JP2018164059A - Ferromagnetic Multilayer Thin Film and Thin Film Inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferromagnetic multilayer thin film having a high magnetic permeability, a high saturated magnetic flux density and a low coercive force.SOLUTION: A ferromagnetic multilayer thin film 12 comprises an underlying layer 14 and a ferromagnetic layer. The ferromagnetic layer includes Fe, α1 and α2, where α1 represents one or more kinds selected from Cu, Ag and Au, and α2 represents one or more kinds selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W. The ferromagnetic layer includes a nanocrystal layer 16a and an amorphous layer 16b. The underlying layer 14 is in contact with the nanocrystal layer 16a. The nanocrystal layer 16a includes microcrystal 16a' having Fe as a primary component. The underlying layer 14 includes 10 atom% or more of one or more kinds selected from Al, Ga, In, Tl, Ge, Sn and Pb in total.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ferromagnetic multilayer thin film and a thin film inductor.

  A thin film inductor in which a coil and a magnetic core are manufactured by a thin film process such as sputtering is mainly used in a high frequency region.

  Here, the magnetic core of a thin film inductor used particularly in a high frequency region often has a multilayer structure in which an insulating film and a magnetic film are alternately repeated in order to suppress the generation of eddy currents. Therefore, there is a need for a magnetic layer having a high magnetic permeability, a high saturation magnetic flux density, and a low coercive force when the film thickness is thin and the frequency region is high.

  Here, as a material having both a high magnetic permeability, a high saturation magnetic flux density, and a low coercive force, a nanocrystalline material that generates a microcrystal having a nano-sized bcc-Fe structure in an amorphous by heat treatment is known. As such a nanocrystal material, it describes in the patent documents 1-3 shown below, for example. However, a magnetic layer having a high magnetic permeability, a high saturation magnetic flux density, and a low coercive force has been demanded even when the magnetic layer is thin.

Japanese Patent Laid-Open No. 04-168706 Japanese Patent No. 2675062 Japanese Patent No. 2556863

  An object of the present invention is to obtain a ferromagnetic multilayer thin film having a high magnetic permeability, a high saturation magnetic flux density, and a low coercive force.

In order to achieve the above object, the ferromagnetic multilayer thin film according to the present invention comprises:
A ferromagnetic multilayer thin film comprising an underlayer and a ferromagnetic layer,
The ferromagnetic layer includes Fe, α1, and α2,
The α1 is at least one selected from Cu, Ag and Au;
Α2 is at least one selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W;
The ferromagnetic layer includes a nanocrystalline layer and an amorphous layer;
The underlayer and the nanocrystal layer are in contact with each other;
The nanocrystal layer includes a microcrystal mainly composed of Fe,
The underlayer contains at least one selected from Al, Ga, In, Tl, Ge, Sn, and Pb in a total of 10 atomic% or more.

  The ferromagnetic multilayer thin film according to the present invention has high magnetic permeability, high saturation magnetic flux density, and low coercive force due to the above characteristics.

  In the ferromagnetic multilayer thin film according to the present invention, the ferromagnetic layer may have a thickness of 30 nm to 500 nm.

  In the ferromagnetic multilayer thin film according to the present invention, the underlayer includes one or more selected from Al, Sn, and Ge, and the total content of Al, Sn, and Ge in the underlayer is 30 atomic% or more. There may be.

  In the ferromagnetic multilayer thin film according to the present invention, the Fe concentration may change when the Fe concentration is measured along the film thickness direction in the ferromagnetic layer.

  In the ferromagnetic multilayer thin film according to the present invention, when the Fe concentration is measured along the film thickness direction in the ferromagnetic layer, the peak of the Fe concentration may exist in the nanocrystal layer.

  In the ferromagnetic multilayer thin film according to the present invention, when the concentration of α1 is measured along the film thickness direction in the ferromagnetic layer, the concentration of α1 may change.

  The ferromagnetic multilayer thin film according to the present invention may have the α1 peak between the underlayer and the interface between the nanocrystal layer and the amorphous layer.

  In the ferromagnetic multilayer thin film according to the present invention, when the concentration of α2 is measured along the film thickness direction in the ferromagnetic layer, the concentration of α2 may change.

  In the ferromagnetic multilayer thin film according to the present invention, the point where the concentration of α2 is maximum may be present in the amorphous layer.

  In the ferromagnetic multilayer thin film according to the present invention, the α1 may be Cu.

  In the ferromagnetic multilayer thin film according to the present invention, the grain size of the microcrystal may be 3 nm to 30 nm.

  In the ferromagnetic multilayer thin film according to the present invention, the underlayer has a thickness of 0.2 nm to 50 nm, the nanocrystal layer has a thickness of 3 nm to 50 nm, and the amorphous layer has a thickness of the nanocrystal layer. The thickness of the ferromagnetic layer may be 30 nm to 500 nm.

  The ferromagnetic multilayer thin film according to the present invention may have a structure including at least two ferromagnetic multilayer thin films described above.

  A ferromagnetic multilayer thin film according to the present invention has a structure including at least two ferromagnetic multilayer thin films according to any one of the above, and an intermediate layer between any two adjacent ferromagnetic multilayer thin films. May be.

  In the ferromagnetic multilayer thin film according to the present invention, the intermediate layer may include an insulating layer.

  A thin film inductor according to the present invention includes any one of the above-described ferromagnetic multilayer thin films.

It is a schematic diagram which shows the cross-section of the ferromagnetic multilayer thin film 12 which concerns on one Embodiment of this invention. 2 is a STEM image obtained by STEM observation in Example 1. FIG. 2 is a mapping image obtained by EPMA observation in Example 1. FIG. 2 is a mapping image obtained by EPMA observation in Example 1. FIG. It is a schematic diagram which shows the cross-section of the ferromagnetic multilayer thin film 12 which concerns on one Embodiment of this invention. It is a schematic diagram which shows the cross-section of the ferromagnetic multilayer thin film 12 which concerns on one Embodiment of this invention. It is a schematic diagram which shows an example of the cross-sectional structure of the intermediate | middle layer 20 in FIG. It is a schematic diagram which shows an example of the cross-sectional structure of the intermediate | middle layer 20 in FIG. It is a schematic diagram which shows an example of the cross-sectional structure of the intermediate | middle layer 20 in FIG. It is a schematic diagram which shows an example of the cross-sectional structure of the intermediate | middle layer 20 in FIG. It is a mimetic diagram showing the section structure of thin film inductor 2 concerning one embodiment of the present invention. It is a graph which shows the change of coercive force with respect to the change of heat processing temperature. It is a graph which shows the change of the magnetic permeability with respect to the change of heat processing temperature.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments described below.

  The thin film inductor 2 according to this embodiment has a structure shown in the cross-sectional view of FIG. The thin film inductor 2 has a structure in which a lower magnetic layer 12a, an inductor insulating layer 10 and an upper magnetic layer 12b are sequentially laminated on a thin film inductor substrate 11, and a coil 10a exists inside the inductor insulating layer 10. .

  The ferromagnetic multilayer thin film 12 according to this embodiment is included in the lower magnetic layer 12a and / or the upper magnetic layer 12b of the thin film inductor 2 shown in FIG.

  The ferromagnetic multilayer thin film 12 according to this embodiment has a multilayer structure shown in the sectional view of FIG. The ferromagnetic multilayer thin film 12 includes an underlayer 14 and a ferromagnetic layer 16. The ferromagnetic layer 16 includes a nanocrystal layer 16a and an amorphous layer 16b. As shown in FIG. 1, the underlayer 14 and the nanocrystal layer 16a are in contact with each other.

  In the nanocrystal layer 16, microcrystals 16 a ′ containing Fe as a main component exist. Moreover, amorphous 16b 'may be mixed. On the other hand, the amorphous layer 16b includes an amorphous 16b ′ and does not include the microcrystal 16a ′. Further, the amorphous layer 16 does not include a crystal that is not the microcrystal 16a ′ containing Fe as a main component. Here, the “microcrystal 16a ′ containing Fe as a main component” is a microcrystal 16a ′ having an Fe content of 50 atomic% or more.

  Hereinafter, the composition of each layer included in the ferromagnetic multilayer thin film 12 will be described.

  The ferromagnetic layer 16 contains Fe, α1, and α2. α1 is at least one selected from Cu, Ag and Au, and is preferably Cu. α2 is at least one selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, and is preferably Nb and / or Zr.

  The underlayer 14 includes one or more selected from Al, Ga, In, Tl, Ge, Sn, and Pb. The total content of the above elements in the underlayer 14 is 10 atomic% or more.

  When the underlayer 14 contains a metal element belonging to Group 13 or 14 in the periodic table and the ferromagnetic layer 16 contains Fe, α1, and α2, the Fe layer is subjected to an annealing process to be described later. As a result, the ferromagnetic multilayer thin film 12 is separated from the nanocrystal layer 16a and the amorphous layer 16b in the ferromagnetic layer 16. It becomes easy to take a structure in which the underlayer 14 and the nanocrystal layer 16a are in contact with each other. And a low coercive force and a high magnetic permeability can be obtained.

  Further, from the viewpoint of obtaining the ferromagnetic multilayer thin film 12 having a lower coercive force and a higher magnetic permeability, the underlayer 14 preferably contains one or more selected from Al, Ge and Sn, and contains Al. Is more preferable. Further, the Al content in the underlayer 14 is preferably 50 atomic% or more, and particularly preferably 80 atomic% or more.

  The ferromagnetic layer 16 may further contain elements other than Fe, α1, and α2. For example, B, Si, etc. are mentioned.

  The content of Fe in the ferromagnetic layer 16 is not particularly limited. For example, it may be 50 atomic% or more and 95 atomic% or less with respect to the entire ferromagnetic layer 16.

  The ferromagnetic layer 16 may further include one or more selected from Co and Ni so as to replace a part of Fe.

  When the ferromagnetic layer 16 contains α1, it becomes easy to form a microcrystal 16a ′ having Fe as a main component and having a bcc-Fe structure. When α1 is not included, it is difficult to control the grain size of the microcrystal 16a ′. And it becomes difficult to obtain the ferromagnetic multilayer thin film 12 with low coercive force and high magnetic permeability.

  The content of α1 in the ferromagnetic layer 16 is not particularly limited. For example, it may be 0.1 atomic percent or more and 10 atomic percent or less with respect to the entire ferromagnetic layer 16.

  When the concentration of α1 is measured along the film thickness direction in the ferromagnetic layer 16, the concentration of α1 is preferably changed. That is, it is preferable that the concentration of α1 in the ferromagnetic layer 16 is not constant along the film thickness direction. It is preferable that the point where the concentration of α1 is maximum in the ferromagnetic layer 16 exists between the interface between the underlayer 14 and the ferromagnetic layer 16 and the interface between the nanocrystalline layer 16a and the amorphous layer 16b.

  When the ferromagnetic layer 16 contains α2, the ability to form nanocrystals can be improved.

  The content of α2 in the ferromagnetic layer 16 is not particularly limited. For example, it may be 1 atomic% or more and 15 atomic% or less with respect to the entire ferromagnetic layer 16.

  When the concentration of α2 is measured along the film thickness direction in the ferromagnetic layer 16, it is preferable that the concentration of α2 changes. That is, it is preferable that the concentration of α2 in the ferromagnetic layer 16 is not constant along the film thickness direction. The amorphous layer 16b preferably has a point where the concentration of α2 is maximum in the ferromagnetic layer 16.

  Since the ferromagnetic multilayer thin film 12 according to the present embodiment has the above-described multilayer structure, it has a magnetic property with a low coercive force and a high permeability even when the thickness of the ferromagnetic layer 16 is as small as 500 nm or less.

  Here, since the film thickness of the ferromagnetic material layer 16 is small, the ferromagnetic multilayer thin film 12 according to the present embodiment and the thin film inductor 2 including the same can correspond to a high frequency region of 100 MHz or more. It is also possible to deal with a high frequency region in the GHz band.

  The ferromagnetic multilayer thin film 12 according to this embodiment may or may not have another layer (not shown) on the amorphous layer 16b shown in FIG. In the case of having another layer, the composition of the other layer is not particularly limited.

  As shown in FIG. 1, the microcrystals 16 a ′ may be arranged side by side along the base layer 14. The thickness of the nanocrystal layer 16a is preferably not more than twice the average grain size of the microcrystal 16a ′. Moreover, although the preferable average particle diameter of microcrystal 16a 'changes with materials and the target characteristic of a ferromagnetic multilayer thin film, it is usually preferable to set it as 5 to 20 nm.

  There are no particular restrictions on the thickness of the underlayer 14, the thickness of the nanocrystal layer 16a, and the thickness of the amorphous layer 16b.

  The thickness of the underlayer 14 is preferably 0.2 nm or more and 50 nm or less, and more preferably 0.5 nm or more and 20 nm or less. By setting the thickness of the underlayer 14 within the above range, a high saturation magnetic flux density, a low coercive force, and a high magnetic permeability can be provided.

  The thickness of the nanocrystal layer 16a is preferably 3 nm or more and 50 nm or less, and more preferably 5 nm or more and 30 nm or less. A low coercive force can be obtained by setting the thickness of the nanocrystal layer 16a within the above range.

  The thickness of the amorphous layer 16b is preferably 60% or more (0.6 times or more) of the thickness of the nanocrystal layer 16a, and more preferably 100% or more (1 time or more). A low coercive force can be obtained by setting the thickness of the amorphous layer 16b within the above range.

  The thickness of the amorphous layer 16b is not particularly limited, but the thickness of the ferromagnetic layer 16, that is, the total thickness of the nanocrystal layer 16a and the amorphous layer 16b is preferably 30 nm or more and 500 nm or less. More preferably, the thickness is 30 nm or more and 300 nm or less. By setting the thickness of the ferromagnetic layer 16 to 30 nm or more, uniform nanocrystals can be formed. Moreover, by setting the thickness of the ferromagnetic layer 16 to 500 nm or less, generation of eddy currents in the ferromagnetic layer 16 is reduced, eddy current loss is reduced, and excellent magnetic properties are easily obtained.

  Here, when the Fe concentration is measured along the film thickness direction in the ferromagnetic layer 16, it is preferable that the Fe concentration is changed. That is, it is preferable that the Fe concentration in the ferromagnetic layer 16 is not constant along the film thickness direction. Furthermore, it is preferable that a peak of Fe concentration exists in the nanocrystal layer 16a. In the present application, the peak is a maximum point. The peak of the Fe concentration is a point where the Fe concentration is higher than any point before and after the film thickness direction.

  Note that the nanocrystal layer 16a and the amorphous layer 16b in the ferromagnetic layer 16 are distinguished using a STEM. An arbitrary cross section obtained by cutting the ferromagnetic multilayer thin film 12 along the film thickness direction is observed at a magnification of 500,000 to 2,000,000 times, and a layer in which the microcrystal 16a ′ is confirmed in the ferromagnetic layer 16 is obtained. The nanocrystal layer 16a is a layer in which no crystal is confirmed, such as the microcrystal 16a ', and is the amorphous layer 16b. The thickness of each layer in the ferromagnetic multilayer thin film 12 and the grain size of the microcrystal 16a ′ are measured using the STEM length measurement function. The average particle size of the microcrystals 16a ′ is calculated by averaging the particle sizes of at least 10 microcrystals 16a ′, preferably 100 or more. The particle size of the microcrystal 16a ′ can also be calculated by performing XRD measurement on the ferromagnetic multilayer thin film 12 and using Scherrer's equation. Usually, the particle size of the microcrystal 16a ′ measured using the STEM length measurement function and the particle size of the microcrystal 16a ′ calculated using the Scherrer equation generally coincide.

  In addition, the composition of each layer and the change in the concentration of Fe, α1, and α2 are observed by analyzing with EPMA at a magnification of 500,000 to 2,000,000 times.

  Further, as shown in FIG. 5, the ferromagnetic multilayer thin film 12 according to the present embodiment may have a structure including two or more layers of the ferromagnetic multilayer thin film 12 according to the present embodiment.

  Moreover, as shown in FIG. 6, you may have a structure which contains the intermediate | middle layer 20 between the adjacent two layers of the ferromagnetic multilayer thin film 12. As shown in FIG.

  There is no restriction | limiting in particular in the structure of the intermediate | middle layer 20, The insulating layer 20a may be included. There is no particular limitation on the way the insulating layer 20a is included. For example, as shown in FIG. 7A, the intermediate layer 20 may be composed only of the intermediate insulating layer 20a. As shown in FIG. 7B, the intermediate layer may have a metal layer 20b on the side in contact with the amorphous 16b. As shown in FIG. 7C, the intermediate layer may have a metal layer 20 b on the side in contact with the base layer 14. As shown in FIG. 7D, both sides of the intermediate insulating layer 20a may be sandwiched between metal layers 20b.

The thickness of the intermediate layer 20 is not particularly limited. For example, it may be 1 nm or more and 100 nm or less. There is no restriction | limiting in particular in the material of the insulating layer 20a. For example, it may consist of SiO ₂ and / or Al ₂ O ₃ . There is no restriction | limiting in particular also in the material of the metal layer 20b. For example, it may be made of Ta and / or Mo.

  The reason why the magnetic multilayer thin film 12 according to this embodiment can obtain a high magnetic permeability and a low coercive force even if the film thickness of the ferromagnetic layer 16 is 500 nm or less is unknown, but is considered as follows. It is done.

  First, it is considered that in the ferromagnetic multilayer thin film 12 according to the present embodiment, the force for controlling the crystal grain size of the microcrystal 16a ′ is large and the crystal grain size is difficult to be coarsened. Next, it is considered that the interval between the microcrystals 16a 'in the direction perpendicular to the film thickness direction is shortened by forming the microcrystals 16a' in a relatively narrow area. Further, it is considered that the amorphous layer 16b functions as a stress relaxation layer of the ferromagnetic multilayer thin film 12. For the above reasons, it is considered that the ferromagnetic multilayer thin film 12 according to the present embodiment can obtain a high permeability and a low coercive force even when the thickness of the ferromagnetic layer 16 is 500 nm or less.

  Hereinafter, a method for manufacturing the ferromagnetic multilayer thin film 12 according to this embodiment will be described.

  First, a substrate 11a on which the ferromagnetic multilayer thin film 12 is laminated is prepared. Although there is no restriction | limiting in particular in the kind of board | substrate 11a, It is preferable that it is a board | substrate which can form the base layer 14 on the board | substrate 11a easily. Specific examples include a silicon substrate with an oxide film and a nonmagnetic ferrite substrate.

  Next, the underlying layer 14 is formed by performing sputtering on the prepared substrate 11a using a sputtering apparatus. Further, the ferromagnetic layer 16 is formed by sputtering the underlayer 14. The sputtering conditions are not particularly limited, and are adjusted as appropriate so that the underlayer 14 and the ferromagnetic layer 16 having the intended composition and thickness can be obtained.

  Further, in order to have a structure including two or more layers of the ferromagnetic multilayer thin film 12 as shown in FIG. 6, an underlayer 14 is formed again on the ferromagnetic layer 16 by sputtering, and thereafter the same as above. This process may be repeated.

  Further, as shown in FIG. 7, in order to have a structure including at least two ferromagnetic multilayer thin films 12 and including an intermediate layer 20 between any two adjacent ferromagnetic multilayer thin films 12, strong The intermediate layer 20 is formed on the magnetic layer 16 by sputtering, and the underlayer 14 is formed again on the intermediate layer 20 by sputtering. Thereafter, the same steps as described above may be repeated.

  After forming the ferromagnetic layer 16, annealing is performed to generate microcrystals 16 a ′ in a state of being arranged side by side along the underlayer 14, and the nanocrystalline layer 16 a is formed inside the ferromagnetic layer 16. And the amorphous layer 16b can be produced and the ferromagnetic multilayer thin film 12 can be obtained.

  There are no particular restrictions on the conditions for the annealing treatment, but 400 ° C. or higher and 650 ° C. or lower is preferable. By setting the conditions for the annealing treatment within the above range, the nanocrystal layer 16a and the microcrystal 16a ′ can be easily generated in an appropriate size. Further, the average grain size of the microcrystal 16a ′ and the thickness of the nanocrystal layer 16a can be changed by changing the annealing temperature or time. Specifically, the higher the temperature, the larger the average grain size of the microcrystal 16a ′ and the greater the thickness of the nanocrystal layer 16a. Further, the longer the time, the larger the average grain size of the microcrystals 16a 'and the greater the thickness of the nanocrystal layer 16a.

  Note that if the annealing temperature is too high, the grain size of the microcrystal 16a 'tends to be too large. If the annealing temperature is too high, components (one or more selected from Al, Ga, In, Tl, Ge, Sn, and Pb) contained in the underlayer 14 diffuse into the ferromagnetic layer 16. In some cases, a structure in which the microcrystals 16 a ′ exist along the base layer 14 cannot be obtained. In addition, when the ferromagnetic layer 16 contains Fe and B, if the annealing temperature becomes too high, Fe and B combine to form a boride, which may lower the magnetic permeability.

  As shown in FIG. 6 and FIG. 7, when the structure includes two or more layers of the ferromagnetic multilayer thin film 12, annealing may be performed after all the ferromagnetic multilayer thin films 12 are formed by sputtering, Annealing treatment may be performed each time one ferromagnetic multilayer thin film 12 is formed. In this case, the annealing method is not particularly limited.

  When performing measurements such as STEM measurement and EPMA measurement, the Pt protective film 18 may be formed by sputtering the ferromagnetic multilayer thin film 12.

  Moreover, there is no restriction | limiting in particular in the method of obtaining the thin film capacitor 2 using the obtained ferromagnetic multilayer thin film 12, The method of manufacturing a normal thin film capacitor can be used.

  As a method of using the ferromagnetic multilayer thin film 12 for the thin film capacitor 2, for example, the ferromagnetic multilayer thin film 12 of FIG. 1 is peeled from the substrate 11a, and the ferromagnetic multilayer thin film 12 is placed on the thin film inductor substrate 11 of FIG. The ferromagnetic multilayer thin film 12 may be the lower magnetic layer 12a in FIG. The ferromagnetic multilayer thin film 12 of FIG. 1 may be disposed on the inductor insulating layer 10 of FIG. 8, and the ferromagnetic multilayer thin film 12 may be used as the upper magnetic layer 12b of FIG. Further, the ferromagnetic multilayer thin film 12 of FIG. 1 may be removed from the substrate 11a, and the substrate 11a of FIG. 1 may be used as the thin film inductor substrate 11 of FIG. In this case, the ferromagnetic multilayer thin film 12 of FIG. 1 becomes the lower magnetic layer 12a of FIG. 8 as it is.

  The ferromagnetic multilayer thin film, the thin film capacitor, and the manufacturing method thereof according to the present embodiment have been described above. However, the ferromagnetic multilayer thin film, the thin film capacitor, and the manufacturing method thereof according to the present invention are not limited to the above embodiment.

  Hereinafter, the present invention will be specifically described based on examples.

(Experimental example 1)
First, a silicon substrate with an oxide film was cut into a size of 6 × 6 mm and prepared as a test substrate.

  Next, 5 nm of base layers were formed on the said test substrate using the sputtering device (Eiko ES-350). The material of the underlayer is shown in Table 1 below. Further, a ferromagnetic layer of 100 nm was formed on the underlayer. The composition of the ferromagnetic layer is shown in Table 1 below. The ferromagnetic multilayer thin film of each Example was produced by the above process.

  In Comparative Example 1, a base layer was not formed, and a ferromagnetic layer was laminated directly on the test substrate. In Comparative Examples 2 to 4, an underlayer made of only a transition metal was formed.

  The ferromagnetic multilayer thin film of each example and comparative example was annealed in vacuum at 500 ° C. for 15 minutes. Then, the BH characteristic was measured by VSM (Tamagawa Seisakusho TM-VSM331484), and the magnetic permeability was measured by the impedance analyzer (HP 4194A).

  Furthermore, the crystal grain size of the microcrystal contained in each ferromagnetic multilayer thin film which performed the above process was calculated | required. Specifically, each ferromagnetic multilayer thin film was measured by XRD (Panalytical Empirean) and calculated from Scherrer's equation. The above results are shown in Tables 1 and 2. In addition, about Comparative Examples 1-4, the thickness of the nanocrystal layer and the thickness of the amorphous crystal layer were not measured.

  From Table 1 and Table 2, it can be seen that Examples 1 to 4 and 4a to 4g have a very high magnetic permeability as compared with Comparative Examples 1 to 4, and exhibit a very low coercive force.

(Experimental example 2)
About Example 1, Example 2, Comparative Example 1, and Comparative Example 2 of Table 1, it implemented by changing the conditions of annealing treatment. Specifically, Example 1 and Example 2 were carried out under conditions of 400 ° C. for 15 minutes, 500 ° C. for 15 minutes, 550 ° C. for 15 minutes, 600 ° C. for 15 minutes, and 500 ° C. for 60 minutes. Comparative Example 1 and Comparative Example 2 were carried out under the conditions of 500 ° C. for 15 minutes, 550 ° C. for 15 minutes, and 600 ° C. for 15 minutes. Further, the crystal grain size of each ferromagnetic multilayer thin film was determined in the same manner as in Experimental Example 1. The results are shown in Table 3 and Table 4. 9 to 10 are graphs of the results of Tables 3 and 4.

  From Tables 3 and 4, and FIGS. 9 to 10, when the material of the underlayer is Al (100 atomic%) (Example 1), and the material of the underlayer is Al (50 atomic%)-Sn (50 atoms) %), When there is no underlayer (Comparative Example 1) and when the material of the underlayer is Mo (100 atomic%) (Comparative Example 2), the magnetic permeability and coercive force are particularly high. It can be seen that it can be obtained. The saturation magnetic flux density was also better in Example 1 and Example 2 than in Comparative Example 1 and Comparative Example 2.

(Experimental example 3)
As shown in Table 3, each example and comparative example were produced by changing the material of the underlayer and the composition of the ferromagnetic layer. Each ferromagnetic multilayer thin film was produced under the same conditions as in Example 1 except that the material of the underlayer and the composition of the ferromagnetic layer were changed and the annealing temperature was changed. The results are shown in Tables 5 and 6. For Comparative Examples 6 to 13, the average crystal grain size of the microcrystals, the thickness of the nanocrystal layer, and the thickness of the amorphous layer were not measured.

  From Table 5 and Table 6, when the underlayer contains one or more selected from Al, Sn, and Ge, the ferromagnetic layer contains Cu, and the ferromagnetic layer contains Nb or Zr In addition, it was found that the magnetic characteristics were greatly improved.

(Experimental example 4)
In order to perform various measurements described later on the ferromagnetic multilayer thin film 12 of Example 1, a Pt protective film 18 was formed by sputtering.

  Next, the ferromagnetic multilayer thin film after the Pt protective film was formed was cut along the film thickness direction. The obtained cross section was observed with a STEM (HITACHI HD2000) at a magnification of 500,000 to 2,000,000 times. Furthermore, analysis was performed at a magnification of 500,000 to 2,000,000 times using EPMA (NORAN SYSTEM 6 manufactured by Thermo Fisher Scientific). The thickness of each layer in the ferromagnetic multilayer thin film was measured using the STEM length measurement function. An image obtained by STEM observation is shown in FIG. In FIG. 2 this time, the underlayer 14 and the substrate 11 could not be distinguished.

  As shown in FIG. 2, in Example 1, in the ferromagnetic layer, a nanocrystal layer in which microcrystals and amorphous are mixed, and an amorphous layer in which crystals cannot be confirmed under the STEM observation conditions, are arranged in the film thickness direction. I found it separated. Specifically, the nanocrystal layer is disposed along the base layer, and the amorphous layer is disposed so as to cover the upper portion of the nanocrystal layer. In FIG. 2, there are a case where the microcrystal is displayed brightly and a case where it is displayed darkly. This is because the angle at which each microcrystal is scattered and the angle at which the electron beam is scattered and diffracted are different. It is. Regardless of the brightness of the microcrystal of FIG. 2, the composition of the microcrystal of FIG. 2 is the same.

  Furthermore, when the particle size of the microcrystal was measured using the length measurement function of STEM, it was 10 nm to 20 nm, and the average value measured at 10 points was 13.5 nm. The crystal grain size measured using the STEM length measurement function and the crystal grain size calculated from Scherrer's equation using the XRD measurement results shown in Table 1 almost coincided.

  From the results of EPMA analysis (FIGS. 3 and 4), it was found that the ferromagnetic layer of Example 1 had a change in Fe concentration in the film thickness direction. It was also found that a peak of Fe concentration exists in the nanocrystal layer. This shows that the microcrystal has Fe as a main component. 3 and 4, the vicinity of the base layer 14 and the nanocrystal layer 16a is enlarged, and only a part of the amorphous layer 16b is shown.

  From the analysis result of EPMA (FIG. 4), it was found that the ferromagnetic layer of Example 1 also changed the Nb concentration in the film thickness direction. Further, it was found that the point where the Nb concentration is maximum exists in the amorphous layer.

  From the analysis result of EPMA (FIG. 3), it was found that the concentration of Cu in the ferromagnetic layer of Example 1 also changed in the film thickness direction. It was also found that a peak of Cu concentration exists between the underlayer and the interface between the nanocrystal layer and the amorphous layer.

  (Experimental Example 5) In Experimental Example 5, a ferromagnetic multilayer thin film in which a plurality of the ferromagnetic multilayer thin films of Example 1 were laminated was produced.

  On the test substrate, an underlayer and a ferromagnetic layer were formed by sputtering in the same manner as in Example 1. Further, an underlayer and a ferromagnetic layer were formed on the ferromagnetic layer in the same manner as in Example 1. Further, heat treatment was performed at 500 ° C. for 15 minutes (Example 6).

On the test substrate, an underlayer and a ferromagnetic layer were formed by sputtering in the same manner as in Example 1. Further, an insulating layer made of SiO ₂ was formed to 10 nm on the ferromagnetic layer. Further, an underlayer and a ferromagnetic layer were formed on the insulating layer in the same manner as in Example 1. Further, heat treatment was performed at 500 ° C. for 15 minutes (Example 7).

  For the ferromagnetic multilayer thin films of Example 6 and Example 7, soft magnetic characteristics were measured by VSM, and permeability was measured by an impedance analyzer. The results are shown in Table 7 and Table 8.

  From Table 7 and Table 8, Example 6 and Example 7 having a structure including two layers of the ferromagnetic multilayer thin film of Example 1 also showed high soft magnetic characteristics as in Example 1.

DESCRIPTION OF SYMBOLS 2 ... Thin film inductor 10 ... Inductor insulating layer 10a ... Coil 11 ... Thin film inductor substrate 12a ... Lower magnetic layer 12b ... Upper magnetic layer 12 ... Ferromagnetic multilayer thin film 11a ... Substrate 14 ... Underlayer 16 ... Ferromagnetic layer 16a ... Nanocrystal Layer 16a '... Microcrystal 16b ... Amorphous layer 16b' ... Amorphous 18 ... Pt protective layer 20 ... Intermediate layer 20a ... Intermediate insulating layer 20b ... Metal layer

Claims (16)

A ferromagnetic multilayer thin film comprising an underlayer and a ferromagnetic layer,
The ferromagnetic layer includes Fe, α1, and α2,
The α1 is at least one selected from Cu, Ag and Au;
Α2 is at least one selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W;
The ferromagnetic layer includes a nanocrystalline layer and an amorphous layer;
The underlayer and the nanocrystal layer are in contact with each other;
The nanocrystal layer includes a microcrystal mainly composed of Fe,
The ferromagnetic multilayer thin film characterized in that the underlayer contains at least one selected from Al, Ga, In, Tl, Ge, Sn and Pb in a total of 10 atomic% or more.   The ferromagnetic multilayer thin film according to claim 1, wherein the ferromagnetic layer has a thickness of 30 nm to 500 nm. The said base layer contains 1 or more types selected from Al, Sn, and Ge, and the total content of Al, Sn, and Ge in the said base layer is 30 atomic% or more. Ferromagnetic multilayer thin film. The ferromagnetic multilayer thin film according to claim 1, wherein the Fe concentration changes when the Fe concentration is measured along the film thickness direction in the ferromagnetic layer. The ferromagnetic multilayer according to any one of claims 1 to 4, wherein a peak of the Fe concentration exists in the nanocrystal layer when the concentration of Fe is measured along the film thickness direction in the ferromagnetic layer. Thin film. 6. The ferromagnetic multilayer thin film according to claim 1, wherein the concentration of α <b> 1 changes when the concentration of α <b> 1 is measured along the film thickness direction in the ferromagnetic layer. The ferromagnetic multilayer thin film according to claim 6, wherein the α1 concentration peak exists between the underlayer and the interface between the nanocrystal layer and the amorphous layer. The ferromagnetic multilayer thin film according to any one of claims 1 to 7, wherein the concentration of α2 changes when the concentration of α2 is measured along the film thickness direction in the ferromagnetic layer. The ferromagnetic multilayer thin film according to any one of claims 1 to 8, wherein a point at which the concentration of α2 is maximum exists in the amorphous layer. The ferromagnetic multilayer thin film according to claim 1, wherein α1 is Cu. The ferromagnetic multilayer thin film according to any one of claims 1 to 10, wherein a particle diameter of the microcrystal is 3 nm to 30 nm. The ferromagnetic layer has a thickness of the underlayer of 0.2 nm to 50 nm, a thickness of the nanocrystal layer of 3 nm to 50 nm, a thickness of the amorphous layer of 60% or more of the thickness of the nanocrystal layer, The ferromagnetic multilayer thin film according to any one of claims 1 to 11, wherein the layer has a thickness of 30 nm to 500 nm. A ferromagnetic multilayer thin film having a structure including at least two layers of the ferromagnetic multilayer thin film according to claim 1. A ferromagnetic multilayer thin film having a structure including at least two layers of the ferromagnetic multilayer thin film according to claim 1 and including an intermediate layer between any two adjacent layers of the ferromagnetic multilayer thin film. The ferromagnetic multilayer thin film according to claim 14, wherein the intermediate layer includes an insulating layer. A thin film inductor comprising the ferromagnetic multilayer thin film according to claim 1.

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