Magnetic random access memory cell and method of making the same

Abstract

The application provides a magnetic random storage unit, comprising: a first spin-orbit moment providing layer, having two or more regions, the two or more regions at least having a first region and a second region; wherein the first region has a first doping characteristic, and the second region has a second doping characteristic; and a magnetic tunnel junction, disposed on the spin-orbit moment providing layer, covering at least a part of each region. The magnetic random storage unit and the preparation method thereof can generate different spin Hall angles through different interface effects of the first region and the second region, break the symmetry, and realize the flip of a free layer of the magnetic tunnel junction under the condition of no external magnetic field.

Description

Technical Field

[0001] This invention relates to the field of magnetic memory technology, and in particular to a magnetic random access memory cell and its fabrication method. Background Technology

[0002] Spin-orbit moment magnetic RAM (SOT-MRAM) offers advantages such as non-volatility, fast erase / write speeds, and low power consumption. An SOT-MRAM device cell consists of a magnetic tunnel junction (MTJ) and a spin-orbit moment providing layer (or spin Hall effect layer, SHE layer). The MTJ includes a free layer, a barrier layer, and a reference layer. The magnetization direction of the reference layer is fixed, while the magnetization direction of the free layer is variable. When the free layer and the reference layer are parallel, it is in a low-resistance state; when they are antiparallel, it is in a high-resistance state. The spin-orbit moment providing layer is typically made of heavy metal (HM). When current flows through the heavy metal, the symmetry is broken with the assistance of an external magnetic field, achieving a deterministic flip of the free layer's magnetic moment. However, the assistance of the external magnetic field increases the complexity of the operation. In existing technologies, to reduce operational complexity, a magnetic bias layer is used to achieve the flipping of the free layer. However, using a magnetic bias layer is not conducive to improving integration density. Summary of the Invention

[0003] The magnetic random access memory cell and its fabrication method provided by this invention can generate different spin Hall angles through different interface effects in the first and second regions, breaking the symmetry and realizing the flipping of the free layer of the magnetic tunnel junction under the condition of no external magnetic field.

[0004] In a first aspect, the present invention provides a magnetic random access memory (MRM) unit, comprising:

[0005] A first spin orbital moment providing layer includes two or more regions, wherein the two or more regions have at least a first region and a second region; wherein the first region has a first doping characteristic and the second region has a second doping characteristic;

[0006] A magnetic tunnel junction is disposed on the spin-orbit moment providing layer, the magnetic tunnel junction covering at least a portion of each region.

[0007] Optionally, the material of the spin orbital moment providing layer includes W, Ta, Pt, Pd, Au, Cu, Ru, Hf, Mo, Ti, Ir, Mn, and Bi. x Se (1-x) Sb x Te (1-x) and Bi x Te (1-x) Any one or more combinations thereof.

[0008] Optionally, the doping concentration in the first region is lower than that in the second region.

[0009] Optionally, the doping concentration in the first region is 0.

[0010] Optionally, the first region is doped with a first doping element, and the second region is doped with a second doping element.

[0011] Optionally, the first region and / or the second region may be doped with any one or a combination of two or more of N, O, P and S.

[0012] Optionally, it also includes:

[0013] The second spin orbit moment providing layer is disposed below the first spin orbit moment providing layer and is in contact with the first spin orbit moment providing layer.

[0014] Secondly, the present invention also provides a method for preparing a magnetic random access memory cell, comprising:

[0015] The layer is formed to provide spin orbital moments;

[0016] A mask is formed at a position corresponding to the first region of the spin orbit moment providing layer;

[0017] The second region of the spin orbital moment providing layer is doped;

[0018] Remove the mask and planarize the spin orbit moment providing layer;

[0019] A magnetic tunnel junction is formed on the spin orbital moment providing layer, and the magnetic tunnel junction is patterned, with the patterned magnetic tunnel junction covering part of the first region and part of the second region.

[0020] Optionally, doping the second region of the spin-orbit moment providing layer includes doping the second region of the spin-orbit moment providing layer by means of oxidation or ion implantation.

[0021] Optionally, when doping the second region of the spin orbital moment providing layer using ion implantation, before forming a mask at the corresponding location of the first region of the spin orbital moment providing layer, the method further includes:

[0022] A protective layer is formed on the spin orbital moment providing layer to protect the surface of the spin orbital moment providing layer during the doping process.

[0023] Optionally, doping the second region of the spin-orbit moment providing layer includes:

[0024] The thickness of the second region being doped is less than the thickness of the spin-orbit moment providing layer.

[0025] In the technical solution provided by this invention, a first region and a second region are formed on a first spin orbital moment providing layer, and the first and second regions are configured to have different doping characteristics. This results in different interface effects when the first and second regions come into contact with the magnetic tunnel junction. Due to these different interface effects, the spin Hall angles of the first and second regions are different, breaking the symmetry and thus enabling the flipping of the free layer of the magnetic tunnel junction under conditions without an external magnetic field. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a magnetic random access memory unit according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the connection between the magnetic random access memory unit and the peripheral circuit according to another embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the mask formation process in a magnetic random access memory (MRM) cell fabrication method according to an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of the formation of an oxide layer in a method for preparing a magnetic random access memory cell according to an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of mask removal in a magnetic random access memory cell fabrication method according to an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the formation of a magnetic tunnel junction in a method for preparing a magnetic random access memory cell according to an embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram of a magnetic tunnel junction in a method for preparing a magnetic random access memory cell according to an embodiment of the present invention.

[0033] Figure 8 This is a schematic diagram illustrating the logical division between the first spin orbital moment providing layer and the second spin orbital moment providing layer in a method for preparing a magnetic random access memory cell according to an embodiment of the present invention;

[0034] Figure 9 This is a schematic diagram of the mask formation process in a magnetic random access memory (MRM) cell fabrication method according to an embodiment of the present invention.

[0035] Figure 10 This is a schematic diagram of the formation of an oxide layer in a method for preparing a magnetic random access memory cell according to an embodiment of the present invention;

[0036] Figure 11 This is a schematic diagram of mask removal in a magnetic random access memory cell fabrication method according to an embodiment of the present invention;

[0037] Figure 12This is a schematic diagram of the formation of a magnetic tunnel junction in a method for preparing a magnetic random access memory cell according to an embodiment of the present invention;

[0038] Figure 13 This is a schematic diagram of a magnetic tunnel junction in a method for preparing a magnetic random access memory cell according to an embodiment of the present invention.

[0039] Figure 14 This is a schematic diagram illustrating the logical division between the first spin orbital moment providing layer and the second spin orbital moment providing layer in a magnetic random access memory cell fabrication method according to an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] This invention provides a magnetic random access memory (MRM) unit, such as... Figure 1 As shown, it includes:

[0042] A first spin-orbit moment providing layer includes two or more regions, wherein the two or more regions have at least a first region and a second region; wherein the first region has a first doping characteristic, and the second region has a second doping characteristic; in some embodiments, the first doping characteristic and the second doping characteristic may refer to two doping concentration characteristics formed using different doping concentrations, or to two doping element characteristics formed using different doping elements. In the two doping concentration characteristics with different concentrations, one of the doping concentrations may be 0.

[0043] A magnetic tunnel junction is disposed on the spin-orbit moment providing layer, the magnetic tunnel junction covering at least a portion of each region. In some embodiments, when the first spin-orbit moment providing layer comprises two regions, the magnetic tunnel junction can be bisected by the boundary between the first and second regions, or it can be disposed offset to one side of the boundary. The magnetic tunnel junction includes a free layer, a barrier layer, and a reference layer. In other embodiments, when the first spin-orbit moment providing layer comprises more than two regions, for example, when there are three regions, the magnetic tunnel junction can be bisected by the axis of the middle region and cover portions of the two side regions. It can also be disposed offset to one side of the axis of the middle region and cover portions of the two side regions. Of course, the first spin-orbit moment providing layer can also have more regions. The magnetization directions of the free layer and the reference layer can be in-plane magnetization or perpendicular magnetization. The shape of the magnetic tunnel junction can be circular, elliptical, rectangular, rhomboid, or triangular. In a magnetic tunnel junction, the materials of the free layer and the reference layer can be any one or more alloys of Co, Fe, Ni, and B, as well as one or more combinations of the above elements or alloys with Co, Fe, Ni, Pt, Pd, Mo, W, Ir, Ta, Ru, Nb, and Hf to form a multilayer film. The materials of the barrier layer can be any one or more combinations of MgO, MgAl2O4, Al2O3, Gd2O3, and HfO2.

[0044] In the technical solution provided by the embodiments of the present invention, by setting a first region and a second region on the first spin orbital moment providing layer, and setting the first region and the second region to have different doping characteristics, different interface effects are generated when the first region and the second region come into contact with the magnetic tunnel junction. Due to the different interface effects, the spin Hall angles of the first region and the second region are different, breaking the symmetry, thereby realizing the flipping of the free layer of the magnetic tunnel junction under the condition of no external magnetic field. When using the technical solution provided by the embodiments of the present invention to fabricate a memory, the magnetic random access memory unit provided by the embodiments of the present invention can be connected to the peripheral circuit according to... Figure 2 Make electrical connections as shown.

[0045] As an optional implementation, the material of the spin orbital moment providing layer includes any one or a combination of two or more of W, Ta, Pt, Pd, Au, Cu, Ru, Hf, Mo, Ti, Ir, Mn, BixSe(1-x), SbxTe(1-x), and BixTe(1-x).

[0046] As an optional implementation, the doping concentration of the first region is lower than that of the second region. In some embodiments, the first region and the second region are set with different doping concentrations to produce different interface effects; for example, the first region is set as a lightly doped region and the second region is set as a heavily doped region.

[0047] As an optional implementation, the doping concentration of the first region is 0. In some embodiments, when the second region is doped, the first region can still produce different interface effects than the second region even without doping. Therefore, to simplify the fabrication process, the first doping concentration can be set to 0.

[0048] As an optional implementation, the first region is doped with a first dopant element, and the second region is doped with a second dopant element. In some embodiments, different doping elements can produce different interface effects; therefore, in this embodiment, different elements can be used to dope the first region and the second region.

[0049] As an optional implementation, the first region and / or the second region may be doped with any one or a combination of two or more of N, O, P and S.

[0050] As an optional implementation, it further includes: a second spin-orbit moment providing layer, disposed below and in contact with the first spin-orbit moment providing layer. In some embodiments, since the doping process is usually performed on the already prepared spin-orbit moment providing layer by means of oxidation or ion implantation, when the processed thickness during oxidation or ion implantation is smaller than the already formed spin-orbit moment providing layer, the processed thickness portion can be used as the first spin-orbit moment providing layer, and the unprocessed thickness portion can be used as the second spin-orbit moment providing layer. Those skilled in the art should understand that during oxidation or ion implantation, the entire thickness of the already formed spin-orbit moment providing layer can be processed. In this case, the magnetic random access memory cell does not have a second spin-orbit moment providing layer, but only a first spin-orbit moment providing layer.

[0051] This invention also provides a method for preparing a magnetic random access memory (MRM) cell, such as... Figure 3-7 As shown, it includes:

[0052] A spin-orbit moment providing layer is formed; in some embodiments, the spin-orbit moment providing layer may be formed using a heavy metal, for example, tungsten or tantalum.

[0053] A mask is formed at a location corresponding to the first region of the spin orbital moment providing layer. In some embodiments, forming a mask at a location corresponding to the first region allows the first region to be protected during the doping process in the second region, preventing the doping process in the second region from affecting the first region. The structure after this step is as follows: Figure 3 As shown.

[0054] The second region of the spin orbital moment providing layer is doped; in some embodiments, the doping process of the second region may be, for example, an oxidation process or an ion implantation process. Figure 4 The example illustrates the structure processed by the sampling oxidation process.

[0055] The mask is removed, and the spin-orbit moment providing layer is planarized. In some embodiments, the mask can be photoresist or a hard mask formed of a dielectric material. For hard masks, etching or grinding can be used for removal. The process of removing photoresist includes resist stripping and cleaning. Planarization provides a good plane for subsequent magnetic tunnel junction formation. The structure after this step is as follows... Figure 5 As shown.

[0056] A magnetic tunnel junction is formed on the spin-orbit moment providing layer. The magnetic tunnel junction is patterned, and the patterned magnetic tunnel junction covers a portion of the first region and a portion of the second region. In some embodiments, after patterning, the magnetic tunnel junction covers a portion of the first region and a portion of the second region, thereby enabling different interface effects between the magnetic tunnel junction and the first and second regions. In some embodiments, the first region in this embodiment is doped, or it may not be doped. When the first region is doped, the doping of the first region can be performed before or after the doping of the second region. The processing of the first doped region can be as follows: a mask is formed at the corresponding position of the second region of the spin-orbit moment providing layer; the first region of the spin-orbit moment providing layer is doped; the mask is removed, and the spin-orbit moment providing layer is planarized. Those skilled in the art should understand that regardless of whether the first region is doped, the first region and the second region can be used as the first spin-orbit moment providing layer, and the portion below the first and second regions can be used as the second spin-orbit moment providing layer, with the structure as follows. Figure 8 As shown. Figure 8The dashed lines in the diagram represent the logical division between the first region and the second spin-orbit moment providing layer. When the first region is doped, there are property differences between the first region and the second spin-orbit moment providing layer. When the first region is not doped, the first region and the second spin-orbit moment providing layer are an integral structure with no property differences.

[0057] In the technical solution provided by the embodiments of the present invention, a first region and a second region are formed on the first spin orbital moment providing layer, and the first region and the second region are configured to have different doping characteristics, thereby causing different interface effects when the first region and the second region come into contact with the magnetic tunnel junction. Due to the different interface effects, the spin Hall angles of the first region and the second region are different, breaking the symmetry, thereby realizing the flipping of the free layer of the magnetic tunnel junction under the condition of no external magnetic field.

[0058] As an optional implementation, doping the second region of the spin-orbit moment providing layer includes doping the second region of the spin-orbit moment providing layer by means of oxidation or ion implantation.

[0059] As an optional implementation, when doping the second region of the spin orbital moment providing layer using ion implantation, before forming a mask at the corresponding location of the first region of the spin orbital moment providing layer, such as... Figure 9-13 As shown, the method further includes forming a protective layer on the spin-orbit moment providing layer to protect the surface of the spin-orbit moment providing layer during the doping process. In some embodiments, when the spin-orbit moment providing layer is doped by ion implantation, the ion implantation process may damage the surface of the spin-orbit moment providing layer. To mitigate surface damage to the spin-orbit moment providing layer, this embodiment uses a protective layer to protect the surface of the spin-orbit moment providing layer. The material of the protective layer can be one or a combination of two or more of magnesium oxide or aluminum oxide. In some embodiments, the first region in this embodiment may be doped or not. When the first region is doped, the doping treatment of the first region can be performed before or after the doping treatment of the second region. The processing of the first doped region can be as follows: forming a mask on the protective layer at a position corresponding to the second region of the spin-orbit moment providing layer; doping the first region of the spin-orbit moment providing layer; removing the mask and the protective layer; and planarizing the spin-orbit moment providing layer. Those skilled in the art should understand that, regardless of whether the first region is doped, the first and second regions can be used as a first spin-orbit moment providing layer, and the portion below the first and second regions can be used as a second spin-orbit moment providing layer, with the structure as follows: Figure 14 As shown. Figure 8The dashed lines in the diagram represent the logical division between the first region and the second spin-orbit moment providing layer. When the first region is doped, there are property differences between the first region and the second spin-orbit moment providing layer. When the first region is not doped, the first region and the second spin-orbit moment providing layer are an integral structure with no property differences.

[0060] As an optional implementation, doping the second region of the spin-orbit moment providing layer includes: doping the second region to a thickness smaller than the thickness of the spin-orbit moment providing layer. For example... Figure 8 and Figure 13 As shown, when the doping depth of the first region and the second region is less than the spin orbital moment providing layer, the thickness portion outside the first region and the second region forms the second spin orbital moment providing layer, while the first region and the second region form the first spin orbital moment providing layer.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A magnetic random access memory (MRM) cell, characterized in that, include: A first spin orbital moment providing layer includes two or more regions, wherein the two or more regions have at least a first region and a second region; wherein the first region has a first doping characteristic and the second region has a second doping characteristic; A magnetic tunnel junction is disposed on the spin-orbit moment providing layer, the magnetic tunnel junction covering at least a portion of each region; The first region and / or the second region are doped with any one or more of N, O, P and S.

2. The magnetic random access memory unit according to claim 1, characterized in that, The materials for the spin orbital moment providing layer include W, Ta, Pt, Pd, Au, Cu, Ru, Hf, Mo, Ti, Ir, Mn, and Bi. x Se (1-x) Sb x Te (1-x) and Bi x Te (1-x) Any one or more combinations thereof.

3. The magnetic random access memory unit according to claim 1, characterized in that, The doping concentration in the first region is lower than that in the second region.

4. The magnetic random access memory unit according to claim 3, characterized in that, The doping concentration in the first region is 0.

5. The magnetic random access memory unit according to claim 1, characterized in that, The first region is doped with a first doping element, and the second region is doped with a second doping element.

6. The magnetic random access memory unit according to claim 1, characterized in that, Also includes: The second spin orbit moment providing layer is disposed below the first spin orbit moment providing layer and is in contact with the first spin orbit moment providing layer.

7. A method for fabricating a magnetic random access memory (MRM) cell, characterized in that, include: The layer is formed to provide spin orbital moments; A mask is formed at a position corresponding to the first region of the spin orbit moment providing layer; The second region of the spin orbital moment providing layer is doped; Remove the mask and planarize the spin orbit moment providing layer; A magnetic tunnel junction is formed on the spin orbit moment providing layer, and the magnetic tunnel junction is patterned. The patterned magnetic tunnel junction covers part of the first region and part of the second region. The second region is doped with any one or a combination of two or more of N, O, P and S.

8. The method for preparing a magnetic random access memory cell according to claim 7, characterized in that, Doping the second region of the spin-orbit moment providing layer includes doping the second region of the spin-orbit moment providing layer by means of oxidation or ion implantation.

9. The method for preparing a magnetic random access memory cell according to claim 8, characterized in that, When doping the second region of the spin orbital moment providing layer using ion implantation, before forming a mask at the corresponding position of the first region of the spin orbital moment providing layer, the process further includes: A protective layer is formed on the spin orbital moment providing layer to protect the surface of the spin orbital moment providing layer during the doping process.

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