JPH08172015A - Thin-film laminated magnetic induction element - Google Patents

Abstract

PURPOSE: To improve the performance of a magnetic induction element, such as the reactor constituted by laminating thin film coils or magnetic cores, transformer, etc., by sufficiently utilizing the magnetic anisotropy of the magnetic material constituting the magnetic cores. CONSTITUTION: Magnetic cores 20 composed of a magnetic material having magnetic anisotropy are put on both surfaces of a spiral coil 10 composed of a thin film conductor, such as copper, etc., with insulating films 30 in between and the magnetic cores 20 are divided into a plurality of magnetic core parts 21 and 22 by forming radial or diagonal slits Sd extended outward from the center of the spiral coil 10. Then the axis Me of easy magnetization of the magnetic thin film is oriented in the direction parallel or perpendicular to the direction of magnetization M caused by the coil 10 at every magnetic core part 21 or 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film laminated type such as a reactor or a transformer which is a thin film laminated body in which a coil formed of a thin film conductor and a magnetic core formed of a magnetic thin film are laminated with an insulating film interposed therebetween. The magnetic induction element of.

[0002]

2. Description of the Related Art Electronic devices such as switching power supplies are often constructed by combining magnetic induction elements such as reactors and transformers with electronic circuits. However, electronic devices are becoming smaller and lighter and highly integrated. The volume and weight ratio of the power supply unit to the total increase, and how to reduce the size and weight of the power supply unit has become a major issue. Against this background, there is an increasing trend toward miniaturization of power supplies. Above all, in recent years, research into miniaturization of magnetic elements has become popular, and development of micro magnetic elements such as thin film inductors, thin film transformers, and thin film bulk magnetic cores has made great progress.
However, as compared with the semiconductor integrated circuit technology, the magnetic element integration technology is still behind and presents a problem.

As this thin film laminated magnetic induction element, a so-called inner iron structure in which a coil is wound around the magnetic core of a magnetic thin film is known, but a thin film conductor is formed into two layers and the coil is wound around the magnetic core. Since it is not easy to form and there is no shielding against the magnetic flux generated by the current flowing through the outer coil, the integrated circuit may malfunction when the magnetic induction element is mounted on the semiconductor chip. These drawbacks can be almost eliminated by adopting a so-called outer iron structure in which a coil formed of a thin film conductor is sandwiched by a pair of magnetic thin film magnetic cores from both sides. Further, regarding this outer iron structure, there are roughly known two methods, that is, a coil is formed into a zigzag shape and a coil is formed into a spiral shape, but the latter is more advantageous in obtaining a large inductance in a small area. The present invention relates to a magnetic induction element having an outer iron structure using this spiral coil, and the basic structure thereof will be briefly described below with reference to the perspective view of FIG.

The coil 10 shown in the center of FIG. 6 is formed by photo-etching a thin film conductor on which a highly conductive metal such as copper is formed to form a spiral, and a magnetic material is formed on this coil. By sandwiching a pair of upper and lower magnetic cores 20 made of a magnetic thin film from both sides through a thin insulating film 30 such as silicon oxide, as shown in the figure, a thin film laminated magnetic induction element.
Make up 40. The terminal To may be derived from the outer end of the spiral of the coil 10 as it is, but it is necessary to derive the terminal Ti from the inner end through the intersection C as shown in the figure. In C, the thin-film conductor for the terminal Ti is used as the thin-film conductor for the coil 10, and the insulating film 30a is schematically shown by a thin line in the figure.
The films are formed so as to overlap with each other through and patterned by photoetching. In addition, in the example shown in the figure, the pair of magnetic cores 20 form an open magnetic path.However, the insulating film 30 is formed in a pattern smaller than the magnetic core 20 and having a window in the central portion, and the upper and lower magnetic cores 20 are contacted at the peripheral edge portion and the central portion. By doing so, a closed magnetic circuit can be formed and the inductance of the magnetic induction element 40 can be increased.

[0005]

With the conventional thin film laminated structure described above, it is possible to construct a thin magnetic induction element 40 having a small area, a large inductance, and suitable for mounting on a semiconductor chip. If a thin film is made of a magnetic material such as amorphous metal having excellent magnetic anisotropy, there is a problem that the advantage cannot be fully utilized. Hereinafter, this will be described with reference to FIG. 7.

FIG. 7 is a top view of FIG. 6 viewed from above, in which the coil 10 is simply shown by a thin wire in a rectangular magnetic core 20, and the current flowing through the coil 10 exerts a magnetic field on the magnetic core 20. The direction is indicated by arrow M. When the coil 10 has a spiral shape, the magnetizing direction M is substantially perpendicular to each side of the square of the magnetic core 20 as shown. On the other hand, since the magnetic thin film made of the [high] magnetic material used for the magnetic core 20 has the magnetic anisotropy as described above, its easy axis Me is made to coincide with the magnetization direction M which is vertically oriented as shown in the figure. However, it becomes difficult to magnetize because it becomes perpendicular to the magnetizing direction M that is directed to the left and right.
For this reason, the magnetic field generated inside the magnetic core 20 is strong in the vertical direction of the figure, but becomes much weaker in the horizontal direction, so even if a magnetic material is used for the magnetic thin film, the magnetic induction element 40 has a large inductance corresponding to its magnetic performance. It becomes difficult to have.

In order to improve the high frequency performance of the magnetic induction element 40, the hard axis of the magnetic thin film of the magnetic core 20 is set to the magnetization direction M.
However, even if the hard axis of magnetization is aligned with one of the upper and lower and left and right magnetization directions M, the axis of easy magnetization is aligned with the other, so that the high frequency characteristics cannot be improved as desired. For this reason, as shown in FIG. 8, the coil 10 is elongated and the magnetic core 20 is provided only in the central portion 10c, and for example, the easy axis Me is perpendicular to the magnetization direction M acting on the coil 20 (Japanese Patent Laid-Open No. Hei 10 (1999) -135242). 4-363006) is known, but since an extra area is required for both ends 10e of the coil 10, there is a problem that the inductance value per area of the magnetic induction element 50 decreases. is there. In addition, inductors and transformers (magnetic induction elements) that use so-called compound anisotropic films that form magnetic cores by laminating magnetic thin films in multiple layers and sequentially rotate the direction of magnetic anisotropy for each magnetic thin film in each layer It is also known that the characteristic that isotropic permeability is shown in the film surface of the magnetic core and the magnetization is effectively induced by the excitation by the coil can be used in any direction, but the opposite effect is also available. However, the effect of the magnetic anisotropy that is canceled out on average and induced in the magnetic thin film is not fully utilized.

Further, in the conventional magnetic induction element 40 of FIG. 6, as described above, the coil 10 has a terminal from the inner end of the spiral.
The magnetic flux generated by the coil 10 interlinks with the magnetic core 20 due to the occurrence of the intersection C when deriving Ti is generated by the current flowing through the terminal Ti and interfering with the interlinkage to the magnetic core. The magnetic flux is disturbed in the vicinity of the intersection C, resulting in a loss and a decrease in the inductance value of the magnetic induction element 40.
There is a problem that the Q value of the magnetic induction element 40 decreases particularly in a high frequency region because eddy current loss occurs due to the magnetic flux linked to 20.

Further, in order to reduce the loss due to the eddy current loss of the magnetic core, the magnetic core is divided into slits. However, in the slit spiral S as shown in FIG. Since the coil 10 excites in two directions, the magnetic core is not effectively used. If such a slit is provided, the loss can be reduced, but the magnetic anisotropy feature of the magnetic material cannot be effectively utilized.

An object of the present invention is to solve the above-mentioned conventional problems and to improve the performance of the magnetic induction element by utilizing the magnetic anisotropy of the magnetic thin film for the magnetic core.

[0011]

According to the present invention, the above object is achieved by sandwiching a coil made of a thin film conductor formed in a spiral shape and a coil made of a magnetic thin film having magnetic anisotropy from both sides. A pair of planar magnetic cores are laminated with an insulating film interposed therebetween to form a magnetic induction element, and the magnetic core is divided into a plurality of magnetic core portions by radial slits extending from the inside of the spiral of the coil to the outside, This is achieved by orienting either the easy axis or the hard axis of the magnetic thin film for each magnetic core portion in the direction of magnetization by the coil.

When the magnetic core is formed in a rectangular shape, it is preferable that the slits are provided in a diagonal line with respect to the rectangular shape, and if necessary, the slits are provided in parallel with the magnetization direction of the coil so as to divide each magnetic core portion. Good. When forming the coil and the magnetic core in a rectangular shape, a pair of trapezoids each having a long side and a short side of the rectangular core as a magnetic core are formed by diagonal slits passing through the apexes of the rectangle and a slit extending in the central portion in the longitudinal direction. Is preferably divided into triangular magnetic core portions, and in this case as well, the trapezoidal magnetic core portions are preferably divided by slits parallel to the magnetization direction of the coil.

Further, a plurality of spiral coils are miniaturized and two or more coils are two-dimensionally arranged and sandwiched from both sides by a pair of magnetic cores.
It is advantageous to reduce eddy current loss that each magnetic core is divided into continuous magnetic core portions over two adjacent coils by slits provided in a radial pattern for each coil. In this mode, it is advantageous to connect a plurality of coils in series in order to increase the inductance, and further, the outer ends of the spirals of two adjacent coils with all the spiral directions of the plurality of coils aligned. It is preferable to connect them to each other on the array surface. In order to improve high-frequency performance, it is advantageous to connect a series circuit of multiple coils in parallel. Furthermore, the spiral direction is the same for coils that should be connected in series, and opposite for coils that should be connected in parallel. The outer ends of the spirals of the two opposite coils adjacent to each other may be connected to each other on the arrangement plane of the coils.

In the magnetic induction element according to the present invention, the distribution of the magnetic field inside the magnetic core is achieved by connecting the inner ends of the spiral of each coil through the gaps formed by the slits between the magnetic cores and the windows opened therein. It is particularly advantageous in preventing the disturbance of Further, in the present invention, the division of the magnetic core by the slit is preferably performed so as to be divided into two magnetic core subgroups having different easy magnetization axes or hard magnetization axes in the same plane, and one specific means therefor is one of them. A magnetic thin film is formed in a state where the portion where the magnetic core subgroup is to be arranged is masked and the other magnetic core subgroup is left by the lift-off method, and then the magnetic thin film is formed in a state where the other magnetic core subgroup is masked. It is preferable to leave one magnetic core subgroup by the lift-off method. At this time, in order to give the magnetic thin film magnetic anisotropy, if a [ high ] magnetic material is deposited by a sputtering method or the like while a magnetic field is applied in a predetermined direction, the magnetic thin film in which the easy axis of magnetization is oriented in the magnetization direction is obtained. can get. Also, to further reduce the eddy current losses in the magnetic core of a high frequency may have to the multilayer structure of the magnetic thin film, an insulating silicon oxide or the like [high] about magnetic material and 0.05μm of about 0.1μm is for this purpose It is preferable that the films are alternately stacked to form, for example, about 10 layers by a sputtering method.

The magnetic induction element according to the present invention is used as a reactor having a coil formed of a thin film conductor formed in a single layer, or is formed from a thin film conductor formed by laminating a plurality of layers through insulating films. It can be used as a transformer or a transformer provided with a plurality of formed coils.

According to the present invention, a magnetic core formed of magnetic thin films sandwiching a coil formed in a spiral shape from both sides is divided into a plurality of magnetic core portions by radial slits extending from the inside to the outside of the spiral as described above. In addition to reducing the eddy current loss of the magnetic core and the stray capacitance between the coil and the magnetic core, the magnetic thin film of the magnetic material is formed by orienting either the easy axis or the hard axis of the magnetic thin film for each magnetic core portion in the magnetization direction of the coil. By effectively utilizing the magnetic anisotropy of the magnetic induction element, the performance of the magnetic induction element was successfully improved.

That is, the direction in which the current flowing in the spiral coil excites the magnetic core sandwiching it from both sides is perpendicular to the coil winding direction, and the eddy current loss generated in the magnetic core is in the direction perpendicular to this magnetization direction. Since it increases as a hyperbolic function with respect to the effective width of the magnetic core, the eddy current loss is reduced to a fraction or less by dividing the magnetic core into magnetic core parts by radial slits along the magnetization direction and limiting the maximum width appropriately. To do. Further, since the coupling path due to the stray capacitance passing through the magnetic core between the respective parts in the winding direction of the coil is divided by the slit, the internal stray capacitance of the coil as a whole is usually reduced to less than half.

Further, when the magnetic easy axis of the magnetic thin film of each magnetic core portion divided by the slit is oriented in the direction of magnetization by the coil, the magnetic field generated in the magnetic core increases, and accordingly the unit of the magnetic induction element is increased accordingly. The inductance value per area increases, and when the hard magnetization axis is oriented in the magnetization direction, the magnetic permeability of the magnetic core is maintained substantially constant up to the high frequency region, so that the usable frequency region of the magnetic induction element is expanded. As described above, in the magnetic induction element of the present invention, the Q value is increased by decreasing the eddy current loss of the magnetic core, the resonance frequency thereof is increased by decreasing the internal stray capacitance of the coil, and further, the magnetic anisotropy of the magnetic thin film is increased for each magnetic core portion. The inductance value can be increased or the operating frequency can be extended to a high frequency region by appropriately selecting the direction of sex.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic embodiment of a magnetic induction element according to the present invention, FIG. 2 shows an embodiment in which a plurality of coils are divided, and FIG. 3 shows an embodiment in which the present invention is applied to a transformer.
FIG. 5 shows an embodiment in which the magnetic core portion is subdivided, and FIG. 5 shows an embodiment in which the coil is formed in a rectangular shape. 6 to 8 described before these figures are denoted by the same reference numerals.

In FIG. 1, (a) is a developed perspective view of the magnetic induction element 40, and (b) and (c) of FIG. 1 show that the easy axes Me of the magnetic core portions 21 and 22 are magnetized by the coil 10. The top view of the magnetic core 20 orient | assigned respectively to the parallel direction and the orthogonal direction with respect to the direction M is shown. The coil 10 shown in the center of FIG. 1A is formed by photo-etching a thin film conductor on which a metal having a high conductivity such as copper is formed into a rectangular spiral shape in the example of the drawing. A pair of magnetic cores 20
Is formed so that a magnetic thin film made of a [high] magnetic material is formed into a substantially square shape corresponding to the coil 10, and the coil 10 is sandwiched from both upper and lower sides of the drawing with an insulating film 30 such as silicon oxide interposed therebetween. The actual stacking order of these layers is from the bottom to the top of the drawing.

In the embodiment of FIG. 1, the slits Sd of each magnetic core 20 are provided in a diagonal line with respect to the rectangular shape, so that the magnetic core 20 forms a pair of magnetic core portions shown in FIGS. 1 (b) and 1 (c). 21 and
Divided into 22. The terminal To is led out laterally from the outer end of the spiral of the coil 10, but the connecting wire for the terminal Ti is utilized from the inner end by utilizing the gap between the magnetic core portions 21 and 22 by the slit Sd. In the example shown in the figure, it is led out downward through the window W provided and through the lower magnetic core 20.

In the illustrated example, the insulating film 30 is formed to be slightly smaller than the magnetic core 20 while insulating the terminals To, and the opening 31 is provided in the central portion, so that the upper and lower magnetic cores 20 are arranged inside and outside the spiral of the coil 10. To contact each other to form a closed magnetic circuit. The high frequency magnetic induction element 40 may have an open magnetic circuit, but the closed magnetic circuit is advantageous in increasing the inductance value in a relatively low frequency region. Further, a window 32 is opened in the insulating film 30 so as to correspond to the window W on the side of the magnetic core 20 and for the connection wire of the terminal Ti. For this connecting wire, the thin film conductor of the coil 10 may be filled in the window 32 or W at the time of film formation and connected to the aluminum wiring film for the terminal Ti or the like.

As shown in FIG. 1 (b) and FIG. 1 (c), the magnetic core portions 21 and 22 of this embodiment are right-angled isosceles triangles, and the direction of magnetization M by the coil 10 is substantially perpendicular to the bottom side. become. In the example of FIG. 1 (b), the easy magnetization axis Me of the magnetic thin films of the magnetic core portions 21 and 22 is aligned with this magnetization direction M. In the example of FIG. 1 (c), the easy magnetization axis Me is perpendicular to the magnetization direction M. To be done. In the example of Fig. 1 (b), a high magnetic field is generated in the magnetic core parts 21 and 22 even with a small coil current, so it is suitable for high inductance in a relatively low frequency region, and the example of Fig. 1 (c) is difficult to magnetize the magnetic thin film. Although the axis is in the magnetization direction M and the generated magnetic field in the magnetic core portions 21 and 22 is low, its magnetic permeability is substantially constant up to the high frequency region, and is therefore suitable for relatively low inductance in the high frequency region. Since the reactance value of the magnetic induction element 50 is proportional to the product of the inductance and the frequency, there is no great difference between the two examples.

As described above, in the present invention, the magnetic core 20 has the slit.
Sd divides the magnetic core into two magnetic core subgroups 21 and 22 having different magnetic anisotropy directions. An example of a specific method of forming a magnetic thin film for these magnetic core subgroups 21 and 22 will be described. First, for example, the magnetic core subgroup
After the magnetic thin film is formed on the entire surface in a state where 22 locations are masked with a positive photoresist, the magnetic core subgroup 22 is removed by removing the magnetic core subgroup 22 by a so-called lift-off method in which the photoresist is dissolved with a remover liquid, and only the magnetic core subgroup 21 is removed. Leave. Next, after forming the magnetic thin film on the entire surface in a state where the magnetic core subgroup 21 is masked with a photoresist so as to be slightly wider than that, a portion overlapping the magnetic core subgroup 21 is similarly removed by the lift-off method to remove the magnetic core subgroup. Leave 22 This allows slitting on the same plane
Two magnetic core subgroups 21 and 22 separated by Sd can be deposited.
In order to orient the magnetic anisotropy in each of the magnetic core subgroups 21 and 22 in a desired direction, when the magnetic thin film is formed by, for example, the sputtering method, the static magnetic field is set in the direction that should be the easy axis Me of magnetization. It should be applied with a strength of about 10 Oe.

If the above-mentioned lift-off method is not used, the magnetic core subgroup 21 is formed on the entire surface of the magnetic thin film by the usual film formation and photoetching, and then covered with an insulating film.
Next, a magnetic core subgroup 22 is formed in the same manner, and both magnetic core subgroups 21 and 22 are formed.
Is a magnetic core 20 arranged on two surfaces which are slightly displaced from each other. For high frequencies of several MHz or more, it is advantageous to configure the magnetic core subgroups 21 and 22 with multilayer magnetic thin films in order to reduce eddy current loss. In this case, for example, Co-based amorphous magnetic material and silicon oxide are used. Alternating 0.1 μm and 0.05
It is preferable that a film having a thickness of about μm is laminated in several to 10 layers by the RF magnetron sputtering method or the like. In any case, it is the same to form a magnetic thin film under a static magnetic field and orient the easy axis of magnetization in a predetermined direction.

As can be seen from the embodiment shown in FIG. 1 described above, in the present invention, the magnetic easy axis Me of the magnetic thin film of each magnetic core portion 21 or 22 is oriented in the magnetization direction M by the coil 10 so that By increasing the generated magnetic field to increase the inductance value per unit area of the magnetic induction element 50 or by orienting the easy axis of magnetization Me at right angles to the magnetization direction M, the magnetic permeability of the magnetic core 20 can be kept constant up to the high frequency region. The frequency range in which the inductance value and the Q value are hardly reduced can be expanded to the high frequency side as compared with the conventional case. Further, the magnetic core 20 is divided into magnetic core portions 21 and 22 by radial slits Sd substantially along the magnetizing direction M to reduce the width in the direction perpendicular to the magnetizing direction M, thereby reducing the eddy current loss from the conventional number to 1/10
Can be reduced to Furthermore, by dividing the coupling path of the distributed stray capacitance between each part in the winding direction of the coil 10 through the magnetic core 20 with the slit Sd, the internal stray capacitance of the coil 10 is reduced to about half or less of the conventional value and the resonance frequency is reduced. It is possible to increase the applicable frequency range of the magnetic induction element 40 while increasing the above.

In the next embodiment shown in FIG. 2, the coil is composed of a plurality of small partial coils arranged two-dimensionally. Figure 2 (a)
2 (b) is a front view of the magnetic core 20 of this embodiment,
The partial coil 10a is shown by a thin line. In any case, the number of partial coils 10a is four, but the mode of connection is different. These square partial coils 10a are arranged in a square shape, and the magnetic cores 20 sandwiching them from both sides are provided with slits Sd diagonally to each square for each partial coil 10. As a result, the magnetic core 20 has a triangular magnetic core portion 21 and
In addition to being divided into 22, the magnetic core is divided into square magnetic core portions 23 and 24 which are continuous over two adjacent partial coils 10a.

In the embodiment shown in FIG. 2A, a plurality of partial coils 10 are provided.
All of a are connected in series to increase the inductance value. Therefore, for example, all partial coils 10
The outer ends of the two spirals that are aligned in the vertical direction in the figure are aligned with each other, and the outer ends of the two adjacent spirals are connected to each other on the surface where the coil 10 is arranged. It is preferable to lead the connection terminal through the portion. In the illustrated example, the terminals Tc derived from the upper ends of the series circuits of the two partial coils 10a arranged in the vertical direction are connected to each other, and the external connection terminals Ta and Tb are derived from the lower ends of the series circuits.

FIG. 2 (b) shows an advantageous mode for improving the high frequency performance of the inductance and Q value, in which a series circuit of two partial coils 10a is connected in parallel. For this purpose, for example, the winding directions of the partial coils 10a connected in series are reversed, the winding directions of the partial coils 10a connected in parallel are made the same, and the outer ends of the spirals whose winding directions are opposite to each other as shown in FIG. The terminals Ta and Tb for external connection are derived after interconnecting on the arrangement surface, and the terminals Tc and Td are derived from the inner end of the spiral of the partial coil 10a having the same winding direction through the gap portion of the magnetic core 20. And then interconnect. In the illustrated example, the terminal Ta is a pair of magnetic cores.
The terminals Tb are led out downwardly through the central window Wc of the magnetic core 20 from the mutual side to the side. In this embodiment, FIG.
Contrary to (a), it is advantageous to orient the hard magnetization axes of the magnetic thin films of the magnetic core portions 21 to 24 in the magnetization direction of the coil. 2 (a) and 2 (b), the coil is composed of a plurality of small partial coils 10a and thus the magnetic core 20
1 is divided into small magnetic core portions 21 to 24.
It is possible to further reduce the eddy current loss of the magnetic core 20 and the internal stray capacitance of the coil, as compared with the above case.

FIG. 3 is a perspective view corresponding to FIG. 1, showing an application example of the magnetic induction element of the present invention to the transformer 41. Usually, two coils 11 and 12 having different numbers of turns are arranged in two layers in a pattern of mutually rotating 180 degrees and sandwiched by a pair of rectangular magnetic cores 20. The insulating film disposed between these is omitted in the figure. The magnetic core 20 is divided into magnetic core portions 21 and 22 by a diagonal slit Sd in the same manner as the embodiment of FIG. 1, and the coils 11 and 12 are connected to the terminal To1 from the outer ends of the spirals.
To2 is led out laterally, and terminals Ti1 and Ti2 are led out from the inner end through the window W in the gap of the magnetic core 20, respectively.

FIG. 4 shows an embodiment in which the magnetic core 20 is finely divided into magnetic core portions. 4 (a) corresponds to the embodiment of FIG. 1, and FIGS. 4 (b) and 4 (c) correspond to the embodiment of FIG. 2, respectively. The coil 10 of FIG. 1 and the partial coil 10a of FIG. Is omitted in. In any of the embodiments, the magnetic core 20 is divided not only by the diagonal slits Sd but also by the cross-shaped slits Sc along the magnetization direction M by the above-mentioned coil. As shown in the figure, this slit Sc causes the magnetic core portions 21 and 22 of FIGS. 1 and 2 to be divided into two magnetic core portions 21d and 22d, respectively, as shown in FIGS. 4 (b) and 4 (c).
2 further divides the core portions 23 and 24 of FIG. 2 into two core portions 23d and 24d, respectively. Note that FIG.
The patterns for dividing the magnetic core 20 in (b) and FIG. 4 (c) are the same, but the position of the window W is slightly different.
It differs from the former in that a central window Wc is provided corresponding to the embodiment of (b). By subdividing the cores in the embodiment of FIG. 4, it can be further reduced than the embodiment of FIGS. 1 and 2 the internal stray capacitance of the eddy current loss and the coil of the magnetic core.

FIG. 5 shows an embodiment in which the coil and the partial coil are formed in a rectangular shape. In the embodiment shown in FIG. 5 (a), the coil 10 is formed in a vertically long rectangular shape, the magnetic core 20 is also formed in a rectangular shape accordingly, and a diagonal slit Sd passing through each vertex of the rectangle and a central portion are formed in the vertical direction. The slit Sc that passes through divides into a pair of triangular magnetic core portions 22 having the short sides as the base and a pair of trapezoidal magnetic core portions 25 having the long sides as the base.

In the next embodiment shown in FIG. 5 (b), two rectangular partial coils 10a are arranged side by side in the lateral direction,
Moreover, the magnetic core 20 is formed in a rectangular shape to cover them, and the slits Sd and Sc similar to those in FIG. As a result, the magnetic core 20 is similarly divided into a triangular magnetic core portion 22 and a trapezoidal magnetic core portion 25, and a hexagonal magnetic core portion 26 in which the trapezoid is continuous over the two partial coils 10a in the central portion.
Is divided into In the illustrated example, two partial coils 10
Are connected in series and have the same winding direction and are connected to each other by the outer terminals of the spiral.

The embodiment of FIG. 5 (c) is almost the same as that of FIG. 5 (b), but the slits Sc of FIG. 5 (b) are provided in a cross shape so that two magnetic core portions 25 and 26 are further provided. The difference is that it is divided into parts 25d and 26d. In any of these embodiments shown in FIG. 5, the magnetic core 20 is divided by slits Sd and Sc into magnetic core portions of an appropriate size to reduce the eddy current loss of the magnetic core and the internal stray capacitance of the coil. You can

In the magnetic induction element according to the present invention described above, for example, the thin film conductor for the coil is made of copper with a thickness of 3 to 10 μm, and the magnetic thin film for the magnetic core is made of an amorphous magnetic material such as an alloy of Co type. A film having a thickness of 1 to 2 μm is formed. The insulating film may be formed of silicon oxide with a film thickness of about 1 μm. However, the insulating film provided on the upper side of the coil is filled with the flattening film as the base to fill the concave portion on the upper surface of the coil. It's good to leave. The magnetic induction element is a very thin planar element that is suitable for being mounted on or built in a semiconductor chip. In the case of a reactor having a size of several to 10 mm square, an inductance value of about several μH and a Q of 10 to several tens of Q. It is possible to give a value, and it depends on the design, of course, several tens of kHz
It can be used in the frequency range of 10 MHz. The current capacity is set depending on the application, but it is usually several hundred mA.

[0036]

As described above, in the magnetic induction device of the present invention, a planar coil made of a thin film conductor formed in a spiral shape and a pair of faces made of a magnetic thin film having magnetic anisotropy sandwiching the coil from both sides. Magnetic cores are sequentially laminated with an insulating film between them, and the magnetic cores are divided into multiple magnetic core parts by radial slits that go from the inside to the outside of the spiral of the coil, and the magnetic thin film in each magnetic core part is easily magnetized. The following effects can be obtained by orienting either the axis or the hard axis of magnetization in the direction of magnetization by the coil.

(A) When the easy axis of magnetization of the magnetic thin film of each magnetic core portion is oriented in the direction of magnetization by the coil, the magnetic field generated in the magnetic core is increased to increase the inductance value per unit area of the magnetic induction element, When the hard axis is oriented in the magnetization direction, the magnetic permeability of the magnetic core can be kept almost constant up to the high frequency range, and the usable frequency of the magnetic induction element can be expanded toward the high frequency range. The performance of the magnetic induction element can be enhanced according to the application while effectively utilizing the magnetic anisotropy of the magnetic material.

(B) The magnetic core is divided into a plurality of magnetic core portions by radial slits so that the effective width of each magnetic core portion in a direction perpendicular to the magnetization direction is substantially aligned with the magnetization direction received from the spiral coil. since then appropriately limited to less than the allowable maximum limit can reduce eddy current loss of the magnetic core, especially conventional number of eddy current <br/> current losses in the magnetic core of the magnetic induction device used in a high frequency range By reducing the frequency to less than or equal to one-half, the frequency that can guarantee a high Q value can be expanded to a higher frequency side than in the conventional case.

(C) By effectively dividing the coupling path of the distributed stray capacitance between the coil portions in the winding direction of the coil through the magnetic core by the slit for dividing the magnetic core, the internal stray capacitance of the magnetic induction element is reduced. It is possible to increase the resonance frequency by reducing it to about half or less of the conventional value and increase the upper limit of the applicable frequency range. The magnetic induction element according to the present invention having such features is suitable for being incorporated into various electronic devices as a small and thin thin film laminated reactor or transformer, or mounted on a semiconductor chip. This can make a significant contribution to downsizing and cost reduction of small-capacity electronic devices.

The embodiment of the present invention in which the coil is composed of a plurality of small partial coils arranged two-dimensionally and the magnetic core is divided into magnetic core parts by slits provided in a radial pattern for each partial coil is has the effect of reducing further the internal stray capacitance of the current loss and a coil, aspects all connected in series a plurality of partial coils when this is advantageous in increasing the inductance of the magnetic induction unit for relatively low frequency, The mode in which the partial coils are connected in series and parallel is particularly suitable for a magnetic induction element for high frequencies.

Further, in the embodiment in which the coil is connected to the inner end of the spiral through the gap portion formed by the slits between the magnetic core portions, the magnetic core formed by the intersection of the coil and the terminal lead-out connecting wire as in the prior art. It is very advantageous in preventing the disturbance of the internal magnetic field distribution and improving the performance of the magnetic induction element. When the magnetic core is divided into two magnetic core subgroups having different axes of easy magnetization or hard magnetization in the plane, a lift-off method is used to sequentially form and form both magnetic core subgroups one by one. This is advantageous in simplifying the film forming process of the magnetic core composed of a large number of magnetic core parts as much as possible. Furthermore, embodiments of the magnetic thin film of the magnetic core for a very thin film thickness of the magnetic material film and the multilayer structure of the insulating film, a high-frequency region the applicable range of the magnetic induction significantly reduces the eddy current loss of the magnetic core It is especially advantageous for further expansion to

[Brief description of drawings]

FIG. 1 shows a basic embodiment of a magnetic induction element according to the present invention. FIG. 1 (a) is a developed perspective view thereof, and FIG. 1 (b) shows a magnetic core whose easy axis of magnetization is parallel to the magnetization direction. Top view, same figure (c)
FIG. 4 is a top view of a magnetic core in which the easy axis of magnetization of the magnetic core portion is perpendicular to the magnetization direction.

FIG. 2 shows an embodiment of the present invention in which a coil is divided into a plurality of partial coils. FIG. 2 (a) is a front view of a magnetic induction element in which partial coils are connected in series, and FIG. It is a front view of the magnetic induction element connected in series and parallel.

FIG. 3 is a developed perspective view showing an embodiment in which the magnetic induction element of the present invention is applied to a transformer.

FIG. 4 shows an embodiment of the present invention for subdividing a magnetic core portion,
The figure (a) is a top view of the magnetic core in the case of a single coil, the figure (b)
FIG. 3A is a top view of a magnetic core when the coil is composed of a plurality of partial coils connected in series, and FIG. 6C is a top view of a magnetic core when the coil is composed of a plurality of partial coils connected in series / parallel.

5A and 5B show an embodiment of the present invention in which a coil is formed in a rectangular shape. FIG. 5A is a front view of a magnetic induction element in the case of a single coil, and FIG. 5B is a series of two coils. FIG. 3C is a front view of the magnetic induction element in the case of being composed of connected partial coils, and FIG. 6C is a front view of the magnetic induction element in the case where the magnetic core portion is subdivided.

FIG. 6 is a developed perspective view showing a typical example of a conventional magnetic induction element.

7 is a top view of the magnetic core showing the relationship between the magnetic anisotropy of the magnetic core in the magnetic induction element of FIG. 6 and the magnetization direction of the coil in order to explain the problems of the prior art.

FIG. 8 is a top view of a conventional magnetic induction element in which a coil is formed elongated in order to solve the conventional problems.

FIG. 9 is a top view of a magnetic induction element when a conventional magnetic core portion is subdivided.

[Explanation of symbols]

 10 coil 10a partial coil 11 primary coil when magnetic induction element is a transformer 12 secondary coil when magnetic induction element is a transformer 20 magnetic core 21,22 triangular magnetic core portion 21d, 22d further divided magnetic core portion 23 , 24 Square magnetic core part 23d, 24d Further divided magnetic core part 25 Trapezoidal magnetic core part 25d Further divided trapezoidal magnetic core part 26 Hexagonal magnetic core part 26d Further divided hexagonal magnetic core part 30 Insulation Film 31 Central opening of insulating film 32 Window of insulating film 40 Magnetic induction element or reactor 41 Transformer as magnetic induction element Magnetization direction by M coil Easy magnetization axis Sc Cross slit Sd Diagonal slit W Between core parts The window of the gap Wc The center window of the magnetic core

Claims (12)

[Claims] 1. An insulating film is provided between a planar coil made of a thin film conductor formed in a spiral shape and a pair of planar magnetic cores made of a magnetic thin film having magnetic anisotropy and sandwiching the coil from both sides. The magnetic core is divided into a plurality of magnetic core portions by radial slits extending from the inside to the outside of the spiral of the coil, and for each magnetic core portion, either the easy axis or the hard axis of the magnetic thin film is coiled. A thin-film laminated magnetic induction element characterized in that it is oriented in the same direction as the magnetization direction. 2. The thin-film laminated magnetic induction element according to claim 1, wherein the magnetic core is formed in a square shape and the slits are provided in a diagonal line with respect to the square shape. 3. The thin-film laminated magnetic induction element according to claim 2, further comprising slits parallel to the magnetization direction of the coil so as to divide each magnetic core portion. 4. The device according to claim 1, wherein the coil and the magnetic core are formed in a rectangular shape, and the magnetic core has a long side and a short side of the rectangle formed by diagonal slits passing through the vertices of the rectangle and slits extending in the longitudinal direction of the rectangle. A thin film laminated magnetic induction element characterized by being divided into a pair of trapezoids each having a base as a base and a triangular magnetic core portion. 5. The thin-film laminated magnetic device according to claim 1, wherein the coil is connected to the inner end of the spiral through a gap portion formed by slits between the magnetic core portions. Inductive element. 6. The device according to claim 1, wherein a plurality of spiral coils are two-dimensionally arranged and sandwiched from both sides by a pair of magnetic cores formed of a rectangular magnetic thin film,
A thin film laminated magnetic induction element, wherein a magnetic core is divided into continuous magnetic core portions over two coils adjacent to each other by slits provided in a radial pattern for each coil. 7. The element according to claim 6, wherein a plurality of coils are arranged so that the directions of magnetic flux generated in adjacent coils are opposite to each other, and the spiral coils are arranged in different winding directions. A thin film laminated magnetic induction element characterized in that coils are connected in series. 8. The device according to claim 6, wherein a series circuit of a plurality of coils is connected in parallel by changing the directions of the series coils so that the directions of magnetic flux generated in adjacent coils are opposite to each other. A thin-film laminated magnetic induction device characterized by the above. 9. The thin-film laminated magnetic device according to claim 1, wherein the magnetic core is divided into two magnetic core subgroups having different easy axis or hard axis by a slit in the same plane. Inductive element. 10. The device according to claim 9, wherein a magnetic thin film is formed in a state where one magnetic core subgroup is to be disposed in a masked state, and the other magnetic core subgroup is left by a lift-off method. A thin film laminated magnetic induction characterized in that a magnetic thin film is formed with the other magnetic core subgroup masked, and one magnetic core subgroup is left by a lift-off method to form both magnetic core subgroups. element. 11. The thin-film laminated magnetic induction element according to claim 1, wherein the magnetic induction element is a reactor including a coil formed of a thin-film conductor formed in a single layer. . 12. The element according to claim 1, wherein the magnetic induction element is a transformer including coils each formed of a thin film conductor laminated in a plurality of layers with insulating films interposed therebetween. Thin film laminated magnetic induction element.