WO2022142712A1 - Magnetic storage unit and magnetic memory - Google Patents

Abstract

Provided are a magnetic storage unit and a magnetic memory. The magnetic storage unit successively comprises, from bottom to top: a magnetic reference layer, a tunnel layer, a magnetic free layer and a cap layer, wherein the magnetic free layer comprises a plurality of storage structure units; each of the storage structure units successively comprises, from bottom to top, a first ferromagnetic layer, a non-magnetic metal spacing layer, a second ferromagnetic layer and an oxide interface layer; a side wall of the magnetic free layer is covered with a highly conductive layer, an upper edge of the highly conductive layer is in conductive contact with the cap layer, and a lower edge of the highly conductive layer is not lower than the oxide interface layer of a first storage structure unit; and the lower edge of the highly conductive layer is not in contact with the second ferromagnetic layer of the first storage structure unit. By means of the present invention, short-circuit connections among multiple storage structure units are realized, thereby reducing the ratio of series resistance generated by the stacking to the total resistance of a magnetic tunnel junction, reducing the total resistance of the magnetic tunnel junction, and prolonging the duration of data storage.

Description

Magnetic storage unit and magnetic memory

This application claims the priority of the Chinese patent application with the application number 202011604390.5 and the invention title "A Magnetic Memory Cell and Magnetic Memory", which was filed with the China Patent Office on December 29, 2020, the entire contents of which are incorporated herein by reference. middle.

technical field

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

Background technique

Current-read and write magnetic random access memory (STT-MRAM) is a new type of memory with great potential. Different from other existing types of memory, magnetic random access memory has considerable storage capacity and read and write speed. However, to replace or partially replace the existing mainstream memory, it also faces a problem that traditional memory has not faced, namely magnetic memory. The data storage time is limited. For the consideration of data security, if the magnetic random access memory is to be put into use, the storage time of the memory needs to be further extended.

In the prior art, in order to increase the data retention time, the size of the storage bit can be increased, and the physical diameter of the magnetic memory can be increased to reduce the storage density, thereby increasing the storage time. Of course, this is not conducive to the miniaturization of the device, which is inconsistent with the current development trend of memory. On the other hand, in some technologies, the multi-layer interface superposition is used to increase the bit thickness and increase the data retention time, but the multi-layer will bring new interface resistance problems, which will reduce the memory performance.

Therefore, how to prolong the data storage time without affecting the read and write performance of the memory and without increasing the volume of the memory is an urgent problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

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

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

The magnetic free layer includes a plurality of storage structural units;

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

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

The lower edge of the highly conductive layer is not in contact with the second ferromagnetic layer of the first memory structure unit.

Preferably, in the magnetic memory unit, the lower edge of the high-conductivity layer is not higher than the oxide interface layer of the second memory structure unit; wherein, the second memory structure unit is the second distance from the tunnel layer. Two close storage units.

Preferably, in the magnetic storage unit, the number of the storage structural units ranges from 2 to 5, inclusive.

Preferably, in the magnetic memory cell, the oxide interface layer has a thickness ranging from 0.5 nm to 1 nm, inclusive.

Preferably, in the magnetic storage unit, the highly conductive layer includes 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, At least one of a metal platinum layer, a metal gold layer or a metal nitride conductive layer.

Preferably, in the magnetic memory cell, the thickness of the non-magnetic metal spacer layer ranges from 0.1 nm to 0.5 nm, inclusive.

Preferably, in the magnetic storage unit, the preparation method of 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 etched according to a preset pattern to obtain a columnar substrate;

An insulating protective layer is provided on the sidewall of the columnar base;

The insulating protection layer is etched through the top layer through hole etching technology to form through holes; wherein, the staying surface of the through holes 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 to obtain the magnetic memory unit.

Preferably, in the magnetic storage unit, the preparation method of the magnetic storage unit comprises:

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

performing surface deposition on the primary etched body to obtain a highly conductive layer disposed on the primary etched body;

The magnetic memory cell is obtained by performing secondary etching on the primary etched body on which the highly conductive layer has been deposited.

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

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

The magnetic storage unit provided by the present invention includes a magnetic reference layer, a tunnel layer, a magnetic free layer and a cap layer in sequence from bottom to top; the magnetic free layer includes a plurality of storage structure units; and the storage structure units sequentially include 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 high conductive layer, and the upper edge of the high conductive layer is conductive with the cap layer contact setting, the lower edge of the high conductivity 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 high conductivity The lower edge of the layer is not in contact with the second ferromagnetic layer of the first memory structure unit.

The present invention proposes a structure in which a plurality of storage structure units are repeatedly arranged to prolong the data storage time. The magnetic free layer maintains vertical anisotropy through the anisotropy of the multi-layer interface, and the ferromagnetic properties of the multi-layer ferromagnetic layer Coupling stacking increases the thickness of the magnetic free layer, but does not significantly increase the size of the storage bit. In addition, based on the existing multi-layer interface stacking magnetic memory cells, a contact arrangement is arranged on the periphery of the magnetic free layer. The highly conductive layer forms an electrical short-circuit connection between the multi-layer storage structure units, reduces the ratio of the series resistance generated by stacking to the total resistance of the magnetic tunnel junction, reduces the total resistance of the magnetic tunnel junction, and maintains the high tunnel magnetic properties of the magnetic tunnel junction. The resistance change rate greatly increases the data storage time. The present invention also provides 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 structural diagram of a specific implementation manner of a magnetic storage unit provided by the present invention;

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 5 are process flow diagrams of a method for preparing a magnetic memory cell provided by the present invention;

FIG. 6 is a schematic flowchart of another specific embodiment of the method for manufacturing a magnetic memory cell provided by the present invention.

Detailed ways

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 magnetic memory cell, a schematic structural diagram of a specific implementation manner of which is shown in FIG. Free layer 300 and cap layer 400;

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

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

The sidewall of the magnetic free layer 300 is covered with a highly conductive layer 500 , the upper edge of the highly conductive layer 500 is arranged in conductive contact with the cap layer 400 , and the lower edge of the highly conductive layer 500 is not lower than the first storage structure The oxide interface layer 311 of the unit 310; wherein, the first memory structure unit 310 is the memory 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 memory structure unit 310.

It should be noted that in the present invention, from bottom to top refers to outward from the fixed base of the storage unit, and in actual production, in order to obtain a complete magnetic storage unit, it is usually also disposed below the magnetic reference layer 100 For epitaxial structures such as transition layers, pinning layers, and seed layers, each epitaxial layer in the present invention is a layer formed by deposition.

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

As a preferred embodiment, the lower edge of the high conductive layer 500 is not higher than the oxide interface layer 311 of the second memory structure unit 310 ; Two nearest storage structure units 310 . Of course, the lower the lower edge of the highly conductive layer 500 is, which means that the more structures of the magnetic free layer 300 covered by the highly conductive layer 500 are, the lower the total resistance of the magnetic free layer 300 is. memory performance.

Specifically, the number of the storage structure units 310 ranges from 2 to 5, including the endpoint value, such as any one of 2.0, 3.0, or 5.0. Of course, the corresponding selection can also be made according to the actual situation.

In addition, the thickness of the oxide interface layer 311 ranges from 0.5 nanometers to 1 nanometer, inclusive, such as any one of 0.50 nanometers, 0.79 nanometers, or 1.00 nanometers; the thickness of the oxide interface layer is thin enough to make the upper and lower two The memory structure unit 310 forms a strong ferromagnetic coupling. Further, the oxide interface layer 311 is a magnesium oxide layer, of course, it can be changed to other oxide layers according to actual needs, such as aluminum oxide, silicon oxide, titanium oxide, magnesium aluminate, tantalum oxide, zirconium oxide, hydrated oxide layer Iron etc.

Specifically, the highly conductive layer 500 is a metal copper layer or a tantalum nitride layer, of course, it can also be selected according to the actual situation.

The thickness of the non-magnetic metal spacer layer 313 ranges from 0.1 nm to 0.5 nm, inclusive, such as any one of 0.10 nm, 0.30 nm, or 0.50 nm. The non-magnetic metal spacer layer 313 is a thin metal layer that absorbs boron. Also, the non-magnetic metal spacer layer 313 is any one of a metal molybdenum layer, a metal tantalum layer, a metal magnesium layer, a metal tungsten layer, a metal iridium layer, or a metal ruthenium layer.

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

As a preferred embodiment, an insulating protective layer 700 is further provided on the sidewall of the magnetic memory cell, and the insulating protective layer 700 is a silicon oxide layer and/or a silicon nitride layer.

The magnetic storage unit provided by the present invention includes a magnetic reference layer 100, a tunnel layer 200, a magnetic free layer 300 and a cap layer 400 in order from bottom to top; the magnetic free layer 300 includes a plurality of storage structure units 310; the storage structure The unit 310 sequentially includes a first ferromagnetic layer 314, a non-magnetic metal spacer layer 313, a second ferromagnetic layer 312 and an oxide interface layer 311 from bottom to top; the sidewall of the magnetic free layer 300 is covered with a high conductive layer 500, so 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 memory structure unit 310; wherein, the first memory The structure unit 310 is the memory 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 memory structure unit 310 . The present invention proposes a structure in which a plurality of storage structure units 310 are repeatedly arranged to prolong the data storage time, and the magnetic free layer 300 maintains vertical anisotropy through the anisotropy of the multi-layer interface. The ferromagnetic coupling stacking increases the thickness of the magnetic free layer 300, but does not significantly increase the size of the storage bit. In addition, on the basis of stacking magnetic memory cells at the existing multi-layer interface, the magnetic free layer 300 The high-conductivity layer 500 is arranged in the peripheral contact, so that an electrical short-circuit connection is formed between the multi-layer storage structure units 310, the ratio of the series resistance generated by the stacking to the total resistance of the magnetic tunnel junction is reduced, the total resistance of the magnetic tunnel junction is reduced, and the magnetic properties are maintained. The high tunnel magnetoresistance change rate of the tunnel junction greatly improves the data storage time.

The present invention also provides a method for preparing a magnetic storage unit, which is referred to as the specific embodiment 2. The schematic flowchart of the method is shown in FIG. 2 , including:

S101 : Disposing the magnetic reference layer 100 , the tunnel layer 200 , the magnetic free layer 300 and the cap layer 400 in sequence on a predetermined substrate, and etching according to a predetermined pattern to obtain a columnar substrate.

S102: Disposing an insulating protective layer 700 on the sidewall of the columnar base.

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

S103 : Etch the insulating protection layer 700 through the top layer via hole 600 etching technique to form a via hole 600 ; wherein the stop surface 710 of the via hole 600 is not lower than the oxide interface layer 311 of the first memory structure unit 310 .

As can be seen from FIG. 4 , the through hole 600 is a through hole 600 formed in the insulating protection layer 700 .

S104 : deposit a highly conductive material into the through hole 600 to form the highly conductive layer 500 to obtain the magnetic memory cell.

The schematic diagram of the structure after etching through the top through hole 600 in this specific embodiment is shown in FIG. 4 . In this specific embodiment, the entire structure of the magnetic storage unit is completed by a single etching (ie, the columnar substrate). , and then adding the insulating protection layer 700 and the high conductive layer 500 , the process is simple and the production efficiency is high.

At the same time, the present invention also provides another method for preparing a magnetic storage unit, which is referred to as the specific embodiment 3. The schematic flowchart of the method is shown in FIG. 3 , including:

S201 : Disposing the magnetic reference layer 100 , the tunnel layer 200 , the magnetic free layer 300 and the cap layer 400 in sequence on a preset substrate, and etching to the preset stop surface 710 to obtain one etching wherein, the stay surface 710 is not lower than the oxide interface layer 311 of the first memory structure unit 310 .

S202: Perform surface deposition on the primary etched body to obtain a high conductive layer 500 disposed on the primary etched body.

The schematic diagram of the structure after deposition is shown in FIG. 5 , the primary etching body is bounded 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-conductivity layer 500 is deposited on the whole of the primary etched body, and the high-conductivity layer 500 covers the top, the upper surface of the columnar structure and the flat surface where the stop surface 710 is located.

S203: Perform secondary etching on the primary etched body on which the highly conductive layer 500 has been deposited to obtain the magnetic memory cell.

Since the etching is generally a vertical downward etching, in the secondary etching, the highly 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, while the columnar structure side is etched. The highly conductive layer 500 of the wall will remain, and the schematic diagram of the magnetic memory cell structure after etching is shown in FIG. The diameter of the etched layer is slightly larger than that above, but this has no effect on the use. Compared with other technologies, the magnetic memory unit prepared in this specific embodiment has a smaller volume, which is more conducive to the miniaturization of the device.

It should be noted that, for the magnetic memory cells in the various specific embodiments described above, as a preferred embodiment, the resistivity of the oxide interface layer 311 of the first memory structure unit 310 is lower than that of the magnetic free layer The resistivity of other oxide interfacial layers in .

The method for disposing the oxide interface layer 311 of the first memory structure unit 310 includes:

Set the metal element layer;

Oxygen doping is performed on the metal element layer to obtain the oxide interface layer 311 of the first memory structure unit 310 .

or

set the metal oxide layer;

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

The oxide interface layer 311 obtained by the above two methods has low oxygen content and high electrical conductivity, which greatly improves the process window when the high conductive layer 500 is provided, that is, improves the process fault tolerance and ensures that the magnetic free layer 300 overall low resistance. Of course, other processes can also be selected according to actual needs, so that the resistivity of the oxide interface layer 311 obtained from the first memory structure unit 310 is lower than that of other oxide interface layers 311 , which is not repeated here.

The present invention also provides a magnetic memory, which includes the magnetic storage unit described in any of the above. The magnetic storage unit provided by the present invention includes a magnetic reference layer 100, a tunnel layer 200, a magnetic free layer 300 and a cap layer 400 in order from bottom to top; the magnetic free layer 300 includes a plurality of storage structure units 310; the storage structure The unit 310 sequentially includes a first ferromagnetic layer 314, a non-magnetic metal spacer layer 313, a second ferromagnetic layer 312 and an oxide interface layer 311 from bottom to top; the sidewall of the magnetic free layer 300 is covered with a high conductive layer 500, so 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 memory structure unit 310; wherein, the first memory The structure unit 310 is the memory 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 memory structure unit 310 . The present invention proposes a structure in which a plurality of storage structure units 310 are repeatedly arranged to prolong the data storage time. The magnetic free layer maintains vertical anisotropy through the anisotropy of the multi-layer interface. The magnetic coupling stacking increases the thickness of the magnetic free layer, but does not significantly increase the size of the storage bit. In addition, based on the existing multi-layer interface stacking magnetic memory cells, a contact arrangement is placed on the periphery of the magnetic free layer. The highly conductive layer is formed to form an electrical short-circuit connection between the multi-layer storage structure units, reduce the ratio of the series resistance generated by stacking to the total resistance of the magnetic tunnel junction, reduce the total resistance of the magnetic tunnel junction, and maintain the high tunneling of the magnetic tunnel junction. The magnetoresistance change rate greatly increases the data storage time.

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, etc. 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 a non-exclusive inclusion such that a process, method, article or device that includes 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 device. 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 device that includes the element.

The magnetic storage unit 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 magnetic storage unit, characterized in that it comprises a magnetic reference layer, a tunnel layer, a magnetic free layer and a cap layer in order from bottom to top;

   The magnetic free layer includes a plurality of storage structural units;

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

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

   The lower edge of the highly conductive layer is not in contact with the second ferromagnetic layer of the first memory structure unit.
2. The magnetic memory cell according to claim 1, wherein the lower edge of the high conductive layer is not higher than the oxide interface layer of the second memory structure unit; wherein, the second memory structure unit is a distance from the The second-closest storage structure unit of the tunnel layer.
3. The magnetic storage unit of claim 1, wherein the number of the storage structure units ranges from 2 to 5, inclusive.
4. The magnetic memory cell of claim 1, wherein the oxide interface layer has a thickness ranging from 0.5 nm to 1 nm, inclusive.
5. The magnetic memory cell of claim 1, wherein the highly conductive layer comprises 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 layer At least one of a magnesium layer, a metal platinum layer, a metal gold layer or a metal nitride conductive layer.
6. The magnetic memory cell of claim 1, wherein the thickness of the non-magnetic metal spacer layer ranges from 0.1 nm to 0.5 nm, inclusive.
7. The magnetic storage unit according to claim 1, wherein the preparation method of the magnetic storage unit comprises:

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

   An insulating protective layer is provided on the sidewall of the columnar base;

   The insulating protection layer is etched through the top layer through hole etching technology to form a through hole; wherein, the stop 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 to obtain the magnetic memory unit.
8. The magnetic storage unit according to claim 1, wherein the preparation method of the magnetic storage unit comprises:

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

   performing surface deposition on the primary etched body to obtain a highly conductive layer disposed on the primary etched body;

   The magnetic memory cell is obtained by performing secondary etching on the primary etched body on which the highly conductive layer has been deposited.
9. The magnetic memory cell according to any one of claims 1 to 9, wherein the resistivity of the oxide interface layer of the first memory structure unit is lower than that of other oxide interface layers in the magnetic free layer resistivity.
10. A magnetic memory, characterized in that the magnetic memory comprises the magnetic storage unit according to any one of claims 1 to 9.

Images