Giant magnetoresistance effect spin valve multilayer film structure based on thermal oxidation silicon wafer, preparation method of giant magnetoresistance effect spin valve multilayer film structure and magnetoresistance element

Abstract

The invention provides a giant magnetoresistance effect spin valve multilayer film structure based on a thermal oxidation silicon wafer, a preparation method of the giant magnetoresistance effect spin valve multilayer film structure and a magnetoresistance element, and belongs to the technical field of magnetic sensing electronic devices. The giant magnetoresistance effect spin valve multilayer film structure based on the thermal oxidation silicon wafer comprises the thermal oxidation silicon wafer, a seed layer and a giant magnetoresistance effect spin valve multilayer film structure, wherein the seed layer and the giant magnetoresistance effect spin valve multilayer film structure are sequentially formed on the thermal oxidation silicon wafer; the giant magnetoresistance effect spin valve multilayer film structure comprises a free layer, a non-magnetic metal layer, a reference layer and an Ir22Mn78 antiferromagnetic layer which are sequentially formed; wherein the seed layer comprises a Co40Fe40B20 layer, an Mg layer and an MgO layer which are formed in sequence, and the seed layer is suitable for epitaxial growth of the giant magnetoresistance effect spin valve multilayer film structure on a thermal oxidation silicon wafer; the free layer and the reference layer are made of Fe50Co50 alloy with an ordered body-centered cubic structure; the non-magnetic metal layer is an Ag layer or a Cu layer.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic sensor electronic devices, and in particular relates to a giant magnetoresistance effect spin valve multilayer film structure based on thermally oxidized silicon wafers, a preparation method thereof, and a magnetoresistance element. Background Art

[0002] Magnetic field sensors based on the giant magnetoresistance effect have the advantages of high sensitivity, small size, easy integration, and low power consumption. They have been widely used in magnetic field sensing technologies such as mechanical hard disk data reading, current sensing, navigation positioning, and biomedicine, showing great application value. With the development of technologies such as "big data", "cloud computing", and "Internet of Things", the demand for accurate reading of massive data and precise perception of complex physical information is increasing, and it is urgent to develop giant magnetoresistance effect sensors with higher magnetic field resolution. The magnetoresistance ratio is the core indicator that determines the sensitivity of giant magnetoresistance effect sensors. A higher magnetoresistance ratio helps to obtain magnetic field measurement results with a higher signal-to-noise ratio. How to improve the magnetoresistance ratio is the key to improving the performance of giant magnetoresistance effect sensors.

[0003] The magnetoresistance ratio of the giant magnetoresistance effect is related to the spin polarization rate P of the Fermi surface of the ferromagnetic material in the giant magnetoresistance effect spin valve multilayer film (the spin polarization rate is defined as P=(N↑-N↓) / (N↑+N↓), where N↑ and N↓ are the electron densities with spin up and down on the Fermi surface). The larger the spin polarization rate of the ferromagnetic material, the larger the spin polarization current, the stronger the giant magnetoresistance effect, and the higher the magnetoresistance ratio. The spin polarization rate is related to the crystal order of the ferromagnetic material. Ferromagnetic materials with higher crystal order have fewer defects and impurities, which can reduce the scattering of spin electrons during propagation, maintain the direction of electron spins, and ensure higher spin polarization currents. This can further enhance the spin filtering effect and provide favorable conditions for improving the magnetoresistance ratio.

[0004] Therefore, improving the crystalline order of ferromagnetic materials in giant magnetoresistance effect spin valve multilayer films is the key to improving the performance of giant magnetoresistance sensors. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a giant magnetoresistance effect spin valve multilayer film structure based on thermally oxidized silicon wafers and a preparation method and a magnetoresistance element, in order to at least partially solve the above technical problems. The specific technical solutions provided by the present invention are as follows.

[0006] As a first aspect of the present invention, a giant magnetoresistance effect spin valve multilayer film structure based on thermally oxidized silicon wafer is provided, comprising: Thermally oxidized silicon wafer, and a seed layer and a giant magnetoresistance effect spin valve multilayer film structure sequentially formed on the thermally oxidized silicon wafer, wherein the giant magnetoresistance effect spin valve multilayer film structure comprises a free layer, a non-magnetic metal layer, a reference layer and an Ir 22 Mn 78Antiferromagnetic layer; The seed layer includes Co 40 Fe 40 B 20 The free layer and the reference layer are Fe with an ordered body-centered cubic structure. 50 Co 50 alloy; the non-magnetic metal layer is an Ag layer or a Cu layer.

[0007] As a second aspect of the present invention, a method for preparing a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer is provided, comprising: Providing pre-treated thermally oxidized silicon wafers; Co was sputtered and deposited on the surface of thermally oxidized silicon wafer. 40 Fe 40 B 20 layer, Mg layer and MgO layer, and obtaining a seed layer after thermal annealing; Fe and Co are alternately sputtered and deposited on the seed layer to obtain a free layer. The free layer is Fe with an ordered body-centered cubic structure. 50 Co 50 alloy; sputtering and depositing non-magnetic metal Ag or Cu on the free layer to obtain a Ag or Cu non-magnetic metal layer; Fe and Co are alternately sputtered on Ag or Cu non-magnetic metal layers to obtain a reference layer. The reference layer is Fe with an ordered body-centered cubic structure. 50 Co 50 alloy; Sputtering Ir on the reference layer 22 Mn 78 Alloy, Ir 22 Mn 78 Antiferromagnetic layer.

[0008] As a third aspect of the present invention, a magnetoresistive element is provided, which is manufactured using the above-mentioned giant magnetoresistive effect spin valve multilayer film structure based on thermally oxidized silicon wafers.

[0009] Based on the above technical solution, a giant magnetoresistance effect spin valve multilayer film structure based on thermally oxidized silicon wafer and a preparation method thereof and a magnetoresistance element provided by the present invention have at least one of the following beneficial effects.

[0010] (1) In the embodiments of the present invention, the existing giant magnetoresistance effect spin valve thin film structure with a high magnetoresistance ratio usually uses a single crystal MgO substrate as a substrate, but the preparation conditions of the single crystal MgO substrate are relatively complex, which is not conducive to industrial production. Therefore, the present invention uses a thermally oxidized silicon wafer as a substrate. The thermally oxidized silicon wafer is low in cost and simple to prepare, which is conducive to large-scale promotion. Since the silicon oxide layer on the surface of the thermally oxidized silicon wafer is usually amorphous (atomic arrangement is disordered), in order to better epitaxially grow a giant magnetoresistance effect spin valve multilayer film structure (referred to as a GMR film layer structure) on the thermally oxidized silicon wafer, the present invention proposes to grow a seed layer on the thermally oxidized silicon wafer, and the seed layer includes Co 40 Fe 40 B 20 layer, Mg layer and MgO layer, among which Co 40 Fe 40 B 20 The polycrystalline structure of the layer can provide a good direction for the growth of the MgO layer with a single crystal structure (001 orientation), and the MgO layer with a single crystal structure lays the foundation for the epitaxial growth of the subsequent GMR film structure. 40 Fe 40 B 20 A Mg layer is formed between the Co layer and the MgO layer to prevent the diffusion of oxygen atoms in the MgO layer to 40 Fe 40 B 20 Further, the giant magnetoresistance effect spin valve multilayer film structure of the present invention includes a free layer (Fe 50 Co 50 alloy), Ag or Cu non-magnetic metal layer, reference layer (Fe 50 Co 50 Alloy) and Ir 22 Mn 78 The antiferromagnetic layer consists of Fe 50 Co 50 Alloy / Ag or Cu / Fe 50 Co 50 The sandwich layer formed by the alloy is the core structure of the giant magnetoresistance effect spin valve multilayer structure. 50 Co 50The alloy has an ordered body-centered cubic structure, and the high order of the crystal ensures the density difference of the two spin electrons (spin-up and spin-down electrons) at the Fermi surface energy level in the material band structure, which can provide a high spin polarization rate, so that the GMR film structure has a higher magnetoresistance ratio. The present invention provides a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer, which uses an easily prepared thermally oxidized silicon wafer as a substrate, grows an ordered structure seed layer on the thermally oxidized silicon wafer, and then grows a GMR film structure on the seed layer, which has a higher magnetoresistance ratio, providing a basis for improving the sensitivity of the giant magnetoresistance effect sensor.

[0011] (2) In the embodiment of the present invention, in order to facilitate the epitaxial growth of the GMR film structure on the surface of the thermally oxidized silicon wafer, the present invention proposes to first deposit Co on the surface of the thermally oxidized silicon wafer by sputtering. 40 Fe 40 B 20 The free layer, non-magnetic metal layer, reference layer and Ir layer are then formed by sputtering deposition. 22 Mn 78 The antiferromagnetic layer, in which the free layer and the reference layer are Fe with an ordered body-centered cubic structure formed by alternate sputtering of Fe and Co. 50 Co 50 The invention provides a method for preparing a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer, which has simple operation and controllable process and is suitable for large-scale promotion.

[0012] (3) In the embodiments of the present invention, the magnetoresistive element made by using the giant magnetoresistive effect spin valve multilayer film structure based on thermally oxidized silicon wafer with a high magnetoresistance ratio has the advantages of high sensitivity, low noise, wide dynamic range, excellent linearity, small size, low power consumption and good thermal stability. These advantages make the magnetoresistive element have broad application prospects and important research value in the field of giant magnetoresistive effect sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer in an embodiment of the present invention;

[0014] Figure 2 for Figure 1 Flow chart of the preparation method of giant magnetoresistance effect spin valve multilayer film structure based on thermal oxidation silicon wafer.

[0015] Explanation of symbols:

[0016] 101. Thermally oxidized silicon wafer;

[0017] 102, seed layer; 1021, Co 40 Fe 40 B 20 layer; 1022, Mg layer; 1023, MgO layer; 1024, Ta layer;

[0018] 103. Giant magnetoresistance effect spin valve multilayer film structure; 1031. Free layer; 1032. Nonmagnetic metal layer; 1033. Reference layer; 1034. Ir 22 Mn 78 Antiferromagnetic layer; 1035, first interface layer; 1036, second interface layer; 1037, Ru spacer layer; 1038, Co 75 Fe 25 pinning layer; 1039, protective layer; 10391, Ru protective layer; 10392, Ta protective layer. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0020] At present, the GMR film structure made of traditional ferromagnetic materials such as Fe, CoFe, and NiFe has a magnetoresistance ratio of about 10 to 20%. This type of GMR film structure does not have high requirements for the crystal order of ferromagnetic materials, and this type of GMR film structure is easy to prepare. However, in order to break through the single magnetic field resolution of the giant magnetoresistance effect sensor to the pico-Tesla (pT) level, it is necessary to further improve the magnetoresistance ratio of the GMR film structure, providing a basis for improving the sensitivity of the giant magnetoresistance effect sensor. At present, the laboratory uses the highly ordered L21 structure of Co2Fe 0.4 Mn 0.6 As a ferromagnetic material, Si alloy can provide a higher spin polarization rate and generate a larger spin polarization current, providing a higher magnetoresistance ratio, so that the maximum magnetoresistance ratio of the prepared GMR film structure at room temperature can reach 70%. However, the GMR film structure has high requirements for the crystal order of the ferromagnetic material, and the preparation conditions of the ferromagnetic material with a higher crystal order are more stringent; and the GMR film structure uses a single crystal MgO substrate as a substrate, and the preparation process of the single crystal MgO substrate is complicated, which is not conducive to the expansion of the application field of the GMR film structure.

[0021] In view of this, the present invention improves the traditional ferromagnetic materials and substrate materials, that is, the present invention mainly focuses on two technical problems: 1. How to prepare a single crystal substrate based on a thermally oxidized silicon wafer to provide a preparation basis for a higher-order GMR film structure and provide mass production conditions for large-scale preparation of magnetoresistive electronic devices; 2. How to prepare a cobalt-iron alloy with a higher order B2 structure to provide a method for preparing a GMR film structure with a higher magnetoresistance ratio. Theoretical and experimental results have proved that compared with single-element ferromagnetic materials Ni, Fe, Co and polycrystalline, A2 structure (simple body-centered cubic structure: all atoms are the same and arranged in disorder) Co-Fe alloys with a higher order B2 structure (ordered body-centered cubic structure: different atoms are arranged in order at specific positions in the unit cell) 50 Fe 50 The alloy has a high spin polarization rate. Solving the above two technical problems can not only solve the current difficulty of improving the magnetoresistance ratio of the GMR film structure, but also provide a material basis for improving the sensitivity of the giant magnetoresistance effect sensor. At the same time, the preparation of a highly ordered GMR film structure based on thermally oxidized silicon wafers is easy to prepare on a large scale, which is conducive to the expansion of the application field of the GMR film structure.

[0022] Therefore, the present invention provides a giant magnetoresistance effect spin valve multilayer film structure based on thermally oxidized silicon wafers, a preparation method thereof, and a magnetoresistance element. A thermally oxidized silicon wafer is used as a substrate, and a high-quality seed layer is grown on its surface, providing conditions for achieving epitaxial growth of a highly ordered GMR film layer structure, ensuring the spin polarization rate of the ferromagnetic material, and improving the magnetoresistance ratio.

[0023] Figure 1 Schematic diagram of a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer in an embodiment of the present invention.

[0024] like Figure 1 As shown, the present invention provides a giant magnetoresistance effect spin valve multilayer film structure based on thermally oxidized silicon wafer, comprising: A thermally oxidized silicon wafer 101, and a seed layer 102 and a giant magnetoresistance effect spin valve multilayer film structure 103 formed sequentially on the thermally oxidized silicon wafer 101. The giant magnetoresistance effect spin valve multilayer film structure 103 includes a free layer 1031, a non-magnetic metal layer 1032, a reference layer 1033 and an Ir 22 Mn 78 The antiferromagnetic layer 1034, the free layer 1031 and the reference layer 1033 are Fe having an ordered body-centered cubic structure. 50 Co 50 alloy; the non-magnetic metal layer 1032 is an Ag layer or a Cu layer. The seed layer 102 includes Co 40 Fe 40 B 20The seed layer 102 is suitable for epitaxial growth of a giant magnetoresistance effect spin valve multilayer film structure 103 on a thermally oxidized silicon wafer 101 .

[0025] In the embodiment of the present invention, the existing giant magnetoresistance effect spin valve thin film structure with a high magnetoresistance ratio usually uses a single crystal MgO substrate as a substrate, but the preparation conditions of the single crystal MgO substrate are relatively complex, which is not conducive to industrial production. Therefore, the present invention uses a thermally oxidized silicon wafer as a substrate. The thermally oxidized silicon wafer has a low cost and is simple to prepare, which is conducive to large-scale promotion. Since the crystal order of the thermally oxidized silicon wafer is lower than that of the single crystal MgO substrate, in order to better epitaxially grow a giant magnetoresistance effect spin valve multilayer film structure (referred to as a GMR film layer structure) on the thermally oxidized silicon wafer, the present invention proposes to grow a seed layer 102 on the thermally oxidized silicon wafer 101, and the seed layer 102 includes Co 40 Fe 40 B 20 layer 1021, Mg layer 1022 and MgO layer 1023, wherein Co 40 Fe 40 B 20 The polycrystalline layer 1021 can provide a good direction for the growth of the MgO layer 1023 with a single crystal structure (001 orientation). The MgO layer 1023 with a single crystal structure lays a foundation for the subsequent epitaxial growth of the GMR film layer structure 103. 40 Fe 40 B 20 A Mg layer 1022 is formed between the layer 1021 and the MgO layer 1023 to prevent the diffusion of oxygen atoms in the MgO layer 1023 from affecting the Co 40 Fe 40 B 20 Further, the giant magnetoresistance effect spin valve multilayer film structure 103 of the present invention includes a free layer 1031 (Fe 50 Co 50 alloy), Ag or Cu non-magnetic metal layer 1032, reference layer 1033 (Fe having an ordered body-centered cubic structure 50 Co 50 Alloy) and Ir 22 Mn 78 The antiferromagnetic layer 1034 is composed of Fe 50 Co 50 Alloy / Ag or Cu / Fe 50 Co 50 The sandwich layer formed by the alloy is the core structure of the giant magnetoresistance effect spin valve multilayer structure. 50 Co 50The alloy has an ordered body-centered cubic structure, and the high order of the crystal ensures the density difference of two types of spin electrons (spin-up and spin-down electrons) at the Fermi surface energy level in the material band structure, which can provide a high spin polarization rate, so that the GMR film layer structure 103 has a higher magnetoresistance ratio. The present invention provides a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer, which uses an easily prepared thermally oxidized silicon wafer 101 as a substrate, grows an ordered structure seed layer 102 on the thermally oxidized silicon wafer 101, and then grows a GMR film layer structure 103 on the seed layer 102, which has a higher magnetoresistance ratio, providing a basis for improving the sensitivity of the giant magnetoresistance effect sensor.

[0026] According to an embodiment of the present invention, continue as Figure 1 As shown, in order to increase the adhesion between the subsequent GMR film layer structure 103 and the thermally oxidized silicon wafer 101, the seed layer 102 further includes: a Ta layer 1024. 40 Fe 40 B 20 A Ta layer 1024 is formed between the layers 1021 . The Ta layer 1024 can increase the flatness of the thermally oxidized silicon wafer 101 and reduce the roughness of the thermally oxidized silicon wafer 101 .

[0027] According to an embodiment of the present invention, in the free layer 1031 and the reference layer 1033, Fe 50 Co 50 The alloy is formed by alternating deposition of two metals, Fe and Co. The Fe with superlattice structure is formed by alternating deposition of two metal targets, Fe and Co. 50 Co 50 alloy, compared with Fe formed directly by a FeCo alloy metal target 50 Co 50 The alloy is more regular and orderly, so that the final giant magnetoresistance effect spin valve multilayer film structure has a higher magnetoresistance ratio.

[0028] According to an embodiment of the present invention, the giant magnetoresistance effect spin valve multilayer film structure 103 further includes: a first interface layer 1035 and a second interface layer 1036. When electrons are transmitted between the free layer 1031 and the non-magnetic metal layer 1032 and between the non-magnetic metal layer 1032 and the reference layer 1033, they are not only affected by the body scattering in the ferromagnetic layer (free layer 1031, reference layer 1032), but also by the interface spin-related scattering caused by the interface band structure between the ferromagnetic layer and the non-magnetic metal layer 1032. Therefore, a first interface layer 1035 is formed between the free layer 1031 and the non-magnetic metal layer 1032, and a second interface layer 1036 is formed between the non-magnetic metal layer 1032 and the reference layer 1033. Preferably, the first interface layer 1035 and the second interface layer 1036 are Fe layers. The interface spin scattering phenomenon is stronger due to the matching degree of conduction bands at the Fermi surface of spin-up and spin-down electrons of the ferromagnetic material Fe and the non-magnetic metal layer Ag or Cu, thereby improving the magnetoresistance ratio of the GMR film structure.

[0029] According to an embodiment of the present invention, in order to further improve the sensitivity of the giant magnetoresistance effect spin valve multilayer film structure to magnetic field changes, the giant magnetoresistance effect spin valve multilayer film structure 103 further includes: a Ru spacer layer 1037 and a Co 75 Fe 25 Pinning layer 1038, Ru spacer layer 1037 and Co 75 Fe 25 The pinning layer 1038 is formed on the reference layer 1033 and the Ir 22 Mn 78 Between the antiferromagnetic layers 1034. Ir 22 Mn 78 Antiferromagnetic layer 1034 and Co 75 Fe 25 The pinned layers 1038 generate exchange coupling, which 75 Fe 25 The magnetic moment of the pinned layer 1038 is fixed, and the magnetic moment of the reference layer 1033 is then fixed through the spatial coupling effect of the Ru spacer layer 1037. This dual fixing mechanism (i.e., the fixing of the pinned layer by the antiferromagnetic layer and the indirect fixing of the reference layer by the spacer layer) further improves the stability of the GMR film structure and reduces the noise and error caused by magnetic moment fluctuations. At this time, the free layer 1031 becomes the only magnetic layer that can respond to changes in the external magnetic field, which enables the GMR film structure to detect a wider range of magnetic field changes, including weak magnetic field changes and rapidly changing magnetic field signals, providing higher accuracy and a wider range of applications for applications in the fields of magnetic sensors and magnetic storage.

[0030] According to an embodiment of the present invention, the giant magnetoresistance effect spin valve multilayer film structure 103 further includes: 22 Mn78 The protective layer 1039 on the surface of the antiferromagnetic layer 1034 includes a Ru protective layer 10391 and a Ta protective layer 10392 formed in sequence. The Ru protective layer 10391 mainly optimizes the performance of the GMR film structure through its coupling effect, protective effect and thermal stability improvement; while the Ta protective layer 10392 mainly enhances the stability and reliability of the GMR film structure through its buffer layer effect, magnetic property adjustment and protective effect. The combined effect of these two protective layers enables the GMR film structure to maintain stable performance output in various complex environments.

[0031] Figure 2 for Figure 1 Flow chart of the preparation method of giant magnetoresistance effect spin valve multilayer film structure based on thermal oxidation silicon wafer.

[0032] like Figure 2 As shown, the present invention provides a method for preparing a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer, comprising steps S1-S6.

[0033] S1: providing a pre-treated thermally oxidized silicon wafer 101 .

[0034] S2: sputtering and depositing Co on the surface of the thermally oxidized silicon wafer 101 40 Fe 40 B 20 The seed layer 102 is obtained by thermal annealing the layer 1021, the Mg layer 1022 and the MgO layer 1023.

[0035] S3: Fe and Co are alternately sputtered and deposited on the seed layer 102 to obtain a free layer 1031. The free layer 1031 is Fe with an ordered body-centered cubic structure. 50 Co 50 alloy.

[0036] S4: Ag or Cu is sputter-deposited on the free layer 1031 to obtain an Ag or Cu non-magnetic metal layer 1032 .

[0037] S5: sputtering Fe and Co alternately on the Ag or Cu non-magnetic metal layer 1032 to obtain a reference layer 1033. The reference layer 1033 is Fe with an ordered body-centered cubic structure. 50 Co 50 alloy.

[0038] S6: Sputtering Ir on the reference layer 1033 22 Mn 78 Alloy, Ir 22 Mn 78 Antiferromagnetic layer 1034 .

[0039] In the embodiment of the present invention, in order to facilitate epitaxial growth of the GMR film structure 103 on the surface of the thermally oxidized silicon wafer 101, the present invention proposes to first deposit Co on the surface of the thermally oxidized silicon wafer 101 by sputtering. 40 Fe 40 B 20 The seed layer 1021, Mg layer 1022 and MgO layer 1023 are formed on the surface of the thermally oxidized silicon wafer 101 after thermal annealing. The thermal annealing makes the MgO layer 1023 show the (001) orientation texture, which leads to the advantage that the subsequent free layer 1031 can be crystallized along the (001) orientation, providing a basis for the epitaxial growth of the GMR film structure. Subsequently, the free layer 1031, the non-magnetic metal layer 1032, the reference layer 1033 and the Ir are formed by sputtering deposition. 22 Mn 78 The antiferromagnetic layer 1034, wherein the free layer 1031 and the reference layer 1033 are Fe with an ordered body-centered cubic structure formed by alternately sputtering Fe and Co. 50 Co 50 The invention provides a method for preparing a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer, which has simple operation and controllable process and is suitable for large-scale promotion.

[0040] In the embodiment of the present invention, the pretreatment of the thermally oxidized silicon wafer 101 includes: cleaning with acetone and ethanol in sequence, blowing off the ethanol on the surface of the thermally oxidized silicon wafer with N2 gas, and then placing it in the chamber of the magnetron sputtering system for in-situ high-temperature heating to 600°C and continuing baking for 1 hour.

[0041] According to an embodiment of the present invention, in the above preparation method, Co 40 Fe 40 B 20 The thickness of the layer 1021 is 5 nm, the thickness of the Mg layer 1022 is 0.4 nm, and the thickness of the MgO layer 1023 is 10-20 nm; the thickness of the Fe and Co deposited by alternate sputtering is 0.14 nm, and the total number of deposited layers of Fe and Co is 37; the thickness of the non-magnetic metal layer 1032 is 3-5 nm; the thickness of the Ir 22 Mn 78 The thickness of the antiferromagnetic layer 1034 is 5 nm.

[0042] In the embodiment of the present invention, the thickness of the MgO layer 1023 is 10-20 nm, within which the interface roughness of the thermally oxidized silicon wafer 101 is suppressed to below 0.4 nm, providing a material basis for the subsequent epitaxial growth of the giant magnetoresistance effect spin valve multilayer film structure 103. 50 Co 50 The alloy is made by sputtering atomically thin layers of Fe and Co alternately, which makes Fe 50 Co 50The alloy has a high crystal order, and thus has a high spin polarization current, providing a large magnetoresistance ratio for the giant magnetoresistance effect spin valve multilayer film structure 103. The interface of the non-magnetic metal layer 1032 can provide a large spin-related scattering effect, thereby improving the magnetoresistance ratio of the giant magnetoresistance effect spin valve multilayer film structure 103. Among them, the thickness of the non-magnetic metal layer 1032 is 3-5nm. If the thickness is too thin, the non-magnetic metal layer 1032 will produce through holes to connect the adjacent ferromagnetic layers; if the thickness is too large, the magnetoresistance ratio of the giant magnetoresistance effect spin valve multilayer film structure 103 will decrease.

[0043] According to an embodiment of the present invention, the above-mentioned preparation method further comprises: sputtering and depositing Co on the surface of the thermally oxidized silicon wafer 101 40 Fe 40 B 20 Before the thermal oxide layer 1021, a Ta layer 1024 is sputtered and deposited. The Ta layer 1024 can increase the flatness of the thermal oxide silicon wafer 101, reduce the roughness of the thermal oxide silicon wafer 101, and increase the adhesion between the subsequent GMR film layer structure 103 and the thermal oxide silicon wafer 101. The thickness of the Ta layer 1024 is preferably 5 nm.

[0044] According to an embodiment of the present invention, the preparation method further includes: sputtering and depositing a first metal on the surface of the free layer 1031 to obtain a first interface layer 1035; sputtering and depositing a second metal on the surface of the non-magnetic metal layer 1032 to obtain a second interface layer 1036. The first interface layer 1035 and the second interface layer 1036 can enhance the magnetism at the interface, thereby improving the spin electron correlation scattering at the interface. The first metal and the second metal are preferably Fe, and the thickness of the first interface layer 1035 and the second interface layer 1036 is preferably 0.5-1 nm, and more preferably 0.5 nm.

[0045] According to an embodiment of the present invention, the preparation method further comprises: sputtering and depositing Ru on the surface of the reference layer 1033 to obtain a Ru spacer layer 1037; sputtering and depositing Co on the surface of the Ru spacer layer 1037; 75 Fe 25 Alloy, get Co 75 Fe 25 Pinning layer 1038. Ir 22 Mn 78 The antiferromagnetic layer 1034 is Co 75 Fe 25 The magnetic moment of the pinned layer 1038 is fixed, and the Ru spacer layer 1037 indirectly fixes the magnetic moment of the reference layer 1033. The thickness of the Ru spacer layer 1037 is preferably 0.85 nm. 75 Fe 25 The thickness of the pinned layer 1038 is preferably 3 nm.

[0046] According to an embodiment of the present invention, the preparation method further comprises: 22 Mn 78 Ru and Ta are sequentially sputtered and deposited on the surface of the antiferromagnetic layer 1034 to obtain a Ru protective layer 10391 and a Ta protective layer 10392, that is, a protective layer 1039. The protective layer 1039 can protect the core structure of the giant magnetoresistance effect spin valve multilayer film structure 103 from being oxidized, and will not increase parasitic resistance unrelated to the giant magnetoresistance effect. The thickness of the Ru protective layer 10391 in the protective layer 1039 is preferably 3 nm, and the thickness of the Ta protective layer 10392 is preferably 2 nm.

[0047] As an example, the present invention provides a method for preparing a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer by magnetron sputtering, which is specifically described as follows.

[0048] The thermally oxidized silicon wafer 101 is cleaned, and the cleaning method includes: cleaning with acetone for 10 minutes, then cleaning with ethanol for 10 minutes, blowing off the ethanol on the surface of the thermally oxidized silicon wafer with N2 gas, and then placing it in the cavity of the magnetron sputtering system and heating it in situ to 600°C, and continuously baking it for 1 hour to thermally clean the thermally oxidized silicon wafer.

[0049] After the temperature in the magnetron sputtering chamber was cooled to room temperature, 5 nm of Ta was sputtered and deposited at a DC power of 30 W and an argon pressure of 0.1 Pa (deposition rate 0.29 Å / sec); 5 nm of Co was sputtered and deposited at a DC power of 100 W and an argon pressure of 0.1 Pa. 40 Fe 40 B 20 (deposition rate 0.62Å / sec); sputtering deposited 0.4nm of Mg (deposition rate 0.45Å / sec) at a DC power of 30W and an argon pressure of 0.13Pa; sputtering deposited MgO (deposition rate 0.097Å / sec) at an RF power of 200W and an argon pressure of 0.36Pa, wherein the thickness of MgO was 10-20nm. The thermally oxidized silicon wafer was placed in the chamber of the magnetron sputtering system and heated to 600°C in situ, and then subjected to a 30-minute thermal annealing treatment until the temperature in the magnetron sputtering chamber was cooled to room temperature to obtain a seed layer 102.

[0050] The vacuum chamber was in-situ heated to 75°C, and 1.4Å of Fe was sputter-deposited at a DC power of 30W and an argon pressure of 0.1Pa (deposition rate: 0.29Å / sec). Under the conditions of a DC power of 10W and an argon pressure of 0.3Pa, 1.4Å of Co was sputter-deposited at a deposition rate of 0.11Å / sec. Fe and Co were sputter-deposited alternately to prepare a total of 37 layers of free layer 1031 with a total thickness of 5.18nm.

[0051] After completing the superlattice structure [Fe / Co]37 After the artificial ferromagnetic alloy material is deposited, 0.5-1 nm of Fe (deposition rate 0.17 Å / sec) is sputtered and deposited under the conditions of a DC power of 10 W and an argon pressure of 0.3 Pa. The thickness of the Fe layer is preferably 0.5 nm, thereby obtaining a first interface layer 1035 .

[0052] After the temperature in the magnetron sputtering chamber is cooled to room temperature, 5 nm of Cu is sputter-deposited at a DC power of 30 W and an argon pressure of 0.36 Pa (a deposition rate of 0.68 Å / sec), or 5 nm of Ag is sputter-deposited at a DC power of 30 W and an argon pressure of 0.67 Pa (a deposition rate of 0.90 Å / sec), to obtain a non-magnetic metal layer 1032.

[0053] After the non-magnetic metal layer 1032 is completed, 0.5-1 nm of Fe is sputtered and deposited (deposition rate 0.17 Å / sec) under the conditions of a DC power of 10 W and an argon gas pressure of 0.3 Pa to obtain a second interface layer 1036 .

[0054] The vacuum chamber was in-situ heated to 75°C, and 1.4Å of Fe was sputter-deposited at a DC power of 30W and an argon pressure of 0.1Pa (deposition rate: 0.29Å / sec). Under the conditions of a DC power of 10W and an argon pressure of 0.3Pa, 1.4Å of Co was sputter-deposited at a deposition rate of 0.11Å / sec. Fe and Co were sputter-deposited alternately to prepare a total of 37 reference layers 1033 with a total thickness of 5.18nm.

[0055] When the temperature in the magnetron sputtering chamber is cooled to room temperature, 0.85nm Ru spacer 1037 (deposition rate 0.23Å / sec), 2nm Co 75 Fe 25 Pinning layer 1038 (deposition rate 0.24Å / sec), 5nm Ir 22 Mn 78 Antiferromagnetic layer 1034 (deposition rate 0.43Å / sec), 3nm Ru protective layer 10391 (deposition rate 0.23Å / sec) and 2nm Ta protective layer 10392 (deposition rate 0.29Å / sec).

[0056] Through the above method, the present invention prepares a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer. After an ordered seed layer is prepared on the thermally oxidized silicon wafer, the giant magnetoresistance effect spin valve multilayer film structure is epitaxially grown, which can greatly reduce the lattice mismatch of the giant magnetoresistance effect spin valve multilayer film structure, improve the lattice order of the giant magnetoresistance effect spin valve multilayer film structure on the thermally oxidized silicon wafer, and improve the magnetoresistance ratio, providing a technical basis in terms of materials and processes for a higher-sensitivity giant magnetoresistance effect sensor, and is expected to improve the weak magnetic detection capability of the giant magnetoresistance effect sensor.

[0057] The present invention selects Ta / Co 40 Fe 40 B 20 The Ta / Mg / MgO structure is used as the seed layer structure for epitaxial growth of the giant magnetoresistance effect spin valve multilayer film structure on the thermal oxide silicon wafer, providing preparation conditions for improving the order of the giant magnetoresistance effect spin valve multilayer film structure on the thermal oxide silicon wafer. Among them, by adjusting the DC magnetron sputtering parameters such as gas pressure, power and film thickness, Ta / Co is deposited on the thermal oxide silicon wafer. 40 Fe 40 B 20 / Mg film layer, ensuring the flatness of the seed layer while providing conditions for the epitaxial growth of the MgO layer. By adjusting the RF magnetron sputtering parameters, such as gas pressure, power and film thickness, a single crystal MgO layer with an epitaxial growth of 001 orientation is prepared, providing conditions for the epitaxial growth of the giant magnetoresistance effect spin valve multilayer film structure.

[0058] The present invention adopts a DC magnetron sputtering method to alternately deposit submicron Fe and Co film layers at a certain temperature, and then performs a high-temperature annealing treatment to achieve the preparation of a cobalt-iron alloy with a high-order B2 single crystal structure. The order and spin polarization rate of the cobalt-iron alloy crystal are regulated by the sputtering time, gas pressure, and power parameters during the magnetron sputtering process.

[0059] The present invention adopts a cobalt-iron alloy / Ag or Cu / cobalt-iron alloy sandwich layer as the core structure of a giant magnetoresistance effect spin valve multilayer film structure. Due to the strong spin-related scattering effect of the Fe / Ag or Fe / Cu interface, the magnetoresistance ratio of the giant magnetoresistance effect spin valve multilayer film structure is further improved on the basis of adopting an artificial high-order B2 alloy.

[0060] As a third aspect of the present invention, a magnetoresistive element is provided, which is manufactured using the above-mentioned giant magnetoresistive effect spin valve multilayer film structure based on thermally oxidized silicon wafers.

[0061] In the embodiment of the present invention, the magnetoresistive element made by using the giant magnetoresistive effect spin valve multilayer film structure based on thermally oxidized silicon wafer with a high magnetoresistance ratio has the advantages of high sensitivity, low noise, wide dynamic range, excellent linearity, small size, low power consumption and good thermal stability. These advantages make the magnetoresistive element have broad application prospects and important research value in the field of magnetic sensors.

[0062] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A giant magnetoresistance effect spin valve multilayer film structure based on thermally oxidized silicon wafer, comprising: Thermally oxidized silicon wafer, and a seed layer and a giant magnetoresistance effect spin valve multilayer film structure sequentially formed on the thermally oxidized silicon wafer, wherein the giant magnetoresistance effect spin valve multilayer film structure comprises a free layer, a non-magnetic metal layer, a reference layer and an Ir 22 Mn 78 Antiferromagnetic layer; Wherein, the seed layer includes Co 40 Fe 40 B 20 A seed layer, a Mg layer and a MgO layer, wherein the seed layer is suitable for epitaxial growth of a giant magnetoresistance effect spin valve multilayer film structure on the thermally oxidized silicon wafer; The free layer and the reference layer are Fe having an ordered body-centered cubic structure. 50 Co 50 alloy; The non-magnetic metal layer is an Ag layer or a Cu layer.

2. The giant magnetoresistance effect spin valve multilayer film structure according to claim 1, wherein: The seed layer further comprises: The thermal oxide silicon wafer and the Co 40 Fe 40 B 20 Ta layer between layers.

3. The giant magnetoresistance effect spin valve multilayer film structure according to claim 1, wherein: In the free layer and the reference layer, the Fe 50 Co 50 The alloy is formed by alternating deposition of two metals, Fe and Co.

4. The giant magnetoresistance effect spin valve multilayer film structure according to claim 1 or 2, wherein: The giant magnetoresistance effect spin valve multilayer film structure also includes: a first interface layer formed between the free layer and the nonmagnetic metal layer, and forming a second interface layer between the nonmagnetic metal layer and the reference layer; Preferably, the first interface layer and the second interface layer are Fe layers.

5. The giant magnetoresistance effect spin valve multilayer film structure according to claim 4, wherein: The giant magnetoresistance effect spin valve multilayer film structure also includes: Sequentially formed on the reference layer and the Ir 22 Mn 78 Ru spacer and Co between the antiferromagnetic layers 75 Fe 25 a pinning layer; and / or Formed in the Ir 22 Mn 78 The protective layer on the surface of the antiferromagnetic layer comprises a Ru protective layer and a Ta protective layer formed in sequence.

6. A method for preparing a giant magnetoresistance effect spin valve multilayer film structure based on a thermally oxidized silicon wafer, comprising: Providing pre-treated thermally oxidized silicon wafers; On the surface of the thermally oxidized silicon wafer, Co 40 Fe 40 B 20 layer, Mg layer and MgO layer, and obtaining a seed layer after thermal annealing; Fe and Co are alternately sputtered and deposited on the seed layer to obtain a free layer, wherein the free layer is Fe having an ordered body-centered cubic structure. 50 Co 50 alloy; sputtering and depositing Ag or Cu on the free layer to obtain an Ag or Cu non-magnetic metal layer; Fe and Co are alternately sputtered and deposited on the Ag or Cu non-magnetic metal layer to obtain a reference layer, wherein the reference layer is Fe having an ordered body-centered cubic structure. 50 Co 50 alloy; Ir was sputter-deposited on the reference layer. 22 Mn 78 Alloy, Ir 22 Mn 78 Antiferromagnetic layer.

7. The preparation method according to claim 6, wherein: The Co 40 Fe 40 B 20 The thickness of the layer is 5 nm, the thickness of the Mg layer is 0.4 nm, and the thickness of the MgO layer is 10-20 nm; The thickness of the Fe and Co deposited by the alternating sputtering is 0.14 nm, and the total number of deposited layers of Fe and Co is 37; The thickness of the non-magnetic metal layer is 3-5 nm; The Ir 22 Mn 78 The thickness of the antiferromagnetic layer is 5 nm; Preferably, the preparation method further comprises: Co is sputtered and deposited on the surface of the thermally oxidized silicon wafer. 40 Fe 40 B 20 Before the layer, a Ta layer is sputter-deposited; More preferably, the thickness of the Ta layer is 5 nm.

8. The preparation method according to claim 6 or 7, wherein: The preparation method further comprises: sputtering and depositing a first metal on the surface of the free layer to obtain a first interface layer; sputtering and depositing a second metal on the surface of the non-magnetic metal layer to obtain a second interface layer; Preferably, the first metal and the second metal are Fe; More preferably, the thickness of the first interface layer and the second interface layer is 0.5-1 nm.

9. The preparation method according to claim 8, wherein: The preparation method further comprises: Sputtering and depositing Ru on the surface of the reference layer to obtain a Ru spacer layer; Co is sputtered and deposited on the surface of the Ru spacer layer. 75 Fe 25 Alloy, get Co 75 Fe 25 Pinning layer; Preferably, the thickness of the Ru spacer layer is 0.85 nm, and the Co 75 Fe 25 The thickness of the pinning layer is 3 nm; and / or In the Ir 22 Mn 78 Ru and Ta are sequentially sputtered and deposited on the surface of the antiferromagnetic layer to obtain a Ru protective layer and a Ta protective layer; Preferably, the thickness of the Ru protective layer is 3 nm, and the thickness of the Ta protective layer is 2 nm.

10. A magnetoresistive element, made of the giant magnetoresistive effect spin valve multilayer film structure based on thermally oxidized silicon wafer as claimed in any one of claims 1 to 5.

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