Nanogranular magnetic films and electronic components

Abstract

To provide a nanogranular magnetic film with satisfactory saturation magnetic flux density Bs and high resistivity ρ.SOLUTION: The nanogranular magnetic film has a structure in which minute regions of the first phase are dispersed in the second phase, the volume ratio of the first phase to the total volume of the first and second phases is 65% or less. Defining that the Fe content rate in the first phase is A(Fe1), the Fe content rate in the second phase is A(Fe2), the Co content rate in the first phase is A(Co1), the Co content rate in the second phase is A(Co2), the Ni content rate in the first phase is A(Ni1), and the Ni content rate in the second phase is A(Ni2), the largest value among A(Fe1) / A(Fe2), A(Co1) / A(Co2) and A(Ni1) / A(Ni2) is 1.20 or more and 8.00 or less, and the average crystal grain size of the micro-region of the first phase is 2 nm or more and 30 nm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a nanogranular magnetic film and an electronic component.

Background Art

[0002] In recent years, in mobile devices such as smartphones and smartwatches, an increase in the size of the display screen, an increase in the battery capacity, miniaturization, and weight reduction have been required simultaneously. The requirements for an increase in the size of the display screen and an increase in the battery capacity are requirements contrary to the requirements for miniaturization and weight reduction. In order to realize these contrary requirements, miniaturization of the circuit board has been required. Among these circuit boards, miniaturization of the power supply circuit, which occupies a particularly large area, has been required.

[0003] As a method for miniaturizing an inductor, increasing the frequency of the power supply circuit can be mentioned. In order to increase the frequency of the power supply circuit, it is required that the switching element included in the power supply circuit can be driven at a high frequency.

[0004] In recent years, semiconductors other than silicon such as GaN and SiC have been increasingly used as switching elements. [[ID=二十一]] [[ID=二十二]]

[0005] [[ID=二十三]] By using a semiconductor having excellent high-frequency characteristics such as GaN as a switching element, high-frequency driving of the switching element becomes possible. As the high-frequency driving of the switching element becomes possible, it becomes possible to increase the driving frequency of the power supply circuit. That is, the power supply circuit can be made high-frequency.

[0006] As the power supply circuit can be made high-frequency, there is a further demand for a small inductor that can support high-frequency driving and realize miniaturization of the power supply circuit.

[0007] Thin-film inductors are ideal for small inductors that can handle high-frequency driving. Thin-film inductors are manufactured by laminating coils, terminals, magnetic films, and insulating layers on a substrate using semiconductor processes. In thin-film inductors, the magnetic film acts as the magnetic core. Therefore, the characteristics of a thin-film inductor largely depend on the characteristics of the magnetic film contained within it.

[0008] Furthermore, Patent Document 1 describes an amorphous alloy having a structure in which fine particles containing a metal element are dispersed in an amorphous film made of a nitrogen compound. Such a structure is now sometimes called a nanogranular structure.

[0009] Furthermore, Patent Document 2 describes a piezoelectric film in which AlN is the main component and metal elements are intentionally added.

[0010] Patent Document 3 describes a nanogranular magnetic film having a structure in which nano-sized crystals are dispersed in an insulating matrix. The nano-sized crystals are mainly composed of elemental metals, alloys, or compounds. Examples of elemental metals include elemental Fe, elemental Co, or elemental Ni. Examples of alloys include alloys containing one or more selected from Fe, Co, and Ni. Examples of compounds include compounds containing one or more selected from Fe, Co, and Ni. The insulating matrix consists of an insulator such as SiO2 or Al2O3.

[0011] Nanogranular magnetic films have a higher saturation magnetic flux density (Bs) compared to ferrite materials. Furthermore, nanogranular magnetic films have a higher resistivity (ρ) compared to ordinary metallic materials. Because nanogranular magnetic films have high saturation magnetic flux density (Bs) and resistivity (ρ), they also have high permeability in the high-frequency range. Due to their high permeability in the high-frequency range, the application of nanogranular magnetic films to thin-film components for high-frequency applications, such as thin-film inductors, is being investigated.

[0012] However, while typical nanogranular magnetic films have a higher saturation magnetic flux density (Bs) compared to magnetic films made from typical ferrite materials, their saturation magnetic flux density (Bs) is lower compared to other common thin-film inductor magnetic metal films, such as CoZrTa (CZT) films. The magnitude of Bs in a magnetic film is proportional to the volume of the magnetic core using that film, and is also roughly proportional to the area of ​​the inductor using that film. Therefore, improving Bs is desired for nanogranular magnetic films.

[0013] Furthermore, reducing losses during high-frequency driving is required for thin-film inductors using nanogranular magnetic films. Here, the smaller the resistivity ρ of the nanogranular magnetic film, the greater the eddy current loss. Therefore, there is a need for nanogranular magnetic films with even higher resistivity ρ. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] Japanese Patent Application Publication No. 152651 / 1983 [Patent Document 2] Japanese Patent Publication No. 2020-065160 [Patent Document 3] Patent No. 3956061 [Overview of the project] [Problems that the invention aims to solve]

[0015] The present invention aims to provide a nanogranular magnetic film with good saturation magnetic flux density Bs and high resistivity ρ. [Means for solving the problem]

[0016] To achieve the above objective, the nanogranular magnetic film according to the present invention is The structure has a micro-region of the first phase dispersed in the second phase, and the first phase and the second phase contain one or more elements selected from Fe, Co, and Ni. The second phase has a higher content of one or more selected from O, N, and F compared to the first phase, the volume ratio of the first phase to the total volume of the first phase and the second phase is 65% or less, let the content ratio of Fe in the first phase be A(Fe1), and the content ratio of Fe in the second phase be A(Fe2), let the content ratio of Co in the first phase be A(Co1), and the content ratio of Co in the second phase be A(Co2), let the content ratio of Ni in the first phase be A(Ni1), and the content ratio of Ni in the second phase be A(Ni2), the largest of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) is 1.20 or more and 8.00 or less, the average size of the micro-regions of the first phase is 2 nm or more and 30 nm or less.

[0017] The average size of the micro-regions of the first phase may be 2 nm or more and 15 nm or less.

[0018] The first phase may have a crystal structure of bcc.

[0019] The nano-granular magnetic film may contain Fe and Co, and {A(Co1) / A(Co2)} / {A(Fe1) / A(Fe2)} may be > 1.05.

[0020] The nano-granular magnetic film may contain Fe and Co, and {A(Co1) / A(Co2)} / {A(Fe1) / A(Fe2)} may be > 2.00.

[0021] The electronic component according to the present invention has the above nano-granular magnetic film.

Brief Description of Drawings

[0022] [Figure 1] It is a cross-sectional schematic diagram of a nano-granular magnetic film. [Figure 2] It is a HAADF-STEM image of sample number 12. [Figure 3] This is the Co mapping image of sample number 12. [Figure 4] This is the Fe mapping image of sample number 12. [Figure 5] This is the Si mapping image of sample number 12. [Figure 6] This is the O-mapping image of sample number 12. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described below with reference to the drawings.

[0024] As shown in Figure 1, the nanogranular magnetic film 1 according to this embodiment has a structure in which minute regions of the first phase 11 are dispersed in the second phase 12, i.e., a nanogranular structure. Furthermore, when a cross-section of the nanogranular magnetic film 1 is observed with a STEM (scanning transmission electron microscope), the HAADF (high-angle annular dark-field)-STEM image shown in Figure 2 is obtained. Note that the HAADF-STEM image shown in Figure 2 is the HAADF-STEM image (magnification 2.5 million times) of sample number 12, which will be described later.

[0025] The average size of the microregions of the first phase 11 is nanometer-sized, i.e., 30 nm or less. The average size of the microregions of the first phase 11 may also be 15 nm or less. There are no particular restrictions on the method for measuring the size of the microregions of the first phase 11. For example, the microregions of the first phase 11 in the cross-section of the nanogranular magnetic film 1. Short axis length This may be used as the size of the microregion of the first phase 11.

[0027] Phase 11 is a phase containing metallic elements. Specifically, it contains one or more elements selected from Fe, Co, and Ni. There are no particular restrictions on how one or more elements selected from Fe, Co, and Ni are included in Phase 11. For example, one or more elements selected from Fe, Co, and Ni may be included in Phase 11 as elemental elements, as alloys with other metallic elements, or as compounds with other elements. The compounds included in Phase 11 may be oxide magnetic materials. For example, they may be ferrites.

[0028] There are no particular restrictions on the total content of Fe, Co, and / or Ni in Phase 1 11. The ratio of the total content of Fe, Co, and Ni to the total content of Fe, Co, Ni, X1, and X2 in Phase 1 11 may be 75 at% or more, or 80 at% or more. However, when calculating this ratio, elements whose content in Phase 2 12 is higher than their content in Phase 1 11 are not included in X1 and X2.

[0029] X1 is a metalloid element. For example, it may be one or more metalloid elements selected from B, Si, P, C, and Ge.

[0030] X2 is a metallic element other than Fe, Co, and Ni. For example, it may be one or more metallic elements selected from Cr, Ti, Zr, V, Nb, Mo, Mn, Cu, Zn, Al, and Y.

[0031] Phase 11 may contain elements other than Fe, Co, Ni, X1, and X2. The ratio of the total content of elements other than Fe, Co, Ni, X1, and X2 to the total content of Fe, Co, Ni, X1, and X2 may be 5 at% or less.

[0032] Phase 2 12, like Phase 1 11, contains one or more elements selected from Fe, Co, and Ni. Furthermore, Phase 2 12 is a phase containing nonmetallic elements. Specifically, it may contain one or more elements selected from O, N, and F. There are no particular restrictions on how the one or more elements selected from O, N, and F are included in Phase 2 12. For example, one or more elements selected from O, N, and F may be included in Phase 2 12 as compounds with other elements.

[0033] There are no particular restrictions on the types of compounds included in Phase 2 12. Examples include SiO2, Al2O3, AlN, ZnO, MgF2, SnO2, GaO2, GeO2, Si3N4·Al2O3, etc.

[0034] The nanogranular magnetic film 1 according to this embodiment may contain impurities that are not included in either the elements constituting the first phase 11 or the elements constituting the second phase 12. The nanogranular magnetic film may contain impurities at a concentration of 5 at% or less, with a total percentage of elements (excluding O, N, and F) of the nanogranular magnetic film being 100 at%.

[0035] The volume ratio of the first phase 12 to the total volume of the first phase 11 and the second phase 12 is 65% or less. That is, if V1 is the volume ratio of the first phase 11 and V2 is the volume ratio of the second phase 12, then V1 / (V1+V2) is 0.65 or less. V1 / (V1+V2) may also be 0.60 or less. If the volume ratio of the first phase 11 to the total volume of the first phase 11 and the second phase 12 is too large, the resistivity ρ of the nanogranular magnetic film decreases. This is because the first phase 11 has higher conductivity than the second phase 12.

[0036] There is no particular lower limit to the volume ratio of Phase 11 to the total volume of Phase 11 and Phase 212, but even if it is 30% or more Yoi. That is, V1 / (V1+V2) may be 0.30 or greater. V1 / (V1+V2) may be 0.38 or greater, or 0.40 or greater. The smaller the volume ratio of the first phase 11 to the total volume of the first phase 11 and the second phase 12, the higher the resistivity ρ and the lower the coercivity Hc, but the lower the saturation magnetic flux density.

[0037] In the nanogranular magnetic film 1, the first phase 11 contains more metallic elements (Fe, Co, and / or Ni) compared to the second phase 12. Specifically, let A(Fe1) be the Fe content in the first phase 11, A(Fe2) be the Fe content in the second phase 12, A(Co1) be the Co content in the first phase 11, A(Co2) be the Co content in the second phase 12, A(Ni1) be the Ni content in the first phase 11, and A(Ni2) be the Ni content in the second phase 12. The largest of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) is between 1.20 and 8.00.

[0038] The above Fe content ratio is calculated as the atomic ratio of Fe to the total content of Fe, Co, Ni, and the elements constituting the compounds in Phase 2 12. Note that the elements constituting the compounds in Phase 2 12 do not include O, N, and F. The same applies to the above Co content ratio and Ni content ratio.

[0039] Furthermore, if Z is defined as an element among Fe, Co, and Ni whose content in the nanogranular magnetic film 1 is less than 5 at%, then A(Z1) / A(Z2) is not considered. For example, if the content of Ni is less than 5 at%, then A(Ni1) / A(Ni2) is not considered.

[0040] When at least one of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) is 1.20 or higher, the resistivity ρ improves, and the saturation magnetic flux density Bs also tends to improve, compared to when all of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) are less than 1.20. When at least one of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) is above 8.00, the resistivity ρ does not improve sufficiently, and the coercivity Hc tends to increase.

[0041] The following describes how to measure the content ratio of each element in each phase of the nanogranular magnetic film 1.

[0042] First, the nanogranular magnetic film 1 is observed using TEM or STEM. The resolution of the resulting TEM or STEM image shall be such that each pixel is between 0.01 nm and 0.3 nm. The magnification of the resulting TEM or STEM image shall be between 100,000x and 10,000,000x.

[0043] The first phase 11 and the second phase 12 are identified visually from the TEM or STEM image. In bright-field images, the second phase 12 tends to appear brighter than the first phase 11. In dark-field images, the first phase 11 tends to appear brighter than the second phase 12. If necessary, mapping images of each element, including Fe, Co, Ni, and the elements constituting the compounds in the second phase 12, may also be used. The mapping images of each element in sample number 12 of the example described later are illustrated in Figures 3 to 6.

[0044] For each of the identified Phase 11 and Phase 212, the content ratios of Fe, Co, Ni, and the elements constituting the compounds in Phase 212 are quantified, and A(Fe1), A(Fe2), A(Co1), A(Co2), A(Ni1), and A(Ni2) are calculated. Then, A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) are calculated.

[0045] The content ratio of each element in the first phase 11 may be the average content ratio of each element in all of the first phase 11 contained in the nanogranular magnetic film 1. The content ratio of each element in the second phase 12 may be the average content ratio of each element in all of the second phase 12 contained in the nanogranular magnetic film 1.

[0046] There are no particular restrictions on the method for quantifying the content ratio of each element in the identified first phase 11 and second phase 12. For example, one or more measurement points may be set in each of the identified first phase 11 and second phase 12, and the content ratio of each element may be quantified using EELS (electron energy loss spectroscopy).

[0047] If two or more measurement points are set in each of the identified Phase 1 11 and Phase 2 12, the obtained quantitative results may be averaged.

[0048] Furthermore, if the nanogranular magnetic film 1 is uniform, it is sufficient to set one measurement point in each of the identified first phase 11 and second phase 12. The content ratio of each element at the measurement point in the first phase 11 may be considered as the average content ratio of each element in all of the first phase 11. The content ratio of each element at the measurement point in the second phase 12 may be considered as the average content ratio of each element in all of the second phase 12.

[0049] Standard samples are not required when quantifying the content ratios of Fe, Co, Ni, and the elements that make up the compounds contained in the second phase 12. This is because relative comparisons of each phase can be accurately performed without using standard samples. In other words, if the measuring device is the same and the content ratios of each element in the first phase 11 and the second phase 12 can be measured simultaneously, A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) can be accurately calculated without using standard samples. On the other hand, the reliability of the individual measured values ​​of A(Fe1), A(Fe2), A(Co1), A(Co2), A(Ni1), and A(Ni2) is not high.

[0050] When the nanogranular magnetic film 1 contains Fe and Co, it is preferable that {A(Co1) / A(Co2)} / {A(Fe1) / A(Fe2)} is greater than 1.05, and more preferably greater than 2.00. When {A(Co1) / A(Co2)} / {A(Fe1) / A(Fe2)} is large, further specific resistance This makes it easier to improve ρ and the saturation magnetic flux density Bs.

[0051] The first phase 11 may have a crystalline structure. Specifically, the first phase 11 may have a bcc crystalline structure. Having a bcc crystalline structure makes it easier to increase the saturation magnetic flux density Bs. The average grain size of the crystals included in the crystalline structure of the first phase may be 2 nm or more and 30 nm or less, and more preferably 2 nm or more and 15 nm or less.

[0052] There are no particular restrictions on the method for confirming the crystal structure and the average grain size of the crystal as described above. For example, the crystal structure can be confirmed by analyzing the X-ray diffraction pattern using XRD, or by analyzing the electron diffraction pattern using TEM, etc. In addition, the average grain size can be confirmed by TEM images, STEM images, etc. Furthermore, the average size of the minute region of the first phase 11 described above can be considered as the average grain size of the crystal.

[0053] There are no particular restrictions on the method for measuring the volume ratio V1 / (V1+V2) of the first phase 11 to the total volume of the first phase 11 and the second phase 12. For example, it can be calculated from the XRF measurement results of the nanogranular magnetic film 1. Alternatively, it may be calculated by observing the cross-section of the nanogranular magnetic film 1 with a TEM and calculating it from the area of ​​the first phase 11 to the total area of ​​the first phase 11 and the second phase 12. In this case, the area ratio is converted to a volume ratio.

[0054] The nanogranular magnetic film 1 may contain only the first phase 11 and the second phase 12, but it may also contain other phases besides the first phase 11 and the second phase 12. There are no particular restrictions on the proportion of the other phases, but when observing the cross-section of the nanogranular magnetic film 1 with a TEM, the area proportion of the other phases may be 10% or less. Furthermore, some or all of the other phases may be voids.

[0055] In Figure 1, all the first phase 12s are separated from each other, but some of the first phase 12s may be in contact with each other.

[0056] The thickness of the nanogranular magnetic film 1 is arbitrary. For example, it may be between 0.05 μm and 200 μm. Alternatively, a suitable thickness may be selected depending on the application. There are no particular restrictions on the method for measuring the thickness of the nanogranular magnetic film 1. For example, it can be measured using a TEM, SEM, step thickness gauge, etc. Furthermore, the reliability of the obtained measurement results may be confirmed by regulating the results between multiple measuring devices in advance.

[0057] The method for producing a nanogranular magnetic film according to this embodiment will be described below.

[0058] There are no particular limitations on the method for manufacturing the nanogranular magnetic film according to this embodiment. For example, a method of manufacturing by sputtering is one example.

[0059] First, prepare a substrate for sputtering the nanogranular magnetic film. The type of substrate is arbitrary. Examples include silicon substrates, silicon substrates with thermal oxide films, ferrite substrates, non-magnetic ferrite substrates, sapphire substrates, glass substrates, and glass epoxy substrates. However, the type of substrate is not limited to these, and various ceramic substrates and various semiconductor substrates can be used. Also, if it is difficult to confirm various properties using only the thin film deposited on the sample substrate, a dummy substrate may be used as needed. Thin films may be deposited on both the sample substrate and the dummy substrate simultaneously, and the properties of the thin film deposited on the dummy substrate may be considered as the properties of the thin film deposited on the sample substrate.

[0060] Next, prepare the sputtering equipment. Prepare a sputtering equipment capable of simultaneous multi-target sputtering. Furthermore, prepare a sputtering equipment that can vary the distance between the sputtering target and the substrate for each target.

[0061] Next, a metal sputtering target and a ceramic sputtering target are prepared as sputtering targets. The relative abundance of Fe, Co, Ni, X1, and X2 in the metal sputtering target is approximately the same as the relative abundance of Fe, Co, Ni, X1, and X2 in the first phase 11. The ceramic sputtering target is mainly composed of compounds contained in the second phase 12.

[0062] Next, a metal sputtering target is attached to the metal gun of the prepared sputtering apparatus, and a ceramic sputtering target is attached to the ceramic gun. Then, a nanogranular magnetic film is deposited on the substrate by simultaneous multi-point sputtering.

[0063] By controlling the voltage applied to each sputtering target, the volume ratio of the first phase 11 to the total volume of the first phase 11 and the second phase 12, as well as the deposition rate, can be controlled. The deposition rate can be, for example, between 1 Å / s and 100 Å / s.

[0064] By controlling the film deposition rate and deposition time, the thickness of the resulting nanogranular magnetic film can be controlled.

[0065] The inventors have discovered that the film density of the resulting nanogranular magnetic film can be controlled by controlling the distance between the ceramic sputtering target and the sample substrate. The mechanism for controlling the film density will be explained below.

[0066] First, a rare gas such as argon is introduced into a vacuum at low pressure, and a glow discharge is induced by applying a negative potential to the sputtering target, generating a plasma. In the plasma, the rare gas atoms are ionized into rare gas cations and electrons. Next, the rare gas cations are electrically attracted to the negatively charged sputtering target and undergo an elastic collision. During this collision, the rare gas cations receive electrons from the sputtering target and become rare gas atoms. Furthermore, sputtered particles are ejected from the sputtering target by this elastic collision. These ejected sputtered particles then deposit on the substrate to form a sputtered film.

[0067] Sputtered particles ejected from the sputtering target may undergo elastic collisions with noble gas atoms present in the deposition chamber as they fly from the surface of the sputtering target to the substrate. Each time a sputtered particle collides with a noble gas atom, it loses kinetic energy. The higher the energy of the sputtered particles upon reaching the substrate, especially their kinetic energy, the denser the sputtered film formed.

[0068] Here, the shorter the distance between the sputtering target and the substrate, the higher the kinetic energy the sputtered particles maintain when they reach the substrate. As a result, the shorter the distance between the sputtering target and the substrate, the higher the film density of the nanogranular magnetic film, and a denser sputtered film is formed.

[0069] Furthermore, among sputtering targets, the film density of the nanogranular magnetic film tends to increase when the distance between the ceramic sputtering target and the substrate is particularly short. In contrast, the film density does not change easily even if the distance between the metal sputtering target and the substrate changes. Therefore, by bringing only the ceramic sputtering target closer to the substrate, the film density of the nanogranular magnetic film can be increased. Also, if the physical distance between the metal sputtering target and the ceramic sputtering target becomes too close, the plasma generated on each sputtering target during film deposition may interfere with each other, leading to unstable discharge.

[0070] There are no particular restrictions on the method of changing the distance between the ceramic sputtering target and the substrate. It should be changed in a way that is suitable for the sputtering equipment being used. Generally, this can be done by moving the ceramic sputtering gun to change the distance to the substrate.

[0071] If simply moving the ceramic gun is insufficient to reduce the distance between the ceramic sputtering target and the substrate to the desired distance, the substrate holder to which the substrate is mounted may be moved closer to the ceramic gun than the specified value. Alternatively, jigs or shutters around the substrate may be removed. Furthermore, a spacer may be installed between the transport tray and the substrate, or an aluminum plate may be installed between the substrate and the substrate holder. In such cases, the metal gun may be moved as needed to change the distance between the metal gun and the substrate.

[0072] The film density of the nanogranular magnetic film obtained by the above method can be controlled. However, simply increasing the film density of the nanogranular magnetic film improves the saturation magnetic flux density Bs of the nanogranular magnetic film, but decreases its resistivity ρ. Conversely, decreasing the film density of the nanogranular magnetic film improves its resistivity ρ, but decreases its saturation magnetic flux density Bs. In other words, there is a trade-off between improving the resistivity ρ in the nanogranular magnetic film and improving the saturation magnetic flux density Bs.

[0073] The inventors have found that by performing an annealing treatment on a nanogranular magnetic film with controlled film density, metal elements diffuse, and compositional separation between the first phase 11 and the second phase 12 proceeds. In other words, they found that the diffusion state of metal elements can be suitably controlled by controlling the film density of the nanogranular magnetic film. Furthermore, they found that by performing an annealing treatment on a nanogranular magnetic film with controlled film density, a nanogranular magnetic film can be obtained in which at least one of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) has a resistivity of 1.20 or higher. The resistance of the second phase 12 increases because at least one of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) has a resistivity of 1.20 or higher. As a result, a nanogranular magnetic film with high resistivity ρ is obtained.

[0074] As described above, the shorter the distance between the sputtering target and the substrate, the higher the film density of the nanogranular magnetic film, resulting in a denser nanogranular magnetic film. Furthermore, as the film density of the nanogranular magnetic film increases, the diffusion of metal elements due to annealing increases. Consequently, A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) become higher. However, if the diffusion due to annealing becomes too high, the grain growth of the crystal particles contained in the nanogranular magnetic film progresses excessively. Therefore, the coercivity Hc of the nanogranular magnetic film increases. In addition, the number of connections between the first phase 11 particles becomes too high, causing the resistivity ρ of the nanogranular magnetic film to decrease.

[0075] There are no particular restrictions on the temperature of the annealing process, but it may be around 200°C to 350°C, or 250°C to 350°C. There are no particular restrictions on the duration of the annealing process, but it may be between 0.1 minutes and 60 minutes.

[0076] The method for measuring the magnetic properties of the obtained nanogranular magnetic film is arbitrary. For example, it can be measured using a VSM.

[0077] Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment.

[0078] There are no particular limitations on the applications of the nanogranular magnetic film according to this embodiment. Magnetic materials containing the nanogranular magnetic film are particularly suitable for use in electronic components that are used at high frequencies and require high Bs and ρ. Examples include recording media for vertical recording, TMR heads for magnetic random access memory (MRAM), magneto-optical elements, thin-film inductors, noise filters, and high-frequency capacitors.

[0079] Furthermore, the magnetic material containing the nanogranular magnetic film used in the above-mentioned electronic components may be a single-layer structure containing only the nanogranular magnetic film, or a laminated structure in which the nanogranular magnetic film and a film made of another material (e.g., an SiO2 film) are laminated together. There is also no limit to the number of layers. [Examples]

[0080] The present invention will be specifically described below based on examples.

[0081] (Experimental Example 1) Two 6x6x0.6mmt silicon substrates with a thermal oxide film were prepared as sample substrates for VSM measurement. One substrate was prepared as a dummy substrate for film thickness measurement, consisting of a 6x6x0.6mmt silicon substrate with a thermal oxide film on which a resist with a length of 6mm and a width of 0.5-1mm was placed. , A 2-inch, 0.4mm thick sapphire substrate was prepared as a dummy substrate for measuring magnetic resistance. Nanogranular magnetic films were then deposited on these substrates. A multi-location simultaneous sputtering system (Eikoh Co., Ltd. ES340) was used for film deposition. Further details are provided below.

[0082] In Experimental Example 1, Fe was used as the sputtering target in an atomic ratio. 60 Co 40A metal sputtering target made of an alloy and a ceramic sputtering target made of SiO2 were prepared. Next, each sputtering target was mounted on a separate gun.

[0083] In Experimental Example 1, the Ar gas pressure during sputtering was fixed at 0.4 Pa. The distance between the ceramic sputtering target and the sample substrate (TS distance) was set to the values ​​shown in Table 1. The distance between the metal sputtering target and the sample substrate was set to 90 mm.

[0084] Then, the volume ratio of the first phase to the total volume of the first and second phases was set to approximately 55% (V1 / (V1+V2) = approximately 0.55), and the power supplied to each sputtering target was controlled to achieve a deposition rate of 1.0 Å / s. A nanogranular magnetic film was then deposited by sputtering. The thickness of the nanogranular magnetic film was set to 300 nm.

[0085] Next, the samples were annealed. Specifically, they were held for 1 minute at the annealing temperatures shown in Table 1. Samples where the annealing temperature is left blank were not annealed.

[0086] The composition of the nanogranular magnetic film was determined by performing a simple quantitative analysis using EDX (manufactured by JEOL Ltd.) on the nanogranular magnetic film that was deposited on a silicon substrate with a thermal oxide film and annealed.

[0087] The film thickness of the nanogranular magnetic film was measured using a step thickness gauge (KLA Tencor P-16+) that had been pre-correlated with a TEM. Specifically, the film thickness of a thin film deposited on a dummy substrate for film thickness measurement and annealed was measured using the step thickness gauge. As described above, it was confirmed to be 300 nm.

[0088] The nanogranular film, deposited on a sample substrate using an XRF (Primus4, manufactured by Rigaku Corporation) and annealed, was measured, and the volume ratio of the first phase to the total volume of the first and second phases was calculated. The results are shown in Table 1.

[0089] Using a TEM (JEM2100F manufactured by JEOL Ltd.), it was confirmed that the nanogranular magnetic films of each sample, which were deposited on a sample substrate and annealed, had a structure in which minute regions of the first phase were dispersed within the second phase.

[0090] The crystal structure of the first phase of the nanogranular magnetic film was confirmed by electron diffraction to identify the crystal structure of the nanogranular magnetic film that was deposited on a silicon substrate with a thermal oxide film and annealed.

[0091] The average grain size (average size of a micro-region in the first phase) of the crystals in the first phase of the nanogranular magnetic film was confirmed using HAADF-STEM imaging. The grain size was defined as the short axis length of the particle. The short axis length was measured for at least 100 particles, and the average value was taken to determine the average grain size.

[0092] A(Fe1), A(Fe2), A(Co1), and A(Co2) were measured using STEM-EELS (Quantum, GATAN).

[0093] This section describes the measurement method using STEM-EELS. First, a sample for STEM observation was prepared. A 30 nm thick Pt film was deposited by sputtering onto a nanogranular magnetic film that had been deposited on a silicon substrate with a thermal oxide film and then annealed.

[0094] Next, a microsample was cut out using a FIB (Focused Ion Beam Processing and Observation System, Hitachi High-Tech Fielding NX5000) to select the area to be picked up. Then, a 2 μm thick Pt film was further formed on the above Pt film in the selected area and its surroundings using electron beam deposition and ion beam deposition.

[0095] Next, microsamples of the nanogranular magnetic film were cut and picked up using FIB. Specifically, the substrate, nanogranular magnetic film, and Pt film were cut and picked up together to form a rectangle with one side length (sample thickness, described later) of 1 μm when viewed from the thickness direction of the nanogranular magnetic film. Then, a microsample was obtained in which the substrate, nanogranular magnetic film, and Pt film were arranged in this order and the sample thickness was 1 μm.

[0096] Then, microsamples with a sample thickness of 1 μm were thinned to a sample thickness of 10 nm or less to prepare samples for STEM observation.

[0097] Next, using the prepared STEM observation sample, a HAADF-STEM image with a pixel size of approximately 0.1 nm was obtained. The first phase (crystalline phase) and the second phase (amorphous phase) were then visually identified from the HAADF-STEM image. Fe mapping images, Co mapping images, Si mapping images, and / or O mapping images were also used as needed. The average grain size of the crystals in the first phase was then confirmed. Specifically, the average size of a minute region in the first phase was considered to be the average grain size of the crystals in the first phase.

[0098] For the first phase, the proportion of Fe relative to the total number of Fe, Co, and Si atoms was measured to obtain A(Fe1). The proportion of Co relative to the total number of Fe, Co, and Si atoms was measured to obtain A(Co1).

[0099] For the second phase, the proportion of Fe relative to the total number of Fe, Co, and Si atoms was measured to obtain A(Fe2). The proportion of Co relative to the total number of Fe, Co, and Si atoms was measured to obtain A(Co2).

[0100] O mapping images confirmed that the second phase contained more oxygen than the first phase in all samples shown in Table 1.

[0101] Bs and Hc were measured using a VSM for each nanogranular magnetic film deposited on a sample substrate and annealed. Magnetic properties were measured using a VSM (TM-VSM331483-HGC) manufactured by Tamagawa Seisakusho Co., Ltd. The measurement magnetic field ranged from -10000 Oe to +10000 Oe. The results are shown in Table 1. Furthermore, Bs (Bs0) was measured for samples deposited on the sample substrate but not annealed. The Bs ratio, Bs / Bs0, was then calculated. Furthermore, Hc (Hc0) was measured for samples deposited on the sample substrate but not annealed. The Hc ratio, Hc / Hc0, was then calculated. The results are shown in Table 1. Bs was considered good if Bs / Bs0 was 1.15 or higher. Hc was considered good if Hc was 5.00 Oe or lower.

[0102] The ρ of each sample was determined by measuring the sheet resistance using a resistivity meter (Mitsubishi Chemical Loresta-EP MCP-T360). The sheet resistance of thin films deposited on sapphire substrates used for composition confirmation and sheet resistance measurement, and then annealed, was measured, and the obtained sheet resistances were considered to be the sheet resistance of the thin films in each experimental example. Then, the ρ of each sample was calculated using the film thickness of the thin films deposited on dummy substrates used for film thickness measurement.

[0103] The ρ(ρ0) of samples that were deposited on sample substrates but not annealed was measured. The ρ / ρ0 ratio was then calculated. The results are shown in Table 1. A ρ / ρ0 ratio of 1.20 or higher was considered to indicate good ρ.

[0104] [Table 1]

[0105] Table 1 shows that in the example where the TS distance was greater than 90 mm and the annealing temperature was set to 300°C for sufficient annealing, the largest of the A(Fe1) / A(Fe2) and A(Co1) / A(Co2) ratios was between 1.20 and 8.00, and the average crystal grain size was between 2 nm and 30 nm. In this example, ρ and Bs were significantly improved compared to before annealing. Furthermore, this example resulted in a nanogranular magnetic film with superior magnetic properties and a high ρ compared to the comparative example, which was carried out under the same conditions except for the annealing temperature being 150°C or lower.

[0106] When annealing was performed at a temperature of 300°C with a TS distance of 90 mm or less, the largest of A(Fe1) / A(Fe2) and A(Co1) / A(Co2) exceeded 8.00. As a result, Hc increased. This is thought to be due to the progression of grain growth of the nanocrystals constituting the first phase. Furthermore, when annealing was performed at a temperature of 300°C with a TS distance of 90 mm or less, ρ and / or Bs did not increase sufficiently. This is thought to be because the first phases became excessively bonded together due to the annealing.

[0107] (Experimental Example 2) Experimental Example 2 was conducted in the same manner as Experimental Example 1, except that the sputtering conditions were adjusted to change the volume ratio of the first phase to the total volume of the first and second phases, i.e., V1 / (V1+V2). As a result, it was confirmed that the V1 / (V1+V2) for each sample was as shown in Table 2. The results are shown in Table 2.

[0108] [Table 2]

[0109] Table 2 shows that in the example where the TS distance was increased to more than 90 mm and the annealing temperature was set to 300°C for sufficient annealing, the largest of the A(Fe1) / A(Fe2) and A(Co1) / A(Co2) values ​​was between 1.20 and 8.00, and the average grain size was between 2 nm and 30 nm. In this example, ρ and Bs were significantly improved compared to before the annealing treatment.

[0110] In the example, the nanogranular magnetic film in which the volume ratio of the first phase to the total volume of the first and second phases was 65% or less had a coercivity Hc of 5.00Oe or less. This confirmed that a low-loss thin-film inductor can be fabricated using the nanogranular magnetic film in the example. In contrast, the nanogranular magnetic film in the comparative example, in which the volume ratio was greater than 65%, had a coercivity Hc greater than 5.00Oe, regardless of whether or not it was annealed. This indicates that it is difficult to fabricate a low-loss thin-film inductor using the nanogranular magnetic film in the comparative example, in which the volume ratio of the first phase to the total volume of the first and second phases is too large.

[0111] (Experimental Example 3) The experiment was conducted in the same manner as in Experimental Example 1, except that the type of ceramic sputtering target was changed to alter the types of compounds contained in the second phase, as shown in Table 3. The results are shown in Table 3. Note that, due to the change in the types of compounds contained in the second phase, the volume ratio of the first phase to the total volume of the first and second phases may have deviated slightly from 55%.

[0112] [Table 3]

[0113] Table 3 shows that even when the compound included in the second phase was changed, in the example where the TS distance was increased to more than 90 mm and the annealing temperature was set to 300°C for sufficient annealing, the largest of A(Fe1) / A(Fe2) and A(Co1) / A(Co2) was between 1.20 and 8.00, and the average grain size was between 2 nm and 30 nm. In this example, ρ and Bs were significantly improved compared to before annealing.

[0114] (Experimental Example 4) For samples 10-12 in Experimental Example 1, the experiment was conducted under the same conditions except for a change in the annealing temperature. The results are shown in Table 4. It was confirmed that all samples in Table 4 had a V1 / (V1+V2) ratio of 0.55.

[0115] [Table 4]

[0116] Table 4 shows that in the examples where the annealing temperature was suitably controlled so that the largest of A(Fe1) / A(Fe2) and A(Co1) / A(Co2) was between 1.20 and 8.00, and the average grain size was between 2 nm and 30 nm, ρ and Bs were significantly improved compared to before the annealing treatment.

[0117] In contrast, in the comparative example where the annealing temperature was too high, the largest of the A(Fe1) / A(Fe2) and A(Co1) / A(Co2) ratios exceeded 8.00, and the average grain size exceeded 30 nm. As a result, ρ decreased and Hc increased.

[0118] (Experimental Example 5) The experiment was conducted in the same manner as in Experimental Example 1, except that the composition of the nanogranular magnetic film was changed to the compositions shown in Tables 5 to 9 by changing the type of metal sputtering target. The results are shown in Tables 5 to 9. It was confirmed that all samples shown in Tables 5 to 9 had a V1 / (V1+V2) of 0.55.

[0119] [Table 5]

[0120] [Table 6]

[0121] [Table 7]

[0122] [Table 8]

[0123] [Table 9]

[0124] Tables 5 to 9 show that even when the composition of the nanogranular magnetic film was changed to the compositions shown in Tables 5 to 9, in the example where the TS distance was increased to more than 90 mm and the annealing temperature was set to 300°C for sufficient annealing, the largest of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) was between 1.20 and 8.00, and the average crystal grain size was between 2 nm and 30 nm. In this example, ρ and Bs were significantly improved compared to before the annealing treatment. [Explanation of symbols]

[0125] 1…Nanogranular magnetic film 11…Phase 1 12...Phase 2

Claims

1. comprising at least Fe and Co, The structure has a micro-region of the first phase dispersed in the second phase, and the first phase and the second phase each contain one or more elements selected from Fe, Co, and Ni. The second phase has a higher content of one or more elements selected from O, N, and F compared to the first phase. The volume ratio of the first phase to the total volume of the first and second phases is 65% or less. The Fe content ratio in the first phase is A(Fe1), and the Fe content ratio in the second phase is A(Fe2). The Co content ratio in the first phase is A(Co1), and the Co content ratio in the second phase is A(Co2). Let A(Ni1) be the Ni content in the first phase and A(Ni2) be the Ni content in the second phase. The largest of A(Fe1) / A(Fe2), A(Co1) / A(Co2), and A(Ni1) / A(Ni2) is between 1.20 and 7.

99. 2.03 ≤ {A(Co1) / A(Co2)} / {A(Fe1) / A(Fe2)} ≤ 4.97, A nanogranular magnetic film in which the average size of the first phase micro-region is 2 nm or more and 30 nm or less.

2. The nanogranular magnetic film according to claim 1, wherein the average size of the minute region of the first phase is 2 nm or more and 15 nm or less.

3. The nanogranular magnetic film according to claim 1 or 2, wherein the first phase has a crystalline structure in which bcc.

4. An electronic component having a nanogranular magnetic film according to any one of claims 1 to 3.

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