Magnetic storage unit and magnetic memory

Abstract

The present invention discloses a magnetic storage unit provided by the present invention, which comprises, from bottom to top, a magnetic reference layer, a tunnel layer, a magnetic free layer, and a cap layer; the magnetic free layer comprises a plurality of storage structure units; the storage structure unit comprises, from bottom to top, a first ferromagnetic layer, a non-magnetic metal spacer layer, a second ferromagnetic layer, and an oxide interface layer; the sidewalls of the magnetic free layer are covered with a high-conductivity layer, the upper edge of the high-conductivity layer is in conductive contact with the cap layer, and the lower edge of the high-conductivity layer is not lower than the oxide interface layer of the first storage structure unit; the lower edge of the high-conductivity layer does not contact the second ferromagnetic layer of the first storage structure unit. The present invention short-circuits the multi-layer storage structure units, reduces the ratio of the series resistance generated by the stacking to the total resistance of the magnetic tunnel junction, reduces the total resistance of the magnetic tunnel junction, and increases the data storage time. The present invention also provides a magnetic memory.

Description

Technical Field

[0001] The present invention relates to the field of storage technology, and in particular to a magnetic storage unit and a magnetic memory. Background Art

[0002] Magnetic random access memory (STT-MRAM) is a new type of memory with great potential. Unlike other existing memory types, MRAM offers impressive storage capacity and read / write speeds. However, in order to replace or partially replace existing mainstream memory, it faces a challenge not faced by traditional memory: the limited data retention time of magnetic memory. For data security reasons, the practical application of MRAM requires further extension of its storage time.

[0003] In order to improve data retention time, existing technologies can increase the storage bit size and increase the physical diameter of the magnetic storage to reduce the storage density and thus increase the storage time. Of course, this is not conducive to device miniaturization and is inconsistent with the current development trend of memory. On the other hand, some technologies use multi-layer interface stacking to increase bit thickness and increase data retention time, but multi-layer will bring new interface resistance problems, causing memory performance to decline.

[0004] Therefore, how to extend the data retention time without affecting the read and write performance of the memory and without increasing the size of the memory is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The object of the present invention is to provide a magnetic storage unit and a magnetic memory to solve the problem in the prior art that read and write performance, device volume and data retention time cannot be achieved simultaneously.

[0006] In order to solve the above technical problems, the present invention provides a magnetic storage unit, which includes, from bottom to top, a magnetic reference layer, a tunnel layer, a magnetic free layer and a cap layer;

[0007] The magnetic free layer includes a plurality of storage structure units;

[0008] The storage structure unit includes, from bottom to top, a first ferromagnetic layer, a non-magnetic metal spacer layer, a second ferromagnetic layer and an oxide interface layer;

[0009] The sidewall of the magnetic free layer is covered with a highly conductive layer, the upper edge of the highly conductive layer is in conductive contact with the cap layer, and the lower edge of the highly conductive layer is not lower than the oxide interface layer of the first storage structure unit; wherein the first storage structure unit is the storage structure unit closest to the tunnel layer;

[0010] A lower edge of the highly conductive layer is not in contact with the second ferromagnetic layer of the first storage structure unit.

[0011] Preferably, in the magnetic storage unit, the lower edge of the highly conductive layer is not higher than the oxide interface layer of the second storage structure unit; wherein the second storage structure unit is the storage structure unit that is second closest to the tunnel layer.

[0012] Preferably, in the magnetic storage unit, the number of the storage structure units ranges from 2 to 5, including endpoint values.

[0013] Preferably, in the magnetic storage unit, the thickness of the oxide interface layer ranges from 0.5 nanometers to 1 nanometer, inclusive.

[0014] Preferably, in the magnetic storage unit, the high conductive layer includes at least one of a metal copper layer, a metal tantalum layer, a metal ruthenium layer, a metal tungsten layer, a metal titanium layer, a metal aluminum layer, a metal molybdenum layer, a metal magnesium layer, a metal platinum layer, a metal gold layer or a metal nitride conductive layer.

[0015] Preferably, in the magnetic storage unit, the thickness of the non-magnetic metal spacer layer is in a range from 0.1 nanometers to 0.5 nanometers, both inclusive.

[0016] Preferably, in the magnetic storage unit, the preparation method of the magnetic storage unit includes:

[0017] The magnetic reference layer, the tunnel layer, the magnetic free layer and the cap layer are sequentially arranged on a preset substrate, and are etched according to a preset pattern to obtain a columnar matrix;

[0018] Disposing an insulating protective layer on the side wall of the columnar base;

[0019] Etching the insulating protection layer by a top through-hole etching technique to form a through-hole; wherein the stopping surface of the through-hole is not lower than the oxide interface layer of the first storage structure unit;

[0020] A highly conductive material is deposited into the through hole to form the highly conductive layer, thereby obtaining the magnetic storage unit.

[0021] Preferably, in the magnetic storage unit, the preparation method of the magnetic storage unit includes:

[0022] The magnetic reference layer, the tunnel layer, the magnetic free layer and the cap layer are sequentially arranged on a preset substrate, and are etched to a preset stop surface to obtain a primary etched body; wherein the stop surface is not lower than the oxide interface layer of the first storage structure unit;

[0023] Performing surface deposition on the primary etched body to obtain a highly conductive layer disposed on the primary etched body;

[0024] The primary etched body on which the high conductive layer is deposited is subjected to secondary etching to obtain the magnetic storage unit.

[0025] Preferably, in the magnetic storage unit, the resistivity of the oxide interface layer of the first storage structure unit is lower than the resistivity of other oxide interface layers in the magnetic free layer.

[0026] A magnetic memory comprises any one of the magnetic storage units described above.

[0027] The magnetic storage unit provided by the present invention includes, from bottom to top, a magnetic reference layer, a tunnel layer, a magnetic free layer and a cap layer; the magnetic free layer includes a plurality of storage structure units; the storage structure unit includes, from bottom to top, a first ferromagnetic layer, a non-magnetic metal spacer layer, a second ferromagnetic layer and an oxide interface layer; the sidewalls of the magnetic free layer are covered with a high conductive layer, the upper edge of the high conductive layer is in conductive contact with the cap layer, and the lower edge of the high conductive layer is not lower than the oxide interface layer of the first storage structure unit; wherein, the first storage structure unit is the storage structure unit closest to the tunnel layer; the lower edge of the high conductive layer is not in contact with the second ferromagnetic layer of the first storage structure unit.

[0028] The present invention proposes a structure that utilizes a repeated arrangement of multiple storage structural units to extend data storage time. The anisotropic energy of the multi-layer interface maintains perpendicular anisotropy in the magnetic free layer. The ferromagnetic coupling of multiple ferromagnetic layers increases the thickness of the magnetic free layer without significantly increasing the size of the storage bit. Furthermore, based on existing multi-layer interface stacked magnetic storage units, a highly conductive layer is provided at the periphery of the magnetic free layer, creating an electrical short circuit between the multi-layer storage structural units. This reduces the ratio of the series resistance generated by the stacking to the total resistance of the magnetic tunnel junction, thereby reducing the total resistance of the magnetic tunnel junction and maintaining a high tunnel magnetoresistance change rate of the magnetic tunnel junction, significantly improving data storage time. The present invention also provides a magnetic storage device with the aforementioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1A schematic structural diagram of a specific embodiment of a magnetic storage unit provided by the present invention;

[0031] Figure 2 A schematic flow chart of a specific embodiment of a method for preparing a magnetic storage unit provided by the present invention;

[0032] Figure 3 A schematic flow chart of another specific embodiment of the method for preparing a magnetic storage unit provided by the present invention;

[0033] Figures 4 and 5 A process flow chart of a method for preparing a magnetic storage unit provided by the present invention;

[0034] Figure 6 The present invention provides a flow chart of another specific embodiment of the method for preparing a magnetic storage unit. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0036] The core of the present invention is to provide a magnetic storage unit, a structural diagram of a specific embodiment of which is shown as follows: Figure 1 As shown, it is referred to as a specific embodiment 1, which includes, from bottom to top, a magnetic reference layer 100, a tunnel layer 200, a magnetic free layer 300 and a cap layer 400;

[0037] The magnetic free layer 300 includes a plurality of storage structure units 310;

[0038] The storage structure unit 310 includes, from bottom to top, a first ferromagnetic layer 314, a non-magnetic metal spacer layer 313, a second ferromagnetic layer 312 and an oxide interface layer 311;

[0039] The sidewalls of the magnetic free layer 300 are covered with a highly conductive layer 500. The upper edge of the highly conductive layer 500 is in conductive contact with the cap layer 400, and the lower edge of the highly conductive layer 500 is not lower than the oxide interface layer 311 of the first storage structure unit 310. The first storage structure unit 310 is the storage structure unit 310 closest to the tunnel layer 200.

[0040] The lower edge of the highly conductive layer 500 is not in contact with the second ferromagnetic layer 312 of the first storage structure unit 310 .

[0041] It should be noted that, in the present invention, "from bottom to top" refers to from the fixed base of the storage unit outward, and in actual production, in order to obtain a complete magnetic storage unit, epitaxial structures such as a transition layer, a pinning layer and a seed layer are usually set under the magnetic reference layer 100. The various epitaxial layers in the present invention are layers set by deposition.

[0042] In addition, the lower edge of the highly conductive layer 500 described in the present invention may be in contact with the oxide interface layer 311 of the first memory structure unit 310 , but may not be lower than the oxide interface layer 311 of the first memory structure unit 310 .

[0043] As a preferred embodiment, the lower edge of the highly conductive layer 500 is no higher than the oxide interface layer 311 of the second memory structure unit 310; wherein the second memory structure unit 310 is the memory structure unit 310 that is second closest to the tunnel layer 200. Of course, the lower the lower edge of the highly conductive layer 500 is, the more of the magnetic free layer 300 structure is covered by the highly conductive layer 500, and the lower the total resistance of the magnetic free layer 300 is, thereby improving memory performance.

[0044] Specifically, the number of the storage structure units 310 ranges from 2 to 5, including endpoint values, such as any one of 2.0, 3.0 or 5.0. Of course, corresponding selections can also be made according to actual conditions.

[0045] Furthermore, the thickness of the oxide interface layer 311 ranges from 0.5 nm to 1 nm, including any of endpoints, such as 0.50 nm, 0.79 nm, or 1.00 nm. The thickness of the oxide interface is sufficiently thin to form a strong ferromagnetic coupling between the upper and lower memory structure units 310. Furthermore, the oxide interface layer 311 is a magnesium oxide layer, but can be replaced with other oxide layers such as aluminum oxide, silicon oxide, titanium oxide, magnesium aluminate, tantalum oxide, zirconium oxide, hydrated iron oxide, etc., as needed.

[0046] Specifically, the highly conductive layer 500 is a metal copper layer or a tantalum nitride layer. Of course, the corresponding selection can also be made according to actual conditions.

[0047] The thickness of the non-magnetic metal spacer layer 313 ranges from 0.1 nanometers to 0.5 nanometers, including any of endpoints, such as 0.10 nanometers, 0.30 nanometers, or 0.50 nanometers. The non-magnetic metal spacer layer 313 is a thin metal layer that absorbs boron. Alternatively, the non-magnetic metal spacer layer 313 can be any of a molybdenum layer, a tantalum layer, a magnesium layer, a tungsten layer, an iridium layer, or a ruthenium layer.

[0048] A typical material of the non-magnetic metal spacer layer 313 is any one of Mo, Ta, W, Mg, Ir, and Ru.

[0049] As a preferred embodiment, the sidewalls of the magnetic storage unit are further provided with an insulating protection layer 700 , and the insulating protection layer 700 is a silicon oxide layer and / or a silicon nitride layer.

[0050] The magnetic storage unit provided by the present invention includes, from bottom to top, a magnetic reference layer 100, a tunnel layer 200, a magnetic free layer 300 and a cap layer 400; the magnetic free layer 300 includes a plurality of storage structure units 310; the storage structure unit 310 includes, from bottom to top, a first ferromagnetic layer 314, a non-magnetic metal spacer layer 313, a second ferromagnetic layer 312 and an oxide interface layer 311; the side wall of the magnetic free layer 300 is covered with a high conductive layer 500, the upper edge of the high conductive layer 500 is arranged in conductive contact with the cap layer 400, and the lower edge of the high conductive layer 500 is not lower than the oxide interface layer 311 of the first storage structure unit 310; wherein, the first storage structure unit 310 is the storage structure unit 310 closest to the tunnel layer 200; the lower edge of the high conductive layer 500 is not in contact with the second ferromagnetic layer 312 of the first storage structure unit 310. The present invention proposes a structure that utilizes a repeated arrangement of multiple storage structure units 310 to extend data storage time. The magnetic free layer 300 maintains perpendicular anisotropy through the anisotropy of the multi-layer interface. The ferromagnetic coupling stacking of multiple ferromagnetic layers increases the thickness of the magnetic free layer 300 without significantly increasing the size of the storage bit. In addition, based on the existing multi-layer interface stacked magnetic storage unit, the highly conductive layer 500 is provided at the outer contact of the magnetic free layer 300 to form an electrical short circuit connection between the multi-layer storage structure units 310, reducing the ratio of the series resistance generated by the stacking to the total resistance of the magnetic tunnel junction, reducing the total resistance of the magnetic tunnel junction, maintaining the high tunnel magnetoresistance change rate of the magnetic tunnel junction, and significantly improving data storage time.

[0051] The present invention also provides a method for preparing a magnetic storage unit, which is referred to as a second embodiment. The flow chart is shown in FIG. Figure 2 Shown, including:

[0052] S101: The magnetic reference layer 100, the tunnel layer 200, the magnetic free layer 300 and the cap layer 400 are sequentially arranged on a preset substrate, and are etched according to a preset pattern to obtain a columnar base.

[0053] S102: Disposing an insulating protection layer 700 on the sidewall of the columnar base.

[0054] The insulating protection layer 700 is a silicon oxide layer and / or a silicon nitride layer.

[0055] S103 : etching the insulating protection layer 700 by top-layer through-hole 600 etching technology to form a through-hole 600 ; wherein the stopping surface 710 of the through-hole 600 is not lower than the oxide interface layer 311 of the first storage structure unit 310 .

[0056] Depend on Figure 4 It can be seen that the through hole 600 is a through hole 600 formed in the insulating protection layer 700 .

[0057] S104 : depositing a highly conductive material into the through hole 600 to form the highly conductive layer 500 , thereby obtaining the magnetic storage unit.

[0058] The schematic diagram of the structure after etching through the top through hole 600 in this specific embodiment is as follows Figure 4 As shown, in this specific embodiment, the entire structure of the magnetic storage unit is completed by a single etching (ie, the columnar base), and then the insulating protection layer 700 and the high conductive layer 500 are added, which has a simple process and high production efficiency.

[0059] The present invention also provides another method for preparing a magnetic storage unit, which is referred to as the third embodiment. The flow chart is as follows: Figure 3 Shown, including:

[0060] S201: The magnetic reference layer 100 , the tunnel layer 200 , the magnetic free layer 300 and the cap layer 400 are sequentially arranged on a preset substrate, and etched to a preset stop surface 710 to obtain a primary etched body; wherein the stop surface 710 is not lower than the oxide interface layer 311 of the first storage structure unit 310 .

[0061] S202: performing surface deposition on the primary etched body to obtain a highly conductive layer 500 disposed on the primary etched body.

[0062] The schematic diagram of the structure after deposition is as follows Figure 5 As shown, the first etched body is divided by the stop surface 710, the upper part of the stop surface 710 is the etched columnar structure, and the lower part is the unetched flat surface. In this step, a high conductive layer 500 is deposited on the entire first etched body, and the high conductive layer 500 covers the top, upper surface of the columnar structure and the flat surface where the stop surface 710 is located.

[0063] S203: performing a second etching on the primary etched body on which the highly conductive layer 500 is deposited, to obtain the magnetic storage unit.

[0064] Since etching is generally performed vertically downward, the high conductive layer 500 located on the top of the columnar structure and the flat surface where the stop surface 710 is located will be etched during the secondary etching, while the high conductive layer 500 on the sidewall of the columnar structure will remain. The schematic diagram of the magnetic storage unit structure after etching is shown in FIG. Figure 6 As shown, in the secondary etching, due to the shielding of the high conductive layer 500 on the side wall of the columnar structure, the diameter of the etching layer below will be slightly larger than that above, but this has no effect on the use. Compared with other technologies, the magnetic storage unit prepared in this specific embodiment is smaller in size and more conducive to device miniaturization.

[0065] It should be noted that, in the magnetic storage unit in various specific embodiments described above, as a preferred embodiment, the resistivity of the oxide interface layer 311 of the first storage structure unit 310 is lower than the resistivity of other oxide interface layers in the magnetic free layer.

[0066] The method for providing the oxide interface layer 311 of the first storage structure unit 310 includes:

[0067] Providing a metal single substance layer;

[0068] The metal single-substance layer is doped with oxygen to obtain the oxide interface layer 311 of the first storage structure unit 310 .

[0069] or

[0070] providing a metal oxide layer;

[0071] The metal oxide layer is doped with a metal element to obtain the oxide interface layer 311 of the first storage structure unit 310 .

[0072] The oxide interface layer 311 obtained by the above two methods has a low oxygen content and high conductivity, which greatly improves the process window for providing the highly conductive layer 500, thereby improving process tolerance and ensuring low overall resistance of the magnetic free layer 300. Of course, other processes can also be used according to actual needs to ensure that the resistivity of the oxide interface layer 311 of the first storage structure unit 310 is lower than that of other oxide interface layers 311, which will not be described in detail here.

[0073] The present invention also provides a magnetic memory, comprising a magnetic memory cell as described above. The magnetic memory cell provided by the present invention comprises, from bottom to top, a magnetic reference layer 100, a tunnel layer 200, a magnetic free layer 300, and a cap layer 400; the magnetic free layer 300 comprises a plurality of storage structure units 310; the storage structure unit 310 comprises, from bottom to top, a first ferromagnetic layer 314, a non-magnetic metal spacer layer 313, a second ferromagnetic layer 312, and an oxide interface layer 311; the sidewalls of the magnetic free layer 300 are covered with a high conductive layer 500, the upper edge of the high conductive layer 500 is in conductive contact with the cap layer 400, and the lower edge of the high conductive layer 500 is not lower than the oxide interface layer 311 of the first storage structure unit 310; wherein the first storage structure unit 310 is the storage structure unit 310 closest to the tunnel layer 200; and the lower edge of the high conductive layer 500 is not in contact with the second ferromagnetic layer 312 of the first storage structure unit 310. The present invention proposes a structure that utilizes a repeated arrangement of multiple storage structure units 310 to extend data storage time. The anisotropy of the multi-layer interface enables the magnetic free layer to maintain perpendicular anisotropy. The ferromagnetic coupling stacking of multiple ferromagnetic layers increases the thickness of the magnetic free layer without significantly increasing the size of the storage bit. In addition, based on the existing multi-layer interface stacked magnetic storage unit, the highly conductive layer is provided at the periphery of the magnetic free layer to form an electrical short circuit connection between the multi-layer storage structure units, reducing the ratio of the series resistance generated by the stacking to the total resistance of the magnetic tunnel junction, reducing the total resistance of the magnetic tunnel junction, maintaining a high tunnel magnetoresistance change rate of the magnetic tunnel junction, and significantly improving data storage time.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0075] It should be noted that, in this specification, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements.

[0076] The magnetic storage unit and magnetic memory provided by the present invention are described in detail above. The principles and implementation methods of the present invention are described herein using specific examples. The description of the above embodiments is intended only to facilitate understanding of the method and core concept of the present invention. It should be noted that those skilled in the art may make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A magnetic storage unit, characterized in that From bottom to top, it includes a magnetic reference layer, a tunnel layer, a magnetic free layer and a cap layer; The magnetic free layer includes a plurality of storage structure units; The storage structure unit includes, from bottom to top, a first ferromagnetic layer, a non-magnetic metal spacer layer, a second ferromagnetic layer and an oxide interface layer; The sidewall of the magnetic free layer is covered with a highly conductive layer, the upper edge of the highly conductive layer is in conductive contact with the cap layer, and the lower edge of the highly conductive layer is not lower than the oxide interface layer of the first storage structure unit; wherein the first storage structure unit is the storage structure unit closest to the tunnel layer; A lower edge of the highly conductive layer is not in contact with the second ferromagnetic layer of the first storage structure unit.

2. The magnetic storage unit according to claim 1, wherein The lower edge of the highly conductive layer is no higher than the oxide interface layer of the second storage structure unit; wherein the second storage structure unit is the storage structure unit that is second closest to the tunnel layer.

3. The magnetic storage unit according to claim 1, wherein The number of the storage structure units ranges from 2 to 5, including endpoint values.

4. The magnetic storage unit according to claim 1, wherein The thickness of the oxide interface layer ranges from 0.5 nanometers to 1 nanometer, inclusive.

5. The magnetic storage unit according to claim 1, wherein The highly conductive layer includes at least one of a metal copper layer, a metal tantalum layer, a metal ruthenium layer, a metal tungsten layer, a metal titanium layer, a metal aluminum layer, a metal molybdenum layer, a metal magnesium layer, a metal platinum layer, a metal gold layer or a metal nitride conductive layer.

6. The magnetic storage unit according to claim 1, wherein The thickness of the non-magnetic metal spacer layer ranges from 0.1 nanometers to 0.5 nanometers, inclusive.

7. The magnetic storage unit according to claim 1, wherein The method for preparing the magnetic storage unit includes: The magnetic reference layer, the tunnel layer, the magnetic free layer and the cap layer are sequentially arranged on a preset substrate, and are etched according to a preset pattern to obtain a columnar matrix; Disposing an insulating protective layer on the side wall of the columnar base; Etching the insulating protection layer by a top through-hole etching technique to form a through-hole; wherein the stopping surface of the through-hole is not lower than the oxide interface layer of the first storage structure unit; A highly conductive material is deposited into the through hole to form the highly conductive layer, thereby obtaining the magnetic storage unit.

8. The magnetic storage unit according to claim 1, wherein The method for preparing the magnetic storage unit includes: The magnetic reference layer, the tunnel layer, the magnetic free layer and the cap layer are sequentially arranged on a preset substrate, and are etched to a preset stop surface to obtain a primary etched body; wherein the stop surface is not lower than the oxide interface layer of the first storage structure unit; Performing surface deposition on the primary etched body to obtain a highly conductive layer disposed on the primary etched body; The primary etched body on which the high conductive layer is deposited is subjected to secondary etching to obtain the magnetic storage unit.

9. The magnetic storage unit according to any one of claims 1 to 8, wherein: The resistivity of the oxide interface layer of the first storage structure unit is lower than the resistivity of other oxide interface layers in the magnetic free layer.

10. A magnetic memory, characterized in that: The magnetic memory comprises the magnetic storage unit according to any one of claims 1 to 9.

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