pt) multilayers, cobalt- nickel (Co/Ni) multilayers, L10 alloys, suplerlattice magnets, other hard magnetic materials, and/or ruthenium, rhodium, iridium or similar metals that can generate Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions and effects. In one embodiment, RKKY can refer to a coupling mechanism of nuclear magnetic moments or localized inner d or f shell electron spins in a metal, for example, by means of an interaction through the conduction electrons. In another embodiment the synthetic antiferromagnetic (SAF) layer 106 can have a thickness of approximately 3 nm to 20 nm with example thicknesses of approximately 5 nm to approximately 10 nm. In another embodiment the synthetic antiferromagnetic (SAF) layer 106 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0032] Further the device 100 can include a reference layer 108. The reference layer can include alloys of cobalt, iron, boron, and/or any transition metal and/or any transition metal oxides. In another embodiment the reference layer 108 can have a thickness of approximately 0.5 nm to 5 nm with example thicknesses of approximately 1.5 nm to approximately 3 nm. In another embodiment the reference layer 108 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0033] In various embodiments the SAF layer 106 and the reference layer 108 serve as a p-n magnetic assembly. In one embodiment, the SAF layer 106 and/or reference layer 108 can produce an electric field during operation that can be referred to as a stray field, the stray field being non-zero in magnitude. In another embodiment, the stray field can affect a tunneling layer that is part of the active layer 110 (not shown, to be discussed in connection with FIG. 2). In one embodiment, it may be ideal that the SAF layer 106 and/or the reference layer 108 do not exert any stray fields; however, in fabricated devices 100, the stray field is typically non-zero and can have a positive or negative magnitude. Accordingly, the sign of the stray field can determine which magnetic state of the device 100 is more stable, that is the parallel or the anti-parallel state.
[0034] In an embodiment, the SAF layer 106 has magnetic anisotropy and can pin the magnetic state of the device 100. In another embodiment, the reference layer 108 has a weaker anisotropy as compared with the SAF layer 106. In one embodiment, the reference layer 108 can be at least partially anchored in terms of its antimagnetic anisotropy to the SAF layer 106.
[0035] In another embodiment, the reference layer 108 can have one or more of its magnetic properties, thickness, and/or electronic properties be adjusted or preselected to result in the maximum tunnel magnetoresistance (TMR) across a tunneling layer (not shown, but a part of the active layer 110) in the device 100. In another embodiment, it may be desirable to have the TMR of the device 100 be as high as possible so that the high resistant state (HRS) and the low resistant (LRS) of the device 100 are well defined.
[0036] In another embodiment, the device 100 can further include an active layer 110. In some embodiments, the active layer 110 can include the reference layer 108. Alternatively or additionally, the active layer 110 can include a tunnel barrier, a first magnetic layer, a coupling layer, and a second ferromagnetic layer (not shown, but to be shown and described in connection with FIG. 2). In one embodiment, the active layer 110 and/or any of its constituent layers (for example, a tunnel barrier, a first magnetic layer, a coupling layer, and a second ferromagnetic layer) can be deposited (that is, formed) using any suitable technique, including PVD, CVD, and/or ALD.
[0037] In yet another embodiment, the device 100 can include a buffer layer 112. In an embodiment, the buffer layer 112 can include magnesium oxide (MgO), and/or any transition metal or transition metal oxides. In another embodiment, the buffer layer 112 can have a thickness of 0.3 nm to 5 nm. In one embodiment, the buffer layer 112 can be deposited (that is, formed) using any suitable technique, including PVD, CVD, and/or ALD. [0038] In another embodiment, the device 100 can include a top electrode 114. In one embodiment, the top electrode 114 can include, for example, a copper, tungsten, titanium nitride, platinum, and/or any other suitable material. In another embodiment the top electrode 114 can have a thickness of approximately 2 nm to 100 nm with example thicknesses of approximately 5 nm to approximately 60 nm. In another embodiment the top electrode 114 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0039] In some embodiments, the bottom electrode 104 and/or the top electrode 114 can serve as the anode and/or the cathode in the device 100. In an embodiment if the bottom electrode 104 has a lower potential with respect to the neighboring layers (for example, the SAF layer 106 and/or the reference layer 108), then the bottom electrode 104 can serve as a cathode in the device 100. Alternatively or additionally, if the bottom electrode 104 has a higher potential with respect to the neighboring layers (for example, the SAF layer 106 and/or the reference layer 108), then the bottom electrode 104 can serve as an anode in the device 100. [0040] Similarly, the top electrode 114 can serve as a cathode if it has a lower potential with respect to its neighboring layer(s) (for example, the buffer layer 112). In another embodiment, the top electrode 114 can serve as an anode if it has a higher potential with respect to its neighboring layer(s) (for example, the buffer layer 112). As such, the device 100 can be a bidirectional current-driven device, transporting current (for example, spin current) in different directions through the active layer 110. For example, the device can send current from the bottom electrode 104 to the top electrode 114 or vice versa, from the top electrode 114 to the bottom electrode 104 in the device 100.
[0041] In one embodiment the active layer 110 (which can include a tunnel barrier, a first magnetic layer, a coupling layer, and a second ferromagnetic layer, not shown) can include a switching mechanism that can serve to permit the memory functionality of the device 100. For example, in a first polarity, the switching mechanism can operate as follows: the SAF layer 106 and/or the reference layer 108 can have a perpendicular anisotropy vector that points substantially in the positive z direction with respect to the z- axis of the device 100. Similarly, one or more magnetic layers in the active layer 110 can have a perpendicular anisotropy vector pointing in the positive z direction with respect to the z-axis of the device. Under forward bias, current can pass through the active layer 110. In one embodiment, forward bias can refer to the application of a positive voltage to both the bottom electrode 104 and/or the top electrode 114, while grounding one of the electrodes, for example, the bottom electrode 104. Accordingly, under forward bias, the tunneling layer 1 10, which can be a relatively thin layer relative to the other layer thicknesses, can pass current. This passage of current by the active layer 1 10 can be considered synonymous to achieving a low resistant state in the device.
[0042] At higher current levels and/or higher temperatures in the device 100, the SAF layer 106 and/or the reference layer 108 can continue to maintain its perpendicular anisotropy magnetic vector in the positive z direction with respect to the z-axis of the device 100. However, at the higher current levels and/or higher temperatures in the device 100, a magnetic layer in the active layer 110 can flip its magnetic anisotropy vector to the negative z direction with respect to the z-axis of the device 100. This can then cause the device 100 to pass into a high resistant state leading to a reduction further current passage through the active layer 110 of the device 100. [0043] FIG. 2 shows another example of pMTJ device, in accordance with one or more example embodiments of the disclosure. In one embodiment, the device 200 can include a substrate 202. In one embodiment, the substrate 202 can be a thin slice of material such as silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide, an alloy of silicon and germanium, or indium phosphide, and/or glass. In one or more embodiments, the substrate 202 can serve as a heat sink for the device 200 allowing for the dissipation of heat generated by the various layers in the device 200.
[0044] The device 200 can also include a bottom electrode 204. In one embodiment the bottom electrode 204 can include, for example, copper, tungsten, titanium nitride, platinum, and/or any other suitable material. In another embodiment the bottom electrode 204 can have a thickness of approximately 5 nm to approximately 25 nm with example thicknesses of approximately 10 nm to approximately 15 nm. In another embodiment the bottom electrode 204 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0045] In one embodiment, the device 200 can further include a SAF layer 206. The SAF layer can include (Co/Pt) multilayers, cobalt-nickel (Co/Ni) multilayers, L10 alloys, suplerlattice magnets, other hard magnetic materials, and/or ruthenium, rhodium, iridium or similar metals that can generate RKKY interactions and effects. In another embodiment the SAF layer 206 can have a thickness of approximately 3 nm to approximately 20 nm with example thicknesses of approximately 5 nm to approximately 10 nm. In another embodiment the SAF layer 206 can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0046] In one embodiment, the device 200 can further include a reference layer 208. The reference layer can include alloys of cobalt, iron, boron, and/or any transition metal and/or any transition metal oxides. In another embodiment the reference layer 108 can have a thickness of approximately 0.5 nm to approximately 5 nm with example thicknesses of approximately 1.5 nm to approximately 3 nm. In another embodiment the reference layer 108 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0047] In another embodiment, the device 200 can include a tunneling layer 210. In one embodiment, the tunneling layer 210 can include magnesium oxides (MgO), aluminum oxides (AlOx), and/or any oxides of magnesium or aluminum. In another embodiment the tunneling layer 210 can have a thickness of approximately 0.5 nm to 5 nm with example thicknesses of approximately 1 nm to approximately 3 nm. In another embodiment the tunneling layer 210 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0048] In one embodiment, the device 200 may further include a first ferromagnetic layer 212. In one embodiment, the first ferromagnetic layer 212 can include alloys of cobalt, iron, boron, and/or other magnetic materials. In another embodiment the first ferromagnetic layer 212 can have a thickness of approximately 0.4 nm to 4 nm with example thicknesses of approximately 0.8 nm to approximately 2 nm. In another embodiment the first ferromagnetic layer 212 can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0049] In one embodiment, the device 200 can further include a coupling layer 214. In one embodiment, the coupling layer 214 can include tantalum, tungsten, molybdenum or other transition metals or their oxides. In another embodiment the coupling layer 214 can have a thickness of approximately 0.1 nm to 1 nm with example thicknesses of approximately 0.2 nm to approximately 0.6 nm. In another embodiment the coupling layer 214 can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0050] In an embodiment, the device 200 can include a second ferromagnetic layer 216. In one embodiment, the second ferromagnetic layer 216 can include alloys of cobalt, iron and boron and/or any other magnetic materials. In another embodiment the second ferromagnetic layer 216 can have a thickness of approximately 0.3 nm to 3 nm with example thicknesses of approximately 0.5 nm to approximately 2 nm. In another embodiment the tunneling layer 210 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0051] In one embodiment, the first ferromagnetic layer 212 and/or the second ferromagnetic layer 216 can comprise a cobalt boron iron system. In an embodiment, the first ferromagnetic layer 212 and the second ferromagnetic layer 216 can comprise the same materials. That is, for example, the cobalt boron iron system; however, they may have different thicknesses.
[0052] In another embodiment, the first ferromagnetic layer 212 and the second ferromagnetic layer 216 can have a different cobalt to boron ratio. In another embodiment, the first ferromagnetic layer 212 and the second ferromagnetic layer 216 can have perpendicular anisotropy and parallel or anti-parallel magnetization with respect to the reference layer 208.
[0053] In one embodiment, the device 200 can further include a buffer layer 218. In one embodiment, the buffer layer 218 can include can include magnesium oxide (MgO), and/or any transition metal or transition metal oxides. In another embodiment the tunneling layer 210 can have a thickness of approximately 0.3 nm to 5 nm with example thicknesses of approximately 0.6 nm to approximately 3 nm. In another embodiment the tunneling layer 210 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0054] In an embodiment, the device 200 can include a top electrode 220. In one embodiment the top electrode 220 can include, for example, copper, tungsten, titanium nitride, platinum, and/or any other suitable material. In another embodiment the top electrode 220 can have a thickness of approximately 2 nm to 100 nm with example thicknesses of approximately 5 nm to approximately 60 nm. In another embodiment the top electrode 220 can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0055] In an embodiment, the coupling layer 214 can include a metal oxide, for example, an oxide of tungsten, molybdenum and/or tantalum. In an embodiment, the coupling layer 214 comprising a metal oxide can have metal atoms that are coupled to oxygen atoms, causing less interaction between charge carriers (for example, electrons) transported through the multilayer comprising the first ferromagnetic layer 212, the coupling layer 214 and the second ferromagnetic layer 216, and thereby leading to less Gilbert damping in the device 200.
[0056] In an embodiment, Gilbert damping in the device 200 can be due to spin orbit coupling with metal in the coupling layer 214. In one embodiment, the spin orbit coupling can be reduced by the introduction of a metal oxide as the coupling layer 214. In one embodiment, this metal oxide serving as the coupling layer 214 can increase the TMR and reduce the RA of the device 200. Accordingly, the switching current in both polarities (that is, the switching current from the top electrode 220 to the bottom electrode 204, or vice versa, the switching current from the bottom electrode 204 to the top electrode 220) can be reduced.
[0057] In another embodiment, a metal oxide coupling layer 214 can allow for the coersivity of the device 200 to be reduced. In an embodiment, the reduction in coersivity can be due to a reduction in the magnetic anisotropy in the multilayer 224 that can serve as the free layer in the device 200. In another embodiment, the reduction in the coersivity of the device 200 may be due to the reduced damping, that is, the reduced Gilbert damping in the device 200.
[0058] In an embodiment, the reduction of the magnetic anisotropy in the multilayer 224 can be likened to the reduction and the depth of an energy well that represents the energetic transition that charge carriers (for example, electrons) overcome in going between the second ferromagnetic layer 216 and the first ferromagnetic layer 212 through the coupling layer 214.
[0059] In another embodiment, the reduction in the Gilbert damping can be likened to a reduction in a frictional force for the charge carriers to overcome in being transported from the second ferromagnetic layer 216 to the first ferromagnetic layer 212 through the coupling layer 214, or vice versa. In an embodiment the coupling layer 214 can have a thickness of approximately 1 angstrom to approximately 10 angstroms with example thicknesses of approximately 2 angstroms to approximately 3 angstroms.
[0060] In another embodiment, the thickness of the coupling layer 214 can be one or a few atomic layers. In another embodiment, the resistance of the buffer layer 218 and the resistance of the tunneling layer 210 can dominate the resistivity of the system, then the resistance of the coupling layer 214 may have a reduced impact on the overall resistance area (RA) of the device 200. In an embodiment, the coupling layer 214 can be deposited (that is, formed) using PVD and a post-deposition oxidation, for example, including flowing oxygen on the deposited (that is, formed) coupling layer 214. [0061] In another embodiment, the coupling layer 214 can comprise a metal oxide deposited (that is, formed) by a variety of techniques, including but not limited to, pulsed DC and/or RF sputtering, CVD, ALD, and/or PVD followed by a post oxidation step.
[0062] In an embodiment, the post-oxidation of the coupling layer 214 may need to be optimized. For example, if a transition metal is used as the coupling layer 214, the transition metal can have different magnetic states based on the oxidation state of the transition metal, then the overall electronic properties of the device 200 can change. This can lead to different device performance parameters of the device, for example, including but not limited to, different TMR, different RA, different damping, different switching currents, and/or different coercivities. For example, using a chromium oxide may lead to different oxidation states and/or different magnetic states that may alter the performance parameters of the device 200. Accordingly, the device may need to be optimized for a given thickness and composition of the coupling layer 214.
[0063] FIG. 3 shows a diagram 300 representing the performance parameters of an example pMTJ device, in accordance with one or more example embodiments of the disclosure. In an embodiment, a device structure for the performance parameters depicted in diagram 300 can be as follows: a substrate, followed by a bottom electrode, followed by an SAF layer, followed by a reference layer, followed by a tunneling layer, followed by a first ferromagnetic layer, followed by a coupling layer, followed by a second ferromagnetic layer, followed by a buffer layer, and followed by a top electrode. [0064] In an embodiment, the bottom electrode can include a copper layer that serves as a cathode. In another embodiment, the tunnel barrier layer can include a magnesium oxide. In another embodiment the tunnel layer can be approximately 1 angstrom to approximately 2 nanometers thick. In another embodiment, the first ferromagnetic layer and the second ferromagnetic layer can include a cobalt boron iron system having different thicknesses and/or a different cobalt to boron ratio. In another embodiment, the coupling layer can include a tungsten, molybdenum, and/or tantalum oxide. In another embodiment, the thickness of the coupling layer may be approximately 2 angstroms to approximately 3 angstroms thick. In another embodiment, the buffer layer can include a magnesium oxide. Finally, in an embodiment the top electrode can include an inert electrode, for example, a palladium, a gold, or other inert material.
[0065] As shown in diagram 300, row 302 represents various properties of the devices, for example, the type of coupling layer 303 used in the device, the TMR 306 of the device, the RA 308 of the device and the damping 310 of the device. In one embodiment, column 304 of diagram 300 shows the different types of materials that can be used as the coupling layer 303 in the devices, for example, a non-magnetic metal 312 or a non-magnetic oxide 314.
[0066] As shown in diagram 300, devices having a non-magnetic metal 312 as the coupling layer 303 show a TMR 306 of approximately 142%, a RA 308 of approximately 4.9 Ω-μ2, and a damping 310 of approximately 0.016. Additionally, as represented by the data for the non-magnetic oxide 314, the TMR of the devices having a non-magnetic oxide as the coupling layer can be approximately 142%. The RA 308 of the devices having a non-magnetic oxide as the coupling layer is slightly smaller at 4.7 Q^2with respect to the RA 308 of the non-magnetic metal 312 based devices. Further, the damping 310 of the devices having a non-magnetic oxide as the coupling layer is smaller than the damping 310 of the non-magnetic metal 312, at about 0.013 as compared to 0.016. Consequently, for the devices having a non-magnetic oxide have similar TMR values but lower RA and damping factors, damping parameters, performance parameters, with respect to similar devices but having a non-magnetic metal coupling layer. [0067] In one embodiment, diagram 300 represents data from a blanket wafer having the device architecture mentioned. Accordingly, diagram 300 shows the different RA and damping parameters for devices having different coupling layers (non-magnetic metal and non-magnetic oxide). Further, the data shows that the pMTJ devices having a nonmagnetic metal and the non-magnetic oxide coupling layers show comparable TMR and RA on the blanket wafer. Further, pMTJ devices having the non-magnetic oxide coupling layer show an approximately 20% damping reduction as compared to devices having a non-magnetic metal coupling layer. In an embodiment, the damping (for example, Gilbert damping) in the devices may be proportional to the switching current. Accordingly a reduction of the damping can lead to a reduction in the switching current.
[0068] FIG. 4 shows a diagram 400 representing the performance parameters of example pMTJ devices, in accordance with one or more example embodiments of the disclosure. In one embodiment, the diagram 400 represents the performance parameters for devices that are approximately 40 nanometers by 40 nanometers in dimensions.
[0069] In an embodiment, a device structure for the devices having the performance parameters depicted in diagram 400 can be as follows: a substrate, followed by a bottom electrode, followed by an SAF layer, followed by a reference layer, followed by a tunneling layer, followed by a first ferromagnetic layer, followed by a coupling layer, followed by a second ferromagnetic layer, followed by a buffer layer, and followed by a top electrode.
[0070] In an embodiment, the bottom electrode can include a copper layer that serves as a cathode. In another embodiment, the tunnel barrier layer can include a magnesium oxide. In another embodiment the tunnel layer can be approximately 1 nm to approximately 2 nm thick. In another embodiment, the first ferromagnetic layer and the second ferromagnetic layer can include a cobalt boron iron system having different thicknesses and/or a different cobalt to boron ratio. In another embodiment, the coupling layer can include a tungsten, molybdenum, and/or tantalum oxide. In another embodiment, the thickness of the coupling layer may be approximately 2 angstroms to approximately 3 angstroms thick. In another embodiment, the buffer layer can include a magnesium oxide. Finally, in an embodiment the top electrode can include an inert electrode, for example, a palladium, a gold, or other inert material. [0071] In an embodiment, the diagram 400 includes a first row 401 that shows the various parameters of the devices tested. The parameters include the coupling layer 402 used in the devices tested, a TMR 404 of the devices tested, a RA 406 of the devices tested, a switching current having a first polarity 408 of the devices tested, a switching current having a second polarity 410 of the devices tested, and a coercivity 412 of the devices tested. [0072] In an embodiment, the first column 403 of the diagram 400 shows the two materials used as the coupling layer, that is, the non-magnetic coupling layer 414 and the non-magnetic oxide coupling layer 416. As is shown in diagram 400, the diagram with the non-magnetic coupling layer 414 has a TMR of approximately 85% and an RA of approximately 6.5 Ω-μηι2, a switching current having a first polarity of approximately 150 μΑ, a second switching current having a second polarity of approximately 100 μΑ, and a coercivity of approximately 1250 De.
[0073] In a second embodiment, the device having a non-magnetic oxide coupling layer 416 shows an increased TMR of approximately 95% and a slightly increased RA of 7.5 Ω-μιτι2, a reduced switching current having a first polarity of 80 μΑ, a reduced second switching current having a second polarity of 35 μΑ, and a reduced coercivity of 350 De. Consequently, the device having the non-magnetic oxide coupling layer is shown to provide a higher TMR as compared with the device having a non-magnetic coupling layer.
[0074] In an embodiment, the device with the non-magnetic oxide coupling layer is shown to provide approximately 3 times the reduction in the switching current as compared with devices having a non-magnetic coupling layer. In one embodiment, the reduction in the coercivity (that is, 350 De in the non-magnetic oxide coupling layer case, as compared with 1250 De in the non-magnetic coupling layer case) can be the result of having the non-magnetic oxide coupling layer. That is to say that by using a non-magnetic oxide coupling layer, the magnetic anisotropy and/or the damping in the device can be reduced, leading to the performance data show in diagram 400.
[0075] In one embodiment, the coercivity can represent the device stability, which may be a performance parameter of a pMTJ device. In one example, the non-volatility of a pMTJ device may be measured in units of kT of stability. For example, for a non-volatility of 10 years, approximately 60 kT of stability may be needed in the device. [0076] In one embodiment, the RA parameter of the device can determine the resistance of the device. That is, the RA multiplied by the critical dimension defining the area of the device can provide an indication of the resistance of the device. In one embodiment, the RA may need to have a magnitude that is sufficient to produce a resistance that is in the range of the output of the driving transistor driving the device. For example, the RA may need to produce a resistance of approximately 2 kilo ohms to approximately 3 kilo ohms in order to be in the range of the output of the driving transistor. As such a device having a critical of approximately 60 nanometers and an RA of approximately 2 kilo ohms to approximately 3 kilo ohms can work with such driving transistors. In order to scale the devices critical dimension up, the device may need a higher RA. In another embodiment, continuing with the present example, in order to scale the critical dimension of the device down from 60 nanometers, the device may need a lower RA to continue working with the driving transistors. In one embodiment, a lower RA may cause a lower TMR, which presents a challenge in the fabrication of smaller PMTJ memory devices.
[0077] FIG. 5 shows a diagram 500 of an example processing flow for the fabrication of example pMTJ device, in accordance with example embodiments of the disclosure.
[0078] In block 502 a substrate can be provided. In one embodiment, the substrate can be a thin slice of material such as silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide, an alloy of silicon and germanium, or indium phosphide, and/or glass. In one or more embodiments, the substrate can serve as a heat sink for the device allowing for the dissipation of heat generated by the various layers in the device.
[0079] In block 504 a first electrode that injects charge carriers into a first magnetic layer can be deposited (that is, formed) on the substrate. In one embodiment the bottom electrode can include, for example, the bottom electrode can include copper, tungsten, titanium nitride, platinum, and/or any other suitable material. In another embodiment the bottom electrode can have a thickness of approximately 1 nm to 150 nm with example thicknesses of approximately 5 nm to approximately 25 nm. In another embodiment the bottom electrode can be deposited (that is, formed) using PVD, CVD and/or ALD. [0080] In block 506 the first magnetic layer can be deposited (that is, formed), the first magnetic layer having a first magnetic moment oriented parallel or antiparallel to a second magnetic moment of a multilayer, the multilayer comprising a first ferromagnetic layer, a coupling layer, and a second ferromagnetic layer.
[0081] In one embodiment, the first magnetic layer can also be referred to as a reference layer and can include alloys of cobalt, iron and boron, any of the transition metals or transition metal oxides. In another embodiment the first magnetic layer or reference layer can have a thickness of approximately 3 nm to 20 nm, with example thicknesses of approximately 5 nm to approximately 10 nm. In another embodiment the first magnetic layer or reference layer can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0082] In one embodiment, the first magnetic layer or reference layer can be deposited (that is, formed) on a SAF layer. In various embodiments, the SAF layer and the first magnetic layer or reference layer can serve as a PIN magnetic assembly. In one embodiment, the SAF layer and/or the first magnetic layer or reference layer can produce an electric field during operation that can be referred to as a stray field, the stray field being non-zero in magnitude. In another embodiment, the stray field can affect a tunneling layer of the device. In another the stray field from the SAF layer can determine which magnetic state of the device (for example, parallel or anti-parallel) is more stable. In one embodiment, it may be ideal that the SAF layer and/or the first magnetic layer or reference layer do not exert any stray fields, however, in real devices, the stray field is typically non- zero and can have a positive or negative magnitude. Accordingly the sign of the stray field can determine which magnetic state of the device is more stable, that is the parallel or the anti-parallel state.
[0083] In an embodiment, the SAF layer can have a magnetic anisotropy and can pin the magnetic state of the device. In another embodiment, the first magnetic layer or the reference layer can have a weaker anisotropy as compared with the SAF layer. In one embodiment, the reference layer can be at least partially anchored, in terms of its antimagnetic anisotropy, to the SAF layer.
[0084] In another embodiment, the first magnetic layer or the reference layer can have one or more of its magnetic properties, thickness, and/or electronic properties be adjusted or preselected to result in the maximum TMR across a tunneling layer in the device. In another embodiment, it may be desirable to have the TMR of the device be as high as possible so that the HRS and the LRS of the device are well defined.
[0085] In block 508 a tunneling layer, that transports the charge carriers from the first magnetic layer to the multilayer, can be deposited (that is, formed) on the first magnetic layer. In one embodiment, the tunneling layer can include can include magnesium oxide (MgO), and/or any transition metal or transition metal oxides. In another embodiment the tunneling layer 210 can have a thickness of approximately 0.5 nm to 5 nm with example thicknesses of approximately 1 nm to approximately 3 nm. In another embodiment the tunneling layer can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0086] In one embodiment, under forward bias, the tunneling layer, which can be a relatively thin layer relative to the other layer thicknesses, can pass current. This passage of current by the active layer can be considered synonymous to achieving a low resistant state in the device.
[0087] In block 510 the first ferromagnetic layer can be deposited (that is, formed) on the tunneling layer. In one embodiment, the first ferromagnetic layer can comprise a cobalt boron iron system. In one embodiment, the first ferromagnetic layer can include alloys of cobalt, iron, boron, and/or other magnetic materials. In another embodiment the first ferromagnetic layer can have a thickness of approximately 0.4 nm to 4 nm with example thicknesses of approximately 0.8 nm to approximately 2 nm. In another embodiment the first ferromagnetic layer 212 can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0088] In block 512 the coupling layer can be deposited (that is, formed) on the first ferromagnetic layer. In an embodiment, the coupling layer can include a metal oxide, for example, an oxide of tungsten, molybdenum and/or tantalum. In another embodiment the coupling layer can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0089] In an embodiment, the coupling layer comprising a metal oxide can have metal atoms that are coupled to oxygen atoms, causing less interaction between charge carriers (for example, electrons) transported through the multilayer comprising the first magnetic layer, the coupling layer, and the second ferromagnetic layer, and thereby leading to less Gilbert damping in the device. [0090] In an embodiment, Gilbert damping in the device can be due to spin orbit coupling with metal in the coupling layer. In one embodiment, the spin orbit coupling can be reduced by the introduction of a metal oxide as the coupling layer. In one embodiment, this metal oxide serving as the coupling layer can increase the TMR and reduce the RA of the device. Accordingly, the switching current in both polarities (that is, the switching current from the top electrode to the bottom electrode, or vice versa, the switching current from the bottom electrode to the top electrode) can be reduced.
[0091] In another embodiment, the metal oxide coupling layer can allow for the coersivity of the device to be reduced. In an embodiment, the reduction in coersivity can be due to a reduction in the magnetic anisotropy in the multilayer. In another embodiment, the reduction in the coersivity of the device may be due to the reduced damping, that is, the reduced Gilbert damping in the device.
[0092] In an embodiment, the reduction of the magnetic anisotropy in the multilayer can be likened to the reduction and the depth of an energy well that represents the transition that charge carriers (for example, electrons) overcome in going between the second magnetic layer and the first magnetic layer through the coupling layer.
[0093] In another embodiment, the reduction in the Gilbert damping can be likened to a reduction in a frictional force for the charge carriers to overcome in being transported from the second magnetic layer to the first magnetic layer through the coupling layer, or vice versa. In an embodiment the coupling layer can have a thickness of approximately 1 angstrom to approximately 10 angstroms with example thicknesses of approximately 2 angstroms to approximately 3 angstroms.
[0094] In block 514 the second ferromagnetic layer can be deposited (that is, formed) on the coupling layer. [0095] In one embodiment, the second ferromagnetic layer can include alloys of cobalt, iron, boron, and/or other magnetic materials. In another embodiment the second ferromagnetic layer can have a thickness of approximately 0.4 nm to 4 nm with example thicknesses of approximately 0.8 nm to approximately 2 nm. In another embodiment the second ferromagnetic layer 212 can be deposited (that is, formed) using PVD, CVD, and/or ALD. [0096] In an embodiment, the first ferromagnetic layer and the second ferromagnetic layer can comprise the same materials. That is, for example, the cobalt boron iron system; however, they may have different thicknesses.
[0097] In another embodiment, the first ferromagnetic layer and the second ferromagnetic layer can have a different cobalt to boron ratio. In another embodiment, the first ferromagnetic layer and the second ferromagnetic layer can have perpendicular anisotropy and parallel or anti-parallel magnetization with respect to the reference layer.
[0098] In block 516 a second electrode can be deposited (that is, formed), the second electrode collects the charge carriers from the multilayer. [0099] In one embodiment the second electrode can include any suitable metal; for example, copper, tungsten, titanium nitride, platinum, and/or any other suitable material. In another embodiment the second electrode can have a thickness of approximately 2 nm to 100 nm with example thicknesses of approximately 5 nm to approximately 60 nm. In another embodiment the second electrode can be deposited (that is, formed) using PVD, CVD, and/or ALD.
[0100] FIG. 6 depicts an example of a system 600 according to one or more embodiments of the disclosure. In one embodiment, the systems, methods, and apparatus disclosed herein, including for example, the pMTJ devices described herein can be used in connection with system 600. For example, the pMTJ devices described herein can be used in connection with system 600 to improve the performance of system 600 or to provide memory capabilities to one or more devices of system 600. In one embodiment, system 600 includes, but is not limited to, a desktop computer, a laptop computer, a netbook, a tablet, a notebook computer, a personal digital assistant (PDA), a server, a workstation, a cellular telephone, a mobile computing device, a smart phone, an Internet appliance or any other type of computing device. In some embodiments, system 600 can include a system on a chip (SOC) system.
[0101] In one embodiment, system 600 includes multiple processors including processor 610 and processor N 605, where processor N 605 has logic similar or identical to the logic of processor 610. In one embodiment, processor 610 has one or more processing cores (represented here by processing core 1 612 and processing core N 612N, where 612N represents the Nth processor core inside processor 610, where N is a positive integer). More processing cores can be present (but not depicted in the diagram of FIG. 6). In some embodiments, processing core 612 includes, but is not limited to, pre-fetch logic to fetch instructions, decode logic to decode the instructions, execution logic to execute instructions, a combination thereof, or the like. In some embodiments, processor 610 has a cache memory 616 to cache instructions and/or data for system 600. Cache memory 616 may be organized into a hierarchical structure including one or more levels of cache memory.
[0102] In some embodiments, processor 610 includes a memory controller (MC) 614, which is configured to perform functions that enable the processor 610 to access and communicate with memory 630 that includes a volatile memory 632 and/or a non-volatile memory 634. In some embodiments, processor 610 can be coupled with memory 630 and chipset 620. Processor 610 may also be coupled to a wireless antenna 678 to communicate with any device configured to transmit and/or receive wireless signals. In one embodiment, the wireless antenna antenna 678 operates in accordance with, but is not limited to, the IEEE 802.11 standard and its related family, Home Plug AV (HPAV), Ultra Wide Band (UWB), Bluetooth, WiMax, or any form of wireless communication protocol.
[0103] In some embodiments, volatile memory 632 includes, but is not limited to, Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM), and/or any other type of random access memory device. Non-volatile memory 634 includes, but is not limited to, flash memory, phase change memory (PCM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or any other type of non-volatile memory device. [0104] Memory device 630 stores information and instructions to be executed by processor 610. In one embodiment, memory 630 may also store temporary variables or other intermediate information while processor 610 is executing instructions. In the illustrated embodiment, chipset 620 connects with processor 610 via Point-to-Point (PtP or P-P) interface 617 and P-P interface 622. Chipset 620 enables processor 610 to connect to other elements in system 600. In some embodiments of the disclosure, P-P interface 617 and P-P interface 622 can operate in accordance with a PtP communication protocol, such as the Intel® QuickPath Interconnect (QPI) or the like. In other embodiments, a different interconnect may be used.
[0105] In some embodiments, chipset 620 can be configured to communicate with processor 610, the processor N 605, display device 640, and other devices 672, 676, 674, 660, 662, 664, 666, 677, etc. Chipset 620 may also be coupled to the wireless antenna 678 to communicate with any device configured to transmit and/or receive wireless signals.
[0106] Chipset 620 connects to display device 640 via interface 626. Display 640 may be, for example, a liquid crystal display (LCD), a plasma display, cathode ray tube (CRT) display, or any other form of visual display device. In some embodiments of the disclosure, processor 610 and chipset 620 are integrated into a single SOC. In addition, chipset 620 connects to bus 650 and/or bus 655 that interconnect various elements 674, 660, 662, 664, and 666. Bus 650 and bus 655 may be interconnected via a bus bridge 672. In one embodiment, chipset 620 couples with a non-volatile memory 660, a mass storage device(s) 662, a keyboard/mouse 664, and a network interface 666 via interface 624 and/or 604, smart TV 676, consumer electronics 677, etc.
[0107] In one embodiment, mass storage device(s) 662 can include, but not be limited to, a solid state drive, a hard disk drive, a universal serial bus flash memory drive, or any other form of computer data storage medium. In one embodiment, network interface 666 is implemented by any type of well-known network interface standard including, but not limited to, an Ethernet interface, a universal serial bus (USB) interface, a Peripheral Component Interconnect (PCI) Express interface, a wireless interface and/or any other suitable type of interface. In one embodiment, the wireless interface operates in accordance with, but is not limited to, the IEEE 802.11 standard and its related family, Home Plug AV (HPAV), Ultra Wide Band (UWB), Bluetooth, WiMax, or any form of wireless communication protocol.
[0108] While the modules shown in FIG. 7 are depicted as separate blocks within the system 600, the functions performed by some of these blocks may be integrated within a single semiconductor circuit or may be implemented using two or more separate integrated circuits. For example, although cache memory 616 is depicted as a separate block within processor 610, cache memory 616 or selected elements thereof can be incorporated into processor core 612. [0109] It is noted that the system 600 described herein may be any suitable type of microelectronics packaging and configurations thereof, including, for example, system in a package (SiP), system on a package (SOP), package on package (PoP), interposer package, 3D stacked package, etc. Further, any suitable type of microelectronic components may be provided in the semiconductor packages, as described herein. For example, microcontrollers, microprocessors, baseband processors, digital signal processors, memory dies, field gate arrays, logic gate dies, passive component dies, MEMSs, surface mount devices, application specific integrated circuits, baseband processors, amplifiers, filters, combinations thereof, or the like may be packaged in the semiconductor packages, as disclosed herein. The semiconductor packages (for example, the semiconductor packages described in connection with any of FIGS. 1-6), as disclosed herein, may be provided in any variety of electronic device including consumer, industrial, military, communications, infrastructural, and/or other electronic devices.
[0110] In various embodiments, the devices, as described herein, may be used in connection with one or more processors. The one or more processors may include, without limitation, a central processing unit (CPU), a digital signal processor(s) (DSP), a reduced instruction set computer (RISC), a complex instruction set computer (CISC), a microprocessor, a microcontroller, a field programmable gate array (FPGA), or any combination thereof. The processors may also include one or more application specific integrated circuits (ASICs) or application specific standard products (ASSPs) for handling specific data processing functions or tasks. In certain embodiments, the processors may be based on an Intel® Architecture system and the one or more processors and any chipset included in an electronic device may be from a family of Intel® processors and chipsets, such as the Intel® Atom® processor(s) family or Intel-64 processors (for example, Sandy Bridge®, Ivy Bridge®, Haswell®, Broadwell®, Skylake®, etc.).
[0111] Additionally or alternatively, the devices, as described herein, may be used in connection with one or more additional memory chips. The memory may include one or more volatile and/or non-volatile memory devices including, but not limited to, magnetic storage devices, read-only memory (ROM), random access memory (RAM), dynamic RAM (DRAM), static RAM (SRAM), synchronous dynamic RAM (SDRAM), double data rate (DDR) SDRAM (DDR-SDRAM), RAM-BUS DRAM (RDRAM), flash memory devices, electrically erasable programmable read-only memory (EEPROM), non-volatile RAM (NVRAM), universal serial bus (USB) removable memory, or combinations thereof.
[0112] In example embodiments, the electronic device in which the disclosed devices are used and/or provided may be a computing device. Such a computing device may house one or more boards on which the devices may be disposed. The board may include a number of components including, but not limited to, a processor and/or at least one communication chip. The processor may be physically and electrically connected to the board through, for example, electrical connections of the devices. The computing device may further include a plurality of communication chips. For instance, a first communication chip may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth, and a second communication chip may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, EV-DO, and others. In various example embodiments, the computing device 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, a digital video recorder, combinations thereof, or the like. In further example embodiments, the computing device may be any other electronic device that processes data. [0113] According to example embodiments (example 1) of the disclosure, there may be a perpendicular magnetic tunnel junction (pMTJ) device. The device may comprise: a first magnetic layer having a first magnetic moment; a multilayer comprising a first ferromagnetic layer, a coupling layer, and a second ferromagnetic layer, wherein the multilayer includes a second magnetic moment perpendicular to the first magnetic moment of the first magnetic layer; a first electrode configured to inject charge carriers into the first magnetic layer; a tunneling layer configured to transport the charge carriers from the first magnetic layer to the multilayer; a second electrode configured to collect the charge carriers from the multilayer; and wherein the coupling layer comprises a non-magnetic metal oxide layer, and the coupling layer positioned between the first ferromagnetic layer and the second ferromagnetic layer. [0114] Implementation may include one or more of the following features. The coupling layer may have a thickness of about 2 angstroms (example 2). The coupling layer may comprise a transition metal oxide, a tungsten oxide, a molybdenum oxide, or a tantalum oxide (example 3). The first ferromagnetic layer of the device comprising cobalt and boron having a first weight ratio and the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may be different weight ratios (example 4). The first ferromagnetic layer of the device comprising cobalt and boron having a first weight ratio and the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may be the same weight ratio and wherein further, the first ferromagnetic layer has a first thickness and the second ferromagnetic layer has a second thickness, wherein the first thickness may be different than the second thickness (example 5). The tunneling layer of the device may comprise a metal oxide, a magnesium oxide or an aluminum oxide (example 6). The device may further comprise a synthetic antiferromagnetic (SAF) layer disposed between the first electrode and the first magnetic layer (example 7). The SAF layer may include a cobalt layer, a platinum layer, a nickel layer, a L10 alloy layer, a suplerlattice magnet layer, a ruthenium layer, a rhodium layer, or a iridium layer (example 8). A buffer layer may be disposed between the multilayer and the second electrode and the buffer layer may comprise a metal oxide (example 9). In various embodiment, any of the aforementioned examples may be used in part or in whole in connection with any other example in any combination or subcombination.
[0115] According to example embodiments of the disclosure, there may be a method for fabricating a perpendicular magnetic tunnel junction (pMTJ) device (example 10). providing a substrate; depositing, on the substrate, a first electrode; depositing a first magnetic layer having a first magnetic moment, wherein the first electrode is configured to inject charge carriers into the first magnetic layer; depositing, on the first magnetic layer, a tunneling layer that transports the charge carriers; depositing, on the tunneling layer, a multilayer having a second magnetic moment, the second magnetic layer having a second magnetic moment is oriented parallel or antiparallel to the first magnetic moment of the first magnetic layer, wherein depositing the multilayer comprises, depositing a first ferromagnetic layer on the tunneling layer, depositing a coupling layer on the first ferromagnetic layer, depositing a second ferromagnetic layer on the coupling layer; and depositing a second electrode that collects the charge carriers from the multilayer.
[0116] Implementation may include one or more of the following features. The method of depositing the couple layer may comprise depositing the coupling layer using radio frequency (RF) sputtering, pulsed DC sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD) (example 11). Depositing the coupling layer may further comprise a post-deposition oxidation(example 12). Depositing the coupling layer on the first ferromagnetic layer may comprise depositing the coupling layer having a thickness of 2 degrees and may comprise depositing a transition metal oxide, a tungsten oxide, a molybdenum oxide, or a tantalum oxide on the first ferromagnetic layer (example 13). Depositing the first ferromagnetic layer on the tunneling layer may comprise depositing the first ferromagnetic layer comprising cobalt and boron having a first weight ratio and depositing the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may have different weight ratios (example 14). Depositing the first ferromagnetic layer on the tunneling layer may comprise depositing the first ferromagnetic layer comprising cobalt and boron having a first weight ratio and depositing the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may have the same weight ratios, wherein further, the first ferromagnetic layer has a first thickness and the second ferromagnetic layer has a second thickness, wherein the first thickness may be different than the second thickness (example 15). The method of depositing the tunneling layer may further comprise depositing metal oxide, a magnesium oxides or an aluminum oxide (example 16). The method may further comprise depositing a synthetic antiferromagnetic (SAF) layer between the first electrode and the first magnetic layer (example 17). The method may further comprise depositing a buffer layer, which may comprise depositing a metal oxide, between the multilayer and the second electrode (example 18). In various embodiment, any of the aforementioned examples may be used in part or in whole in connection with any other example in any combination or subcombination. [0117] According to example embodiments of the disclosure, there may be an electronic device (example 19). The electronic device may comprise: a perpendicular magnetic tunnel junction (pMTJ) which may comprise: a first magnetic layer having a first magnetic moment; a multilayer comprising a first ferromagnetic layer, a coupling layer, and a second ferromagnetic layer, wherein the multilayer includes a second magnetic moment perpendicular to the first magnetic moment of the first magnetic layer; a first electrode configured to inject charge carriers into the first magnetic layer; a tunneling layer configured to transport the charge carriers from the first magnetic layer to the multilayer; a second electrode configured to collect the charge carriers from the multilayer; and wherein the coupling layer comprises a non-magnetic metal oxide layer, and the coupling layer positioned between the first ferromagnetic layer and the second ferromagnetic layer (example 20). [0118] Implementation may include one or more of the following features (example 21). The coupling layer may have a thickness of about 2 angstroms (example 22). The coupling layer may comprise a transition metal oxide, a tungsten oxide, a molybdenum oxide, or a tantalum oxide (example 23). The first ferromagnetic layer of the electronic device comprising cobalt and boron having a first weight ratio and the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may be different weight ratios (example 24). The first ferromagnetic layer of the electronic device comprising cobalt and boron having a first weight ratio and the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio may be the same weight ratio and wherein further, the first ferromagnetic layer has a first thickness and the second ferromagnetic layer has a second thickness, wherein the first thickness may be different than the second thickness (example 25). The tunneling layer of the electronic device may comprise a metal oxide, a magnesium oxide or an aluminum oxide (example 26). The electronic device may further comprise a synthetic antiferromagnetic (SAF) layer disposed between the first electrode and the first magnetic layer (example 27). The SAF layer may include a cobalt layer, a platinum layer, a nickel layer, a L10 alloy layer, a suplerlattice magnet layer, a ruthenium layer, a rhodium layer, or a iridium layer. A buffer layer may be disposed between the multilayer and the second electrode and the buffer layer may comprise a metal oxide (example 28). In various embodiment, any of the aforementioned examples may be used in part or in whole in connection with any other example in any combination or subcombination. [0119] Various features, aspects, and embodiments have been described herein. The features, aspects, and embodiments are susceptible to combination with one another as well as to variation and modification, as will be understood by those having skill in the art. The present disclosure should, therefore, be considered to encompass such combinations, variations, and modifications.
[0120] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims are intended to cover all such equivalents.
[0121] While the disclosure includes various embodiments, including at least a best mode, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, the disclosure is intended to embrace all such alternatives, modifications, and variations, which fall within the scope of the included claims. All matters disclosed herein or shown in the accompanying drawings are to be interpreted in an illustrative and non- limiting sense.
[0122] This written description uses examples to disclose certain embodiments of the disclosure, including the best mode, and also to enable any person skilled in the art to practice certain embodiments of the disclosure, including making and using any apparatus, devices or systems and performing any incorporated methods and processes. The patentable scope of certain embodiments of the invention is defined in the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

CLAIMS The claimed invention is:
1. A perpendicular magnetic tunnel junction (pMTJ) device, comprising:
a first magnetic layer having a first magnetic moment;
a multilayer comprising a first ferromagnetic layer, a coupling layer, and a second ferromagnetic layer, wherein the multilayer includes a second magnetic moment perpendicular to the first magnetic moment of the first magnetic layer;
a first electrode configured to inject charge carriers into the first magnetic layer; a tunneling layer configured to transport the charge carriers from the first magnetic layer to the multilayer; and
a second electrode configured to collect the charge carriers from the multilayer; and
wherein the coupling layer comprises a non-magnetic metal oxide layer, and the coupling layer positioned between the first ferromagnetic layer and the second ferromagnetic layer.
2. The device of claim 1 , wherein the coupling layer has a thickness of about 2 angstroms.
3. The device of claim 1 , wherein the coupling layer comprises a transition metal oxide.
4. The device of claim 1 , wherein the coupling layer comprises a tungsten oxide, a molybdenum oxide, or a tantalum oxide.
5. The device of claim 1 , wherein the first ferromagnetic layer comprises cobalt and boron having a first weight ratio and the second ferromagnetic layer comprises cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio are different weight ratios.
6. The device of claim 1, wherein the first ferromagnetic layer comprises cobalt and boron having a first weight ratio and the second ferromagnetic layer comprises cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio are the substantially equal and wherein further, the first ferromagnetic layer has a first thickness and the second ferromagnetic layer has a second thickness, wherein the first thickness is different than the second thickness.
7. The device of a claim 1, wherein the tunneling layer comprises a metal oxide.
8. The device of a claim 1, wherein the tunneling layer comprises a magnesium oxide or an aluminum oxide.
9. The device of claim 1, further comprising a synthetic antiferromagnetic (SAF) layer disposed between the first electrode and the first magnetic layer.
10. The device of claim 9, wherein the SAF layer includes a cobalt layer, a platinum layer, a nickel layer, a L10 alloy layer, a suplerlattice magnet layer, a ruthenium layer, a rhodium layer, or a iridium layer.
11. The device of claim 1, further comprising a buffer layer disposed between the multilayer and the second electrode.
12. The device of claim 11, wherein the buffer layer comprises a metal oxide.
13. A method for fabricating a perpendicular magnetic tunnel junction (pMTJ) device, the method comprising:
providing a substrate;
depositing, on the substrate, a first electrode;
depositing a first magnetic layer having a first magnetic moment, wherein the first electrode is configured to inject charge carriers into the first magnetic layer;
depositing, on the first magnetic layer, a tunneling layer that transports the charge carriers;
depositing, on the tunneling layer, a multilayer having a second magnetic moment, the second magnetic moment oriented parallel or antiparallel to the first magnetic moment of the first magnetic layer, wherein depositing the multilayer comprises,
depositing a first ferromagnetic layer on the tunneling layer, depositing a coupling layer on the first ferromagnetic layer,
depositing a second ferromagnetic layer on the coupling layer; and depositing a second electrode that collects the charge carriers from the multilayer.
14. The method of claim 13, wherein depositing the coupling layer comprises deposing the coupling layer using radio frequency (RF) sputtering, pulsed DC sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD).
15. The method of claim 13, wherein depositing the coupling layer further comprises a post-deposition oxidation.
16. The method of claim 13, wherein depositing the coupling layer on the first ferromagnetic layer comprises depositing the coupling layer having a thickness of about 2 angstroms.
17. The method of claim 13, wherein depositing the coupling layer on the first ferromagnetic layer comprises depositing a transition metal oxide on the first
ferromagnetic layer.
18. The method of claim 13, wherein depositing the coupling layer on the first ferromagnetic layer comprises depositing a tungsten oxide, a molybdenum oxide, or a tantalum oxide on the first ferromagnetic layer.
19. The method of claim 13, wherein depositing the first ferromagnetic layer on the tunneling layer comprises depositing the first ferromagnetic layer comprising cobalt and boron having a first weight ratio and depositing the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio are different.
20. The method of claim 13, wherein depositing the first ferromagnetic layer on the tunneling layer comprises depositing the first ferromagnetic layer comprising cobalt and boron having a first weight ratio and depositing the second ferromagnetic layer comprising cobalt and boron having a second weight ratio, wherein the first weight ratio and the second weight ratio are substantially equal same, wherein further, the first ferromagnetic layer has a first thickness and the second ferromagnetic layer has a second thickness, wherein the first thickness is different than the second thickness.
21. The method of claim 13, wherein depositing the tunneling layer further comprises depositing a metal oxide.
22. The method of claim 13, wherein depositing the tunneling layer further comprises depositing a magnesium oxides or an aluminum oxide.
23. The method of claim 13, further comprising depositing a synthetic antiferromagnetic (SAF) layer between the first electrode and the first magnetic layer.
24. The method of claim 13, further comprising depositing a buffer layer between the multilayer and the second electrode.
25. The method of claim 24, wherein depositing the buffer layer comprises depositing a metal oxide.
PCT/US2016/069625 2016-12-30 2016-12-30 Perpendicular magnetic tunnel junction (pmtj) devices having a metal oxide layer WO2018125243A1 (en)

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