High-density 3D magnetic memory device

Abstract

This disclosure provides a 3D magnetic memory device comprising a stack of alternating dielectric layers and a silicon substrate, and a magnetic channel extending through the stack. The magnetic channel includes a hollow cylinder made of a magnetic material and a dielectric filling material. A plurality of pinning sites defined by the layers are formed in the magnetic channel, each pinning site configured to store a magnetic bit. A first metallic layer is disposed at a first end of the magnetic channel and on a last layer of the stack. A magnetic tunnel junction (MTJ) is disposed on the first metallic layer and a first electrode spaced apart from the MTJ. The first metallic layer may be configured as a spin-orbit moment (SOT) orbital. Alternatively, a second metallic layer is configured as the SOT orbital, and a second end of the magnetic channel and a first layer of the stack are disposed on the second metallic layer.

Description

Technical Field

[0001] This disclosure relates to magnetic memory devices. In particular, this disclosure proposes a novel three-dimensional (3D) magnetic memory device capable of achieving high storage density (bit density). The magnetic memory device of this disclosure is based on a spinorbit torque (SOT) magnetic random access memory (MRAM) device architecture. Background Technology

[0002] In the field of computing devices, a wide variety of memory architectures have been developed over the past few decades, based on various technological constraints such as speed requirements, memory requirements, density requirements, and application type. For example, Static Random Access Memory (SRAM) architectures were developed due to their high operating speeds but have drawbacks related to their areal density. Conversely, Dynamic Random Access Memory (DRAM) architectures allow for high-capacity working memory but are slower. Furthermore, (3D) NAND offers inexpensive high capacity but is extremely slow compared to other memory types. Recent advances have introduced the Spin-Torque Magnetic Random Access Memory (STT-MRAM) architecture, a non-volatile resistive memory utilizing magnetic tunnel junctions (MTJs).

[0003] STT-MRAM is considered an embedded memory (built on the same wafer as the logic circuitry) due to its relatively fast operating speed (down to a few nanoseconds), robust durability, and compatibility with advanced complementary metal-oxide-semiconductor (CMOS) voltages. It also provides non-volatility by storing bits in a magnetic state, and therefore exhibits improved leakage power compared to alternatives in SRAM and DRAM.

[0004] Various types of magnetic memories exist, with STT-MRAM being the most advanced, but SOT-MRAM and voltage-controlled MRAM are potential next-generation candidates with the potential for faster speed and / or lower power operation. However, all of these magnetic memories are based on MTJ technology. Since the MRAM stack itself is typically a complex collection of more than 20 individual ultrathin layers, physical vapor deposition (PVD) is required, implying a planar construction.

[0005] While the aforementioned MRAM technologies offer promising candidates for SRAM replacement or on-chip memory, their planar architecture ultimately limits the achievable memory density, thus restricting their application in embedded memory technologies with current-density constraints. To target the rest of the memory pyramid, MRAM would have to leverage a third dimension to potentially increase memory density by approximately 100 times, while ideally preserving and controlling the known advantages of MRAM in terms of speed and endurance. Summary of the Invention

[0006] In view of the foregoing, the object of this disclosure is to provide a novel magnetic memory device based on MRAM. Specifically, the object is to utilize all three dimensions, i.e., to move away from planar construction and provide a 3D magnetic memory device. Therefore, the ultimate goal is to significantly increase the achievable memory density to store more information in the magnetic memory device.

[0007] These and other objectives are achieved by the solutions described in the independent claims. Advantageous implementation methods are described in the dependent claims.

[0008] The first aspect of this disclosure provides a 3D magnetic memory device comprising: a stack comprising a plurality of dielectric layers and a silicon substrate, the plurality of dielectric layers and the silicon substrate being alternately disposed on one another; a magnetic channel extending through the layers of the stack, wherein the magnetic channel comprises a hollow cylinder made of a magnetic material and a dielectric material filling the hollow cylinder; wherein a plurality of pinning sites defined by the plurality of layers of the stack are formed in the magnetic channel, each pinning site being configured to store a magnetic bit; a first metallic layer disposed at a first end of the magnetic channel and at a last layer of the stack; a magnetic tunnel junction (MTJ) disposed on the first metallic layer; and a first electrode disposed spaced apart from the MTJ on the first metallic layer; wherein the first metallic layer is configured as a spin-orbit moment (SOT) track, or the magnetic memory device includes a second metallic layer configured as an SOT track and a second end of the magnetic channel and the first layer of the stack are disposed on the second metallic layer.

[0009] Magnetic channels can constitute memory cells in a 3D magnetic memory device of the first aspect. A magnetic channel can store multiple magnetic bits along its length, each magnetic bit corresponding to each layer of the stack. Pinning sites can be generated by alternating layers and their interfaces. A pinning site is a location where magnetic domains (or more specifically, domain walls separating these domains) are "pinned" or stabilized. Thus, each pinning site is configured to stabilize a specific magnetic state in the magnetic channel (and is therefore configured to store that specific magnetic state), which represents a (magnetic) bit of information.

[0010] Magnetic channels can thus store bit sequences. A magnetic memory device may include multiple such magnetic channels formed in multiple stacks in the same manner as described above to realize multiple memory cells of the magnetic memory device. Multiple magnetic channels can thus be arranged parallel to each other and / or can be arranged as magnetic channel arrays (e.g., arrays comprising multiple rows and columns). That is, the magnetic channels can be arranged in a 2D array and can extend along a third dimension. Therefore, the 3D magnetic memory device of the first aspect can utilize all three dimensions and deviates from the usual planar construction. Thus, the magnetic memory device of the first aspect can have a significantly increased memory density and can store more information than conventional planar magnetic memory devices.

[0011] Furthermore, the magnetic memory device of the first aspect can employ a System-on-Touch (SOT) to write information into the magnetic channels of the memory cells, and can employ a TMR using an MTJ to read information from the magnetic channels of the memory cells. Additionally, information can be moved through the magnetic channels by a driving current, thus moving the magnetic bits stored in the magnetic channels from one pinning point to the next. Pinning points are enabled by the periodicity of the stacked layers, and the pinning points can stabilize the magnetic domains within a single layer height. Therefore, the height of the magnetic bits can be defined by the periodicity.

[0012] The magnetic channel of the magnetic storage device in the first aspect provides a further advantage because it is constructed as a “macaroni” type channel comprising a hollow magnetic cylinder and a dielectric filler, compared to exemplary similar devices with all-magnetic material channels of varying diameters.

[0013] In such an exemplary device, the anisotropic shape of the magnetic material channels, as they extend through the stack (e.g., perpendicular to the axis), forces magnetization to align along the axis of the magnetic material channels. The aspect ratio t / CD between the individual thicknesses t of the multiple layers of the stack and the critical dimension (CD) that guarantees this is at least 2 to 3, i.e., t > 2 to 3. CD. Generally, the overall shape anisotropy helps ensure that all magnetizations remain perpendicular, even if the individual bits t / CD ratio is much smaller. For example, CD can range from 30 nm to 50 nm or from 30 nm to 80 nm, while t can range from 15 to 50 nm.

[0014] However, there is a risk that different bit sequences written into the magnetic channels (e.g., {111111} compared to {1010101} compared to {000001}) may contribute to changes in the shape anisotropy effect to varying degrees, potentially leading to a reduction in the effect for some configurations. Further miniaturization of the device (e.g., down to 20 nm CD) remains challenging due to its high cost, the need for dense lithography steps, and the constraints imposed by the high aspect ratio, particularly for etching.

[0015] Another problem is that magnetic domain pinning only occurs every other layer in this exemplary device, rather than between layers. Therefore, magnetic information can only be stored within each bilayer, limiting the total amount of information that the magnetic channels can hold. This halves the potential of 3D magnetic memory devices.

[0016] The flux-core channels used in this disclosure reduce the effective magnetic channel diameter, resulting in a lower drive current. Furthermore, the magnetic channels allow for a looser CD while maintaining low current. This enables cheaper manufacturing or easier CD control. Additionally, the magnetic domains exhibit enhanced magnetic anisotropy, making the memory device more stable. Potentially, the memory device can achieve double the bit density because the magnetic bits are stored adjacent to all layers of the stack.

[0017] In an implementation of a 3D magnetic memory device, the magnetic channel has a first diameter where it extends through the silicon substrate and a second diameter where it extends through the dielectric layer of the stack.

[0018] In the implementation of the 3D magnetic storage device, the first diameter is larger than the second diameter.

[0019] This allows for adjustment of the pinning strength at the corresponding pinning sites in the magnetic channel. Therefore, the performance of the magnetic storage device (e.g., regarding its retention and latency) can also be customized.

[0020] In the implementation of the 3D magnetic storage device, the ratio of the first diameter to the second diameter is in the range of 1.1:1 to 2:1.

[0021] A smaller ratio can be used to support better latency, while a larger ratio can be used to support better retention time for magnetic storage devices.

[0022] In the implementation of the 3D magnetic memory device, the transition between the first diameter and the second diameter is aligned with the interface between the alternately arranged layers of the stack.

[0023] In the implementation of the 3D magnetic storage device, the hollow cylinder is a stepped hollow cylinder.

[0024] In the implementation of the 3D magnetic storage device, the stepped hollow cylinder has a constant wall thickness.

[0025] In one implementation of a 3D magnetic memory device, at the first end of the magnetic channel, the inner core of the hollow cylinder has a radius of up to 100 nm or in the range of 10 nm to 80 nm.

[0026] This facilitates reading the magnetic bit closest to the MTJ.

[0027] In the implementation of the 3D magnetic memory device, the MTJ is positioned directly above the first end of the magnetic material channel on the first metallic layer, or is positioned offset from the first end of the magnetic material channel.

[0028] In the implementation of a 3D magnetic memory device, the MTJ includes a magnetic free layer having coercivity of 20 mT to 40 mT or coercivity in the range of 2 mT to 3 mT.

[0029] Therefore, the stray magnetic field at the pinning site closest to the MTJ can determine the orientation of the free layer.

[0030] In the implementation of 3D magnetic memory devices, the thicknesses of the silicon substrate and dielectric layer are in the range of 5 nm to 150 nm, respectively.

[0031] In the implementation of the 3D magnetic memory device, the length of the magnetic channel along the extension direction through the stack is in the range of 5 nm to 150 nm multiplied by the number of layers of the stack.

[0032] In the implementation of the 3D magnetic storage device, the magnetic material of the hollow cylinder is a ferromagnetic or ferrimagnetic material and / or a conductive material, such as cobalt, iron, nickel or their alloys, or any of the aforementioned materials may additionally contain boron.

[0033] In the implementation of the 3D magnetic memory device, the dielectric layer is a silicon oxide layer and the silicon substrate is a silicon nitride layer, or the dielectric layer is a silicon layer and the silicon substrate is a silicon-germanium layer; and / or the dielectric material filling the hollow cylinder is silicon oxide.

[0034] In the implementation of the 3D magnetic memory device, at least one of the first metallic layer and the second metallic layer is made of tantalum nitride, tungsten nitride, tungsten, tantalum, platinum, hafnium, molybdenum nitride, or an alloy thereof, or is made of a topological insulator.

[0035] These materials allow the use of either a first metallic layer or a second metallic layer as SOT tracks. In other words, this enables the transmission of SOT current through either the first or second metallic layer to write magnetic bits into the magnetic channels of the memory cell.

[0036] In one implementation, the 3D magnetic memory device also includes a second electrode disposed at or directly below the second end of the magnetic channel.

[0037] The second electrode facilitates the transmission of a driving current through the magnetic channel to the first electrode.

[0038] A second aspect of this disclosure provides a method for manufacturing a 3D magnetic memory device, the method comprising the steps of: forming a stack of a plurality of dielectric layers and a silicon substrate, the plurality of dielectric layers and the silicon substrate being alternately disposed on one another; forming holes in the layers extending through the stack; depositing a magnetic material onto the sidewalls of the holes to form a hollow cylinder made of the magnetic material; filling the hollow cylinder with a dielectric material to form a magnetic channel comprising the hollow cylinder and the dielectric material; wherein a plurality of magnetic channels defined by the plurality of layers of the stack are formed in the magnetic channels. Stacked pinning sites, each pinning site configured to store a magnetic bit; a first metallic layer formed on a first end of the magnetic channel and on a last layer of the stack; a magnetic tunnel junction (MTJ) formed on the first metallic layer; and a first electrode formed on the first metallic layer spaced apart from the MTJ; wherein the first metallic layer is configured as a spin-orbit moment (SOT) orbital, or the method further includes forming a second metallic layer configured as an SOT orbital and disposing the second end of the magnetic channel and the first layer of the stack on the second metallic layer.

[0039] In one implementation, the method includes: after forming the hole, selectively etching from within the hole to recess the dielectric layer or the silicon substrate to partially widen the hole; and depositing the magnetic material onto the sidewall of the recessed hole to form a stepped hollow cylinder made of the magnetic material.

[0040] In this method, the magnetic material is formed by conformal deposition on the sidewalls of the aperture, and / or the magnetic material is deposited to a thickness in the range of 5 nm to 20 nm.

[0041] The second approach achieves the same advantages as described above for the magnetic storage device of the first aspect. The second approach can be extended with corresponding implementations to obtain the implementations of the magnetic storage device of the first aspect described above.

[0042] A third aspect of this disclosure provides a method for operating the 3D magnetic memory device of the first aspect or any implementation thereof, wherein the method includes at least one of the following operations: writing magnetic bits into the magnetic channel by passing current through the SOT track, wherein the magnetic bits are written into the pinning site of the magnetic channel closest to the SOT track; pushing the magnetic bits along the magnetic channel from one pinning site to the next pinning site by passing current through a first electrode; and reading magnetic bits from the magnetic channel by passing current through the MTJ and thereby determining the tunneling magnetoresistance, wherein the magnetic bits stored in the pinning site of the magnetic channel closest to the MTJ are read.

[0043] The third aspect of the method allows for the performance of write, read, or push operations using the magnetic memory device of the first aspect, particularly within the memory cells of a magnetic memory device including magnetic channels. Similar operations can be performed sequentially or in parallel on different memory cells of the magnetic memory device.

[0044] In one implementation of the method, the magnetic memory device includes a second electrode, and driving the magnetic bit includes sending current from the second electrode to the first electrode; or the magnetic memory device does not include a second electrode but includes a second metallic layer, and driving the magnetic bit includes sending current from the second metallic layer to the first electrode; or the magnetic memory device includes a second electrode and the first metallic layer is configured as an SOT track, and driving the magnetic bit includes sending bipolar current from the second metallic layer to the first electrode.

[0045] The above implementation provides different ways to perform a pushing operation using the magnetic storage device of the first aspect.

[0046] In this method, when a magnetic bit stored in the magnetic channel is pushed, the magnetic bit stored in the pinning site closest to the first metallic layer in the magnetic material is destroyed, and the method further includes: rewriting the destroyed magnetic bit into the magnetic channel, or storing information corresponding to the destroyed magnetic bit in a memory. Attached Figure Description

[0047] The above aspects and implementations are explained in the following description of embodiments with reference to the accompanying drawings: Figure 1 An example of a magnetic storage device with a bottom SOT track according to the present disclosure is shown.

[0048] Figure 2 Another example of a magnetic storage device with a top SOT track according to this disclosure is shown.

[0049] Figure 3Another example of a magnetic storage device according to the present disclosure is shown, the magnetic storage device having a magnetic channel with a stepped, varying diameter.

[0050] Figure 4 Another example of a magnetic storage device having an out-of-plane MTJ according to the present disclosure is shown.

[0051] Figure 5 Another example of a magnetic memory device with a bottom electrode according to the present disclosure is shown.

[0052] Figure 6 Another example of a magnetic memory device according to the present disclosure is shown, which does not have a bottom electrode but has another top electrode.

[0053] Figure 7 A flowchart of a method for manufacturing a magnetic storage device according to the present disclosure is shown.

[0054] Figure 8 A first example of a method for manufacturing a magnetic memory device having a magnetic channel of constant diameter according to the present disclosure is illustrated.

[0055] Figure 9 A second example of a method for manufacturing a magnetic memory device according to the present disclosure is illustrated, the magnetic memory device having a magnetic channel with a stepped, varying diameter.

[0056] Figure 10 An example of writing magnetic bits into a magnetic memory device according to the present disclosure is shown.

[0057] Figure 11 An example of driving magnetic bits in a magnetic memory device according to the present disclosure is shown. Detailed Implementation

[0058] Figure 1 An example of a 3D magnetic storage device 10 according to the present disclosure is shown. Figure 1 (a) shows a cross-sectional side view, and Figure 1 (b) shows a top view of the cross section.

[0059] Similar to all examples of the 3D magnetic storage device 10 presented in this disclosure, Figure 1The 3D magnetic memory device 10 includes a layer stack 11 comprising a plurality of dielectric layers 11a (e.g., silicon oxide or silicon layers) and a plurality of silicon substrate layers 11b (e.g., silicon nitride or silicon-germanium layers) alternately disposed on top of each other. Magnetic channels 12 are formed through the stack 11. The magnetic channels 12 extend through each layer 11a, 11b of the stack 11. The magnetic channels 12 may extend along a first direction corresponding to the stacking orientation of the layers 11a, 11b of the stack 11. This first direction may be referred to as the "vertical direction," as it is in... Figure 1 Therefore, the magnetic channel 12 can extend perpendicularly to the surfaces of layers 11a and 11b of the stack 11. However, the magnetic channel 12 can also extend at an angle to the surfaces of layers 11a and 11b.

[0060] If available Figure 1 As further seen, and common to all examples of the 3D magnetic memory device 10 presented in this disclosure, the magnetic channel 12 comprises a hollow cylinder 12a made of a magnetic material, and a dielectric material 12b filling the hollow cylinder 12a (its inner core). Therefore, referring to similar channels in 3D NAND devices, the magnetic channel 12 is referred to as a macaroni channel or a macaroni-type channel. Along its extension length through the stack 11, the hollow cylinder 12a may have a constant wall thickness. The hollow cylinder 12a may have a constant outer diameter along its length. The diameter of the inner core of the hollow cylinder 12a filled with the dielectric material 12b may also be constant. In this case, the dielectric material 12b also has a cylindrical shape.

[0061] The magnetic material of the hollow cylinder 12a may be or includes a ferromagnetic or ferrimagnetic material. Alternatively or additionally, it may be or includes a conductive material. As an example, the magnetic material may include at least one of cobalt, iron, and nickel, or an alloy thereof. The magnetic material may also be any of the aforementioned magnetic materials and additionally contain boron. The dielectric material 12b may be an oxide, such as silicon oxide.

[0062] Due to the alternation of layers 11a and 11b of the stack 11, a plurality of pinning sites defined by the plurality of layers 11a and 11b of the stack are formed in the magnetic channel 12. Each of these pinning sites is configured to be stable and to store one magnetic bit.

[0063] like Figure 1As shown, the magnetic memory device 10 of various examples in this disclosure further includes a first metallic layer 13 disposed on a first end of the magnetic channel 12 and on the last layer of the stack 11. "Last layer" refers to the arrangement of layers 11a, 11b from the first layer of the stack to the last layer of the stack 11 along the stacking direction of layers 11a, 11b during the fabrication of the stack 11. The last layer may be a dielectric layer 11a as shown, or a silicon substrate 11b. An MTJ 14 is disposed on the first metallic layer 13. Furthermore, a first electrode 15 (also referred to as the "top electrode") is disposed on the first metallic layer 13 and spaced apart from the MTJ 14. The MTJ 14 includes at least a free layer, a reference layer, and a tunnel barrier layer, enabling the measurement of TMR, as known from conventional MRAMs. Advantageously, the MTJ 14 may include a magnetic free layer having coercive magnetism equal to or less than 20 mT to 40 mT or in the range of 2 mT to 3 mT.

[0064] like Figure 1 As shown in the example, MTJ 14 can be positioned directly above the first end of the magnetic channel 12 on the first metallic layer 13.

[0065] For example, targeting Figure 1 As illustrated, the magnetic memory device 10 may include a second metallic layer 16 configured as a SOT track. In this case, the second end of the magnetic channel 12 and the first layer of the stack 11 are disposed on the second metallic layer 16. The first layer of the stack 11 may be a silicon substrate 11n or a dielectric layer 11a as shown. Being configured as an SOT track means that the second metallic layer 16 can be made of a specific material, can have a specific thickness, and can be connected to suitable electrodes to allow SOT current (IT). SOT The SOT current passes through the second metallic layer 16. The SOT current passes through the SOT track to write magnetic bits into the magnetic channel by means of the SOT, where the magnetic bits are stabilized and thus stored in the pinning sites of the stack 11 defined by the layer closest to the second metallic layer 16, which will be explained later.

[0066] Figure 2 Another example of a 3D magnetic storage device 10 according to the present disclosure is shown. Figure 2 (a) shows a cross-sectional side view, and Figure 2 (b) shows a top view of the cross section. Figure 1 and Figure 2 The same elements in the 3D magnetic storage device 10 share the same reference numerals and can be implemented in the same way.

[0067] For example, regarding Figure 2 As shown in the example, it does not include a second metallic layer 16, and Figure 1Similar to the 3D magnetic memory device 10, the first metallic layer 13 can be configured as an SOT track. That is, the first metallic layer 13 can be made of a specific material, can have a specific thickness, and can be connected to suitable electrodes to allow the SOT current I. SOT Passing through the first metallic layer 13. This allows magnetic bits to be written into the magnetic channel 12 by means of SOT, and the magnetic bits are stabilized and thus stored by pinning sites defined by the layer of the stack 11 closest to the first metallic layer 13.

[0068] At least one of the first metallic layer 13 and the second metallic layer 16, particularly the metallic layers 13 and 16 configured as SOT orbitals, may be made of tantalum nitride, tungsten nitride, tungsten, tantalum, platinum, hafnium, molybdenum nitride, or alloys thereof, or may be made of a topological insulator.

[0069] At the first end of the magnetic channel 12, the inner core of the hollow cylinder 12a has a radius r1 of up to 100 nm or in the range of 10-80 nm. Exemplarily, the magnetic channel 12 may also have an outer diameter r, which may correspond to CD. The magnetic channel 12 may also have a height or length T along its extension direction through the stack 11. This length T may be subdivided into n magnetic units, each representing a magnetic bit. Each magnetic unit may have a height or thickness t, such that the product of n and t equals the height T. In conventionally designed devices, CD may take values ​​of approximately 30 nm, 50 nm, and / or 80 nm, and t may take values ​​from 15 nm to 50 nm. Moreover, depending on the magnetic orientation within the magnetic domains of a given unit, the magnetic bit may take a value of 0 or 1.

[0070] Figure 1 (b) and Figure 2 (b) shows that the magnetic channel 12 is shaped like a "donut" or ring (when viewed from above, i.e., along the extension of the magnetic channel 12). This allows for a reduction in the effective surface area through which current needs to flow. By reducing the surface area in this way, a similar result in terms of current reduction can be achieved, as if the magnetic memory device 10 were being reduced in size. This has the advantage of avoiding such reduction, which would lead to a more challenging and expensive manufacturing process.

[0071] Furthermore, the dielectric core 12b reduces the stray field, but the amount of reduction can be chosen in such a way that the aspect ratio of the macaroni channel can deviate further from the elongated structure while maintaining a stable magnetic orientation.

[0072] Figure 3 Another example of a 3D magnetic storage device 10 according to the present disclosure is shown. Figure 3 (a) shows a cross-sectional side view, and Figure 3 (b) shows a top view of the cross section. Figure 1 and Figure 3 The same elements in the 3D magnetic storage device 10 share the same reference numerals.

[0073] exist Figure 3 In the 3D magnetic memory device 10, the magnetic channel 12 has a first (outer) diameter d1 where it extends through the silicon substrate 11b and a second (outer) diameter d2 where it extends through the dielectric layer 11a of the stack 11. That is, the magnetic channel 12 has a varying diameter. This can be achieved by partially recessing the silicon substrate 11b or dielectric layer 11a of the stack 11 during the fabrication of the memory device 10, prior to forming the magnetic channel 12. For example, the first diameter can be larger than the second diameter, such as... Figure 1 As shown, but it can also be done in the opposite way.

[0074] The hollow cylinder 12a can be a stepped hollow cylinder 12a, because it can include a stepped diameter variation. However, the stepped hollow cylinder 12a can have a constant wall thickness. That is, the hollow cylinder 12a can be stepped relative to the inner core on its outer and inner surfaces. Similarly, the dielectric material 12b, which can be an oxide in this disclosure, can have a stepped cylindrical shape.

[0075] If the transition between the first diameter d1 and the second diameter d2 is aligned with the interface between the alternating layers 11a, 11b of the stack 11, it may be beneficial for pinning sites formed along the magnetic channel 12. In the case where the magnetic hollow channel 12 has varying diameters (d1 and d2), the recess can also enhance the pinning sites between magnetic domains. Therefore, this structure can provide approximately point-like pinning rather than layer pinning, and each individual layer 11a, 11b in the stack 11 (instead of just two layers) can be utilized for the pinning sites.

[0076] Figure 4 Another example of a 3D magnetic storage device 10 according to the present disclosure is shown. Figure 4 The same reference numerals are shared with the memory device 10 shown in the previous figures, and can be implemented similarly. Figure 4 The 3D magnetic storage device 10 is similar to Figure 3 The 3D magnetic memory device 10 includes magnetic channels 12 with varying diameters (d1 and d2). However, the magnetic memory device 10 may also include... Figure 1 or Figure 2 The magnetic channel 12 shown below. That is, the features described below are similar to... Figure 1 and Figure 2 It is compatible with constant diameter magnetic channels 12.

[0077] For example, regarding Figure 4As shown in the example, MTJ 14 can be positioned offset from the first end of magnetic channel 12, i.e., in this case, MTJ 14 is not located directly above the first end of magnetic channel 12. Therefore, MTJ 14 can be closer to or further away from the first electrode 15, such as... Figure 3 In the example shown, the MTJ 14 is also referred to as being set out of plane.

[0078] Figure 5 Another example of a 3D magnetic storage device 10 according to the present disclosure is shown. Figure 5 The same reference numerals are shared with the same elements as those in the magnetic storage device 10 shown in the previous figures, and they can be implemented in the same way. Figure 5 The example is specifically based on Figure 3 In the example, this is because it includes magnetic channels 12 with varying diameters (d1 and d2). However, the following characteristics also apply. Figure 1 and Figure 2 An example of a magnetic storage device 10 is a magnetic channel 12 with a constant diameter.

[0079] For example, regarding Figure 5 As shown in the example, the 3D magnetic memory device 10 may include a second electrode 51 (also referred to as a "bottom electrode") disposed on or directly below the second end of the magnetic channel 12. The second electrode 51 may be disposed on the second metallic layer 16, as shown. However, in the absence of the second metallic layer 16, as in... Figure 2 In this example, the second electrode 51 can be directly disposed at the second end of the magnetic channel 12 and on the first layer of the stack 11. The second electrode 51 can allow the driving current I to be applied. Push It is sent into the magnetic channel 12 and flows to the first electrode 15.

[0080] Figure 6 Another example of a 3D magnetic storage device 10 according to the present disclosure is shown. Figure 6 The same reference numerals are shared with the same elements as those in the memory device 10 shown in the previous figures, and they can be implemented in the same way. Figure 6 The example is specifically based on Figure 3 In the example, this is because it includes magnetic channels 12 with varying diameters (d1 and d2). However, the following characteristics also apply. Figure 1 and Figure 2 An example of a magnetic storage device 10 is a magnetic channel 12 with a constant diameter.

[0081] For example, regarding Figure 6 As shown in the example, the magnetic storage device 10 may include another first electrode 61 (also referred to as "another top electrode"). Furthermore, the magnetic storage device 10 may not include, for example... Figure 5The second electrode 51 is located at the bottom. Without the second electrode 51, a more compact memory cell can be obtained in the memory device 10, resulting in a smaller footprint for the memory device 10 including multiple such memory cells. Figure 6 In the example, the driving current I can be provided by sending current through both sides of the SOT track provided by the second metallic layer 16. Push Specifically, current is pushed from both sides to limit the current density in the second metallic layer 16 and increase its durability and reliability.

[0082] Figure 7 A flowchart of a method 70 for manufacturing a 3D magnetic memory device 10 of the present disclosure is shown, wherein method 70 is applicable to all previous examples. Figure 8 and Figure 9 An exemplary illustration is shown of an exemplary implementation of method 70. Figure 8 This relates to a 3D magnetic memory device 10 with a magnetic channel 12 of constant diameter, and Figure 9 A 3D magnetic memory device 10 relating to a magnetic channel 12 with varying diameters.

[0083] like Figure 7 As shown, method 70 includes step 71 of forming a stack 11 of a plurality of dielectric layers 11a and silicon substrates 11b, wherein the plurality of dielectric layers 11a and silicon substrates 11b are alternately disposed on one over the other (see also...). Figure 8 (a) and Figure 9 (a)). Method 70 further includes step 72 of forming a hole 81 through the stack 11, wherein the hole 81 extends through layers 11a, 11b of the stack 11 (see also...). Figure 8 (b) and Figure 9 (b)). Then, method 70 includes step 73 of depositing magnetic material onto the sidewalls of the hole to form a hollow cylinder 12a made of magnetic material (see also...). Figure 8 (c) and Figure 9 (d)). Magnetic materials can be formed by conformal deposition on the sidewalls of the aperture 81, which is why some magnetic materials, as shown, can also be deposited on the bottom surface of the aperture 81. Then, method 70 includes step 74 of filling the hollow cylinder 12a with dielectric material 12b to form a magnetic channel comprising the hollow cylinder 12a and dielectric filling material 12b (see also...). Figure 8 (d) and Figure 9 (e)). Note that in Figure 8 (e) and Figure 9 In (f), some magnetic material deposited on the top surface of the stack 11 during the formation of the hollow cylinder 12 can be removed to allow subsequent steps, including the formation of the first metallic layer 13, to be carried out.

[0084] like Figure 7 The diagram further shows that method 70 accordingly includes step 75 of forming a first metallic layer 13 on the first end of magnetic channel 12 and the last layer of stack 11, and step 76 of forming MTJ 14 on the first metallic layer 13. Then, method 70 also includes step 77 of forming a first electrode 15 spaced apart from MTJ 14 on the first metallic layer 13.

[0085] If the 3D magnetic storage device 10 is as follows Figures 3 to 6 In the example shown (i.e., having a magnetic channel 12 with varying diameters), method 70 may include the following steps. After forming the aperture 81, method 70 may include a step of selectively etching from within the aperture 81 to form a recess 91 in the dielectric layer 11a or silicon substrate 11b, thereby partially widening the aperture (see [link to documentation]). Figure 9 (c)). Then, step 73 may include depositing magnetic material onto the sidewall of the recessed hole 81 to form a stepped hollow cylinder 12a made of magnetic material (see (c)). Figure 9 (d)). After step 74, in which the magnetic material is filled into the stepped hollow cylinder 12a, a magnetic channel 12 with varying diameters can be formed. That is, the magnetic channel 12 has a first diameter d1 where it extends through the silicon substrate 11b of the stack, and a second diameter d2 where it extends through the dielectric layer 11a of the stack 11. Note that Figure 9 (c) shows that in this case, the dielectric layer 11a is recessed, such that in this case, the first diameter d1 will be smaller than the second diameter d2.

[0086] Figure 10 An example of writing magnetic bits into a magnetic memory device 10 according to the present disclosure is shown. Figure 10 Specifically shown Figure 5 The example of the 3D magnetic storage device 10 is shown to demonstrate the write operation. Figure 10 (a) shows the magnetic memory device 10 before / during a write operation, while Figure 10 (b) shows the magnetic storage device 10 after a write operation.

[0087] By making the current I SOT The writing of magnetic bits into magnetic channel 12 is caused by passing through the second metallic layer 16, which is configured as the SOT track. The magnetic bits are written into magnetic channel 12 and stored by the pinning site in magnetic channel 12 closest to the SOT track, corresponding to the pinning site in the first layer of magnetic channel 12. Positive or negative current I SOT The writing of the magnetic bit is determined as "up" or "down" (for perpendicular magnetization) or "left" or "right" (for in-plane magnetization). For example, in Figure 10In (b), the writing of the magnetic bit has already caused the bit to switch, that is, the switching of magnetization stabilized by the corresponding pinning site.

[0088] Figure 11 An example of driving magnetic bits in a magnetic memory device 10 according to the present disclosure is shown. Figure 11 Specifically shown Figure 5 An example of a 3D magnetic storage device 10, used to demonstrate what happens after a write operation. Figure 11 The push operation is shown. Pushing the magnetic bit moves it along magnetic channel 12 from one pinning point to the next pinning point. When using... Figure 5 In the example, the magnetic bit is Figure 11 The magnetic channel 12 is pushed upward, that is, towards MTJ 14.

[0089] By using current I Push The magnetic bit is driven through the first electrode 15. Figure 11 In this process, current is fed into the second electrode 41 via the first electrode 15. If the second electrode 51 is not present, then... Figure 6 As illustrated, a current I is sent to the first electrode 15 using the second metallic layer 16. Push During the driving operation, the pulse timing can advantageously be synchronized with a period of domain wall motion (the motion of a pinning site). The driving current I... Push Move all magnetic bits (pinned domains) upwards by one pinning point. Figure 7 At the top of the magnetic channel 12, the surface of the first end of the magnetic channel 12 is advantageously flat, for example, it can be flattened by chemical mechanical polishing (CMP). In this case, the first metallic layer 13 can act as a thin metallic spacer layer (where it can be made of TaN) to provide a path for current to reach the first electrode 15.

[0090] To read the magnetic bits, one can... Figure 5 In the example 3D magnetic memory device 10, the magnetic state of the topmost magnetic bit is sensed. This can be accomplished using a top-pinned MTJ 14. The free layer of the MTJ 14 can be deposited in direct contact with the first metallic layer 13. This free layer can have a low coercivity of less than 40 mT, such that the stray magnetic field of the top magnetic bit (e.g., "up" or "down", higher than the coercivity of the free layer) can determine the orientation of the free layer. Actual sensing can then be performed by reading the resistance and TMR effect of the MTJ 14.

[0091] Because in this example, the magnetic bit that reaches the top of magnetic channel 12 (which can be read using MTJ 14) will be annihilated on the next push, the read operation of magnetic memory device 10 can be a destructive read. This magnetic bit can then be rewritten at the bottom of magnetic channel 12 (i.e., at the SOT track), or it can be stored in a buffer memory, for example, for a later burst write.

[0092] The magnetic memory device 10 can operate, for example, in a “full string” write and / or read mode. This means that the minimum addressable bit length can be equal to the number of layers 11a / 11b in the stack 11. However, the operating mode of the magnetic memory device 10 can also be determined by the array and system-level architecture selection.

[0093] As already explained, the memory architecture of the magnetic memory device 10 of this disclosure includes a sequential read / write structure, wherein magnetic bits are vertically stacked within and along the magnetic channel 12, comprising a magnetic material (e.g., cobalt, nickel, iron, alloys thereof), in the form of oriented magnetic domains (stabilized by pinning sites). Magnetic domain pinning is achieved by using a stack of layers 11 having a morphology dependent on the application of interest (e.g., a SiN / SiO matrix).

[0094] On one hand, writing can be performed at the bottom of the stack 11 by generating track injection current through the SOT, allowing the bottommost magnetic bit to have an orientation dependent on the current polarity. On the other hand, reading can be performed at the top by reading the resistance of the MTJ 14 and through the TMR effect, using the MTJ 14 to sense the stray field of the topmost pinning site. After the write operation, the magnetic bit can be pushed upwards by applying current from the bottom electrode of the stack 11 through the magnetic channel 12 to the top electrode.

[0095] In the claims and the description of this disclosure, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single element can perform the function of several entities or items described in the claims. The fact that certain measures are referenced in mutually different dependent claims does not mean that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. A three-dimensional magnetic storage device (10), the magnetic storage device (10) comprising: A stack (11) comprising a plurality of dielectric layers (11a) and a silicon substrate (11b), wherein the plurality of dielectric layers (11a) and the silicon substrate (11b) are alternately disposed on the other; Magnetic channels (12) extend through the layers (11a, 11b) of the stack (11). The magnetic channel (12) includes a hollow cylinder (12a) made of magnetic material and a dielectric material (12b) filling the hollow cylinder (12a). In the magnetic channel (12), a plurality of pinning sites are formed, defined by the plurality of layers (11a, 11b) of the stack (12), and each pinning site is configured to store a magnetic bit. A first metallic layer (13) is disposed on the first end of the magnetic channel (12) and on the last layer of the stack (11); A magnetic tunnel junction (MTJ) (14), wherein the MTJ (14) is disposed on the first metallic layer (13); and The first electrode (15) is disposed on the first metallic layer (13) separately from the MTJ (14); Wherein, the first metallic layer (13) is configured as a spin orbital (SOT) orbital, or the magnetic memory device (10) includes a second metallic layer (16) configured as an SOT orbital and the second end of the magnetic channel (12) and the first layer of the stack (11) are disposed on the second metallic layer (16).

2. The 3D magnetic storage device (10) according to claim 1, wherein, The magnetic channel (12) has a first diameter (d1) where it extends through the silicon substrate (11b) and a second diameter (d2) where it extends through the dielectric layer (11a) of the stack (11).

3. The 3D magnetic storage device according to claim 2, wherein, The first diameter (d1) is larger than the second diameter (d2).

4. The 3D magnetic storage device (10) according to claim 2 or 3, wherein, The ratio of the first diameter (d1) to the second diameter (d2) is in the range of 1.1:1 to 2:

1.

5. The 3D magnetic storage device (10) according to any one of claims 2 to 4, wherein, The transition between the first diameter (d1) and the second diameter (d2) is aligned with the interface between the alternating layers (11a, 11b) of the stack (11).

6. The 3D magnetic storage device (10) according to any one of claims 2 to 5, wherein, The hollow cylinder (12a) is a stepped hollow cylinder (12a).

7. The 3D magnetic storage device (10) according to claim 6, wherein, The stepped hollow cylinder (12a) has a constant wall thickness (t1).

8. The 3D magnetic storage device (10) according to any one of claims 1 to 7, wherein, At the first end of the magnetic channel (12), the inner core of the hollow cylinder (12a) has a radius (r1) of up to 100 nm or in the range of 10 nm to 80 nm.

9. The 3D magnetic storage device (10) according to any one of claims 1 to 8, wherein, The length (T) of the magnetic channel (12) along the extension direction of the magnetic channel (12) through the stack (11) is in the range of 5 nm to 150 nm multiplied by the number of layers (11a, 11b) of the stack (11).

10. The 3D magnetic storage device (10) according to any one of claims 1 to 9, wherein, The magnetic material of the hollow cylinder (12a) is a ferromagnetic or ferrimagnetic material and / or a conductive material, such as cobalt, iron, nickel or their alloys, or any of the foregoing materials may also contain boron.

11. The 3D magnetic storage device (10) according to any one of claims 1 to 10, wherein, The dielectric layer (11a) is a silicon oxide layer and the silicon substrate (11b) is a silicon nitride layer, or the dielectric layer (11a) is a silicon layer and the silicon substrate (11b) is a silicon-germanium layer; and / or The dielectric material (12b) filling the hollow cylinder (12a) is silicon oxide.

12. The 3D magnetic memory device (10) according to any one of claims 1 to 11, the 3D magnetic memory device (10) further includes a second electrode (51) disposed on or directly below the second end of the magnetic channel (12).

13. A method (70) for manufacturing a 3D magnetic memory device (10), the method (70) comprising the following steps: A stack (11) is formed of a plurality of dielectric layers (11a) and silicon substrates (11b), wherein the plurality of dielectric layers (11a) and silicon substrates (11b) are alternately disposed on one another; Form (72) a hole (81) extending through the layers (11a, 11b) of the stack (11). Magnetic material is deposited (73) onto the sidewall of the hole (81) to form a hollow cylinder (12a) made of the magnetic material. The hollow cylinder (12a) is filled (74) with dielectric material (12b) to form a magnetic channel (12) including the hollow cylinder (12a) and the dielectric material (12b). In the magnetic channel (12), a plurality of stacked pinning sites are formed, defined by the plurality of layers (11a, 11b) of the stack (11), and each pinning site is configured to store a magnetic bit. A first metallic layer (13) is formed (75) on the first end of the magnetic channel (12) and on the last layer of the stack (11). A magnetic tunnel junction (MTJ) (14) is formed on the first metallic layer (13); and A first electrode (15) is formed on the first metallic layer (13) spaced apart from the MTJ (14). The first metallic layer (13) is configured as a spin orbital (SOT) orbital, or the method (70) further includes forming a second metallic layer (16) configured as an SOT orbital and placing the second end of the magnetic channel (12) and the first layer of the stack (11) on the second metallic layer (16).

14. The method (70) according to claim 13, wherein the method comprises: After forming (72) the hole (81), selective etching is performed from within the hole (81) to recess (91) the dielectric layer (11a) or the silicon substrate (11b) to partially widen the hole (81); and The magnetic material is deposited (73) onto the sidewall with recessed holes (81) to form a stepped hollow cylinder (12a) made of the magnetic material.

15. The method (10) according to claim 13 or 14, wherein, The magnetic material is formed by conformal deposition on the sidewalls of the hole (81), and / or the magnetic material is deposited to a thickness in the range of 5 nm to 20 nm.

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