Magnetic storage device

Abstract

The application relates to the field of magnetic storage, in particular to a magnetic storage device, which comprises a fixed layer, a channel isolation layer and a free layer; the channel isolation layer is located between the fixed layer and the free layer; further comprising a non-magnetic layer, which is located on the free layer, and the material of the non-magnetic layer is different from that of the free layer. The application can effectively reduce the critical current for changing the magnetization direction of the free layer of the MTJ and reduce the volume of the magnetic storage device.

Description

Technical Field

[0001] This invention relates to the field of magnetic storage devices, and more particularly to an MTJ magnetic storage device. Background Technology

[0002] Compared to existing memory on the market, magnetic storage has attracted much attention due to its faster write speed, longer information retention time, and potential low power consumption.

[0003] The core component of magnetic storage devices is the magnetic tunnel junction (MTJ). An MTJ consists of a free layer, a fixed layer, and a channel isolation layer between them. The free and fixed layers are two layers of magnetic material, and their magnetization directions determine the resistance of the MTJ. When the free and fixed layers are parallel but opposite in magnetization direction, the MTJ resistance is high; when they are parallel and in the same direction, the MTJ resistance is low. By determining the MTJ resistance, magnetic storage devices can be used for reading and writing data.

[0004] Both industrial and consumer-grade magnetic storage devices require increasingly smaller structures. For MTJs, the smaller the structure, the lower the critical current of the free layer (also called the minimum flip magnetization direction current) is required. With the free layer magnetic material remaining unchanged or not significantly improved, reducing the critical current density has become the key to optimizing the MTJ structure. Summary of the Invention

[0005] This invention improves the MTJ structure in existing STT-MRAMs by using a special structure to excite non-parallel atomic magnetic moments in the free layer to help change the magnetization direction of the free layer, thereby significantly reducing the critical current.

[0006] The present invention provides a magnetic storage device, comprising a fixed layer, a channel isolation layer, and a free layer; the channel isolation layer is located between the fixed layer and the free layer; characterized in that the free layer has a first surface and a second surface opposite to each other, the second surface being farther away from the channel isolation layer than the first surface, and the first surface and the second surface being non-parallel.

[0007] Preferably, the first surface is a non-centrally symmetric surface structure.

[0008] Preferably, the first surface is a curved surface structure.

[0009] Preferably, the first surface is a planar structure.

[0010] Preferably, the first surface is in contact with the channel isolation layer.

[0011] Preferably, a non-magnetic thin film layer is provided between the first surface and the channel isolation layer.

[0012] Preferably, the fixed layer and the free layer are at least one of CoFe, NiFe, CoFeB, CoFeCr, CoFePt, CoFePd, CoFeTb, CoFeGd, or CoFeNi.

[0013] Preferably, it further includes a first electrode and a second electrode; the first electrode is located below the fixed layer, and the second electrode is located above the free layer.

[0014] Preferably, the device further includes a semiconductor device electrically connected to the fixed layer.

[0015] Preferably, the system further includes a substrate located below the fixing layer.

[0016] Preferably, the system further includes a non-magnetic structure located within the free layer, the non-magnetic structure being made of a different material than the free layer.

[0017] Preferably, the free layer has a first surface and a second surface opposite to each other, the first surface being opposite to the channel isolation layer, and the non-magnetic structure being located on the surface of the second surface.

[0018] Preferably, the non-magnetic structure is a non-centrosymmetric structure.

[0019] Preferably, the non-magnetic structure is ring-shaped or strip-shaped.

[0020] Preferably, the non-magnetic structure extends through the free layer.

[0021] Preferably, there are at least two non-magnetic structures.

[0022] Preferably, the non-magnetic structural material is at least one of magnesium, titanium, chromium, and copper oxide / nitride.

[0023] Preferably, the free layer has a first side and a second side facing each other, the first side facing the channel isolation layer, and a non-magnetic thin film layer between the first side and the channel isolation layer.

[0024] Preferably, it further includes a non-magnetic layer, the non-magnetic structure being located on the free layer.

[0025] The magnetic storage device provided by this invention improves the structure by using a free layer surface, adding a non-magnetic structure within the free layer, and adding a non-magnetic layer on top of the free layer. This excites non-parallel atomic magnetic moments within the free layer, assisting in the reversal of the magnetization direction of the free layer, thereby significantly reducing the critical current and exhibiting excellent effects in reducing the structure of the MTJ. Attached Figure Description

[0026] Appendix Figure 1This is a cross-sectional schematic diagram of a specific embodiment of the magnetic storage device of the present invention;

[0027] Appendix Figure 2 This is a schematic diagram of a cross-section showing the excitation of atomic magnetic moments near the free-layer surface;

[0028] Appendix Figure 3 This is a cross-sectional schematic diagram of another specific embodiment of the magnetic storage device of the present invention;

[0029] Appendix Figure 4 This is a cross-sectional schematic diagram of the magnetic moments of atoms excited by nonmagnetic bands within the free layer.

[0030] Appendix Figures 5A-5C yes Figure 3 Top view of the nonmagnetic zone at section A-A'.

[0031] Appendix Figure 6 This is a cross-sectional schematic diagram of another specific embodiment of the magnetic storage device of the present invention. Detailed Implementation

[0032] The specific embodiments of the magnetic storage device provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0033] In the accompanying drawings, for ease of description, the dimensions of layers and regions are not actual proportions. When a layer (or film) is referred to as being "on" another layer or substrate, it may be directly on the other layer or substrate, or there may be intermediate layers. Similarly, when a layer is referred to as being "below" another layer, it may be directly below, and there may be one or more intermediate layers. Additionally, when a layer is referred to as being "between" two layers, it may be the only layer between the two layers, or there may be one or more intermediate layers. The same reference numerals always denote the same elements.

[0034] This specific embodiment provides a magnetic storage device, such as... Figure 1 As shown, the core device MTJ includes a fixed layer 41, a channel isolation layer 42, and a free layer 43; the channel isolation layer 42 is located between the fixed layer 41 and the free layer 43; the free layer 43 has a first surface (lower surface) and a second surface (upper surface) opposite to each other, the second surface (upper surface) is farther away from the channel isolation layer 42 than the first surface (lower surface), that is, the first surface (lower surface) is opposite to the channel isolation layer 42, and the first surface (lower surface) and the second surface (upper surface) are not parallel.

[0035] In existing STT-MRAM (free layer with parallel top and bottom surfaces), when a free layer 43 is formed on the channel isolation layer 42, due to time intervals, stress from cooling of the channel isolation layer 42, tension from the temperature of the free layer 43, and the difference in materials between the channel isolation layer 42 and the free layer 43, a locally fused structure will form at the interface. The applicant has discovered that during the read / write process, this fused structure is beneficial for exciting trace atomic magnetic moments (such as those not parallel to the top and bottom surfaces of the free layer 43) in the free layer 43. Figure 2 The AMM shown can assist the free layer 43 in changing its magnetization direction, reducing the critical current required for the free layer 43 to change its magnetization direction; however, at the same time, this fused structure disrupts the uniformity of the channel isolation layer 42, reducing its lifespan. Therefore, how to excite and form more non-parallel atomic magnetic moments in the free layer while taking into account the lifespan of the channel isolation layer has become the main research direction of this invention.

[0036] Therefore, in this embodiment, the free layer 43 has a non-parallel first surface (lower surface) and second surface (upper surface), and the channel isolation layer 42 has a uniform thickness. During the read and write process, it helps to excite more atomic magnetic moments in the vicinity of the first surface (lower surface) of the free layer 43 to assist the free layer 43 in changing the magnetization direction, thereby reducing the critical current required to change the magnetization direction of the free layer 43.

[0037] In another embodiment, the first surface (lower surface) of the free layer 43 is a non-centrosymmetric structure. For example... Figure 1 As shown, the first surface (lower surface) is a curved structure. This structure facilitates the formation of features such as... within the free layer 43 during read / write operations. Figure 2 The atomic magnetic moments AMM shown are for illustrative purposes only; different directions of electron flow will excite the formation of atomic magnetic moments in different directions. A small number of them are horizontally parallel atomic magnetic moments AMM0, while the majority are non-horizontal AMM1 and AMM2. The non-centrosymmetric plane structure helps to balance the number of AMM1 and AMM2, thereby making the sum of the atomic magnetic moment vectors non-parallel. This helps to change the magnetization direction of the free layer 43, thereby reducing the critical current required to change the magnetization direction of the free layer 43.

[0038] In another embodiment, the first surface (lower surface) can be a planar structure (not shown), that is, the cross-section of the free layer 43 is a wedge-shaped structure, which helps to excite more atomic magnetic moments in the vicinity of the first surface (lower surface) of the free layer 43 to assist the free layer 43 in changing the magnetization direction, thereby reducing the critical current required to change the magnetization direction of the free layer 43.

[0039] In this embodiment, as Figure 1 , Figure 2As shown, the first surface (lower surface) of the free layer 43 is in contact with the channel isolation layer 42. By means of the different materials of the free layer 43 and the channel isolation layer 42, atomic magnetic moments are excited in the first surface (lower surface) of the free layer 43 to help change the magnetization direction of the free layer 43.

[0040] In another embodiment, in order to excite atomic magnetic moments according to different materials, the applicant provides a non-magnetic thin film layer (not shown) between the first surface (lower surface) of the free layer 43 and the channel isolation layer 42, thereby exciting and forming more atomic magnetic moments in the first surface (lower surface) of the free layer 43 to help change the magnetization direction of the free layer 43.

[0041] Preferably, the non-magnetic thin film layer (not shown) is a discontinuous structure, and in order to take into account the service life of the channel isolation layer 42, the discontinuous non-magnetic thin film layer is embedded in the first surface (lower surface) of the free layer 43.

[0042] Preferably, the non-magnetic thin film layer (not shown) is a discontinuous structure. This discontinuous non-magnetic thin film layer is part of the upper surface of the channel isolation layer 42. In order to take into account the service life of the channel isolation layer 42, the non-magnetic thin film layer is formed by processing the upper surface of the channel isolation layer 42.

[0043] In this embodiment, the fixed layer 41 and the free layer 43 are at least one of CoFe, NiFe, CoFeB, CoFeCr, CoFePt, CoFePd, CoFeTb, CoFeGd or CoFeNi. It should be noted that the thickness of the fixed layer 41 is greater than that of the free layer 43.

[0044] In this embodiment, as Figure 1 As shown, it also includes a first electrode 3 and a second electrode 5; the first electrode 3 is located below the fixed layer 41, and the second electrode 5 is located above the free layer 43.

[0045] In this embodiment, as Figure 1 As shown, it also includes a semiconductor device (not shown), which is disposed in a substrate 1 located below the fixing layer 41, and the semiconductor device is electrically connected to the fixing layer 41. This electrical connection is formed through a first conductor 200 in the first interlayer dielectric layer 20.

[0046] Preferably, the first conductor 200 is a metal, such as at least one of titanium, tantalum, copper, aluminum or tungsten; or a conductive metal nitride, such as at least one of titanium nitride or tantalum nitride.

[0047] In this embodiment, as Figure 1As shown, the second conductor 210 in the second interlayer dielectric layer 21 is connected to the second electrode 5, thereby electrically connecting the bit line (not shown) to the MTJ.

[0048] Preferably, the second conductor 210 is made of the same material as the first conductor, which will not be described in detail here.

[0049] In another embodiment, such as Figure 3 As shown, it includes a fixed layer 41, a channel isolation layer 42, and a free layer 43; the channel isolation layer 42 is located between the fixed layer 41 and the free layer 43; it also includes non-magnetic structures 61 and 62, which are located in the free layer 43. The non-magnetic structures 61 and 62 are made of a different material than the free layer 43, thereby exciting the formation of a structure like... within the second surface (upper surface) of the free layer 43. Figure 4 The numerous non-parallel atomic magnetic moments (AMMs) shown (the magnetic moment directions shown are for illustrative purposes only; different flow directions of negative electrons will excite the formation of atomic magnetic moments in different directions) help to change the magnetization direction of free layer 43.

[0050] It should be noted that, Figure 3 The non-magnetic structures 61 and 62 are only schematic diagrams. Under the existing process, it is relatively easy to form non-magnetic structures 61 and 62 on the second side (upper surface) of the free layer 43. Due to etching of the free layer 43, the non-magnetic structures 61 and 62 are also more likely to form pits. However, this does not mean that the embodiment in the middle of the free layer (i.e., the free layer completely contains the non-magnetic structures 61 and 62) is excluded.

[0051] It should also be noted that when non-magnetic structures 61 and 62 are provided in the free layer 43, the free layer, the fixed layer, and the channel isolation layer can adopt the strip stacking structure in the existing STT-MRAM technology, without the need for using... Figure 3 The free layer 43 shown has a first surface (lower surface) that is not parallel to the second surface (upper surface), or the first surface (lower surface) is in the form of a curved surface.

[0052] In this embodiment, as Figure 3 , Figure 4 As shown, the non-magnetic structures 61 and 62 are located within the second plane.

[0053] In this embodiment, as Figure 4 As shown, in order to form more non-parallel atomic magnetic moments in the second surface (upper surface), the non-magnetic structures 61 and 62 are each non-centrosymmetric structures in the side cross section.

[0054] In this embodiment, as Figures 5A-5CAs shown, due to the top view structure of the MTJ as a whole or the magnetic storage unit, the top view structure of the non-magnetic structures 61 and 62 is ring-shaped or strip-shaped; of course, strip-shaped non-magnetic structures 61 and 62 can be formed within the top view structure of a circular MTJ or magnetic storage unit, or ring-shaped non-magnetic structures 61 and 62 can be formed within the top view structure of a square MTJ or magnetic storage unit.

[0055] In another embodiment, the non-magnetic structures 61 and 62 penetrate (not shown) the free layer 43, that is, the upper and lower surfaces of the non-magnetic structures 61 and 62 are connected to the second electrode 5 and the channel isolation layer 42, respectively. This structure not only excites the formation of atomic magnetic moments in the upper and lower surfaces of the free layer 43, but also forms atomic magnetic moments in the middle of the free layer 43, which helps to change the magnetization direction of the free layer 43 and greatly reduces the critical current required to change the magnetization direction of the free layer 43.

[0056] In this embodiment, there are at least two non-magnetic structures. This embodiment is not restrictive; if non-magnetic structures 61 and 62 penetrate the free layer 43, there may be only one non-magnetic structure.

[0057] In this embodiment, the non-magnetic structural materials 61 and 62 are at least one of magnesium, titanium, chromium, and copper oxide / nitride.

[0058] Similarly, in this embodiment, in order to excite atomic magnetic moments according to different materials, the applicant provides a non-magnetic thin film layer (not shown) between the first surface (lower surface) of the free layer 43 and the channel isolation layer 42, thereby exciting and forming more atomic magnetic moments in the first surface (lower surface) of the free layer 43 to help change the magnetization direction of the free layer 43.

[0059] Preferably, the non-magnetic thin film layer (not shown) is a discontinuous structure, and in order to take into account the service life of the channel isolation layer 42, the discontinuous non-magnetic thin film layer is embedded in the first surface (lower surface) of the free layer 43.

[0060] Preferably, the non-magnetic thin film layer (not shown) is a discontinuous structure. This discontinuous non-magnetic thin film layer is part of the upper surface of the channel isolation layer 42. In order to take into account the service life of the channel isolation layer 42, the non-magnetic thin film layer is formed by processing the upper surface of the channel isolation layer 42.

[0061] like Figure 3 As shown, the semiconductor device (not shown), substrate 1, first conductor 200, first interlayer dielectric layer 20, first electrode 20, second electrode 5, second interlayer dielectric layer 21, second electrode 210, and bit lines (not shown) and their connection relationships are as follows: Figure 1 The same applies, and the applicant will not elaborate further here.

[0062] In another embodiment, such as Figure 6 As shown, the magnetic storage device includes a fixed layer 41, a channel isolation layer 42, and a free layer 43; the channel isolation layer 42 is located between the fixed layer 41 and the free layer 43; it also includes a non-magnetic layer 6, which is located on the free layer 43. The non-magnetic layer 6 is made of a different material than the free layer 43, thereby exciting the formation of atomic magnetic moments in the second surface (upper surface) of the free layer 43 to assist in changing the magnetization direction of the free layer 43 and reducing the critical current for changing the magnetization direction of the free layer 43.

[0063] It should be noted that when a non-magnetic layer 6 is disposed on the free layer 43, the free layer, the fixed layer, and the channel isolation layer can adopt the strip stacking structure in the existing STT-MRAM technology, without the need for using... Figure 6 The free layer 43 shown has a first surface (lower surface) that is not parallel to the second surface (upper surface), or the first surface (lower surface) is curved. Of course, using... Figure 6 The fact that the first surface (lower surface) and the second surface (upper surface) of the free layer 43 shown are not parallel, or that the first surface (lower surface) is in the form of a curved surface, can further reduce the critical current that changes the magnetization direction of the free layer 43.

[0064] It should also be noted that when a non-magnetic layer 6 is set on the free layer 43, it is not necessary to set a layer such as... Figure 3 The non-magnetic structures 61 and 62 shown can, of course, be used as... Figure 3 The effects of the non-magnetic structures 61 and 62 shown are more pronounced.

[0065] Similarly, in this embodiment, in order to excite atomic magnetic moments according to different materials, the applicant provides a non-magnetic thin film layer (not shown) between the first surface (lower surface) of the free layer 43 and the channel isolation layer 42, thereby exciting and forming more atomic magnetic moments in the first surface (lower surface) of the free layer 43 to help change the magnetization direction of the free layer 43.

[0066] Preferably, the non-magnetic thin film layer (not shown) is a discontinuous structure, and in order to take into account the service life of the channel isolation layer 42, the discontinuous non-magnetic thin film layer is embedded in the first surface (lower surface) of the free layer 43.

[0067] Preferably, the non-magnetic thin film layer (not shown) is a discontinuous structure. This discontinuous non-magnetic thin film layer is part of the upper surface of the channel isolation layer 42. In order to take into account the service life of the channel isolation layer 42, the non-magnetic thin film layer is formed by processing the upper surface of the channel isolation layer 42.

[0068] In this embodiment, as Figure 6 The non-magnetic layer 6 shown is... Figure 3The materials of the non-magnetic structures 61 and 62 and the non-magnetic thin film layer (not shown) can be the same, namely at least one of magnesium, titanium, chromium, and copper oxide / nitride.

[0069] In this embodiment, as Figure 6 As shown, the semiconductor device (not shown), substrate 1, first conductor 200, first interlayer dielectric layer 20, first electrode 20, second electrode 5, second interlayer dielectric layer 21, second electrode 210, and bit lines (not shown) and their connection relationships are as follows: Figure 1 The same applies, and the applicant will not elaborate further here.

[0070] The magnetic storage device provided by this invention improves the structure by using a free layer surface, adding a non-magnetic structure within the free layer, and adding a non-magnetic layer on top of the free layer. This excites non-parallel atomic magnetic moments within the free layer, helps to change the magnetization direction of the free layer, significantly reduces the critical current, and has an excellent effect of reducing the structure of the MTJ.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A magnetic storage device, comprising: Fixed layer, channel isolation layer, free layer; The channel isolation layer is located between the fixed layer and the free layer; Its features are, It also includes a non-magnetic layer, which is located on the free layer and is made of a different material than the free layer. The free layer has a first side and a second side opposite to each other, the second side being farther away from the channel isolation layer than the first side, and a non-magnetic thin film layer is located between the first side and the channel isolation layer. The non-magnetic thin film layer has a discontinuous structure and is formed by processing the upper surface of the channel isolation layer.

2. The magnetic storage device according to claim 1, characterized in that, The non-magnetic layer material is at least one of magnesium oxide, titanium oxide, chromium oxide, copper oxide, magnesium nitride, titanium nitride, chromium nitride, and copper nitride.

3. The magnetic storage device according to claim 1, characterized in that, The fixed layer and the free layer are at least one of CoFe, NiFe, CoFeB, CoFeCr, CoFePt, CoFePd, CoFeTb, CoFeGd, or CoFeNi.

4. The magnetic storage device according to claim 1, characterized in that, It also includes a first electrode and a second electrode; the first electrode is located below the fixed layer, and the second electrode is located above the free layer.

5. The magnetic storage device according to claim 1, characterized in that, It also includes a semiconductor device, which is electrically connected to the fixed layer.

6. The magnetic storage device according to claim 1, characterized in that, It also includes a substrate, which is located below the fixing layer.

Images