Method for producing magnetic tunnel junction element and method for processing laminate

Abstract

One embodiment of the present invention provides a method for producing a magnetic tunnel junction element. The method for producing a magnetic tunnel junction element includes the following steps: a first preparation step for preparing a first laminate in which an anti-ferromagnetic layer and a passivation layer are laminated on a base layer in the stated order, the anti-ferromagnetic layer being configured to exhibit an anomalous Hall effect; a first annealing step for annealing the first laminate at a first annealing temperature; a removal step for preparing a second laminate by removing at least a portion of the passivation layer from the annealed first laminate; a second preparation step for preparing a third laminate by laminating a first ferromagnetic layer, an insulating layer, and a second ferromagnetic layer in the stated order toward the second laminate on which the passivation layer removal has been performed; and a second annealing step for annealing the third laminate at a second annealing temperature lower than the first annealing temperature.

Description

Method for manufacturing a magnetic tunnel junction element and method for processing a laminate.

[0001] The present invention relates to a method for manufacturing a magnetic tunnel junction element and a method for processing a laminate.

[0002] Patent Document 1 discloses a magnetoresistive element equipped with a magnesium oxide passivation layer and a high-speed, ultra-low-power non-volatile memory using the same. This memory incorporates an MgO passivation layer on the sidewalls of a tunnel magnetoresistance (TMR) film consisting of a ferromagnetic free layer, an insulating layer, and a ferromagnetic fixed layer, as well as a protective layer and an orientation control layer. This suppresses elemental diffusion from each layer of the tunnel magnetoresistance (TMR) element due to heat treatment at 350 degrees Celsius or higher, thereby realizing a magnetic memory cell and magnetic random access memory with stable high-power read and low-current write characteristics. Furthermore, when CoFeB is used for the ferromagnetic layer and MgO for the insulating layer, the MgO passivation layer is oriented in the (001) direction.

[0003] International Publication No. 2010 / 067520

[0004] However, there is still room for improvement in magnetic tunnel junction elements that utilize this tunnel magnetoresistance effect.

[0005] According to one aspect of the present invention, a method for manufacturing a magnetic tunnel junction element is provided, comprising the following steps: a first preparation step is to prepare a first laminate in which an antiferromagnetic layer and a passivation layer are sequentially laminated on a base layer, the antiferromagnetic layer being configured to exhibit an anomalous Hall effect; a first annealing step is to anneal the first laminate at a first annealing temperature; a removal step is to prepare a second laminate by removing at least a portion of the passivation layer from the annealed first laminate; a second preparation step is to prepare a third laminate by sequentially laminating a first ferromagnetic layer, an insulating layer, and a second ferromagnetic layer toward the second laminate from which the passivation layer has been removed; and a second annealing step is to anneal the third laminate at a second annealing temperature lower than the first annealing temperature.

[0006] This configuration makes it possible to provide a novel magnetic tunnel junction element.

[0007] This figure shows an example of the configuration of a tunnel junction element. This figure shows an example of the configuration of the first laminate 1000, which is one of the precursors of the MTJ element 11 shown in Figure 1. This flowchart shows an example of the manufacturing process of an MTJ element.

[0008] Embodiments of the present invention will be described below with reference to the drawings. The various features shown in the embodiments below can be combined with each other.

[0009] 1. Diagram 1 shows an example of the configuration of a magnetic tunnel junction element.

[0010] As shown in Figure 1, the magnetic tunnel junction (MTJ) element 11 comprises a substrate 100 and an underlayer 102 as a base layer, a storage layer M, an insulating layer 108, and a fixed layer F. The MTJ element 11 may further comprise an upper layer 112. The MTJ element 11 (or a memory equipped therewith) can be used, for example, in MRAM (Magnetic Random Access Memory), magnetic heads of HDDs (Hard Disk Drives), racetrack memory, etc. The MTJ element 11 is envisioned to be used, for example, in STT (Spin Transfer Torque) type MRAM or SOT (Spin Orbit Torque) type MRAM, but it may also be used in conventional Vertical MRAM.

[0011] The substrate 100 is made of any material used for memory applications, such as silicon. The substrate 100 may also be a flexible substrate.

[0012] The base layer 102 may include layers that perform various mechanical or electromagnetic functions, such as electrodes that can be electrically connected to external elements. The base layer 102 can be laminated on the substrate 100.

[0013] The memory layer M is configured to have spontaneous magnetization. Spontaneous magnetization is not limited to that resulting from ferromagnetic magnetic order, and may include that resulting from antiferromagnetic magnetic order such as so-called tilted antiferromagnetism and ferrimagnetism. In the present embodiment, the magnetization direction of the memory layer M is along the stacking direction in which each layer is stacked in the MTJ element 11. The magnetization direction of the memory layer M is configured to be reversible in accordance with an input signal. The input signal is a signal for reversing the magnetization direction of the memory layer M, and is configured to apply spin angular momentum to the memory layer M. In the present embodiment, the memory layer M includes an antiferromagnetic layer 104 and a first ferromagnetic layer 106.

[0014] The antiferromagnetic layer 104 is a layer that exhibits an anomalous Hall effect, and may include, for example, a non-collinear antiferromagnetic material. The non-collinear antiferromagnetic material can easily rotate spins, for example, by polarization caused by a magnetic octupole. Accordingly, the sign of the anomalous Hall coefficient of the antiferromagnetic material is configured to be reversible in accordance with data written to the MTJ element 11.

[0015] For example, the antiferromagnetic layer 104 contains Mn and at least one element selected from the group consisting of Sn, Ga, Ge, Pt, Ir, and Rh as main components. Specifically, for example, the non-collinear antiferromagnetic material contained as a main component in the antiferromagnetic layer 104 is Mn ３ Sn, Mn ３ Pt, Mn ３ Ge, Mn ３ Ga, and Mn ３ It is composed of one or more substances selected from the group of Ir. The non-collinear antiferromagnetic material contained as a main component in the antiferromagnetic layer 104 is, for example, Mn ３ Sn, Mn ３ Ge, Mn ３ Mn such as Ga ３ It is an X-based alloy. Mn ３Regarding the composition ratio of the X-type alloy, it is preferable that the Mn content is 2.5 times or more and 5 times or less than the Sn, Ge, or Ga (including those containing multiple of these). An anomalous Hall effect can be observed in such an antiferromagnetic material under conditions without a magnetic field. The antiferromagnetic material is, for example, an antiferromagnetic material in which an anomalous Hall effect can be observed at temperatures above room temperature. The antiferromagnetic material is, for example, an antiferromagnetic material that can take at least two values ​​depending on the rotation of its spin. In this embodiment, the antiferromagnetic layer 104 is Mn ３ It is made of Sn and can be laminated on top of the base layer 102.

[0016] In the MTJ element 11 of this embodiment, the antiferromagnetic layer 104 is formed by annealing at a specified annealing temperature. With this configuration, it is possible to promote the crystallization of the antiferromagnetic layer while appropriately suppressing the diffusion of magnetic elements in the antiferromagnetic layer. The annealing temperature is determined by the antiferromagnetic material (for example, Mn) contained in the antiferromagnetic layer 104. ３ The temperature at which the Sn(s) order is performed is arbitrary, but for example, it is between 300 and 550°C, 330 and 500°C, or 340 and 450°C. In other words, in the MTJ element 11, the antiferromagnetic layer 104 may be annealed at a temperature between 300°C and 550°C. Specifically, for example, the annealing temperature is between 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, and 550°C, and may be within the range of any two of the values ​​exemplified here.

[0017] The first ferromagnetic layer 106 may be composed of a ferromagnetic material used in ferromagnetic MTJ elements, such as Co, CoFeB, or CoFe. In other words, the ferromagnetic material may contain magnetic elements having a magnetic moment. Examples of such magnetic elements include Fe, Co, Ni, Nd, Gd, and Tb. The first ferromagnetic layer 106 functions as a free layer in the MTJ element 11. The material constituting the first ferromagnetic layer 106 is not particularly limited as long as it is a material that functions as a free layer, such as CoFeB or CoFe. The first ferromagnetic layer 106 may be a single layer or a multi-layer layer. Furthermore, since the first ferromagnetic layer 106 functions as a free layer, it may contain magnetic materials other than the ferromagnetic material mentioned above, as well as non-magnetic materials. The first ferromagnetic layer 106 is laminated on the antiferromagnetic layer 104.

[0018] Here, the polarity of the antiferromagnetic layer 104 and the magnetization direction of the first ferromagnetic layer 106 are configured to reverse in conjunction with each other. For example, when the magnetization direction of the first ferromagnetic layer 106 is reversed, the polarity of the anomalous Hall effect in the antiferromagnetic layer 104 (i.e., the sign of the Hall voltage with respect to the current) is reversed. This is achieved by the magnetic coupling between the antiferromagnetic layer 104 and the first ferromagnetic layer 106 through magnetic interaction. For example, when the magnetization direction of the first ferromagnetic layer 106 is reversed, the magnetic structure of the antiferromagnetic layer 104 is reversed. Such reversal of the magnetic structure in the antiferromagnetic layer 104 causes a reversal of the polarity of the anomalous Hall effect. Other layers may be interposed between the antiferromagnetic layer 104 and the first ferromagnetic layer 106, as long as the interdependence between the antiferromagnetic layer 104 and the first ferromagnetic layer 106 is maintained.

[0019] The insulating layer 108 is laminated on the memory layer M (for example, the first ferromagnetic layer 106). The insulating layer 108 is a non-magnetic insulating layer provided to exhibit TMR. The insulating layer 108 is not particularly limited as long as it functions as an insulating layer, such as MgO, AlOx, TiOx, etc.

[0020] The fixed layer F is configured to be fixed regardless of the data (e.g., input signal) written to the MTJ element 11. The magnetization direction of the fixed layer F is along the stacking direction, similar to the magnetization direction of the memory layer M. Here, the magnetization direction of the memory layer M is either parallel or antiparallel to the magnetization direction of the fixed layer F for each partial magnetic domain. As a result, the MTJ element 11 is configured to read the magnetization direction of the memory layer M as data 0 or 1 based on the difference in resistance between the parallel spin state and the antiparallel spin state due to the tunnel magnetoresistance effect. The fixed layer F is stacked on an insulating layer 108. For example, the insulating layer 108 is placed between the memory layer M and the fixed layer F, thereby forming a tunnel magnetic junction between the memory layer M and the fixed layer F. In this embodiment, the fixed layer F includes a second ferromagnetic layer 110.

[0021] The second ferromagnetic layer 110 may be a ferromagnetic material used in ferromagnetic MTJ elements, such as CoFeB or CoFe. The second ferromagnetic layer 110 functions as a fixed layer in the MTJ element. The material constituting the second ferromagnetic layer 110 is not particularly limited as long as it functions as a fixed layer F. The second ferromagnetic layer 110 may be a single layer or a multi-layer layer. Furthermore, the second ferromagnetic layer 110 may include magnetic or non-magnetic materials other than the ferromagnetic materials mentioned above, such as synthetic antiferromagnet (SAF). The MTJ element 11 may have a structure in which an antiferromagnetic material such as MnPt or MnIr is laminated on the second ferromagnetic layer 110 in order to make the second ferromagnetic layer 110 function as a fixed layer F. That is, at least one of the memory layer M and the fixed layer F may include an antiferromagnetic layer that exhibits an anomalous Hall effect, a barrier layer, and a ferromagnetic layer. This configuration suppresses the diffusion of magnetic elements contained in the antiferromagnetic layer and appropriately promotes the ordering of the antiferromagnetic layer. The magnetization direction of the ferromagnetic material constituting the second ferromagnetic layer 110 is fixed regardless of the data written to the MTJ element 11.

[0022] The second ferromagnetic layer 110 is laminated on the insulating layer 108. For example, the insulating layer 108 may be placed between the second ferromagnetic layer 110 and the first ferromagnetic layer 106. The antiferromagnetic layer 104 is configured to be connected to the insulating layer 108 via the first ferromagnetic layer 106. With such a configuration, an antiferromagnetic layer 104 having crystallinity suitable for the structure of the first ferromagnetic layer 106 can be obtained. Preferably, the ferromagnetic material constituting the second ferromagnetic layer 110 and the ferromagnetic material constituting the first ferromagnetic layer 106 contain at least the element Co as particles having a magnetic moment, and more preferably, are composed of Co or CoFeB.

[0023] The upper layer 112 is a layer provided on top of the second ferromagnetic layer 110, which serves as the fixed layer F. The upper layer 112 may consist of electrodes or a layer made of a material based on known techniques for making the MTJ element 11 function more efficiently. The configuration of the upper layer 112 is not particularly limited. For example, the upper layer 112 is laminated on the second ferromagnetic layer 110.

[0024] The spin magnetization direction of the antiferromagnetic layer 104, the first ferromagnetic layer 106, and / or the second ferromagnetic layer 110 is preferably perpendicular (i.e., in the stacking direction), but it may also be in the in-plane direction.

[0025] The specific form of the MTJ element 11 is not limited to this. For example, in the above embodiment, the base layer 102, memory layer M, insulating layer 108, fixed layer F, and upper layer 112 were stacked in that order on the substrate 100, but for example, the stacking order of the memory layer M and fixed layer F on the substrate 100 may be reversed. Also, in the memory layer M, the antiferromagnetic layer 104 and the first ferromagnetic layer 106 were stacked on the substrate 100 in that order, but the stacking order of the antiferromagnetic layer 104 and the first ferromagnetic layer 106 may be reversed.

[0026] In this embodiment, a passivation layer 105 is laminated on the antiferromagnetic layer 104 during the manufacturing process of the MTJ element 11. Figure 2 shows an example of the configuration of a first laminate 1000, which is one of the precursors of the MTJ element 11 shown in Figure 1. As shown in Figure 2, the first laminate 1000 includes a substrate 100 and an underlayer 102 as a base layer, an antiferromagnetic layer 104, and a passivation layer 105. The passivation layer 105 is, for example, SiO ２ MgO, AlO ｘ The passivation layer 105 is a layer made of an oxide film such as TaO, and can play a role in protecting the antiferromagnetic layer 104 from oxidation. The passivation layer 105 may, for example, have a configuration that is partially the same as that of the antiferromagnetic layer 104. The passivation layer 105 may also include a third ferromagnetic layer 1051 made of the ferromagnetic material contained in the first ferromagnetic layer 106. The third ferromagnetic layer 1051 is covered with an oxide film and is exposed by removing the oxide film.

[0027] Although some or all of the passivation layer 105 is removed chemically or physically after annealing, it may not be completely removed and may remain, or it may be mixed into the antiferromagnetic layer 104 or the first ferromagnetic layer 106. Furthermore, traces of the removal of the passivation layer 105 may remain, for example, as residual components or physical shape of the antiferromagnetic layer 104.

[0028] 2. Method for Manufacturing MTJ Elements Next, we will explain the various methods for manufacturing MTJ elements described in the previous section. Figure 3 is a flowchart showing an example of the flow of a manufacturing method for MTJ elements. Note that the order of each step included in the manufacturing method shown in Figure 3 can be changed as appropriate. The manufacturing method includes a first preparation step S1, a first annealing step S2, a removal step S3, a second preparation step S4, and a second annealing step S5.

[0029] As shown in Figure 3, the first preparation step S1 is to prepare a first laminate 1000 in which an antiferromagnetic layer 104 and a passivation layer 105 are sequentially laminated on a base layer. The antiferromagnetic layer 104 is configured to exhibit an anomalous Hall effect (at least after annealing). The base layer in this embodiment is the substrate 100 or underlayer 102 (or their precursors) as described above, but is not limited to these and can be any object on which the antiferromagnetic layer 104 can be laminated. Specifically, first, the base layer is prepared by laminating the underlayer 102 onto the substrate 100. The conditions for this lamination are arbitrary. Next, the antiferromagnetic layer 104 and the passivation layer 105 are sequentially laminated onto the prepared base layer substrate 100 and underlayer 102. This gives rise to the first laminate.

[0030] The first annealing step S2 is a step of annealing the first laminate 1000 at a first annealing temperature. The first annealing temperature is any temperature that can promote the ordering of the antiferromagnetic material contained in the antiferromagnetic layer and is higher than the second annealing temperature described later. For example, the first annealing temperature is 300°C or higher. With this configuration, the ordering and crystallization of the compounds constituting the antiferromagnetic layer are promoted, and the assist effect of the deviceized antiferromagnetic layer 104 can be amplified. More preferably, the first annealing temperature may be 350°C or higher, 380°C or higher, or 400°C or higher. Also, the first annealing temperature may be 550°C or lower. With this configuration, the diffusion of magnetic elements (e.g., Mn) contained in the antiferromagnetic layer 104 to other layers such as the passivation layer 105 can be suppressed, and the device characteristics can be improved. More preferably, the first annealing temperature may be 480°C or lower, or 450°C or lower. Specifically, for example, the first annealing temperature can be 300, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, or 550°C, and may be within the range of any two of the values ​​exemplified here. For example, the first annealing temperature may be 300 to 550°C, 380 to 480°C, or 400 to 450°C.

[0031] Further, it is preferable that the atmosphere during the first annealing step S2 is an atmosphere replaced with an inert gas, but it may be an atmosphere containing oxygen (e.g., air).

[0032] It is preferable that the annealing treatment time is 30 minutes or longer. By setting the annealing treatment time to 30 minutes or longer, the ordering of the antiferromagnetic layer can be sufficiently promoted. The upper limit of the annealing treatment time is not particularly limited. From the viewpoint of production efficiency, it may be, for example, 60 minutes or less. The annealing method is not particularly limited, and may be, for example, substrate heating, lamp heating, laser heating, or the like. The cooling method after annealing is also not particularly limited, and natural cooling may be used. Further, the annealing step may be performed on a stage on which the film-formed substrate is placed, or may be performed at another location. Such annealing may be performed in the same chamber as the chamber for laminating the first laminate 1000, but in the present embodiment, it is performed by an external annealing apparatus. When the first laminate 1000 is carried out to the outside, the passivation layer 105 can protect the antiferromagnetic layer 104 from oxidation.

[0033] The removal step S3 is a step of removing at least a part of the passivation layer 105 from the annealed first laminate 1000. Thereby, a second laminate is obtained. The structure of the second laminate is obtained by removing part or all of the passivation layer 105 from the first laminate 1000 shown in FIG. 2. Therefore, for simplicity of explanation, separate illustration is omitted. The method for removing the passivation layer 105 can be appropriately selected depending on the material constituting the passivation layer 105, and can be performed by, for example, ion milling. Ion milling may be performed using a sputter gun of a sputtering apparatus, or may be performed using another apparatus.

[0034] Furthermore, in the removal step S3, the passivation layer 105 may be removed so that only a thickness sufficient to ensure magnetic coupling between the existing antiferromagnetic layer 104 and the first ferromagnetic layer 106 to be laminated in the subsequent second preparation step remains. This allows the remaining passivation layer 105 to suppress diffusion of magnetic elements from the antiferromagnetic layer 104 to the first ferromagnetic layer 106.

[0035] Here, when the passivation layer 105 includes a third ferromagnetic layer 1051 formed of a ferromagnetic material included in the first ferromagnetic layer 106, in the removal step S3, part of the passivation layer 105 may be removed such that a region of the third ferromagnetic layer 1051 that was not exposed when the first annealing step was performed is exposed.

[0036] The second preparation step S4 is a step of preparing a third stacked body by sequentially stacking the first ferromagnetic layer 106, the insulating layer 108, and the second ferromagnetic layer 110 on the second stacked body from which the passivation layer 105 has been removed. At this time, an additional layer such as an upper layer 112 may further be stacked. Since the structure of the third stacked body is the same as that of the MTJ element 11 shown in FIG. 1, illustration thereof is omitted. The stacking for the second stacked body is performed, for example, in the same manner as the stacking when preparing the first stacked body.

[0037] When the above-described third ferromagnetic layer 1051 is exposed from the second stacked body, in the second preparation step S4, the third stacked body may be prepared by sequentially stacking the first ferromagnetic layer 106, the insulating layer 108, and the second ferromagnetic layer 110 on the third ferromagnetic layer 1051 newly exposed by performing the removal step. According to such a configuration, the MTJ element 11 can be manufactured more efficiently. In this case, for example, the third ferromagnetic layer 1051 may be assimilated with the first ferromagnetic layer 106 to be stacked later, and there is a possibility that the boundary between them becomes difficult to distinguish.

[0038] The second annealing step S5 is a step of annealing the third laminate at a second annealing temperature lower than the first annealing temperature. The second annealing temperature can be any temperature that can improve the magnetic properties of the ferromagnetic materials contained in the first ferromagnetic layer 106 and the second ferromagnetic layer 110. For example, the second annealing temperature is 250°C or higher. With this configuration, the crystallinity of the ferromagnetic layer can be improved more efficiently. More preferably, the second annealing temperature may be 260°C or higher, or 280°C or higher. Also, the second annealing temperature may be less than 350°C. With this configuration, the magnetic properties of the ferromagnetic material can be improved efficiently. More preferably, the second annealing temperature may be 320°C or lower, or 300°C or lower. Specifically, for example, the second annealing temperature may be 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, or 350°C, and may be within the range of any two of the values ​​exemplified here. For example, the second annealing temperature may be 250°C or more but less than 350°C, 250°C or more but 320°C or less, or 250°C or more but 300°C or less.

[0039] Furthermore, the atmosphere during the second annealing step S5 is preferably an atmosphere replaced with an inert gas, but it may also be an atmosphere containing oxygen (for example, air). Also, the annealing time in the second annealing step S5 is not particularly limited and can be appropriately determined.

[0040] Through this process, the MTJ element 11 is manufactured from the third laminate. After the second annealing step S5, known microfabrication or packaging processes may be performed as needed.

[0041] By using the method described above, it is possible to suppress the annealing of the ferromagnetic layer at an excessively high temperature suitable for the antiferromagnetic layer, thereby achieving both improved device performance and improved manufacturing yield.

[0042] The laminate described above (the first laminate 1000, etc.) is a precursor to the MTJ element 11 described above, but the thickness of each layer does not substantially change before and after the annealing process. Therefore, the thickness of each layer in the laminate can also be said to be the thickness of each layer in the MTJ element.

[0043] Furthermore, the composition of each layer can be determined, for example, by using a transmission electron microscope and energy-dispersive X-ray spectroscopy, to identify the thickness and constituent elements of each layer.

[0044] Note that the configuration of the MTJ element 11 is merely one example of this embodiment. For example, auxiliary layers such as an artificial antiferromagnetic layer may be added to reinforce the function performed by each layer.

[0045] Furthermore, although an example of forming a passivation layer has been described in this embodiment, the disclosure is not limited to such an example. For example, if the first annealing step S2 is performed in the same chamber as the second preparation step S4, the passivation layer 105 does not need to be provided. That is, the first annealing step S2 may be performed after the antiferromagnetic layer 104 is formed, and then the first ferromagnetic layer 106, etc., may be formed. Alternatively, the first annealing step S2 may be performed after the antiferromagnetic layer 104 is formed, then a part of the antiferromagnetic layer 104 may be ion-milled, and then the ferromagnetic layer may be formed.

[0046] The above manufacturing method can also be described as a method for (annealing) a laminate. The method for processing a laminate includes the following steps: In the first annealing step S2, a first laminate 1000, in which an antiferromagnetic layer 104 and a passivation layer 105 are laminated on a base layer, is annealed at a first annealing temperature. The antiferromagnetic layer 104 is configured to exhibit an anomalous Hall effect. In the removal step S3, a second laminate is prepared by removing at least a portion of the passivation layer 105 from the annealed first laminate 1000. In the second preparation step S4, a third laminate is prepared by sequentially laminating a first ferromagnetic layer 106, an insulating layer 108, and a second ferromagnetic layer 110 onto the second laminate from which the passivation layer 105 has been removed. In the second annealing step S5, the third laminate is annealed at a second annealing temperature lower than the first annealing temperature. This configuration allows for the promotion of crystallization of the antiferromagnetic layer while moderately suppressing the diffusion of magnetic elements within the antiferromagnetic layer.

[0047] Furthermore, the following configurations are included as examples of the present disclosure. (Item 1) A method for manufacturing an element, comprising: forming the antiferromagnetic layer on a substrate; performing a first annealing at a temperature range of 350°C to 550°C; forming a first ferromagnetic layer on the antiferromagnetic layer; forming a first barrier layer on the first ferromagnetic layer; forming a second ferromagnetic layer on the first barrier layer; and performing a second annealing at a temperature of 250°C to 350°C as a laminated structure. (Item 2) A method for manufacturing an element according to Item 1, wherein a part of the antiferromagnetic layer is ion-milled after the first annealing. (Item 3) A method for manufacturing an element according to Item 1, wherein a passivation layer is formed on the antiferromagnetic layer; performing a first annealing; and ion-milling all or part of the passivation layer after the first annealing. (Item 4) A method for manufacturing an element as described in Item 3, wherein the first annealing is performed by an apparatus provided in a space different from the film deposition apparatus. (Item 5) A method for manufacturing an element as described in any of Items 1 to 4, wherein after the first annealing, a second barrier layer is deposited on the antiferromagnetic layer, and the first ferromagnetic layer is deposited on the second barrier layer. (Item 6) A method for manufacturing a device, wherein in the process of manufacturing an element to be provided in the device, the antiferromagnetic layer is deposited on a substrate, a first annealing is performed at a temperature range of 350°C or higher and 550°C or lower, a first ferromagnetic layer is deposited on the antiferromagnetic layer, a first barrier layer is deposited on the first ferromagnetic layer, a second ferromagnetic layer is deposited on the first barrier layer, and these are used as a laminated structure, and a second annealing is performed at a temperature of 250°C or higher and 350°C or lower.

[0048] The above embodiments may also be provided in the following embodiments.

[0049] (1) A method for manufacturing a magnetic tunnel junction element, comprising the following steps: a first preparation step is to prepare a first laminate in which an antiferromagnetic layer and a passivation layer are sequentially laminated on a base layer, wherein the antiferromagnetic layer is configured to exhibit an anomalous Hall effect; a first annealing step is to anneal the first laminate at a first annealing temperature; a removal step is to prepare a second laminate by removing at least a portion of the passivation layer from the annealed first laminate; a second preparation step is to prepare a third laminate by sequentially laminating a first ferromagnetic layer, an insulating layer, and a second ferromagnetic layer toward the second laminate from which the passivation layer has been removed; and a second annealing step is to anneal the third laminate at a second annealing temperature lower than the first annealing temperature.

[0050] This configuration prevents the ferromagnetic layer from being annealed at an excessively high temperature suitable for the antiferromagnetic layer, thereby achieving both improved device performance and improved manufacturing yield.

[0051] (2) A method of manufacturing according to (1) above, wherein the second annealing temperature is less than 350°C.

[0052] With this configuration, it is possible to promote the ordering and crystallization of the antiferromagnetic layer at an appropriate temperature while increasing the crystallinity of the ferromagnetic layer.

[0053] (3) A method for manufacturing according to (1) or (2) above, wherein the second annealing temperature is 250°C or higher.

[0054] With this configuration, it is possible to promote the ordering and crystallization of the antiferromagnetic layer at an appropriate temperature while increasing the crystallinity of the ferromagnetic layer.

[0055] (4) A method of manufacturing according to any one of (1) to (3) above, wherein the first annealing temperature is 300°C or higher.

[0056] (5) A method of manufacturing according to any one of (1) to (4) above, wherein the first annealing temperature is 550°C or lower.

[0057] (6) A method for manufacturing according to any one of (1) to (5) above, wherein the passivation layer includes a third ferromagnetic layer made of a ferromagnetic material included in the first ferromagnetic layer, the removal step involves removing a portion of the passivation layer so as to expose a region of the third ferromagnetic layer that was not exposed when the first annealing step was performed, and the second preparation step involves sequentially laminating the first ferromagnetic layer, an insulating layer, and a second ferromagnetic layer toward the third ferromagnetic layer newly exposed by the removal step, thereby preparing a third laminate.

[0058] This configuration allows for more efficient manufacturing of magnetic tunnel junction elements.

[0059] (7) A method for manufacturing according to any one of (1) to (6) above, wherein the antiferromagnetic layer mainly contains at least one element from Sn, Ga, Ge, Pt, Ir, and Rh, and Mn.

[0060] (8) In the manufacturing method described in (7) above, the antiferromagnetic layer is Mn ３ A method composed of Sn.

[0061] (9) A method for processing a laminate, comprising the following steps: a first annealing step, in which a first laminate having an antiferromagnetic layer and a passivation layer laminated on a base layer is annealed at a first annealing temperature, wherein the antiferromagnetic layer is configured to exhibit an anomalous Hall effect; a removal step, in which a second laminate is prepared by removing at least a portion of the passivation layer from the annealed first laminate; a second preparation step, in which a third laminate is prepared by sequentially laminating a first ferromagnetic layer, an insulating layer, and a second ferromagnetic layer toward the second laminate from which the passivation layer has been removed; and a second annealing step, in which the third laminate is annealed at a second annealing temperature lower than the first annealing temperature.

[0062] This configuration allows for the promotion of crystallization in the antiferromagnetic layer while moderately suppressing the diffusion of magnetic elements within the antiferromagnetic layer. Of course, this is not always the case.

[0063] Finally, while various embodiments relating to this disclosure have been described, these are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0064] The following describes examples and comparative examples that embody the above embodiments.

[0065] [Regarding the preparation of samples] The inventors prepared the samples for Examples 1 to 5 and Comparative Example 1 using the following procedure.

[0066] First, as a preparation step, the inventors prepared a Si substrate (100 μm) as the base layer, with Ta (5 nm) / Ru (20 nm) as the underlayer and Mn as the antiferromagnetic layer. ３ A first laminate according to Examples 1 to 5 and Comparative Example 1 was fabricated by sequentially stacking Sn (30 nm) and MgO (3 nm) as a passivation layer. The numbers in parentheses indicate the thickness of the layer. Each layer was deposited by sputtering.

[0067] Next, as a first annealing step, the inventors performed annealing on the first laminates according to each of Examples 1 to 5 at a first annealing temperature T1. The annealing time was 60 minutes, and the annealing atmosphere was an Ar gas atmosphere. For the first laminate according to Comparative Example 1, annealing at the first annealing temperature T1 was omitted.

[0068] Next, the inventors removed the MgO (3 nm) passivation layer from the first laminates according to each of the annealed Examples 1 to 5, and from the first laminate according to Comparative Example 1 in which annealing was omitted, and Mn ３ Sn was exposed. The passivation layer was removed by Ar ion milling. This prepared the second laminate.

[0069] Next, as a second preparation step, the inventors removed MgO (3 nm) and Mn ３ A third laminate according to Examples 1 to 5 and Comparative Example 1 was fabricated by sequentially laminating a first ferromagnetic layer (free layer) of CoFeB (1.5 nm), an insulating layer of MgO (1.0 nm), a second ferromagnetic layer (fixed layer) of CoFeB (1.2 nm) / Ru (0.9 nm) / CoFe (2.5 nm) / IrMn (10 nm), and an upper layer of Ta (5 nm) / Ru (5 nm) onto a second laminate in which Sn is exposed. Each layer was deposited by sputtering.

[0070] Next, as a second annealing step, the inventors annealed the third laminates according to each of Examples 1 to 5 and Comparative Example 1 at a second annealing temperature T2. The annealing time was 60 minutes, and the annealing atmosphere was an Ar gas atmosphere. As a result, samples (MTJ elements) according to each of Examples 1 to 5 and Comparative Example 1 were obtained.

[0071] [Regarding the evaluation method of the samples] The inventors evaluated whether the spins of the lower CoFeB layer (first ferromagnetic layer) were vertically oriented for the samples of each of Examples 1 to 5 and Comparative Example 1 by magneto-optical Kerr effect (MOKE) measurement. Specifically, the presence or absence of a perpendicular magnetic Kerr signal caused by the vertical orientation of the spins in the lower CoFeB layer was confirmed by measuring the polar Kerr effect. If a perpendicular magnetic Kerr signal was observed, it was judged as "○", and if it was not observed, it was judged as "×". The vertical orientation of the spins in the lower CoFeB layer indicates that the CoFeB layer has good crystallinity based on the epitaxial relationship with the MgO insulating layer, and that the diffusion of Mn element from the antiferromagnetic layer is suppressed. In other words, the presence or absence of a perpendicular magnetic Kerr signal is a clear indicator of the effectiveness of the two-stage annealing process.

[0072] [Results and Discussion] The following table shows the first annealing temperature T1, the second annealing temperature T2, and the evaluation results for the perpendicular magnetic Kerr signal for each of the Examples 1 to 5 and Comparative Example 1.

[0073]

[0074] As shown in the table above, in Comparative Example 1, no perpendicular magnetic Kerr signal was observed from the lower CoFeB layer. This is because the entire laminate containing CoFeB was annealed at 400°C, which is an excessively high temperature for the crystallization of CoFeB, resulting in Mn ３ This suggests that the Mn element in the Sn layer diffused into the adjacent CoFeB layer and MgO insulating layer, resulting in a deterioration of the crystallinity of the CoFeB layer and the interfacial quality with MgO.

[0075] In contrast, in Examples 1 to 5, the perpendicular magnetic Kerr signal was clearly observed. This is because Mn was added before the CoFeB layer was laid. ３ Only the Sn layer is annealed at the first annealing temperature T1 and then Mn ３ By promoting the ordering of Sn and then, after lamination of CoFeB layers, etc., annealing at a second annealing temperature T2 lower than the first annealing temperature T1 promotes the crystallization of CoFeB. ３ This suggests that the diffusion of Mn elements in the Sn layer was suppressed.

[0076] The above results indicate that by setting the second annealing temperature to less than 400°C (for example, less than 350°C), Mn is promoted during the crystallization of CoFeB. ３ This suggests that the diffusion of Mn elements in the Sn layer can be suppressed more efficiently. From another perspective, the observation results of the annealing temperatures T1, T2 and perpendicular magnetic Kerr signals in Examples 1 to 5 indicate that by setting the second annealing temperature to 250°C or higher, the diffusion of Mn during the crystallization of CoFeB can be promoted. ３ This suggests that the diffusion of Mn elements in the Sn layer can be suppressed more efficiently.

[0077] Furthermore, the above results indicate that by setting the first annealing temperature to 300°C or higher, Mn is promoted during the crystallization of CoFeB. ３ This suggests that the diffusion of Mn elements in the Sn layer can be suppressed more efficiently. From another perspective, the above results suggest that by setting the first annealing temperature to 550°C or lower (e.g., 500°C or lower), the diffusion of Mn during the crystallization of CoFeB can be promoted. ３ This suggests that the diffusion of Mn elements in the Sn layer can be suppressed more efficiently.

[0078] 11: MTJ element, 100: substrate, 102: underlayer, 104: antiferromagnetic layer, 105: passivation layer, 1051: third ferromagnetic layer, 106: first ferromagnetic layer, 108: insulating layer, 110: second ferromagnetic layer, 112: top layer, 1000: first laminate, F: fixed layer, M: memory layer, S1: first preparation step, S2: first annealing step, S3: removal step, S4: second preparation step, S5: second annealing step

Claims

1. A method for manufacturing a magnetic tunnel junction element, comprising the following steps: a first preparation step, in which a first laminate is prepared in which an antiferromagnetic layer and a passivation layer are sequentially laminated on a base layer, the antiferromagnetic layer is configured to exhibit an anomalous Hall effect; a first annealing step, in which the first laminate is annealed at a first annealing temperature; a removal step, in which a second laminate is prepared by removing at least a portion of the passivation layer from the annealed first laminate; a second preparation step, in which a third laminate is prepared by sequentially laminating a first ferromagnetic layer, an insulating layer, and a second ferromagnetic layer toward the second laminate from which the passivation layer has been removed; and a second annealing step, in which the third laminate is annealed at a second annealing temperature lower than the first annealing temperature.

2. A method for manufacturing according to claim 1, wherein the second annealing temperature is less than 350°C.

3. A method for manufacturing according to claim 1, wherein the second annealing temperature is 250°C or higher.

4. A method for manufacturing according to claim 1, wherein the first annealing temperature is 300°C or higher.

5. A method for manufacturing according to claim 1, wherein the first annealing temperature is 550°C or lower.

6. A method for manufacturing according to claim 1, wherein the passivation layer includes a third ferromagnetic layer made of a ferromagnetic material included in the first ferromagnetic layer, the removal step involves removing a portion of the passivation layer so that a region of the third ferromagnetic layer that was not exposed when the first annealing step was performed is exposed, and the second preparation step involves preparing a third laminate by sequentially laminating the first ferromagnetic layer, an insulating layer, and a second ferromagnetic layer toward the third ferromagnetic layer newly exposed by the removal step.

7. A method for manufacturing according to any one of claims 1 to 6, wherein the antiferromagnetic layer mainly contains at least one element from Sn, Ga, Ge, Pt, Ir, and Rh, and Mn.

8. In the manufacturing method described in claim 7, the antiferromagnetic layer is Mn ３ A method composed of Sn.

9. A method for processing a laminate, comprising the following steps: a first annealing step, in which a first laminate having an antiferromagnetic layer and a passivation layer laminated on a base layer is annealed at a first annealing temperature, wherein the antiferromagnetic layer is configured to exhibit an anomalous Hall effect; a removal step, in which a second laminate is prepared by removing at least a portion of the passivation layer from the annealed first laminate; a second preparation step, in which a third laminate is prepared by sequentially laminating a first ferromagnetic layer, an insulating layer, and a second ferromagnetic layer toward the second laminate from which the passivation layer has been removed; and a second annealing step, in which the third laminate is annealed at a second annealing temperature lower than the first annealing temperature.

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