WO2022142673A1 - Magnetic memory cell and preparation method therefor, and magnetic memory - Google Patents

Abstract

A preparation method for a magnetic memory cell, a magnetic memory cell, and a magnetic memory. The method comprises: sequentially arranging, from the surface of a preset spin-orbit torque metal substrate to outside, a magnetic free layer, an insulating tunnel layer, a magnetic reference layer, and a mask layer to obtain a cell to be etched; etching the mask layer, the magnetic reference layer, and the insulating tunnel layer to obtain an etched workpiece comprising a columnar protrusion; disposing a protective layer on the surface of the etched workpiece; performing directional processing on the magnetic free layer of a columnar peripheral region to form a high-resistivity region to obtain a memory cell preset object; and removing a protective layer above a mask layer of the memory cell preset object to obtain the magnetic memory cell. According to the present invention, the magnetic free layer plays the role of the protective layer of the spin-orbit torque metal substrate, and it is ensured that the thickness uniformity of the spin-orbit torque metal substrate is not damaged.

Description

A kind of magnetic storage unit and its preparation method, magnetic memory

This application claims the priority of the Chinese patent application filed on December 28, 2020 with the application number 202011582841.X and the invention title "A magnetic memory cell and its preparation method, magnetic memory", all of which are The contents are incorporated herein by reference.

technical field

The invention relates to the technical field of storage, in particular to a magnetic storage unit, a preparation method thereof, and a magnetic memory.

Background technique

Compared with the traditional STT-MRAM (Spin Transfer Torque Magnetic Random Access Memory), SOT-MRAM (Spin Orbit Torque Magnetic Random Access Memory) not only maintains the excellent characteristics of MRAM such as high speed and low power consumption, but also realizes low writing. Voltage and read and write paths are separated. It is expected to replace STT-MRAM and utilize the spin-orbit moment to achieve fast and reliable magnetization inversion. However, in spin-orbit magnetic memory based on MTJ (magnetic tunnel junction), the free layer is in direct contact with the spin-orbit moment providing wire. However, it should be noted that since the amount of current passing through it will directly control the memory cells on it, the surface flatness of the ultra-thin spin-orbit moment material is extremely demanding, and the excessive thickness deviation at different positions will lead to different internal currents, which will lead to memory devices. reliability decreased.

In the prior art, in the process of etching and chemical mechanical polishing for device preparation, the spin-orbit moment of the metal matrix will inevitably be affected, and the non-uniformity of etching and polishing will further increase the spin-orbit moment. Inhomogeneity of the metal matrix.

Therefore, it is an urgent problem for those skilled in the art to find a method for avoiding the damage of the spin-orbit moment metal substrate during the etching and polishing process and improving the thickness uniformity of the spin-orbit moment metal substrate.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a magnetic storage unit, a preparation method thereof, and a magnetic memory, so as to solve the damage to the spin-orbit moment metal substrate caused by the etching and polishing process in the prior art, which in turn leads to the thickness of the spin-orbit moment metal substrate. The problem of poor uniformity.

In order to solve the above-mentioned technical problem, the present invention provides a kind of preparation method of magnetic storage unit, comprising:

On the surface of the predetermined spin-orbit moment metal substrate, a magnetic free layer, an insulating tunnel layer, a magnetic reference layer and a mask layer are sequentially arranged outwards to obtain a unit to be etched;

Etching the mask layer, the magnetic reference layer and the insulating tunnel layer to obtain an etching workpiece including columnar protrusions;

A protective layer is provided on the surface of the etched workpiece;

Orientation treatment is performed on the magnetic free layer in the columnar peripheral region to form a high resistivity region to obtain a memory cell prefab;

The protective layer above the mask layer of the storage unit prefab is removed to obtain a magnetic storage unit.

Optionally, in the method for preparing a magnetic storage unit, the orienting treatment of the magnetic free layer in the columnar peripheral area to form a high resistivity area, and obtaining the storage unit prefab includes:

Doping the magnetic free layer in the columnar peripheral region to form a high resistivity region to obtain a memory cell prefab.

Optionally, in the method for preparing a magnetic storage unit, the orienting treatment of the magnetic free layer in the columnar peripheral area to form a high resistivity area, and obtaining the storage unit prefab includes:

A high-resistivity region is formed by directional oxidation of the magnetic free layer in the columnar peripheral region to obtain a memory cell prefab.

Optionally, in the method for preparing a magnetic storage unit, before performing orientation treatment on the magnetic free layer in the columnar peripheral region to form a high resistivity region, the method further includes:

The protective layer on the surface of the magnetic free layer is removed, and the protective layer on the sidewalls of the columnar protrusions is retained.

Optionally, in the preparation method of the magnetic storage unit, before the protective layer is arranged on the surface of the etched workpiece, the method further includes:

Physically clean the sidewalls of the cylindrical protrusions.

Optionally, in the method for preparing a magnetic storage unit, the physical cleaning includes plasma cleaning or ion beam etching.

Optionally, in the method for preparing a magnetic memory unit, the protective layer is disposed on the surface of the etched workpiece by any one of sputter deposition, ion beam deposition, chemical vapor deposition, or atomic layer deposition.

A magnetic storage unit includes a spin-orbit moment metal substrate, a magnetic free layer, a columnar protrusion and a protective layer in sequence from bottom to top;

The column protrusions sequentially include an insulating tunnel layer, a magnetic reference layer and a mask layer from bottom to top;

The magnetic free layer includes a high resistivity region located in the columnar peripheral region and a low resistivity region located in the columnar region;

The protective layer is disposed on the side surface of the columnar protrusion and the upper surface of the magnetic free layer.

Optionally, in the magnetic storage unit, the protective layer is any one of a silicon nitride layer, a silicon oxide layer or a silicon oxynitride layer.

A magnetic memory, the magnetic memory comprising the magnetic storage unit according to any one of the above.

In the preparation method of the magnetic storage unit provided by the present invention, a magnetic free layer, an insulating tunnel layer, a magnetic reference layer and a mask layer are sequentially arranged outwardly on the surface of a predetermined spin-orbit moment metal substrate to obtain a unit to be etched. ; Etch the mask layer, the magnetic reference layer and the insulating tunnel layer to obtain an etched workpiece comprising columnar protrusions; set a protective layer on the surface of the etched workpiece; The free layer is subjected to orientation treatment to form a high resistivity region to obtain a memory cell prefab; the protective layer above the mask layer of the memory cell prefab is removed to obtain a magnetic memory cell.

Different from the prior art, the present invention does not directly engrave the magnetic free layer into the columnar protrusions during the etching process. In other words, the etching in the present invention is performed after etching the insulating tunnel layer. stop, the magnetic free layer still covers the surface of the spin-orbit moment metal substrate after etching, so that the magnetic free layer acts as a protective layer of the spin-orbit moment metal substrate, Neither the etching process nor the subsequent polishing process will directly act on the spin-orbit moment metal substrate, which ensures that the thickness uniformity of the spin-orbit moment metal substrate will not be damaged. The magnetic free layer corresponding to the columnar peripheral region is doped with oxygen to increase the resistance of the magnetic free layer in the columnar peripheral region, leaving only the magnetic free layer in the columnar region to conduct electricity, thereby completing the preparation of the magnetic tunnel junction. The present invention also provides a magnetic storage unit and a magnetic memory with the above beneficial effects.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following will briefly introduce the accompanying drawings used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only For some embodiments of the present invention, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic diagram of a connection structure of a magnetic storage unit with an external circuit during operation;

2 is a schematic flowchart of a specific embodiment of a method for preparing a magnetic memory cell provided by the present invention;

3 is a schematic flowchart of another specific embodiment of the method for preparing a magnetic memory cell provided by the present invention;

4 to 6 are intermediate process flow diagrams of a specific embodiment of a method for preparing a magnetic memory cell provided by the present invention;

7 is a schematic structural diagram of a specific implementation manner of a magnetic storage unit provided by the present invention;

FIG. 8 is a signal path diagram of a specific implementation manner of a magnetic storage unit provided by the present invention;

FIG. 9 is a signal path diagram of another specific implementation manner of the magnetic memory cell provided by the present invention.

Detailed ways

The connection between the magnetic storage unit and the external circuit is shown in Figure 1. The first port of the magnetic storage unit is connected to the drain of the write word line transistor, the second port is connected to the bit line, and the third port is connected to the read word line transistor. Drain connection. The source of the read word line transistor, and the source of the write word line transistor are connected to the source line.

In order to make those skilled in the art better understand the solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The core of the present invention is to provide a method for preparing a magnetic storage unit, and a schematic flowchart of a specific embodiment thereof is shown in FIG. 2 , which is called the specific embodiment 1, including:

S101 : On the surface of the predetermined spin-orbit moment metal substrate 10 , a magnetic free layer 20 , an insulating tunnel layer 30 , a magnetic reference layer 40 and a mask layer 50 are sequentially arranged outwards to obtain a unit to be etched.

S102 : Etch the mask layer 50 , the magnetic reference layer 40 and the insulating tunnel layer 30 to obtain an etching workpiece including stud bumps.

The schematic structural diagram of the etched workpiece after etching is shown in FIG. 4 . It should be noted that the purpose of retaining the magnetic free layer 20 in the present invention is to protect the spin-orbit moment metal substrate 10 below. Therefore, in this step Even if the etched surface is not perfectly left on the boundary between the insulating tunnel layer 30 and the magnetic free layer 20 , the magnetic free layer 20 with a certain thickness may be etched.

S103: Disposing a protective layer 60 on the surface of the etched workpiece.

The structure of the etching workpiece provided with the protective layer 60 is also schematically shown in FIG. 5 . As a preferred embodiment, before the protective layer 60 is provided on the surface of the etching workpiece, it further includes:

The sidewall of the columnar epitaxial layer is physically cleaned to repair the damage near the tunnel junction, and at the same time, it is also avoided that the edge irregularity of the columnar epitaxial layer or the residual chemical during the etching process affects the protective layer 60 set up. Further, the physical cleaning includes plasma cleaning or ion beam etching.

Still further, the protective layer 60 is disposed on the surface of the etched workpiece by any method in sputtering deposition, ion beam deposition, chemical vapor deposition or atomic layer deposition. Of course, other setting methods can also be selected according to actual conditions. .

S104: Perform orientation treatment on the magnetic free layer 20 in the columnar peripheral region to form a high resistivity region 21 to obtain a memory cell prefab.

The columnar peripheral region refers to an area that is not under the columnar protrusions, but is outside the projection area of the columnar protrusions on the magnetic free layer 20. For details, please refer to FIG. 6, which is not located in the The area under the stud bump is the stud peripheral region. Of course, the high resistance free layer doped with oxygen in actual production may partially extend below the stud bump, which has little effect on the beneficial effects of the present invention.

S105: Remove the protective layer 60 above the mask layer 50 of the memory cell prefab to obtain a magnetic memory cell.

In the preparation method of the magnetic storage unit provided by the present invention, the magnetic free layer 20 , the insulating tunnel layer 30 , the magnetic reference layer 40 and the mask layer 50 are sequentially arranged outwardly on the surface of the metal substrate 10 with a predetermined spin-orbit moment, Obtain the unit to be etched; etch the mask layer 50, the magnetic reference layer 40 and the insulating tunnel layer 30 to obtain an etched workpiece including columnar protrusions; set a protection on the surface of the etched workpiece layer 60; perform orientation treatment on the magnetic free layer 20 in the columnar peripheral region to form a high resistivity region 21 to obtain a memory cell prefab; remove the protective layer 60 above the mask layer 50 of the memory cell prefab to obtain a magnetic storage unit. Different from the prior art, the present invention does not directly etch the magnetic free layer 20 into the stud bumps during the etching process. In other words, the present invention etches the insulating tunnel layer after etching. After 30, it stops, the magnetic free layer 20 still covers the surface of the spin-orbit torque metal substrate 10 after etching, so that the magnetic free layer 20 plays the role of the spin-orbit torque metal substrate 10 The function of the protective layer 60, the etching process and the subsequent polishing process will not directly act on the spin-orbit moment metal substrate 10, which also ensures that the thickness uniformity of the spin-orbit moment metal substrate 10 will not be affected. In addition, the present application increases the resistance of the magnetic free layer 20 in the columnar peripheral region by doping the magnetic free layer 20 corresponding to the columnar peripheral region with oxygen, leaving only the magnetic free layer 20 in the columnar region to conduct electricity. The fabrication of magnetic tunnel junctions.

On the basis of the first embodiment, the protective layer 60 is further processed before oxygen doping is performed on the magnetic free layer 20 in the columnar peripheral region, and the second embodiment is obtained. The schematic diagram of the structure is shown in FIG. 3, including :

S201 : On the surface of the predetermined spin-orbit moment metal substrate 10 , a magnetic free layer 20 , an insulating tunnel layer 30 , a magnetic reference layer 40 and a mask layer 50 are sequentially arranged outwards to obtain a unit to be etched.

S202 : Etch the mask layer 50 , the magnetic reference layer 40 and the insulating tunnel layer 30 to obtain an etching workpiece including stud bumps.

S203: Disposing a protective layer 60 on the surface of the etched workpiece.

S204: Remove the protective layer 60 on the surface of the magnetic free layer 20, and retain the protective layer 60 on the sidewalls of the columnar protrusions.

S205: Perform orientation treatment on the magnetic free layer 20 in the columnar peripheral region to form a high resistivity region 21 to obtain a memory cell prefab.

S206 : removing the protective layer 60 above the mask layer 50 of the memory cell prefab to obtain a magnetic memory cell.

In this specific embodiment, before oxygen doping is performed on the etching workpiece provided with the protective layer 60, the protective layer 60 in the columnar peripheral region is removed first, so that the magnetic free layer 20 in the columnar peripheral region is removed. The upper surface of the metal oxide is directly exposed, so that the subsequent oxygen doping is more rapid, sufficient and uniform. While improving the production efficiency, the quality of the oxidized high-resistivity free region of the final product is improved. The magnetic storage device corresponding to this specific embodiment For a schematic diagram of the structure of the unit, please refer to FIG. 7 .

The present invention also provides a magnetic storage unit, and a schematic structural diagram of a specific embodiment is shown in FIG. 7 , which is called the third embodiment. From bottom to top, it includes a spin-orbit moment metal matrix 10 , a magnetic free layer 20, stud bumps and protective layer 60;

The stud bumps sequentially include an insulating tunnel layer 30, a magnetic reference layer 40 and a mask layer 50 from bottom to top;

The magnetic free layer 20 includes a high resistivity region 21 located in the columnar peripheral region and a low resistivity region 22 located in the columnar region;

The protective layer 60 is disposed on the side surfaces of the columnar protrusions and the upper surface of the magnetic free layer 20 .

As a preferred embodiment, the protective layer 60 is any one of a silicon nitride layer, a silicon oxide layer or a silicon oxynitride layer.

In addition, the spin-orbit moment metal substrate 10 is a metal substrate of platinum, tungsten, gold, molybdenum or tantalum.

Further, the thickness of the spin-orbit moment metal matrix 10 ranges from 1 nanometer to 10 nanometers, including the endpoint value, such as any one of 1.0 nanometers, 5.0 nanometers or 10.0 nanometers; the thickness of the magnetic free layer 20 is in the range of 1 nanometer to 5 nanometers, inclusive, such as any of 1.0 nanometers, 3.2 nanometers, or 5.0 nanometers.

The magnetic storage unit provided by the present invention is suitable for two-port devices and three-port devices, and the signal transmission diagrams thereof are shown in FIG. 8 and FIG. 9 .

Figure 8 shows a two-port device, the device includes two ports, a first port connected to one side of the spin-orbit metal and a second port connected to the top of the MTJ. When writing data, the current passes through the spin-orbit metal material and the MTJ, and writes 0/1 respectively by changing the direction of the current, that is, the write current flows from the first port to the second port, or the write current flows from the second port to the first port. port. When data is read, the read current passes through the MTJ, and the data is read through the resistance value between ports 1 and 2.

Figure 9 shows a three-port device, the device includes three ports, the first and second ports on both sides of the spin-orbit metal MTJ pillars and the third port on the top of the MTJ. When writing data, the current passes through the spin-orbit metal material, and the current direction is changed to realize writing 0/1, that is, the writing current flows from the first port to the second port, or the writing current flows from the second port to the first port. When data is read, the read current passes through the MTJ, and the data is read through the resistance value between ports 1 and 3, or between ports 2 and 3.

The magnetic storage unit provided by the present invention includes, from bottom to top, a spin-orbit moment metal substrate 10, a magnetic free layer 20, stud bumps and a protective layer 60; the stud bumps sequentially include an insulating tunnel layer 30, The magnetic reference layer 40 and the mask layer 50; the magnetic free layer 20 includes a high resistivity region 21 located in the peripheral region of the columnar region and a low resistivity region 22 located in the columnar region; the protective layer 60 is disposed on the columnar protrusion the side surface and the upper surface of the magnetic free layer 20 . Different from the prior art, the present invention does not directly etch the magnetic free layer 20 into the stud bumps during the etching process. In other words, the etching in the present invention etches the insulating tunnel layer After 30, it stops, the magnetic free layer 20 still covers the surface of the spin-orbit torque metal substrate 10 after etching, so that the magnetic free layer 20 plays the role of the spin-orbit torque metal substrate 10 The function of the protective layer 60, the etching process and the subsequent polishing process will not directly act on the spin-orbit moment metal substrate 10, which also ensures that the thickness uniformity of the spin-orbit moment metal substrate 10 will not be affected. In addition, the present application increases the resistance of the magnetic free layer 20 in the columnar peripheral region by doping the magnetic free layer 20 corresponding to the columnar peripheral region with oxygen, leaving only the magnetic free layer 20 in the columnar region to conduct electricity. The fabrication of magnetic tunnel junctions.

The present invention also provides a magnetic memory having the above beneficial effects, the magnetic memory comprising the magnetic storage unit described in any one of the above. In the preparation method of the magnetic storage unit provided by the present invention, the magnetic free layer 20 , the insulating tunnel layer 30 , the magnetic reference layer 40 and the mask layer 50 are sequentially arranged outwardly on the surface of the metal substrate 10 with a predetermined spin-orbit moment, Obtain the unit to be etched; etch the mask layer 50, the magnetic reference layer 40 and the insulating tunnel layer 30 to obtain an etched workpiece including columnar protrusions; set a protection on the surface of the etched workpiece layer 60; perform orientation treatment on the magnetic free layer 20 in the columnar peripheral region to form a high resistivity region 21 to obtain a memory cell prefab; remove the protective layer 60 above the mask layer 50 of the memory cell prefab to obtain a magnetic storage unit. Different from the prior art, the present invention does not directly etch the magnetic free layer 20 into the stud bumps during the etching process. In other words, the etching in the present invention etches the insulating tunnel layer After 30, it stops, the magnetic free layer 20 still covers the surface of the spin-orbit torque metal substrate 10 after etching, so that the magnetic free layer 20 plays the role of the spin-orbit torque metal substrate 10 The function of the protective layer 60, the etching process and the subsequent polishing process will not directly act on the spin-orbit moment metal substrate 10, which also ensures that the thickness uniformity of the spin-orbit moment metal substrate 10 will not be affected. In addition, the present application increases the resistance of the magnetic free layer 20 in the columnar peripheral region by doping the magnetic free layer 20 corresponding to the columnar peripheral region with oxygen, leaving only the magnetic free layer 20 in the columnar region to conduct electricity. The fabrication of magnetic tunnel junctions.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments may be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description of the method.

It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply these entities or operations There is no such actual relationship or order between them. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass non-exclusive inclusion such that a process, method, article or device comprising a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

The magnetic storage unit, the preparation method thereof, and the magnetic memory provided by the present invention are described in detail above. The principles and implementations of the present invention are described herein by using specific examples, and the descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (10)

1. A method for preparing a magnetic storage unit, comprising:

   On the surface of the predetermined spin-orbit moment metal substrate, a magnetic free layer, an insulating tunnel layer, a magnetic reference layer and a mask layer are sequentially arranged outwards to obtain a unit to be etched;

   Etching the mask layer, the magnetic reference layer and the insulating tunnel layer to obtain an etching workpiece including columnar protrusions;

   A protective layer is provided on the surface of the etched workpiece;

   Orientation treatment is performed on the magnetic free layer in the columnar peripheral region to form a high resistivity region to obtain a memory cell prefab;

   The protective layer above the mask layer of the storage unit prefab is removed to obtain a magnetic storage unit.
2. The method for preparing a magnetic memory cell according to claim 1, wherein the orienting treatment of the magnetic free layer in the columnar peripheral region to form a high resistivity region, and obtaining the memory cell preset comprises:

   Doping the magnetic free layer in the columnar peripheral region to form a high resistivity region to obtain a memory cell prefab.
3. The method for preparing a magnetic memory cell according to claim 1, wherein the orienting treatment of the magnetic free layer in the columnar peripheral region to form a high resistivity region, and obtaining the memory cell prefab comprises:

   A high-resistivity region is formed by directional oxidation of the magnetic free layer in the columnar peripheral region to obtain a memory cell prefab.
4. The method for preparing a magnetic memory cell according to claim 1, characterized in that before performing orientation treatment on the magnetic free layer in the columnar peripheral region to form the high resistivity region, the method further comprises:

   The protective layer on the surface of the magnetic free layer is removed, and the protective layer on the sidewalls of the columnar protrusions is retained.
5. The method for preparing a magnetic storage unit according to claim 1, wherein before the protective layer is arranged on the surface of the etched workpiece, the method further comprises:

   Physically clean the sidewalls of the cylindrical protrusions.
6. The method for manufacturing a magnetic memory cell according to claim 5, wherein the physical cleaning comprises plasma cleaning or ion beam etching.
7. The method for manufacturing a magnetic memory cell according to claim 1, wherein the protective layer is disposed on the etching workpiece by any one of sputter deposition, ion beam deposition, chemical vapor deposition, or atomic layer deposition. surface.
8. A magnetic storage unit is characterized in that, from bottom to top, it comprises a spin-orbit moment metal matrix, a magnetic free layer, a columnar protrusion and a protective layer;

   The column protrusions sequentially include an insulating tunnel layer, a magnetic reference layer and a mask layer from bottom to top;

   The magnetic free layer includes a high resistivity region located in the columnar peripheral region and a low resistivity region located in the columnar region;

   The protective layer is disposed on the side surface of the columnar protrusion and the upper surface of the magnetic free layer.
9. The magnetic memory cell of claim 8, wherein the protective layer is any one of a silicon nitride layer, a silicon oxide layer or a silicon oxynitride layer.
10. A magnetic memory, characterized in that the magnetic memory comprises the magnetic storage unit according to any one of claims 8 to 9.

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