A spin-orbit torque magnetic memory and a preparation method thereof

Abstract

The present invention discloses a spin-orbit torque magnetic memory and a preparation method thereof, relating to the field of electronics. The spin-orbit torque magnetic memory includes: a heavy metal layer and a composite magnetic tunnel junction disposed on the heavy metal layer. Among them, the composite magnetic tunnel junction includes: a composite free layer, a non-magnetic barrier layer, and a fixed layer. The composite free layer and the fixed layer are respectively disposed on both sides of the non-magnetic barrier layer. The composite free layer includes a free layer and an induction layer. The induction layer is disposed between the free layer and the tunneling resistance layer. In response to a first signal, the induction layer and the free layer are flipped, and the flipping actions of the two are consistent to achieve the flipping of the composite free layer. The induction layer is used to reduce the demagnetization energy of the free layer to reduce the critical current. It can be seen that by disposing an induction layer in the magnetic tunnel junction to generate perpendicular magnetic anisotropy energy, the effective demagnetization energy of the free layer is reduced, thereby reducing the magnitude of the flipping current and reducing the loss during the operation of the device.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of electronics, and in particular to a method for manufacturing a magnetic random access memory. Background Art

[0002] With the continuous development and maturity of the research and development process of emerging memories, spin-orbit torque magnetic random access memory (SOT-MRAM, Spin Orbit Torque-Magnetic Access Memory) has been increasingly widely used. SOT-MRAM can generate a flip due to the strong spin-orbit coupling (SOC) effect of the heavy metal layer in the spin-orbit torque effect. Therefore, it is usually necessary to reduce the flip current magnitude of SOT-MRAM to improve the flip efficiency of SOT-MRAM and reduce the power consumption during operation.

[0003] In the prior art, the flip current is usually reduced by changing the free layer material in SOT-MRAM or changing the thickness of the free layer. However, this usually reduces the thermal stability of SOT-MRAM and affects the service life of SOT-MRAM. Summary of the Invention

[0004] The embodiments of the present invention provide a spin-orbit torque magnetic random access memory and a method for manufacturing the same, which can reduce the flip current magnitude of SOT-MRAM devices and reduce the power consumption of the devices.

[0005] To solve the above problems, a first aspect of the present invention proposes a spin-orbit torque magnetic random access memory, including:

[0006] A heavy metal layer and a composite magnetic tunnel junction disposed on the heavy metal layer,

[0007] wherein, the composite magnetic tunnel junction includes: a composite free layer, a non-magnetic barrier layer, and a fixed layer. The composite free layer and the fixed layer are respectively disposed on both sides of the non-magnetic barrier layer.

[0008] The composite free layer includes a free layer and an induction layer. The induction layer is disposed between the free layer and the tunneling resistance layer. In response to a first signal, the induction layer and the free layer flip, and the flipping actions of the two are consistent to achieve the flipping of the composite free layer. The induction layer is used to reduce the demagnetization energy of the free layer to reduce the critical current.

[0009] In some embodiments, the induction layer is obtained from at least one of the following materials, including: cobalt, iron, and hafnium. In this way, by selecting the above materials, the induction layer can be made ferromagnetic, supplement the magnetism of the free layer, and increase the thermal stability of the device.

[0010] In some embodiments, the first signal is used to flip the composite free layer, and the forms of the first signal include: electrical signals, magnetic signals, and optical signals.

[0011] In some embodiments, the thickness of the induction layer is 0.1 to 0.5 nanometers. In this way, by setting the thickness within the above size range, the induction layer can have perpendicular magnetic anisotropy, thereby reducing the effective demagnetization energy of the free layer and reducing the switching current.

[0012] In some embodiments, the free layer and / or the fixed layer can be made of at least one of the following materials, including: cobalt iron boron alloy, iron cobalt alloy, and cobalt.

[0013] The atomic ratio of the cobalt iron boron alloy includes at least one of the following: Co 20 Fe 60 B 20 , Co 40 Fe 40 B 20 and Co 60 Fe 20 B 20 ;

[0014] The atomic ratio of the iron cobalt alloy includes at least one of the following: Co 70 Fe 30 , Co 75 Fe 25 and Co 85 Fe 15 ;

[0015] The non-magnetic barrier layer can be made of at least one of the following materials, including: magnesium oxide and aluminum oxide.

[0016] In a second aspect of the present application, a method for manufacturing a spin-orbit torque magnetic memory is further provided.

[0017] Applicable to a spin-orbit torque magnetic memory, the spin-orbit torque magnetic memory includes a composite magnetic tunnel junction, and the method includes:

[0018] Constructing a composite magnetic tunnel junction on top of the heavy metal layer;

[0019] Constructing a capping layer on top of the magnetic tunnel junction.

[0020] In some embodiments, constructing the composite magnetic tunnel junction on top of the bottom heavy metal layer includes:

[0021] Constructing a free layer on top of the heavy metal layer;

[0022] Constructing an induction layer on top of the free layer to obtain a composite free layer;

[0023] Construct a non-magnetic barrier layer above the induced layer;

[0024] Construct a fixed layer above the tunneling resistance layer.

[0025] In some embodiments, the construction of the composite magnetic tunnel junction above the bottom heavy metal layer includes: realizing the construction of the composite magnetic tunnel junction by sputtering.

[0026] In some embodiments, the realization of the construction of the composite magnetic tunnel junction by construction includes: using at least one of the following materials to realize the construction of the induced layer, and the materials include: cobalt, iron, and hafnium.

[0027] In some embodiments, the thickness of the induced layer is 0.1 - 0.5 nanometers.

[0028] In some embodiments, the construction of the free layer above the heavy metal layer and the construction of the fixed layer above the non-magnetic barrier layer are realized by: sputtering using at least one of the following materials, and the materials include: cobalt iron boron alloy, cobalt iron alloy, and cobalt. In some embodiments, the preparation process of the magnetic tunnel junction further includes the following three methods: coating, developing, and etching.

[0029] Embodiments of the present invention provide a SOT-MRAM with a composite heavy metal layer structure and a preparation method thereof. The spin-orbit torque magnetic memory includes: a heavy metal layer and a composite magnetic tunnel junction disposed above the heavy metal layer. Among them, the composite magnetic tunnel junction includes: a composite free layer, a non-magnetic barrier layer, and a fixed layer. The composite free layer and the fixed layer are respectively disposed on both sides of the non-magnetic barrier layer. The composite free layer includes a free layer and an induced layer. The induced layer is disposed between the free layer and the tunneling resistance layer. In response to a first signal, the induced layer and the free layer are flipped, and the flipping actions of the two are consistent to realize the flipping of the composite free layer. The induced layer is used to reduce the demagnetization energy of the free layer to reduce the critical current. By setting an induced layer in the magnetic tunnel junction, the magnetic anisotropy energy in the induced magnetic tunnel junction is reduced to reduce the demagnetizing magnetic field, thereby reducing the magnitude of the reverse current, and thus reducing the loss caused by resistivity during the operation of the device. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application.

[0031] Figure 1 Schematic diagram of the first category of magnetic memory structure according to an embodiment of the present application;

[0032] Figure 2 Schematic diagram of a second type of magnetic memory structure according to an embodiment of the present application. Detailed implementation manners

[0033] In order to make the objectives, features, and advantages of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0034] Those skilled in the art can understand that the terms "first", "second", etc. in the present application are only used to distinguish different devices, modules, or parameters, etc., and neither represent any specific technical meaning nor indicate an inevitable logical order between them.

[0035] An embodiment of the present invention provides a SOT-MRAM with a composite magnetic tunnel junction structure and a preparation method thereof. The spin-orbit torque magnetic memory includes: a heavy metal layer and a composite magnetic tunnel junction disposed on the heavy metal layer. Among them, the composite magnetic tunnel junction includes: a composite free layer, a non-magnetic barrier layer, and a fixed layer. The composite free layer and the fixed layer are respectively disposed on both sides of the non-magnetic barrier layer. The composite free layer includes a free layer and an induced layer. The induced layer is disposed between the free layer and the tunneling resistance layer. In response to a first signal, the induced layer and the free layer are flipped, and the flipping actions of the two are consistent to realize the flipping of the composite free layer. The induced layer is used to reduce the demagnetization energy of the free layer to reduce the critical current. By disposing an induced layer in the magnetic tunnel junction, the magnetic anisotropy energy in the induced magnetic tunnel junction is used to reduce the demagnetizing magnetic field, thereby reducing the magnitude of the reverse current, and thus reducing the loss caused by resistivity during the operation of the device.

[0036] With the continuous development and maturity of the emerging memory research and development process, spin-orbit torque magnetic memory (SOT-MRAM, Spin Orbit Torque-Magnetic Access Memory) has been more and more widely used. The SOT-MRAM can generate flipping due to the strong spin-orbit coupling (Spain Orbit Coupling, SOC) effect of the heavy metal layer in the spin-orbit torque effect. Therefore, it is usually necessary to reduce the magnitude of the flipping current of the SOT-MRAM to improve the flipping efficiency of the SOT-MRAM and reduce the power loss during operation.

[0037] In the prior art, the switching current is usually reduced by changing the free layer material in SOT-MRAM or changing the thickness of the free layer. However, this usually reduces the thermal stability of SOT-MRAM and affects the service life of SOT-MRAM.

[0038] Exemplarily, reducing the free layer thickness will lead to a reduction in the tunneling magnetoresistance of the SOT-MRAM device, making the device vulnerable to the risk of current breakdown. Changing the free layer material will lead to a reduction in the thermal stability during the period and is easily burned by a large current.

[0039] Generally, the core structure of a conventional SOT-MRAM includes: a heavy metal layer, a free layer, a non-magnetic barrier layer, a fixed layer, an antiferromagnetic coupling layer, a pinned layer, and a capping layer from bottom to top. Among them, magnetic anisotropy refers to the phenomenon that the magnetism of a substance changes with direction, which is relatively common in the field of magnetic storage. It is mainly manifested that the magnetic susceptibility of a weak magnet and the magnetization curve of a ferromagnetic body change with the magnetization direction. The magnetic anisotropy of a ferromagnetic body is particularly prominent and is one of the basic magnetisms of a ferromagnetic body, indicating that the free energy density is different when the saturation magnetization is in different crystal directions. The corresponding magnetic anisotropy energy is usually defined as the energy change when the saturation magnetization vector takes different directions in a ferromagnetic body, that is, the magnetization energies required for magnetization along the hard and easy magnetization axes of the ferromagnetic body are different. The magnetization energy required in the easy magnetization direction is smaller, while the magnetization energy required in the hard magnetization direction is larger.

[0040] Exemplarily, in an SOT-MRAM device, the switching current is an important physical parameter that triggers the magnetic field reversal of the free layer of the device. Generally, the smaller the switching current of the device, the better, which can reduce the power loss of the device. The magnitude of the switching current is positively correlated with the magnitude of the switching current density. The formula for the switching current density is expressed as follows:

[0041] J co =(α2e / hη)(μ0Ms)(Hc + Meff)*t

[0042] Among them, J c0 represents the switching current density, H c represents the coercive field, Meff represents the effective demagnetizing field, μ0 represents the vacuum permeability, α represents the damping coefficient, e represents the electron charge, Planck's constant, η represents the switching efficiency, M s represents the free layer saturation magnetic field and t represents the free layer thickness. It can be seen from this that the switching current density can be reduced by reducing the effective demagnetizing field.

[0043] Exemplarily, for the effective demagnetizing field, the calculation formula can be expressed as:

[0044] Meff ≡ Ms -Ks / tFM

[0045] Among them, Ms represents the saturation magnetic field of the free layer, Ks represents the energy density corresponding to the magnetic anisotropy energy, and t FM represents the thickness of the free layer. It can be seen therefrom that the effective demagnetizing field can be reduced by inducing a higher energy density corresponding to the magnetic anisotropy energy, thereby reducing the switching current density, so as to reduce the switching current of the SOT-MRAM device.

[0046] In one embodiment of the present application, in order to ensure that the magnetic tunnel junction can induce a larger magnetic anisotropy energy during use, thereby reducing the switching current, a composite magnetic tunnel structure is used to construct the SOT-MRAM.

[0047] Such as Figure 1 shown in the schematic diagram of the first type of magnetic memory structure with a composite magnetic tunnel junction structure,

[0048] The spin-orbit torque magnetic memory includes:

[0049] a heavy metal layer and a composite magnetic tunnel junction disposed on the heavy metal layer,

[0050] wherein, the composite magnetic tunnel junction includes: a composite free layer, a non-magnetic barrier layer, and a fixed layer, and the composite free layer and the fixed layer are respectively disposed on both sides of the non-magnetic barrier layer,

[0051] The composite free layer includes a free layer and an induction layer. The induction layer is disposed between the free layer and the tunneling resistance layer. In response to the first signal, the induction layer and the free layer are flipped, and the flipping actions of the two are consistent to realize the flipping of the composite free layer. The induction layer is used to reduce the demagnetization energy of the free layer to reduce the critical current.

[0052] In one embodiment of the present application, in order to achieve a reduction in the switching current of the SOT-MRAM, the material of the induction layer is screened and defined.

[0053] Optionally, the induction layer is obtained from at least one of the following materials, including: cobalt, iron, and hafnium.

[0054] In one embodiment of the present application, in order to ensure that the introduced thickness of the induction layer does not affect the overall device function, the thickness of the induction layer is set to 0.1 to 0.5 nanometers.

[0055] In one embodiment of the present application, the free layer and / or the fixed layer can be obtained from at least one of the following materials, including: cobalt-iron-boron alloy, cobalt-iron alloy, and cobalt,

[0056] The atomic ratio of the cobalt-iron-boron alloy includes at least one of the following: Co 20 Fe 60 B 20 、Co 40 Fe 40 B 20 and Co 60 Fe 20 B 20 ;

[0057] The atomic ratio of the cobaltized iron alloy includes at least one of the following: Co 70 Fe 30 、Co 75 Fe 25 and Co 85 Fe 15 ;

[0058] The non-magnetic barrier layer may be made of at least one of the following materials, including magnesium oxide and aluminum oxide. In a possible implementation, the magnetic memory may also have a second type of application form, specifically, Figure 2 As shown, the composite magnetic tunnel junction can also be used in a SOT-MRAM with an artificial rice-pasted secondary coupling layer, which, from bottom to top, are a heavy metal layer, a free layer, an induction layer, a nonmagnetic barrier layer, a fixed layer, a ferromagnetic layer, a pinning layer, and a covering layer.

[0059] Optionally, for the heavy metal layer, an annealing operation is performed after sputtering, and the annealing conditions include: temperature 300° C., magnetic field intensity 1 T, and annealing time 1 hour.

[0060] Optionally, the annealing direction is perpendicular to the current direction in the heavy metal layer.

[0061] Optionally, the film stack produced above is subsequently subjected to operations such as coating, developing, and etching to obtain a complete device. In another embodiment of the present application, a method for preparing a spin-orbit moment magnetic memory is also introduced.

[0062] Applicable to a spin-orbit moment magnetic memory, the spin-orbit moment magnetic memory includes a composite magnetic tunnel junction, and the method includes:

[0063] constructing a composite magnetic tunnel junction on top of the heavy metal layer;

[0064] A capping layer is constructed over the magnetic tunnel junction.

[0065] Optionally, constructing a composite magnetic tunnel junction on the bottom heavy metal layer includes:

[0066] constructing a free layer on the heavy metal layer;

[0067] Construct an induced layer on top of the free layer to obtain a composite free layer;

[0068] Construct a non-magnetic barrier layer on top of the induced layer;

[0069] Construct a fixed layer on top of the tunneling resistance layer.

[0070] Optionally, the construction of the composite magnetic tunnel junction on top of the bottom heavy metal layer includes: realizing the construction of the composite magnetic tunnel junction by sputtering.

[0071] Among them, the sputtering process is a process in which particles (ions or neutral atoms, molecules) with a certain energy bombard the solid surface, so that the atoms or molecules near the solid surface obtain sufficient energy and finally escape from the solid surface. The sputtering process can only be carried out under a certain vacuum state. Here, the growth and construction of the hybrid heavy metal layer can optionally use the sputtering process, but it is not limited to this solution, and other modes are also applicable.

[0072] Optionally, the realization of constructing the composite magnetic tunnel junction by construction includes: using at least one of the following materials to realize the construction of the induced layer, and the materials include: cobalt, iron, and hafnium.

[0073] Optionally, the thickness of the induced layer construction is 0.1 to 0.5 nanometers.

[0074] Optionally, the realization of constructing the free layer on top of the heavy metal layer and the fixed layer on top of the tunneling resistance layer includes: obtaining by sputtering using at least one of the following materials, and the materials include: cobalt iron boron alloy, cobalt iron alloy, and cobalt.

[0075] In some embodiments, before constructing the non-magnetic barrier layer on top of the induced layer, the realization of obtaining the composite free layer further includes:

[0076] Obtain a first target material for constructing the free layer;

[0077] Obtain a second target material for constructing the induced layer;

[0078] In some embodiments, the first target material is the target material for sputtering the free layer, including: cobalt iron boron alloy, cobalt iron alloy, and cobalt.

[0079] In some embodiments, the second target material is the target material for sputtering the induced layer, including: cobalt, iron, and hafnium.

[0080] Embodiments of the present invention provide a spin-orbit torque magnetic random access memory (SOT-MRAM) with a composite heavy metal layer structure and a preparation method thereof. The spin-orbit torque magnetic random access memory includes: a heavy metal layer and a composite magnetic tunnel junction disposed on the heavy metal layer. Among them, the composite magnetic tunnel junction includes: a composite free layer, a non-magnetic barrier layer, and a fixed layer. The composite free layer and the fixed layer are respectively disposed on both sides of the non-magnetic barrier layer. The composite free layer includes a free layer and an induction layer. The induction layer is disposed between the free layer and the tunneling resistance layer. In response to a first signal, the induction layer and the free layer are flipped, and the flipping actions of the two are consistent to realize the flipping of the composite free layer. The induction layer is used to reduce the demagnetization energy of the free layer to reduce the critical current. By providing an induction layer in the magnetic tunnel junction, the magnetic anisotropy energy in the magnetic tunnel junction is induced to reduce the demagnetizing magnetic field, thereby reducing the magnitude of the reverse current, and thus reducing the loss caused by resistivity during the operation of the device.

[0081] As described above, the above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A spin-orbit torque magnetic memory, characterized in that, The spin-orbit torque magnetic memory includes: A heavy metal layer and a composite magnetic tunnel junction disposed on the heavy metal layer, wherein the composite magnetic tunnel junction includes: a composite free layer, a non-magnetic barrier layer, and a fixed layer, and the composite free layer and the fixed layer are respectively disposed on both sides of the non-magnetic barrier layer, The composite free layer includes a free layer and an induction layer, the induction layer is disposed between the free layer and the non-magnetic barrier layer, in response to a first signal, the first signal is an electrical signal or a magnetic signal, the induction layer and the free layer are flipped, and the flipping actions of the two are consistent to realize the flipping of the composite free layer, and the induction layer is used to reduce the demagnetization energy of the free layer to reduce the critical current.

2. The spin-orbit torque magnetic memory according to claim 1, characterized in that, The induction layer is obtained from at least one of the following materials, including: cobalt, iron, and hafnium.

3. The spin-orbit torque magnetic memory according to claim 1, characterized in that, The thickness of the induction layer is 0.1 to 0.5 nanometers.

4. The spin-orbit torque magnetic memory according to claim 1, wherein The free layer and / or the fixed layer can be obtained from at least one of the following materials, including: cobalt iron boron alloy, iron cobalt alloy, and cobalt. The atomic ratio of the cobalt iron boron alloy includes at least one of the following: Co 20 Fe 60 B 20 , Co 40 Fe 40 B 20 and Co 60 Fe 20 B 20 ; The atomic ratio of the cobaltized iron alloy includes at least one of the following: Co 70 Fe 30 、Co 75 Fe 25 and Co 85 Fe 15 ; The non-magnetic barrier layer can be obtained from at least one of the following materials, including: magnesium oxide and aluminum oxide.

5. A method for preparing a spin-orbit torque magnetic memory, characterized in that, Applicable to a spin-orbit torque magnetic memory, the spin-orbit torque magnetic memory includes a composite magnetic tunnel junction, and the method includes: Constructing a composite magnetic tunnel junction on the heavy metal layer; Constructing a covering layer on the magnetic tunnel junction; wherein the composite magnetic tunnel junction includes: a composite free layer, a non-magnetic barrier layer, and a fixed layer, and the composite free layer and the fixed layer are respectively disposed on both sides of the non-magnetic barrier layer, The composite free layer includes a free layer and an induction layer, the induction layer is disposed between the free layer and the non-magnetic barrier layer, in response to a first signal, the first signal is an electrical signal or a magnetic signal, the induction layer and the free layer are flipped, and the flipping actions of the two are consistent to realize the flipping of the composite free layer, and the induction layer is used to reduce the demagnetization energy of the free layer to reduce the critical current.

6. The method according to claim 5, characterized in that, The constructing a composite magnetic tunnel junction on the heavy metal layer includes: Constructing a free layer on the heavy metal layer; Constructing an induction layer on the free layer to obtain a composite free layer; Constructing a non-magnetic barrier layer on the induction layer; Constructing a fixed layer on the non-magnetic barrier layer.

7. The method according to claim 6, characterized in that, The constructing a composite magnetic tunnel junction on the heavy metal layer includes: realizing the construction of the composite magnetic tunnel junction by sputtering.

8. The method according to claim 7, characterized in that, The realizing the construction of the composite magnetic tunnel junction by sputtering includes: using at least one of the following materials to realize the construction of the induction layer, and the materials include: cobalt, iron, and hafnium.

9. The method according to claim 6, wherein The constructed thickness of the induction layer is 0.1 to 0.5 nanometers.

10. The method according to claim 6, characterized in that, The constructing a free layer on the heavy metal layer and the constructing a fixed layer on the non-magnetic barrier layer are realized by: sputtering using at least one of the following materials, and the materials include: cobalt iron boron alloy, iron cobalt alloy, and cobalt.

Images