A magnetic memory cell, a method of fabricating the same, and a magnetic memory

Abstract

The application discloses a preparation method of a magnetic storage unit. The method comprises the following steps: sequentially arranging a magnetic free layer, an insulating tunnel layer, a magnetic reference layer and a mask layer on the surface of a preset spin-orbit torque metal substrate in sequence to obtain a to-be-etched unit; etching the mask layer, the magnetic reference layer and the insulating tunnel layer to obtain an etched workpiece comprising a columnar protrusion; arranging a protective layer on the surface of the etched workpiece; performing directional treatment on the magnetic free layer of a columnar peripheral region to form a high-resistivity region, thereby obtaining a storage unit preset; and removing the protective layer above the mask layer of the storage unit preset to obtain the magnetic storage unit. The magnetic free layer plays the role of the protective layer of the spin-orbit torque metal substrate, and the thickness uniformity of the spin-orbit torque metal substrate is not damaged. The application also provides a magnetic storage unit and a magnetic storage device with the above beneficial effects.

Description

Technical Field

[0001] This invention relates to the field of storage technology, and in particular to a magnetic storage unit and its preparation method, and a magnetic memory. Background Technology

[0002] Compared to traditional STT-MRAM (Spin-Torque Magnetic Random Access Memory), SOT-MRAM (Spin-Orbit Magnetic Random Access Memory) retains the excellent characteristics of MRAM, such as high speed and low power consumption, while achieving low write voltage and read / write path separation. It holds promise as a replacement for STT-MRAM, utilizing spin-orbit moments to achieve fast and reliable magnetization switching. However, in MTJ (Magnetic Tunnel Junction) based spin-orbit magnetic memory, the free layer provides direct line contact with the spin-orbit moment. It is important to note that since the magnitude of the current passing through it directly controls the memory cells, the surface flatness of the ultrathin spin-orbit moment material is extremely critical. Excessive thickness variations at different locations can lead to inconsistent internal currents, thereby reducing the reliability of the memory device.

[0003] In the existing technology, the etching and chemical mechanical polishing processes during device fabrication inevitably affect the spin orbital moment metal substrate, and the inhomogeneity of etching and polishing further increases the inhomogeneity of the spin orbital moment metal substrate.

[0004] Therefore, finding a way to avoid damage to the spin orbital moment metal substrate during etching and polishing processes, and to improve the thickness uniformity of the spin orbital moment metal substrate, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a magnetic storage unit and its preparation method, as well as a magnetic memory, to solve the problem in the prior art where the etching and polishing processes damage the spin-orbit moment metal substrate, resulting in poor uniformity of the spin-orbit moment metal substrate thickness.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for fabricating a magnetic storage cell, comprising:

[0007] On the surface of a pre-defined spin orbital metal substrate, a magnetic free layer, an insulating tunnel layer, a magnetic reference layer, and a mask layer are sequentially arranged outwards to obtain the unit to be etched.

[0008] The mask layer, the magnetic reference layer, and the insulating tunnel layer are etched to obtain an etched workpiece including columnar protrusions;

[0009] A protective layer is provided on the surface of the etched workpiece;

[0010] The magnetic free layer of the columnar peripheral region is oriented to form a high resistivity region, thus obtaining a memory cell preform.

[0011] Remove the protective layer above the mask layer of the storage cell preform to obtain the magnetic storage cell.

[0012] Optionally, in the method for preparing the magnetic storage cell, the directional treatment of the magnetic free layer in the columnar peripheral region to form a high resistivity region, thereby obtaining the storage cell preform, includes:

[0013] The magnetic free layer of the columnar outer region is doped to form a high resistivity region, thus obtaining the memory cell preform.

[0014] Optionally, in the method for fabricating the magnetic storage cell, the directional treatment of the magnetic free layer in the columnar peripheral region to form a high resistivity region, thereby obtaining the storage cell preform, includes:

[0015] The magnetic free layer of the columnar outer region is directionally oxidized to form a high resistivity region, thus obtaining the memory cell preform.

[0016] Optionally, in the method for fabricating the magnetic storage cell, before oriented processing of the magnetic free layer in the columnar peripheral region to form a high resistivity region, the method further includes:

[0017] Remove the protective layer from the surface of the magnetic free layer, while retaining the protective layer on the sidewalls of the columnar protrusions.

[0018] Optionally, in the method for fabricating the magnetic storage cell, before setting the protective layer on the surface of the etched workpiece, the method further includes:

[0019] The sidewalls of the columnar protrusions are physically cleaned.

[0020] Optionally, in the method for fabricating the magnetic storage cell, the physical cleaning includes plasma cleaning or ion beam etching.

[0021] Optionally, in the method for fabricating the magnetic storage cell, the protective layer is deposited on the surface of the etched workpiece by any one of sputtering deposition, ion beam deposition, chemical vapor deposition, or atomic layer deposition.

[0022] A magnetic storage cell, from bottom to top, comprises a spin-orbit-moment metal substrate, a magnetic free layer, columnar protrusions, and a protective layer;

[0023] The columnar protrusions, from bottom to top, include an insulating tunnel layer, a magnetic reference layer, and a mask layer;

[0024] The magnetic free layer includes a high resistivity region located in the outer periphery of the columnar region and a low resistivity region located in the columnar region;

[0025] The protective layer is disposed on the side surface of the columnar protrusion and the upper surface of the magnetic free layer.

[0026] Optionally, in the magnetic storage cell, the protective layer is any one of a silicon nitride layer, a silicon oxide layer, or a silicon oxynitride layer.

[0027] A magnetic memory comprising magnetic storage cells as described in any of the above.

[0028] The method for fabricating a magnetic storage cell provided by this invention involves sequentially depositing a magnetic free layer, an insulating tunnel layer, a magnetic reference layer, and a mask layer outwards on the surface of a pre-defined spin-orbit metal substrate to obtain a cell to be etched; etching the mask layer, the magnetic reference layer, and the insulating tunnel layer to obtain an etched workpiece including columnar protrusions; depositing a protective layer on the surface of the etched workpiece; oriented the magnetic free layer in the peripheral region of the columnar protrusions to form a high resistivity region to obtain a storage cell preform; and removing the protective layer above the mask layer of the storage cell preform to obtain the magnetic storage cell.

[0029] Unlike existing technologies, this invention does not directly etch the magnetic free layer into the columnar protrusions during the etching process. In other words, the etching in this invention stops after etching the insulating tunnel layer. The magnetic free layer still covers the surface of the spin-orbit moment metal substrate after etching, thus acting as a protective layer for the spin-orbit moment metal substrate. The etching process and subsequent polishing processes do not directly affect the spin-orbit moment metal substrate, ensuring that the thickness uniformity of the spin-orbit moment metal substrate is not compromised. Furthermore, this application increases the resistance of the magnetic free layer in the columnar peripheral region by oxygen doping, leaving only the magnetic free layer in the columnar region as conductive, thereby completing the fabrication of the magnetic tunnel junction. This invention also provides a magnetic storage unit and a magnetic memory with the above-mentioned beneficial effects. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic diagram showing the connection structure between the magnetic storage unit and the external circuit when the unit is working.

[0032] Figure 2A flowchart illustrating a specific embodiment of the method for fabricating a magnetic storage cell provided by the present invention;

[0033] Figure 3 A flowchart illustrating another specific embodiment of the method for preparing a magnetic storage cell provided by the present invention;

[0034] Figures 4 to 6 A flowchart of intermediate processes for a specific embodiment of the method for fabricating a magnetic storage cell provided by the present invention;

[0035] Figure 7 A schematic diagram of a specific embodiment of the magnetic storage unit provided by the present invention;

[0036] Figure 8 Signal path diagram of a specific embodiment of the magnetic storage cell provided by the present invention;

[0037] Figure 9 This is a signal path diagram of another specific embodiment of the magnetic storage cell provided by the present invention. Detailed Implementation

[0038] The connection method between the magnetic storage unit and the external circuit is as follows: Figure 1 As shown, the magnetic storage cell has its first port connected to the drain of the write word line transistor, its second port connected to the bit line, and its third port connected to the drain of the read word line transistor. The source of the read word line transistor and the source of the write word line transistor are connected to the source line.

[0039] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The core of this invention is to provide a method for fabricating a magnetic storage cell, and a flowchart of one specific embodiment is shown below. Figure 2 As shown, this is referred to as Specific Implementation Method One, which includes:

[0041] S101: On the surface of the preset spin orbital metal substrate 10, a magnetic free layer 20, an insulating tunnel layer 30, a magnetic reference layer 40 and a mask layer 50 are sequentially arranged outward to obtain the unit to be etched.

[0042] S102: Etch the mask layer 50, the magnetic reference layer 40 and the insulating tunnel layer 30 to obtain an etched workpiece including columnar protrusions.

[0043] A schematic diagram of the etched workpiece after etching is shown below. Figure 4 As shown, it should be noted that the purpose of retaining the magnetic free layer 20 in this invention is to protect the spin orbital moment metal substrate 10 below. Therefore, in this step, even if the etched surface is not perfectly left at the boundary between the insulating tunnel layer 30 and the magnetic free layer 20, but a magnetic free layer 20 of a certain thickness is etched, it is still acceptable.

[0044] S103: A protective layer 60 is provided on the surface of the etched workpiece.

[0045] The structure of the etched workpiece with the protective layer 60 provided is also shown in the schematic diagram below. Figure 5 As shown, in a preferred embodiment, before the protective layer 60 is formed on the etched workpiece surface, the method further includes:

[0046] Physical cleaning of the sidewalls of the columnar epitaxial layer is performed to repair damage near the tunnel junction and to prevent irregular edges or residual chemicals from affecting the protective layer 60 during etching. Furthermore, the physical cleaning includes plasma cleaning or ion beam etching.

[0047] Furthermore, the protective layer 60 is deposited on the surface of the etched workpiece by any one of sputtering deposition, ion beam deposition, chemical vapor deposition, or atomic layer deposition. Of course, other methods can also be selected according to the actual situation.

[0048] S104: Orient the magnetic free layer 20 of the columnar peripheral region to form a high resistivity region 21, and obtain the storage cell preform.

[0049] The columnar peripheral region refers to the area outside the projection area of ​​the columnar protrusion on the magnetic free layer 20, which is not below the columnar protrusion. For details, please refer to [reference needed]. Figure 6 , Figure 6 The area not located below the columnar protrusion is the outer perimeter of the columnar protrusion. Of course, in actual production, the high-resistivity free layer that is oxygen-doped may extend partially below the columnar protrusion, but this has little impact on the beneficial effects of the present invention.

[0050] S105: Remove the protective layer 60 above the mask layer 50 of the storage cell preform to obtain a magnetic storage cell.

[0051] The method for fabricating a magnetic storage cell provided by the present invention involves sequentially depositing a magnetic free layer 20, an insulating tunnel layer 30, a magnetic reference layer 40, and a mask layer 50 outwards on the surface of a pre-defined spin-orbit metal substrate 10 to obtain a cell to be etched; etching the mask layer 50, the magnetic reference layer 40, and the insulating tunnel layer 30 to obtain an etched workpiece including columnar protrusions; depositing a protective layer 60 on the surface of the etched workpiece; oriented the magnetic free layer 20 in the outer region of the columnar protrusions to form a high resistivity region 21 to obtain a storage cell preform; and removing the protective layer 60 above the mask layer 50 of the storage cell preform to obtain the magnetic storage cell. Unlike existing technologies, this invention does not directly etch the magnetic free layer 20 into the columnar protrusion during the etching process. In other words, the etching in this invention stops after etching the insulating tunnel layer 30. The magnetic free layer 20 still covers the surface of the spin-orbit moment metal substrate 10 after etching, so that the magnetic free layer 20 acts as a protective layer 60 for the spin-orbit moment metal substrate 10. The etching process and subsequent polishing process do not directly affect the spin-orbit moment metal substrate 10, thus ensuring that the thickness uniformity of the spin-orbit moment metal substrate 10 is not destroyed. In addition, this application increases the resistance of the magnetic free layer 20 in the columnar peripheral region by oxygen doping, leaving only the magnetic free layer 20 in the columnar region to conduct electricity, thus completing the fabrication of the magnetic tunnel junction.

[0052] Based on Specific Embodiment 1, the protective layer 60 is further processed before oxygen doping of the magnetic free layer 20 in the columnar peripheral region, resulting in Specific Embodiment 2, the structural schematic of which is shown below. Figure 3 As shown, it includes:

[0053] S201: On the surface of the preset spin orbital metal substrate 10, a magnetic free layer 20, an insulating tunnel layer 30, a magnetic reference layer 40 and a mask layer 50 are sequentially arranged outward to obtain the unit to be etched.

[0054] S202: Etch the mask layer 50, the magnetic reference layer 40 and the insulating tunnel layer 30 to obtain an etched workpiece including columnar protrusions.

[0055] S203: A protective layer 60 is provided on the surface of the etched workpiece.

[0056] S204: Remove the protective layer 60 from the surface of the magnetic free layer 20, while retaining the protective layer 60 on the columnar protrusion sidewall.

[0057] S205: Orient the magnetic free layer 20 of the columnar peripheral region to form a high resistivity region 21, and obtain the memory cell preform.

[0058] S206: Remove the protective layer 60 above the mask layer 50 of the storage cell preform to obtain a magnetic storage cell.

[0059] In this specific embodiment, before oxygen doping the etched workpiece with the protective layer 60, the protective layer 60 of the columnar peripheral region is removed, directly exposing the upper surface of the magnetic free layer 20 located in the columnar peripheral region. This allows for faster, more thorough, and more uniform subsequent oxygen doping, improving production efficiency while enhancing the quality of the oxidized high resistivity free region in the final product. A schematic diagram of the magnetic storage unit corresponding to this specific embodiment can be found in [reference needed]. Figure 7 .

[0060] The present invention also provides a magnetic storage unit, the structural schematic diagram of one specific embodiment of which is shown below. Figure 7 As shown, it is referred to as Specific Implementation Method 3, which includes, from bottom to top, a spin orbital metal substrate 10, a magnetic free layer 20, columnar protrusions and a protective layer 60.

[0061] The columnar protrusions, from bottom to top, include an insulating tunnel layer 30, a magnetic reference layer 40, and a mask layer 50.

[0062] The magnetic free layer 20 includes a high resistivity region 21 located in the outer periphery of the columnar region and a low resistivity region 22 located in the columnar region;

[0063] The protective layer 60 is disposed on the side surface of the columnar protrusion and the upper surface of the magnetic free layer 20.

[0064] In a preferred embodiment, the protective layer 60 is any one of a silicon nitride layer, a silicon oxide layer, or a silicon oxynitride layer.

[0065] In addition, the spin orbital moment metal matrix 10 is a matrix of platinum, tungsten, gold, molybdenum or tantalum metal.

[0066] Furthermore, the thickness of the spin-orbit moment metal substrate 10 ranges from 1 nanometer to 10 nanometers, including endpoint values ​​such as 1.0 nanometer, 5.0 nanometer, or 10.0 nanometer; the thickness of the magnetic free layer 20 ranges from 1 nanometer to 5 nanometers, including endpoint values ​​such as 1.0 nanometer, 3.2 nanometer, or 5.0 nanometer.

[0067] The magnetic storage unit provided by this invention is applicable to both two-port and three-port devices, and its signal transmission diagram is as follows. Figure 8 and Figure 9 As shown.

[0068] in Figure 8This is a two-port device, consisting of two ports: port 1, connected to one side of the spin-orbit metal, and port 2, connected to the top of the MTJ. During data writing, current flows through the spin-orbit metal and the MTJ. The write direction (0 / 1) is changed by alternating current flow: either the write current flows from port 1 to port 2, or vice versa. During data reading, the read current flows through the MTJ, and data is read based on the resistance between ports 1 and 2.

[0069] Figure 9 This is a three-port device, comprising three ports: ports 1 and 2 located on either side of the spin-orbit metal (MTJ) pillar, and port 3 located at the top of the MTJ. During data writing, current flows through the spin-orbit metal material. The write current direction is changed to achieve 0 / 1, i.e., the write current flows from port 1 to port 2, or from port 2 to port 1. During data reading, the read current flows through the MTJ, and data is read through the resistance value between ports 1 and 3, or between ports 2 and 3.

[0070] The magnetic storage cell provided by the present invention comprises, from bottom to top, a spin-orbit moment metal substrate 10, a magnetic free layer 20, columnar protrusions, and a protective layer 60; the columnar protrusions comprise, from bottom to top, an insulating tunnel layer 30, a magnetic reference layer 40, and a mask layer 50; the magnetic free layer 20 comprises a high resistivity region 21 located in the peripheral region of the columnar protrusions and a low resistivity region 22 located in the columnar region; the protective layer 60 is disposed on the side surface of the columnar protrusions and the upper surface of the magnetic free layer 20. Unlike existing technologies, this invention does not directly etch the magnetic free layer 20 into the columnar protrusion during the etching process. In other words, the etching in this invention stops after etching the insulating tunnel layer 30. The magnetic free layer 20 still covers the surface of the spin-orbit moment metal substrate 10 after etching, so that the magnetic free layer 20 acts as a protective layer 60 for the spin-orbit moment metal substrate 10. The etching process and subsequent polishing process do not directly affect the spin-orbit moment metal substrate 10, thus ensuring that the thickness uniformity of the spin-orbit moment metal substrate 10 is not destroyed. In addition, this application increases the resistance of the magnetic free layer 20 in the columnar peripheral region by oxygen doping, leaving only the magnetic free layer 20 in the columnar region to conduct electricity, thus completing the fabrication of the magnetic tunnel junction.

[0071] The present invention also provides a magnetic memory with the above-mentioned beneficial effects, the magnetic memory comprising a magnetic memory cell as described in any of the above-described methods. The method for fabricating the magnetic memory cell provided by the present invention involves sequentially depositing a magnetic free layer 20, an insulating tunnel layer 30, a magnetic reference layer 40, and a mask layer 50 outwardly on the surface of a pre-defined spin-orbit metal substrate 10 to obtain a cell to be etched; etching the mask layer 50, the magnetic reference layer 40, and the insulating tunnel layer 30 to obtain an etched workpiece including columnar protrusions; depositing a protective layer 60 on the surface of the etched workpiece; orienting the magnetic free layer 20 in the columnar peripheral region to form a high resistivity region 21 to obtain a memory cell preform; and removing the protective layer 60 above the mask layer 50 of the memory cell preform to obtain the magnetic memory cell. Unlike existing technologies, this invention does not directly etch the magnetic free layer 20 into the columnar protrusion during the etching process. In other words, the etching in this invention stops after etching the insulating tunnel layer 30. The magnetic free layer 20 still covers the surface of the spin-orbit moment metal substrate 10 after etching, so that the magnetic free layer 20 acts as a protective layer 60 for the spin-orbit moment metal substrate 10. The etching process and subsequent polishing process do not directly affect the spin-orbit moment metal substrate 10, thus ensuring that the thickness uniformity of the spin-orbit moment metal substrate 10 is not destroyed. In addition, this application increases the resistance of the magnetic free layer 20 in the columnar peripheral region by oxygen doping, leaving only the magnetic free layer 20 in the columnar region to conduct electricity, thus completing the fabrication of the magnetic tunnel junction.

[0072] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0073] It should be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0074] The magnetic storage unit, its preparation method, and the magnetic memory provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A method for fabricating a magnetic storage cell, characterized in that, include: On the surface of a pre-defined spin orbital metal substrate, a magnetic free layer, an insulating tunnel layer, a magnetic reference layer, and a mask layer are sequentially arranged outwards to obtain the unit to be etched. The mask layer, the magnetic reference layer, and the insulating tunnel layer are etched to obtain an etched workpiece including columnar protrusions; A protective layer is provided on the surface of the etched workpiece; The magnetic free layer of the columnar peripheral region is oriented to form a high resistivity region, thus obtaining a memory cell preform. Remove the protective layer above the mask layer of the storage cell preform to obtain the magnetic storage cell; Before oriented processing of the magnetic free layer in the outer region of the columnar structure to form a high resistivity region, the following steps are also included: Remove the protective layer from the surface of the magnetic free layer, while retaining the protective layer on the columnar protrusion sidewalls.

2. The method for preparing a magnetic storage cell as described in claim 1, characterized in that, The process of orienting the magnetic free layer in the columnar peripheral region to form a high resistivity region, resulting in a memory cell preform, includes: The magnetic free layer in the outer region of the columnar structure is doped to form a high resistivity region, thus obtaining a memory cell preform.

3. The method for preparing a magnetic storage cell as described in claim 1, characterized in that, The process of orienting the magnetic free layer in the columnar peripheral region to form a high resistivity region, resulting in a memory cell preform, includes: The magnetic free layer of the columnar outer region is directionally oxidized to form a high resistivity region, thus obtaining the memory cell preform.

4. The method for preparing a magnetic storage cell as described in claim 1, characterized in that, Before applying a protective layer to the etched workpiece surface, the method further includes: The sidewalls of the columnar protrusions are physically cleaned.

5. The method for preparing a magnetic storage cell as described in claim 4, characterized in that, The physical cleaning includes plasma cleaning or ion beam etching.

6. The method for preparing a magnetic storage cell as described in claim 1, characterized in that, The protective layer is applied to the surface of the etched workpiece by any one of sputtering deposition, ion beam deposition, chemical vapor deposition, or atomic layer deposition.

7. A magnetic storage unit, characterized in that, From bottom to top, it includes a spin orbital metal substrate, a magnetic free layer, columnar protrusions, and a protective layer; The columnar protrusions, from bottom to top, include an insulating tunnel layer, a magnetic reference layer, and a mask layer; The magnetic free layer includes a high resistivity region located in the outer periphery of the columnar region and a low resistivity region located in the columnar region; The protective layer is disposed on the side surface of the columnar protrusion and the upper surface of the magnetic free layer; The method for preparing the magnetic storage cell includes: On the surface of a pre-defined spin orbital metal substrate, a magnetic free layer, an insulating tunnel layer, a magnetic reference layer, and a mask layer are sequentially arranged outwards to obtain the unit to be etched. The mask layer, the magnetic reference layer, and the insulating tunnel layer are etched to obtain an etched workpiece including columnar protrusions; A protective layer is provided on the surface of the etched workpiece; The magnetic free layer of the columnar peripheral region is oriented to form a high resistivity region, thus obtaining a memory cell preform. Remove the protective layer above the mask layer of the storage cell preform to obtain the magnetic storage cell; Before oriented processing of the magnetic free layer in the outer region of the columnar structure to form a high resistivity region, the following steps are also included: Remove the protective layer from the surface of the magnetic free layer, while retaining the protective layer on the columnar protrusion sidewalls.

8. The magnetic storage cell as claimed in claim 7, characterized in that, The protective layer is any one of a silicon nitride layer, a silicon oxide layer, or a silicon oxynitride layer.

9. A magnetic storage device, characterized in that, The magnetic memory includes the magnetic storage unit as described in any one of claims 7 to 8.

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