JP7150317B2 - ELECTRONIC DEVICE, MANUFACTURING METHOD THEREOF, AND MAGNETORESISTIVE ELEMENT - Google Patents

Description

The present invention relates to a high-performance electronic device with high crystallinity formed on a silicon single crystal substrate and a manufacturing method thereof, for example, a magnetoresistive device.

In recent years, research and development of magnetoresistive elements have progressed, and they are used in magnetic memory (MRAM) recording elements, hard disk drive (HDD) read heads, high-frequency oscillation elements for HDD assist recording, magnetic sensors, and the like. However, since the magnetoresistive element is made of polycrystal, there is a problem of variations in recording/writing characteristics and reading characteristics between elements due to the existence of a large number of crystal grains. In addition, it is desired to improve the characteristics of the element, such as the magnetoresistance ratio. The magnetoresistive ratio is a value obtained by dividing the resistance difference ΔR between the two states by the resistance value R of the lower one.

Known magnetoresistive elements include a tunnel magnetoresistive element having a tunnel magnetoresistive layer having an insulating layer as a tunnel barrier layer, a perpendicular current giant magnetoresistive (CPP-GMR) element having a giant magnetoresistive layer, and the like. ing. The tunnel magnetoresistive element has a structure in which main layers are a lower ferromagnetic layer, an upper ferromagnetic layer, and a non-magnetic tunnel barrier layer between the upper and lower ferromagnetic layers.

Patent Document 1 reports a single-crystal magnetoresistive element in which the (001) plane of a ferromagnetic thin film is epitaxially grown on a large-diameter silicon single-crystal substrate. Patent Document 1 discloses, as an example of a magnetoresistive element, a silicon substrate, a B2 structure underlayer laminated on the silicon substrate, a first nonmagnetic layer laminated on the B2 structure underlayer, a giant magnetoresistive layer having at least one laminated layer having a lower ferromagnetic layer, an upper ferromagnetic layer, and a second nonmagnetic layer provided between the lower ferromagnetic layer and the upper ferromagnetic layer; , is shown. As another example, a silicon substrate, a B2 structure underlayer laminated on the silicon substrate, a lower ferromagnetic layer and an upper ferromagnetic layer laminated on the B2 structure underlayer, and the lower ferromagnetic layer A magnetoresistive element is shown comprising a magnetic layer and a tunnel magnetoresistive layer comprising at least one laminate layer with an insulator layer provided between the upper ferromagnetic layer. In Patent Document 1, a Si (001) single crystal substrate is used as the silicon substrate. Further, the underlying layer of the B2 structure is NiAl, CoAl, or FeAl. The first nonmagnetic layer is at least one selected from the group consisting of Ag, V, Cr, W, Mo, Au, Pt, Pd, Ta, Ru, Re, Rh, NiO, CoO, TiN and CuN. is. The lower ferromagnetic layer and the upper ferromagnetic layer are made of at least one selected from the group consisting of Co-based Heusler alloy, Fe, and CoFe. The second nonmagnetic layer is made of at least one selected from the group consisting of Ag, Cr, W, Mo, Au, Pt, Pd, Ta and Rh. The insulator layer is an insulator having a NaCl structure and a spinel structure, and is made of MgO-based oxide, Al ₃ O ₄ , Mg ₂ Al ₂ O ₄ , ZnAl ₂ O ₄ , MgCr ₂ O ₄ , MgMn ₂ O ₄ , CuCr ₂ . _O4 , _{NiCr2O4 , GeMg2O4 , SnMg2O4 , TiMg2O4 , SiMg2O4 , CuAl2O4 , Li0.5Al2.5O4 , γ - Al2O3} consisting of at least one selected from

JP 2017-103419 A

In recent years, as a tunnel magnetoresistive element, for example, a ferromagnetic material based on CoFeB with bcc (001) orientation is used as the lower ferromagnetic layer and the upper ferromagnetic layer, and MgO with cubic (001) orientation is used as the tunnel barrier layer. Structures using non-magnetic layers based on . However, tunneling magnetoresistive elements in practical use are polycrystalline. For example, if the recording element diameter size of the MRAM is reduced to 15 nm, it is at most about three times as large as the crystal grain size (about 5 nm). However, there is a problem that it becomes obvious as an element characteristic. In other words, there is a limit to the device characteristics in the device structure made of polycrystal. In the case of a CoFeB-based ferromagnetic material, when the diameter size of the recording element is set to less than 20 nm, there is a problem that the perpendicular magnetic anisotropy energy is insufficient to maintain the recording retention characteristics.

Therefore, single crystallization is expected as an element. If single-crystallized, only a single crystal grain exists in the wafer, so an effect of suppressing variations in characteristics is desired. Furthermore, it is presumed that the use of materials other than CoFeB for the lower ferromagnetic layer and the upper ferromagnetic layer will bring about an improvement in characteristics.

As a single-crystal magnetoresistive element, for example, technological development using a single-crystal MgO substrate has been advanced. On the other hand, realization of a single crystal magnetoresistive element on a Si wafer used in semiconductor technology has been strongly expected.

Patent document 1 proposes manufacturing a perpendicular current giant magnetoresistive (CPP-GMR) element and a tunnel magnetoresistive element using a Si (001) single crystal substrate. In Patent Document 1, it is reported that a magnetoresistive ratio of 28% was obtained in an example in which a plane-perpendicular current giant magnetoresistive (CPP-GMR) element was produced. However, Patent Literature 1 does not report the result of implementation of a higher magnetoresistance ratio. In addition, the implementation results of the tunneling magnetoresistive element have not been reported.

In Patent Document 1, in an example in which a NiAl B2 structure underlayer is provided on a Si (001) single crystal substrate, the flatness of the NiAl layer is the minimum average surface roughness (Ra) is reported to be 1.17 nm. In addition, in an example in which Ag (001)-oriented single crystal was further grown on the NiAl layer, the average surface roughness as formed was 0.94 nm, and the average surface roughness after post-annealing was improved to 0.29 nm. has been reported. The lower the numerical value of the average surface roughness, the better the flatness.

In general, the B2 type structure refers to an XY type crystal structure typified by cesium chloride, and is a crystal having a composition ratio of X:Y of 1:1.

By the way, in the CPP-GMR element, even if the arithmetic mean surface roughness (Ra) is as rough as 0.3 nm, it is possible to obtain a good magnetoresistance ratio. This is because the second non-magnetic layer provided between the lower ferromagnetic layer and the upper ferromagnetic layer is a metal such as Ag. On the other hand, when the second non-magnetic layer provided between the lower ferromagnetic layer and the upper ferromagnetic layer is an insulating layer as in the tunnel magnetoresistive element, that is, MgO or spinel-based (for example, Mg ₂ AlO ₄ ), an arithmetic mean surface roughness (Ra) of about 0.3 nm is insufficient flatness, and the magnetic resistance ratio is low due to the rough surface undulations. The magnetoresistive ratio is the most important performance index of a magnetoresistive element, and in MRAM, the higher the value, the more power is saved in data writing and the more reliable data is read. In the case of magnetic sensors and HDD read heads, the higher the numerical value, the higher the sensitivity.

In addition, in the manufacture of the magnetoresistive element, if the substrate temperature is as high as 500° C., the upper temperature limit (approximately 400° C.) of the apparatus used for film formation, such as an electrostatic chuck, is not practical. rice field.

The present invention is intended to solve these problems. The object is to provide an element. It is another object of the present invention to provide an electronic device with improved performance. Another object of the present invention is to provide a magnetoresistive element that achieves high performance. Another object of the present invention is to provide a method of manufacturing an electronic device, which can further planarize the surface of the B2 structure underlayer when providing the electronic device layer on the Si(001) single crystal substrate.

The present invention has the following features in order to achieve the above objects.

(1) An electronic device having a laminated structure in which a substrate, an underlying layer, and an electronic element layer are laminated in this order, wherein the substrate is a silicon (001) single crystal substrate, and the underlying layer contains a chemical 1. An electronic device characterized by comprising a B2-type structure single-crystal underlayer made of XAl (X is one or more metals selected from Ni and Co) containing Al in excess of the stoichiometric composition.
(2) The electronic device according to (1), wherein the underlayer contains 53 atomic % or more and 60 atomic % or less of Al.
(3) The electronic device according to (1) or (2), wherein the underlayer has an Al segregation region on its surface.
(4) The electronic device according to any one of (1) to (3), wherein the electronic device layer is laminated on the underlying layer via a single-crystal intervening layer.
(5) The single-crystal intermediate layer has a bcc structure of Cr, W, Nb, V, Fe, Ta, FeCo, an fcc structure of Au, Ag, Pt, Pd, Al, Rh, Ir, or a cubic structure. TiN, NbN, HfN, MoN, TaN, VN, ZrN, CrN, AlN, XY of L10 structure or D022 structure or L12 structure (X = Fe, Co, Mn, Ni, Ag, Y = Al, Mg, Pt, Pd .Si, Ga and Ge).The electronic device according to (4).
(6) The electronic device according to any one of (1) to (5) above includes, as the electronic device layers, a first ferromagnetic layer, a second ferromagnetic layer, and first and second A magnetoresistive element having a magnetoresistive laminated structure comprising at least a nonmagnetic layer provided between ferromagnetic layers.
(7) The magnetoresistive element according to (6), wherein the non-magnetic layer of the magnetoresistive multilayer structure is made of an insulator.
(8) On a silicon (001) single crystal substrate, a B2 type structure single crystal made of XAl (X is one or more metals selected from Ni and Co) containing Al in excess of the stoichiometric composition. A method of manufacturing an electronic device, comprising: a base layer forming step of forming a base layer; and an electronic device layer forming step of sequentially forming an electronic device layer on the base layer.
(9) The method of manufacturing an electronic device according to (8), wherein the underlayer forming step is performed at a temperature of 300° C. or higher and 450° C. or lower.
(10) The above (8) or (9), characterized by including a step of forming a single-crystal intervening layer on the underlying layer after the underlying layer forming step and before the electronic element layer forming step. ).
(11) The step of forming the electronic element layer comprises a step of forming a first ferromagnetic layer, a step of forming a non-magnetic layer provided between the first and second ferromagnetic layers, and a step of forming a second ferromagnetic layer. The method for manufacturing an electronic device according to any one of (8) to (10) above, wherein the step of forming a magnetoresistive laminated structure includes at least a step of forming a layer.

According to the present invention, the surface of the B2 structure underlayer when providing the electronic element layer on the Si(001) single crystal substrate is remarkably flattened compared to the prior art. For example, the arithmetic mean surface roughness (Ra) reached 0.145 nm. According to the present invention, the surface of the B2 structure underlying layer when providing the electronic element layer on the Si (001) single crystal substrate is flattened as compared with the prior art, so that the single crystal intervening layer is formed on the flat surface. The crystallinity of the electronic element layer, which is formed with or without intervening, is improved, and high performance can be achieved.

According to the present invention, when a magnetoresistive laminated structure is formed as an electronic element layer, the magnetoresistive ratio is improved. In the magnetoresistive element of the present invention, the magnetoresistive ratio is increased by one order or more, almost two orders of magnitude, as compared with the case of the prior art in which XAl has a stoichiometric composition. For example, the magnetoresistance ratio has reached 215%.

According to the present invention, it is possible to grow an electronic element layer that mainly functions as a single crystal electronic element using a silicon (001) single crystal substrate. In the present invention, since the surface of the XAl single crystal layer is excellent in flatness, a layer capable of growing a single crystal on the XAl single crystal layer, such as Cr, W, Nb, V, Fe, Ta, FeCo, which have a bcc structure, is used. , fcc structure Au, Ag, Pt, Pd, Al, Rh, Ir, cubic structure TiN, NbN, HfN, MoN, TaN, VN, ZrN, CrN, AlN, L21 structure or B2 structure Co group full Heusler material (Co ₂ YZ: Y=Mn, Fe, Ti, V, Cr, Z=Al, Si, Ga, Ge, Sn), L10 structure or D022 structure Mn-based perpendicular magnetization material (MnGa, MnGe), L10 It is possible to realize an electronic element having a structure with perpendicular magnetization materials (XY: X=Fe, Co, Ni, Cr or alloys thereof, Y=Pd, Pt, Rh or alloys thereof) as electrodes, magnetic layers or the like. Therefore, it is possible to achieve single crystallization of electronic elements that could not be conventionally single crystallized.

By using the B2 structure underlayer having the composition of the present invention, it becomes possible to grow an electronic element such as a (001) oriented single crystal tunnel magnetoresistive element on a (001) oriented single crystal Si wafer.

According to the method of the present invention, the NiAl layer can be formed at a lower substrate temperature than conventionally. For example, it is possible to enable a film formation process at less than 400°C. According to the present invention, since the underlayer of the B2 structure can be formed at a temperature lower than that of the conventional one, the manufacturing process is an energy-saving process, and an electrostatic chuck and other equipment can be used, which is industrially effective. Large.

1 is a cross-sectional view illustrating a first basic structure of a magnetoresistive element of the present invention; FIG. FIG. 4 is a cross-sectional view for explaining a second basic structure of the magnetoresistive element of the present invention; FIG. 4 is a diagram showing characteristics of magnetoresistive elements manufactured in Examples 1-1 and 1-2; 4 is an AFM image of the magnetoresistive element manufactured in Example 1-2. 4 is a TEM image of a cross section of the magnetoresistive element of the first embodiment. It is a figure which shows the characteristic of the magnetoresistive element of 2nd Embodiment. It is a figure which shows the characteristic of the magnetoresistive element of 3rd Embodiment. It is a figure which shows the characteristic of the magnetoresistive element of 4th Embodiment.

Embodiments of the present invention are described below.

In an embodiment of the present invention, in an electronic element such as a magnetoresistive element, a silicon (001) single crystal substrate and a magnetic A single crystal underlayer having a B2 type structure with a specific composition ratio is used between the resistive element layer. As the underlayer, a single crystal underlayer having a B2 type structure made of XAl (X is one or more metals selected from Ni and Co) and containing Al in excess of the stoichiometric composition. use. If the composition ratio of Al is excessive within the range in which the crystal structure of the B2 structure can be maintained, compared to the stoichiometric composition (50 atomic %), the flatness is improved and the magnetoresistive ratio is improved at the same time. Excess is, for example, 51 atomic % or more of Al. From the results of the examples, more preferably 53 atomic % or more and 60 atomic % or less where the increase in the magnetoresistance ratio is noticeable. Furthermore, 54 atomic % or more and 59 atomic % or less is more preferable, and the magnetoresistance ratio is further improved and stabilized. Furthermore, the content is more preferably 54 atomic % or more and 58 atomic % or less, which further improves and stabilizes the magnetoresistance ratio. The underlayer of the B2 structure preferably has a thickness of 10 nm or more and less than 200 nm. Further, it is more preferable that the thickness is 10 nm or more and less than 50 nm in order to suppress the diffusion of silicon to the upper layer and to achieve good flatness.

A first and second basic structure of an electronic device according to an embodiment of the invention will now be described with reference to FIGS. 1A and 1B, respectively.

FIG. 1A is a cross-sectional view illustrating the first basic structure of the electronic device of the present invention. The first basic structure comprises a silicon (001) single crystal substrate 1, a B2 structure underlayer 2, a single crystal intervening layer 3, and electronic element layers (4, 5, 6). When the electronic element is a magnetoresistive element, the intervening single crystal layer is a non-magnetic layer, the electronic element layers 4, 5 and 6 have a magnetoresistive laminated structure, the lower ferromagnetic layer 4, the non-magnetic layer 5 and the upper ferromagnetic layer. layer 6;

FIG. 1B is a cross-sectional view illustrating the second basic structure of the electronic device of the present invention. The second basic structure comprises a silicon (001) single crystal substrate 1, a B2 structure underlayer 2, and electronic element layers (4, 5, 6). When the electronic element is a magneto-resistive element, the electronic element layers (4, 5, 6) are magneto-resistive laminate structures and include a lower ferromagnetic layer 4, a non-magnetic layer 5 and an upper ferromagnetic layer 6. FIG.

In both the first and second basic structures, a silicon (001) single crystal substrate can be used to grow an electronic element layer that mainly functions as a single crystal electronic element. Since the surface of the XAl single crystal layer is remarkably excellent in flatness, it is possible to fabricate an electronic device having a layer grown as a single crystal on the XAl single crystal layer.

The material of the single-crystal intermediate layer 3 is Cr, W, Nb, V, Fe, Ta, FeCo, which has a bcc structure, Au, Ag, Pt, Pd, Al, Rh, Ir, which has a fcc structure, and TiN, which has a cubic structure. , NbN, HfN, MoN, TaN, VN, ZrN, CrN, AlN, L10 structure or D022 structure or L12 structure XY (X=Fe, Co, Mn, Ni, Ag, Y=Al, Mg, Pt, Pd. It is at least one selected from the group consisting of Si, Ga and Ge). The film thickness is preferably 0.5 nm or more and less than 100 nm.

The following materials can be used for each layer constituting the magnetoresistive laminated structure, which is an example of the electronic element layer. In the case of a single crystal, materials for the lower and upper ferromagnetic layers include single crystal Fe, bcc structure FeCo, L21 structure or B2 structure Co-based full Heusler material (Co ₂ YZ: Y=Mn, Fe, Ti, V, Cr, Z=Al, Si, Ga, Ge, Sn), L10 structure or D022 structure Mn-based perpendicular magnetization material (MnGa, MnGe), L10 structure perpendicular magnetization material (XY: X=Fe, Co , Ni, Cr or alloys thereof, Y=Pd, Pt, Rh or alloys thereof). In the present invention, in the case of the tunnel magnetoresistive element, at least the laminated structure from the substrate to the non-magnetic tunnel barrier layer should be a single crystal. The upper ferromagnetic layer may be polycrystalline. In that case, the upper ferromagnetic layer may also be polycrystalline CoFeB or the like. In the case of the tunnel magnetoresistive element, the film thickness of the lower ferromagnetic layer is preferably 1 nm or more and less than 50 nm, and the film thickness of the upper ferromagnetic layer is preferably 1 nm or more. In the case of the perpendicular current giant magnetoresistive element, the film thickness of the lower ferromagnetic layer is preferably 3 nm or more and less than 10 nm, and the film thickness of the upper ferromagnetic layer is preferably 3 nm or more and less than 10 nm.

As the non-magnetic layer of the tunnel magnetoresistive element, MgO-based oxides (MgFeO, MgMnO, MgTiO, MgVO, MgCuO, MgZnO), spinel-based insulators (Mg ₂ AlO ₄ , Mg ₂ GaO _4, γ-Al ₂ O ₃ ), chalcopalite-based compound semiconductors (CuIn _1-x Ga _x Se ₂ , ZnSe, CuGaSe ₂ , ZnS, CuInS ₂ ), and the like. The film thickness of the tunnel barrier layer of the non-magnetic layer is preferably 0.5 nm or more and less than 4 nm.

The non-magnetic layer provided between the lower and upper ferromagnetic layers of the giant magnetoresistive layer is made of at least one selected from the group consisting of Ag, Cr, W, Mo, Au, Pt, Pd, Ta and Rh. . The film thickness of the non-magnetic layer is preferably 1 nm or more and less than 20 nm.

In addition, in the description of the first and second basic structures, the layer formed on the upper ferromagnetic layer is not described. is applied over the top ferromagnetic layer. These are collectively referred to as a cap layer in the present invention. For example, a magnetization fixed layer (IrMn film, etc.), a protective layer, and the like can be used. Materials with in-plane magnetization, such as Fe and Co, require a magnetization direction pinned layer, but materials with perpendicular magnetization used in STT-MRAM provide strong magnetization pinning due to interlayer exchange coupling, and the magnetization direction is fixed. No fixed layer is required. The layers up to the upper ferromagnetic layer are important for the development of magnetoresistance. In the present invention, a structure in which a cap layer is further provided on the basic structure described above is put into practical use.

Film formation of each layer such as the underlayer in this embodiment can be carried out by thin film technology used in conventional magnetoresistive elements. For example, a sputtering method and a vacuum deposition method can be used. In the case of the sputtering method, the composition ratio of XAl can be adjusted by controlling the discharge output value using a plurality of targets. Alternatively, a target having a desired composition ratio may be prepared in advance. In the case of the vacuum deposition method, it can be carried out by controlling each film formation rate using a plurality of sources. Alternatively, a sauce having a desired composition ratio may be prepared in advance.

(First embodiment)
This embodiment relates to the case of using NiAl as a B2 structure underlayer in an electronic device. This embodiment will be described in detail below with reference to the drawings. In this embodiment, in the first basic structure, NiAl was used as the B2 structure underlayer, and the characteristics were examined when the composition was changed. In this embodiment, a magnetoresistive element was produced as an example, and the magnetoresistive ratio was investigated as a characteristic.

The magnetoresistive element of this embodiment includes a silicon (001) single crystal substrate 1, a B2 structure underlayer 2, a single crystal intervening layer 3 made of Cr, a lower ferromagnetic layer 4 made of Fe/Co, and _Mg2AlO . ₄ and a laminated structure of an upper ferromagnetic layer 6 made of Co/Fe. Furthermore, with the cap layer, the laminated structure of this embodiment is silicon (001)/NiAl/Cr/Fe/Co/Mg ₂ AlO ₄ /Co/Fe/IrMn/Ta/Ru.

[Example 1-1]
A silicon (001) single crystal substrate 1 was prepared. A NiAl film (thickness of 30 nm) was epitaxially grown on the heated single crystal substrate in an argon gas atmosphere by a multi-target simultaneous sputtering method using a Ni target and an Al target. A plurality of samples were prepared by setting the substrate temperature to 300 to 450.degree. A plurality of samples were prepared by changing the composition ratio of NiAl by controlling the discharge output values of the Ni target and the Al target. Next, a Cr film (thickness of 30 nm) was epitaxially grown by sputtering in an argon gas atmosphere at room temperature, and then subjected to surface heat treatment with a lamp at 230° C. for 20 minutes. Next, an Fe film (thickness of 3 nm) was epitaxially grown by sputtering in an argon gas atmosphere at room temperature. Next, a Co film (0.4 nm thick) was epitaxially grown at room temperature in an argon gas atmosphere by sputtering. Next, a Mg ₂ AlO ₄ film (thickness of 2 nm) was epitaxially grown by sputtering in an argon gas atmosphere at room temperature, and then subjected to surface heat treatment with a lamp at 450° C. for 6 minutes. Next, a Co film (0.4 nm thick) was epitaxially grown at room temperature in an argon gas atmosphere by sputtering. Next, an Fe film (2.5 nm thick) was epitaxially grown by sputtering in an argon gas atmosphere at room temperature, and then subjected to surface heat treatment with a lamp at 180° C. for 7 minutes. Next, in order to fix the magnetization direction of the Fe film, an IrMn film (10 nm thick) was epitaxially grown by sputtering in a magnetic field at room temperature in a krypton gas atmosphere. The IrMn film is a magnetization direction fixed layer. Next, a Ta film was formed by a sputtering method in a krypton gas atmosphere at room temperature. Next, a Ru film was formed by sputtering in an argon gas atmosphere at room temperature. The Ta film and Ru film are layers for surface protection.

[Example 1-2]
In the film formation of the non-magnetic layer 5 made of Mg ₂ AlO ₄ , the Mg ₂ AlO ₄ surface was exposed to an oxygen gas atmosphere immediately after the Mg ₂ AlO ₄ sputter film formation so as not to cause oxygen deficiency, and then the Mg 2 AlO 4 surface was heated at 450° C. for 6 hours. A surface heat treatment was performed with a lamp for 1 minute. The relationship between the exposure time to the oxygen gas atmosphere and the magnetoresistance ratio was investigated in advance, and the exposure time was determined so as to maximize the magnetoresistance ratio.

FIG. 2 shows the characteristics of the magnetoresistive elements manufactured in Examples 1-1 and 1-2. The horizontal axis is the Al composition ratio (atomic %), and the vertical axis is the magnetoresistance ratio (%). The results of Example 1-1 are indicated by black squares, and the results of Example 1-2 are indicated by circles. The composition of the NiAl layer of the fabricated magnetoresistive element was identified by fluorescent X-ray analysis and ICP emission spectroscopic analysis. The magnetoresistance ratio was measured at room temperature using a multi-terminal probe in-plane current tunneling magnetoresistance measuring device.

In Example 1-1, as shown in FIG. 2, the Al composition ratio is 49.5 atomic % and the magnetoresistance ratio is 2% (hereinafter referred to as "49.5 atomic % Al and 2% MR ratio"). ), Al 50.1 atomic %, MR ratio 2%, Al 50.6 atomic %, MR ratio 5%, Al 51.5 atomic %, MR ratio 37%, Al 52.4 atomic %, MR ratio 98%, Al 53.2 MR ratio is 142% at 54 at.% Al, MR ratio is 149% at 54 at.% Al, MR ratio is 146% at 55.9 at.% Al, MR ratio is 143% at 57.6 at.% Al, MR ratio is 144% at 59 at.% Al, 59.9 at. The MR ratio is 146% with 7 atomic %, 146% with 60.4 atomic % of Al, 144% with 61.2 atomic % of Al, 130% with 63 atomic % of Al, and 120% with 64 atomic % of Al. there were.

In Example 1-2, as shown in FIG. 2, Al 54 atomic % and MR ratio 157%, Al 55 atomic % and MR ratio 200%, Al 55.7 atomic % and MR ratio 215%, Al 57.6 atomic % , the MR ratio was 196% with Al 59.5 atomic % and the MR ratio was 165%.

As shown in FIG. 2, it can be seen that the Al composition ratio exceeds 50 atomic %, for example, in a wide range of 51 atomic % to 64 atomic %, the magnetoresistance ratio is higher than that of 50 atomic %. . A magnetoresistance ratio of about 70% or more was obtained when the Al composition ratio was 52 atomic % or more and 64 atomic % or less, and a magnetoresistance ratio of about 131% or more was obtained when the Al composition ratio was 53 atomic % or more and 60 atomic % or less. Further, when the non-magnetic layer of the magnetoresistive element is manufactured under the optimum conditions, the Al composition is 54 atomic % or more and 59 atomic % or less, and an excellent magnetoresistance ratio of 149% or more is exhibited. I understand. A maximum magnetoresistance ratio of 215% was obtained.

A 5 μm square area on the surface of the NiAl layer (thickness of 30 nm) having an Al composition ratio of 55.7 atomic % in Example 1-2 was observed with an atomic force microscope (AFM). FIG. 3 shows an image obtained by AFM. The vertical and horizontal axes indicate a 5 um square area, and the shading in the figure indicates the unevenness of the surface. According to the results of AFM observation of the surface, the arithmetic mean surface roughness (Ra) was 0.145 nm. Remarkably good flatness was obtained compared to the prior art in the case of 50 atomic %.

From the above results, it is considered that the level of the magnetoresistance ratio reflects the flatness of the NiAl layer. The flatter the better, the higher the magnetoresistance ratio. As in the present embodiment, in a magnetoresistive element composed of a (001) oriented insulator tunnel barrier and a (001) oriented ferromagnet, the magnetoresistive ratio with coherent tunneling as an expression mechanism is the (001) crystal orientation Sensitive to temperature. In other words, the flatness determines the magnitude of the magnetoresistance ratio. The XY-type B2-type crystal structure has a stoichiometric composition of X:Y=50:50 atomic %, but according to the results of the examples of the present embodiment, Al is in excess of 50 atomic %. Thus, the surface flatness of the NiAl layer is improved.

FIG. 4 is a diagram showing images of the cross section of the magnetoresistive element of this embodiment observed with a transmission electron microscope (TEM) arranged in the order of lamination. In the image, it was confirmed that a single crystal had grown from the Si wafer to the uppermost layer of the magnetoresistive element excluding the cap layer. At this time, the interface between the NiAl layer and the upper Cr layer exhibits superflatness at the atomic level, and the Cr layer, the Fe/Co layer, the Mg ₂ AlO ₄ layer, and the Co/Fe layer thereon exhibit flatness. It provides flatness and high single crystal orientation. Also, from the lattice spacing and orientation of the NiAl layer, it was found that NiAl had a B2 structure. Although the surface of the Si wafer has poor flatness, the NiAl layer deposited under these conditions provides a magnetoresistive element in which each layer is flat and single crystal. A composition profile was obtained during the observation, and it was found that Al was slightly segregated on the NiAl layer surface. It is conceivable that this Al segregation may bring about surface flatness, and there is a high possibility that it is an excessive Al composition for causing Al segregation.

According to the cross-sectional TEM image of FIG. 4, a (001) oriented single crystal Cr layer is obtained on the NiAl layer. As a conventional technique, a Co-based full-Heusler material (Co ₂ YZ: Y=Mn, Fe, Ti, V, Cr, Z=Al) having an L21 structure or a B2 structure is grown on a Cr(001) layer grown on a single-crystal MgO substrate. , Si, Ga, Ge, Sn), L10 structure or D022 structure Mn-based perpendicular magnetization materials (MnGa, MnGe), L10 structure perpendicular magnetization materials (XY: X=Fe, Co, Ni, Cr or alloys thereof, Y = Pd, Pt, Rh or alloys thereof) have been realized. If the Al-excess NiAl layer of the present embodiment is used, even on a large-diameter Si single crystal wafer, these high-performance materials developed for a single crystal MgO substrate can be used as the lower ferromagnetic layer and the upper ferromagnetic layer. It is possible to form a resistive element.

(Second embodiment)
This embodiment relates to the case of using CoAl as a B2 structure underlayer in an electronic device. Others are the same as those described in the first embodiment.

[Example 2]
A plurality of magneto-resistive elements were produced by changing the composition of CoAl used as the B2 structure underlayer, and the characteristics of each case were investigated. FIG. 5 shows the characteristics of the magnetoresistive element of this embodiment. The horizontal axis is the Al composition ratio (atomic %) in CoAl, and the vertical axis is the magnetoresistance ratio (%).

In Example 2, as shown in FIG. 5, Al 50.4 atomic % and MR ratio 3%, Al 51.7 atomic % and MR ratio 3%, Al 53.1 atomic % and MR ratio 118%, Al 54.6 The MR ratio was 150% at atomic %, 110% at 56 atomic % Al, 110% at 57.5 atomic % Al, and 20% at 60 atomic % Al.

As shown in FIG. 5, even when X is Co, as a result of investigating changes in the magnetoresistance ratio, it was found that the optimum range of the Al composition ratio has the same tendency as when X is Ni. As shown in FIG. 5, the Al composition ratio exceeds 50 atomic %, for example, in a wide range of 52 atomic % to 60 atomic %, the magnetoresistance ratio is higher than that of 50 atomic %. I understand. A magnetoresistance ratio of 20% or more was obtained when the Al composition ratio was 53 atomic % or more and 60 atomic % or less. Moreover, it can be seen that an Al composition of 54 atomic % or more and 59 atomic % or less exhibits a further excellent magnetoresistance ratio of 56% or more. It can be seen that when the Al composition is 54 atomic % or more and 58 atomic % or less, an excellent magnetoresistance ratio of approximately 90% or more is exhibited. A maximum magnetoresistance ratio of 150% was obtained.

(Third Embodiment)
In this embodiment, the B2 structure underlayer in the electronic element is a single crystal having a B2 type structure made of XAl (X is one or more metals selected from Ni and Co), and in particular, X is a plurality of Co and Ni. Consists of elements. Others are the same as those described in the first embodiment.

[Example 3]
A magnetoresistive element was fabricated using an underlayer with a varied composition x represented by (Co _x Ni _100-x ) ₄₅ Al ₅₅ (where x is 0 or more and 100 or less) as the B2 structure underlayer. . From the first and second embodiments, the optimum Al composition ratio is about 55 atomic %, so when Ni and Co are mixed from 0: 100 to 100: 0 when Al = 55 atomic % We investigated the change in the magnetoresistance ratio of FIG. 6 shows the characteristics of the magnetoresistive element of this embodiment. The horizontal axis is the mixing ratio atomic % (x) of Co, and the vertical axis is the magnetoresistive ratio (%). As shown in FIG. 6, it was found that a magnetoresistance ratio of 100% or more was obtained over the entire region. It can be seen that if the Al composition is within the above range, an excellent magnetoresistance ratio can be obtained even with a mixed composition of X=Ni—Co.

(Fourth embodiment)
The present embodiment relates to temperature conditions in a process of forming a B2 structure underlayer in an electronic device. This embodiment is the same as that described in the first embodiment, except for points that are specifically described in this embodiment.

[Example 4]
In this example, the magnetoresistive ratio was investigated by changing the silicon substrate temperature when forming a B2 structure underlayer with an Al composition ratio of 55 atomic %. FIG. 7 shows the measurement results of the magnetoresistance ratio of this example. The horizontal axis is the wafer temperature of the Si (001) single crystal substrate (from 300° C. to 450° C.), and the vertical axis is the magnetoresistance ratio (%) of the fabricated magnetoresistance element. According to FIG. 7, it can be seen that a sufficiently excellent magnetoresistance ratio can be obtained at a wafer temperature of 300° C. or higher and 450° C. or lower. Also, even when the wafer temperature was lowered to 340° C., a magnetoresistance ratio of 210% or more was obtained, which was substantially the same as when the wafer temperature was 450° C. Therefore, it is more preferable that the temperature is 340° C. or higher and 450° C. or lower. When the Al composition is in the optimum range, the deposition process can be performed at a maximum temperature of less than 400° C. where the electrostatic wafer chuck mechanism can be used.

(Fifth embodiment)
In this embodiment, an electronic element (magnetoresistive element) having a second basic structure will be described. As shown in the first to third embodiments, since the surface of the B2 structure underlayer has good flatness, the single crystal non-magnetic layer provided on the B2 structure underlayer in the first basic structure is omitted as appropriate. Then, an electronic device can be manufactured with the second basic structure.

(Sixth embodiment)
In the present embodiment, a perpendicular current giant magnetoresistive element is used when a single crystal having a B2 type structure made of XAl (where X is one or more metals selected from Ni and Co) is used as the B2 structure underlayer. explain. The plane-perpendicular-current giant magnetoresistive element of this embodiment comprises a (001) silicon substrate, a B2 structure underlayer made of Al-excess XAl laminated on the silicon substrate, and a B2 structure underlayer laminated on the B2 structure underlayer. Laminate layer having optionally provided non-magnetic layer of single crystal intervening layer, lower ferromagnetic layer and upper ferromagnetic layer, and non-magnetic layer provided between said lower ferromagnetic layer and said upper ferromagnetic layer and a giant magnetoresistive layer having at least one of For example, a Co-based full Heusler material (Co ₂ YZ: Y=Mn, Fe, Ti, V, Cr, Z=Al, Si, Ga, Ge, Sn) having an L21 structure or a B2 structure is deposited on the underlayer. A lower ferromagnetic layer, a non-magnetic layer (Ag, Al, Mg) and an upper ferromagnetic layer are stacked to fabricate a perpendicular current giant magnetoresistive element.

(Seventh embodiment)
In the first to sixth embodiments, examples of the magnetoresistive element have been described, but the electronic element is not limited to the magnetoresistive element. An Al-excess XAl single crystal layer is formed on a silicon (001) single crystal substrate, and a layer capable of single crystal growth, such as an L21 structure or a B2 structure, is formed on the surface of the single crystal layer having excellent flatness. Co-based full Heusler materials (Co ₂ YZ: Y=Mn, Fe, Ti, V, Cr, Z=Al, Si, Ga, Ge, Sn), L10 structure or D022 structure Mn-based perpendicular magnetization materials (MnGa, MnGe), L10 structure perpendicular magnetization materials (XY: X=Fe, Co, Ni, Cr or alloys thereof, Y=Pd, Pt, Rh or alloys thereof) as electrodes or magnetic layers, etc. Fabricate the device.

It should be noted that the examples shown in the above embodiments and the like are described to facilitate understanding of the invention, and the invention is not limited to this form.

Since the electronic element such as the magnetoresistive element of the present invention can be made single crystal, the element characteristics such as the magnetoresistive ratio can be significantly improved, and the energy saving in the manufacturing process can be achieved. It is useful for

REFERENCE SIGNS LIST 1 silicon (001) single crystal substrate 2 B2 structure underlayer 3 single crystal intermediate layer 4 lower ferromagnetic layer 5 nonmagnetic layer 6 upper ferromagnetic layer

Claims (10)

An electronic device having a laminated structure in which a substrate, a base layer, and an electronic device layer are laminated in order,
The substrate is a silicon (001) single crystal substrate,
The underlayer is a single-crystal underlayer having a B2 type structure made of XAl (X is one or more metals selected from Ni and Co) containing Al in excess of the stoichiometric composition , and An electronic device comprising an Al segregation region . 2. The electronic device according to claim 1, wherein the underlayer contains 53 atomic % or more and 60 atomic % or less of Al. 3. The electronic device according to claim 1, wherein said electronic device layer is laminated on said underlying layer via a single-crystal intervening layer. The single-crystal intervening layer includes Cr, W, Nb, V, Fe, Ta, FeCo having a bcc structure, Au, Ag, Pt, Pd, Al, Rh, Ir having a fcc structure, and TiN and NbN having a cubic structure. , HfN, MoN, TaN, VN, ZrN, CrN, AlN, L10 structure or D022 structure or L12 structure XY (X = Fe, Co, Mn, Ni, Ag, Y = Al, Mg, Pt, Pd.Si, 4. The electronic device according to claim 3, wherein the element is at least one selected from the group consisting of Ga and Ge. The electronic device according to any one of claims 1 to 4, wherein the electronic device layers include a first ferromagnetic layer, a second ferromagnetic layer, and between the first and second ferromagnetic layers A magnetoresistive element having a magnetoresistive laminated structure comprising at least a nonmagnetic layer provided. 6. A magnetoresistive element according to claim 5, wherein said non-magnetic layer of said magnetoresistive laminated structure is made of an insulator. A single-crystal underlayer having a B2 type structure made of XAl (X is one or more metals selected from Ni and Co) containing Al in excess of the stoichiometric composition on a silicon (001) single-crystal substrate. A base layer forming step of forming a base layer having an Al segregation region on the surface;
an electronic element layer forming step of sequentially forming electronic element layers on the underlayer;
A method for manufacturing an electronic device, comprising: 8. The method of manufacturing an electronic device according to claim 7, wherein said base layer forming step forms said base layer at a temperature of 300[deg.] C. or more and 450[deg.] C. or less. After the base layer forming step and before the electronic element layer forming step,
9. The method of manufacturing an electronic device according to claim 7, further comprising the step of laminating a single-crystal intervening layer on said underlying layer. The electronic element layer forming step includes a step of forming a first ferromagnetic layer, a step of forming a nonmagnetic layer provided between the first and second ferromagnetic layers, and a step of forming a second ferromagnetic layer. 10. The method of manufacturing an electronic device according to any one of claims 7 to 9, characterized in that the step of forming a magnetoresistive multilayer structure comprises at least the steps of:

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