Patent Description:
Miniaturization of an electronic component is a prerequisite for miniaturization of an electronic product. The electronic product may be a wearable device such as a band, a smart watch, or a Bluetooth headset; or a mobile display terminal such as a mobile phone or a tablet computer; or a device such as a server, an AI processor, or a network processor; or the like. A common electronic component includes an inductor.

A voltage converter is usually disposed in the electronic product. In an example of a DC-DC buck circuit in the voltage converter, as shown in <FIG>, an inductor L is disposed in the DC-DC buck circuit. The inductor L has an energy storage function and a filtering function. When a switch transistor Q is conducted, the inductor L is charged. When the switch transistor Q is cut off, the inductor L is discharged. In the buck circuit, when a switch frequency of the switch transistor Q is relatively low, for example, <NUM> to <NUM>, to reduce a ripple of a current output from the buck circuit, an inductance of the inductor L needs to be hundreds of µH to hundreds of nH. In this case, a size of the inductor L is too large to miniaturize the electronic product. <CIT> discloses a thin film inductor having yokes, one or more of which is laminated, and one or more conductors passing between the yokes. The laminated yoke or yokes help reduce eddy currents and/or hysteresis losses. Magnetic layers of the laminated yoke have varying thickness, with the thickness of magnetic layers closer to the winding (that is, in areas of higher density magnetic flux) having relatively lower thickness(es) in order to further reduce eddy currents and related energy losses. <CIT> discloses a thin film inductor having yokes, one or more of which is laminated, and one or more conductors passing between the yokes. The laminated yoke or yokes help reduce eddy currents and/or hysteresis losses. <CIT> discloses techniques for fabricating low-loss magnetic vias within a magnetic core. According to some embodiments, vias with small, well-defined sizes may be fabricated without reliance on precise alignment of layers. According to some embodiments, a magnetic core including a low-loss magnetic via can be wrapped around conductive coils of an inductor. The low-loss magnetic vias can improve performance of an inductive component by improving the quality factor relative to higher loss magnetic vias.

Embodiments of this application provide a thin film inductor and a preparation method thereof, an integrated circuit, and a terminal device, to resolve a problem of a relatively large size of an inductor in an electronic product.

To achieve the foregoing objectives, the invention provides a thin film inductor of claim <NUM> and a terminal device of claim <NUM>. The following technical solutions are used in embodiments of this application:.

According to a first aspect, a thin film inductor is provided. The thin film inductor includes a magnetic core, where the magnetic core includes a first magnetic film and a second magnetic film, and an accommodation cavity exists between the first magnetic film and the second magnetic film; a conductor, located in the accommodation cavity; and an insulating isolation film including regions, disposed on two sides of the conductor and located between the first magnetic film and the second magnetic film. The insulating isolation film is in contact with the first magnetic film and the second magnetic film. In addition, the first magnetic film and the second magnetic film each include magnetic sub-films and insulating sub-films. In the first magnetic film, the magnetic sub-films and the insulating sub-films are alternately disposed. In the second magnetic film, the magnetic sub-films and the insulating sub-films are alternately disposed. The magnetic sub-films and the insulating sub-films in the first magnetic film are exposed from a surface that is of the first magnetic film and that is in contact with the insulating isolation film; and/or the magnetic sub-films and the insulating sub-films in the second magnetic film are exposed from a surface that is of the second magnetic film and that is in contact with the insulating isolation film. In this way, an eddy current at the insulating isolation film can intersect the magnetic sub-films and the insulating sub-films that are exposed from the surface that is of the first magnetic film and that is in contact with the insulating isolation film, and/or the surface that is of the second magnetic film and that is in contact with the insulating isolation film. Therefore, the eddy current at the insulating isolation film is separated, at a position of a plane on which the eddy current is located and that intersects the layers of magnetic sub-films, into a plurality of sub-eddy currents by the layers of magnetic sub-films. Each sub-eddy current enters one layer of magnetic sub-film. In this case, each sub-eddy current can be limited to one layer of magnetic sub-film, to reduce loss of the eddy current.

Optionally, the surface that is of the first magnetic film and that is in contact with the insulating isolation film and/or the surface that is of the second magnetic film and that is in contact with the insulating isolation film is an inclined surface. In addition, the magnetic sub-films and the insulating sub-films in the first magnetic film and the second magnetic film are parallel to a lower surface of the first magnetic film. The lower surface of the first magnetic film is a surface that is of the first magnetic film and that is away from the second magnetic film. In this way, the eddy current can be separated, at the position of the plane on which the eddy current is located and that intersects the layers of magnetic sub-films, into the plurality of sub-eddy currents by the layers of magnetic sub-films. In addition, each sub-eddy current enters one layer of magnetic sub-film. In this case, each sub-eddy current can be limited to each layer of magnetic sub-film, to reduce loss of the eddy current.

Optionally, the surface that is of the first magnetic film and that is in contact with the insulating isolation film and the surface that is of the second magnetic film and that is in contact with the insulating isolation film are inclined surfaces with a same slope. In this case, a thickness of the insulating isolation film between the second magnetic film and the first magnetic film is the same at all positions.

Optionally, the first magnetic film is a trapezoidal frustum. An upper base of the trapezoidal frustum is close to the second magnetic film, and a lower base is away from the second magnetic film. In addition, the thin film inductor further includes a flattened dielectric layer, covering the upper base of the trapezoidal frustum and a part of side surfaces of the trapezoidal frustum; a magnetic flux hole, prepared on the flattened dielectric layer, where the insulating isolation film is located in the magnetic flux hole and covers the other part of the side surfaces of the trapezoidal frustum; and an interlayer dielectric layer, covering an upper surface of the flattened dielectric layer and a sidewall of the magnetic flux hole. The interlayer dielectric layer and the insulating isolation film are made of the same material and are an integrated structure. The flattened dielectric layer is configured to flatten a bearing surface configured to bear the conductor in the thin film inductor. The insulating isolation film in contact with the first magnetic film and the second magnetic film is formed in the magnetic flux hole. The interlayer dielectric layer is configured to form a part of a lower support layer below the conductor.

Optionally, a tail of the second magnetic film covers the sidewall on a side that is of the magnetic flux hole and that is away from the accommodation cavity, and an upper surface that is of the interlayer dielectric layer and that is connected to the sidewall, so that the tail of the second magnetic film has a turning. In addition, an end that is of the tail of the second magnetic film and that is away from the accommodation cavity has a taper angle. The taper angle is from <NUM>° to <NUM>°. In some embodiments of this disclosure, the taper angle β may be <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, or <NUM>°.

Optionally, the first magnetic film is a trapezoidal frustum. An upper base of the trapezoidal frustum is close to the second magnetic film, and a lower base is away from the second magnetic film. Side surfaces of the trapezoidal frustum are fully covered by the insulating isolation film. In addition, the thin film inductor further includes a flattened dielectric layer, covering the upper base of the trapezoidal frustum; and an interlayer dielectric layer, covering the flattened dielectric layer. The interlayer dielectric layer and the insulating isolation film are made of the same material and are an integrated structure. Technical effects of the flattened dielectric layer and the interlayer dielectric layer are the same as those described above.

Optionally, an end that is away from the accommodation cavity and that is of a part that is of the second magnetic film and that is in contact with the insulating isolation film has a taper angle. The taper angle is less than <NUM>°. The taper angle is from <NUM>° to <NUM>°. In some embodiments of this disclosure, the taper angle β may be <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, or <NUM>°. No turning needs to be disposed at the tail of the second magnetic film.

Optionally, the surface that is of the first magnetic film and that is in contact with the insulating isolation film and/or the surface that is of the second magnetic film and that is in contact with the insulating isolation film are/is curved surfaces/a curved surface. In addition, the magnetic sub-films and the insulating sub-films in the first magnetic film and the second magnetic film are parallel to the lower surface of the first magnetic film. The lower surface of the first magnetic film is a surface that is of the first magnetic film and that is away from the second magnetic film. In this way, a plurality of magnetic lines passing through the insulating isolation film are separately perpendicular to the surface that is of the first magnetic film and that is in contact with the insulating isolation film, that is, a tangent plane at a position of an intersecting point between each magnetic line and the curved surface. In this case, a sub-eddy current is induced in an alternating magnetic field at a section perpendicular to a direction of a magnetic line, that is, the tangent plane. Planes at which some sub-eddy currents are located respectively intersect film surfaces of the magnetic sub-films. Therefore, a sub-eddy current intersecting a film surface of a magnetic sub-film can enter the magnetic sub-film. In this case, the sub-eddy currents can be limited to the magnetic sub-films, to reduce loss of the eddy current.

Optionally, the surface that is of the first magnetic film and that is in contact with the insulating isolation film and the surface that is of the second magnetic film and that is in contact with the insulating isolation film are curved surfaces with same curvature. In this case, a thickness of the insulating isolation film between the second magnetic film and the first magnetic film is the same at all positions.

Optionally, the thin film inductor further includes a support pad. The support pad is located below the first magnetic film. A part below the first magnetic film is a side that is of the first magnetic film and that is away from the second magnetic film. An upper surface of the support pad is in contact with the insulating isolation film. In addition, the first magnetic film covers two sides of the upper surface of the support pad. In the first magnetic film covering the support pad, the magnetic sub-films and the insulating sub-films are in contact with the insulating isolation film. A surface that is of the support pad and that is in contact with the first magnetic film is a curved surface. In this case, the plurality of magnetic lines of the alternating magnetic field at a position of the insulating isolation film pass through the insulating isolation film from the second magnetic film, then separately enter the curved magnetic sub-films in the first magnetic film covering the support pad, and then go along a direction of laying the magnetic sub-films. The magnetic sub-films and the insulating sub-films in the first magnetic film covering the support pad intersect a surface at which the insulating isolation film is located. Paths of the plurality of magnetic lines are respectively limited to the layers of curved magnetic sub-films. Therefore, a plane in which an induced sub-eddy current is located and that is in a section perpendicular to a direction of each magnetic line in the alternating magnetic field also intersect the magnetic sub-films covering the support pad. In addition, the sub-eddy current is also limited to each layer of magnetic sub-film. In this way, the sub-eddy currents can be limited to the magnetic sub-films, to reduce loss of the eddy current.

Optionally, to simplify a process for preparing the support pad, the surface that is of the support pad and that is in contact with the first magnetic film is an arc surface. To improve stability of the support pad in the thin film inductor, a lower surface of the support pad is flush with a lower surface of the first magnetic film.

Optionally, the thin film inductor further includes: a seed layer, located in the accommodation cavity. The seed layer is in contact with a surface that is of the conductor and that is close to the first magnetic film. The seed layer is configured to set the conductor on the lower support layer. An upper support layer is located in the accommodation cavity. A surface of the conductor except the surface in contact with the seed layer is covered by the upper support layer. The upper support layer is configured to support the second magnetic film. The upper support layer can be used to adjust an overall thickness of the thin film inductor. An adhesion layer is disposed on a surface that is of the second magnetic film and that is close to the first magnetic film, and is configured to fasten the second magnetic film.

Optionally, a thickness of the insulating sub-film is from <NUM> to <NUM>. When the thickness of the insulating sub-film is less than <NUM>, and a switch frequency in a circuit is a high frequency, an impedance of a capacitor formed between the layers of magnetic sub-films is relatively small, so that sub-eddy currents in the magnetic sub-films easily pass through the insulating sub-films and converge, to reduce an effect of loss of the eddy current. In addition, when the thickness of the insulating sub-film is greater than <NUM>, if the first magnetic film or the second magnetic film is fixed, a proportion of a thickness of the magnetic sub-films in a thickness of the first magnetic film or the second magnetic film decreases, thereby reducing an effective magnetic permeability of the thin film inductor. In addition, the thickness of the magnetic sub-film is from <NUM> to <NUM>. When the thickness of the magnetic sub-film is greater than <NUM>, when the first magnetic film or the second magnetic film is fixed, a proportion of the thickness of the insulating sub-films in the thickness of the first magnetic film or the second magnetic film decreases, so that the sub-eddy currents in the magnetic sub-films easily pass through the insulating sub-films and converge, thereby reducing an effect of loss of the eddy current. In addition, when the thickness t of the magnetic sub-film is greater than <NUM>, and a switch frequency in a circuit is a high frequency, an impedance of an eddy current path of the thin film inductor decreases. This does not facilitate limiting each sub-eddy current to a long and narrow loop of the magnetic sub-film.

Optionally, because the second magnetic film covers the upper support layer with a relatively large thickness, when the first magnetic film and the second magnetic film are anisotropic, a length of the first magnetic film is less than a length of the second magnetic film in a direction of a hard axis of the thin film inductor.

Optionally, the conductor is at least one metal conducting wire. The thin film inductor includes at least two magnetic cores. Two adjacent magnetic cores are spaced along a length direction of the metal conducting wire. The two adjacent magnetic cores are spaced, to reduce loss of the eddy current of the thin film inductor in the length direction of the metal conducting wire.

Optionally, the conductor is a coil. In addition, the thin film inductor includes a first magnetic core and a second magnetic core. The coil includes a plurality of first line segments and a plurality of second line segments. The first line segments are disposed opposite to the second line segments. The plurality of first line segments are located in the first magnetic core. The plurality of second line segments are located in the second magnetic core.

According to a second aspect, an integrated circuit is provided, including a silicon substrate and any thin film inductor described above. The thin film inductor is located on a silicon substrate. The integrated circuit has technical effects the same as the thin film inductor provided in the foregoing embodiment.

Optionally, the integrated circuit further includes a circuit structure disposed on the silicon substrate, a circuit-inductor interconnection layer sequentially covering the circuit structure, and a chip encapsulation structure. The thin film inductor is located between the circuit-inductor interconnection layer and the chip encapsulation structure. The circuit-inductor interconnection layer is configured to electrically connect the thin film inductor to the circuit structure. A first magnetic film in the thin film inductor is closer to the silicon substrate than a second magnetic film. Alternatively, a second magnetic film in the thin film inductor is closer to the silicon substrate than a first magnetic film. Signal interconnection can be implemented between the thin film inductor and the circuit structure by using the circuit-inductor interconnection layer.

According to a third aspect, a terminal device is provided, including at least one integrated circuit described above. The mobile terminal further includes a power management chip and a power bus connected to the power management chip, where the power management chip includes an integrated circuit; and/or the mobile terminal further includes a processor and a data bus connected to the processor, where the processor includes an integrated circuit. The mobile terminal has technical effects the same as the integrated circuit provided in the foregoing embodiment.

According to a fourth aspect, a method for preparing a thin film inductor is provided. The method includes the following: First, a first magnetic film is formed on a substrate by using a composition process. The first magnetic film is a trapezoidal frustum. An upper base of the trapezoidal frustum is away from the substrate, and a lower base is close to the substrate. The first magnetic film includes magnetic sub-films and insulating sub-films that are alternately disposed. The magnetic sub-films and the insulating sub-films in the first magnetic film are exposed from side surfaces of the trapezoid frustum. Next, a first dielectric layer is deposited on the substrate on which the first magnetic film is formed. Then, a flattening process is performed on the first dielectric layer, and a magnetic flux hole is prepared on the first dielectric layer by using the composition process. The first dielectric layer formed by using the composition process covers the upper base of the trapezoidal frustum and a part of the side surfaces of the trapezoidal frustum. Afterwards, a second dielectric layer is deposited on the substrate on which the foregoing structures are formed. The second dielectric layer covers an upper surface of the first dielectric layer and a sidewall of the magnetic flux hole, and is in contact with the other part of the side surfaces of the trapezoidal frustum by using the magnetic flux hole. Apart that is of the second dielectric layer and that is in contact with the side surfaces of the trapezoidal frustum serves as an insulating isolation film. On the substrate on which the insulating isolation film is formed, a conductor is formed above the upper base of the trapezoid frustum by using the composition process. On the substrate on which the conductor is formed, a second magnetic film is formed by using the composition process. The second magnetic film includes magnetic sub-films and insulating sub-films that are alternately disposed. An accommodation cavity for accommodating the conductor is formed between the first magnetic film and the second magnetic film. The method for preparing a thin film inductor has technical effects the same as the thin film inductor provided in the foregoing embodiment.

<NUM>: film inductor; <NUM>: integrated circuit; <NUM>: terminal device; <NUM>: magnetic core; <NUM>: first magnetic film; <NUM>: magnetic sub-film; <NUM>: insulating sub-film; <NUM>: second magnetic film; <NUM>: conductor; <NUM>: first line segment; <NUM>: second line segment; <NUM>: insulating isolation film; <NUM>: support pad; <NUM>: accommodation cavity; <NUM>: flattened dielectric layer; <NUM>: magnetic flux hole; <NUM>: interlayer dielectric layer; <NUM>: tail of a second magnetic film; <NUM>: lower support layer; <NUM>: seed layer; <NUM>: upper support layer; <NUM>: adhesion layer; <NUM>: silicon substrate; <NUM>: circuit structure; <NUM>: transistor; <NUM>: metal interconnection layer; <NUM>: circuit-inductor interconnection layer; <NUM>: chip encapsulation structure; <NUM>: chip encapsulation pin; <NUM>: power management chip; <NUM>: processor; <NUM>: photoresist; <NUM>: mask reticle; <NUM>: first dielectric layer; <NUM>: second dielectric layer.

Clearly, the described embodiments are merely a part rather than all of the embodiments of this application.

The following terms "first" and "second" are merely intended for a purpose of description, and shall not be understood as an indication or implication of relative importance or implicit indication of the number of indicated technical features. Therefore, a feature limited by "first" or "second" may explicitly or implicitly include one or more features.

In addition, in this application, position terms such as "top" and "bottom" are defined relative to positions of components in the accompanying drawings. It should be understood that these position terms are relative concepts used for relative description and clarification, and may correspondingly change according to changes in the positions of the components in the accompanying drawings.

An embodiment of this application provides an integrated circuit. An example in which the integrated circuit is a voltage conversion circuit is used. When a switch frequency of a switch transistor in the voltage conversion circuit is improved, for example, the switch frequency of the switch transistor is increased to <NUM> to <NUM>, an inductor with a very small inductance may be selected in the circuit, to reduce a ripple of a current output from the voltage conversion circuit.

In this case, an area of the inductor is small, thereby resolving a problem of a relatively large size of an inductor in an electronic product.

On this basis, the inductor may be integrated into a silicon substrate of the integrated circuit, and the inductor is prepared at a position near a ball grid array (BGA) of a power supply in the integrated circuit, to form an integrated voltage regulator (IVR) circuit. In this way, a power supply path of the power supply can be shortened, and an impedance of a power delivery network (power delivery network, PDN) of the power supply in a circuit with a high-frequency switch can be reduced.

On this basis, to integrate an inductor with an inductance of <NUM> nH to <NUM> nH into the integrated circuit, the integrated circuit provided in this embodiment of this application includes a thin film inductor.

As shown in <FIG>, the thin film inductor <NUM> includes at least one magnetic core <NUM> and a conductor <NUM> located in each magnetic core <NUM>.

Each magnetic core <NUM> includes a first magnetic film <NUM> and a second magnetic film <NUM> that are disposed opposite to each other.

The second magnetic film <NUM> and the first magnetic film <NUM> are made of a magnetic material. To increase an inductance per unit area of the thin film inductor, a magnetic material with a relatively high magnetic permeability and a relatively good saturation characteristic may be used, for example, a magnetic alloy material such as FeNi, CoZrTa, CoZrTaB, CZTB, FeCoB, FeHfO, or CoFeHfO alloy.

In addition, an accommodation cavity <NUM> exists between the first magnetic film <NUM> and the second magnetic film <NUM>. The conductor <NUM> is located in the accommodation cavity <NUM>.

In some embodiments of this application, as shown in <FIG> or <FIG>, the conductor <NUM> may be at least one metal conducting wire.

In this case, to reduce loss of an eddy current of the thin film inductor <NUM> in a length direction (Z direction) of the metal conducting wire, the thin film inductor <NUM> may include at least two magnetic cores, for example, a first magnetic core 10_a and a second magnetic core 10_b. In addition, the two adjacent magnetic cores, that is, the first magnetic core 10_a and the second magnetic core 10_b are spaced and insulated in the length direction (Z direction) of the metal conducting wire.

In this case, the first magnetic film <NUM> and the second magnetic film <NUM> may be anisotropic. In this case, the length direction (Z direction) of the metal conducting wire is an easy axis (easy axis) of a magnetic field of the first magnetic film <NUM> and the second magnetic film <NUM>.

In addition, when a switch frequency in a circuit in which the thin film inductor <NUM> is located is greater than <NUM>, a width direction (X direction) of the metal conducting wire is a hard axis (hard axis) of the magnetic field of the first magnetic film <NUM> and the second magnetic film <NUM>.

It should be noted that two metal conducting wires are disposed in the same magnetic core <NUM> in <FIG>. A magnetic flux generated by one metal conducting wire is coupled to a magnetic flux generated by the other metal conducting wire. In this case, the thin film inductor <NUM> may be a coupling inductor. To implement that the thin film inductor <NUM> including the two metal conducting wires is the foregoing coupling inductor, the two metal conducting wires need to be separately driven by using two independent circuits.

Alternatively, in other embodiments of this application, as shown in <FIG>, the conductor <NUM> is a coil. In addition, the thin film inductor includes a first magnetic core 10_a and a second magnetic core 10_b.

The coil includes a plurality of first line segments <NUM> and a plurality of line segments <NUM>. The first line segments <NUM> are disposed opposite to the second line segments <NUM>. As shown in <FIG>, the plurality of first line segments <NUM> are an upper part of the coil, and the plurality of second line segments <NUM> are a lower part of the coil.

In this case, the plurality of first line segments <NUM> are located in the first magnetic core 10_a, and the plurality of second line segments <NUM> are located in the second magnetic core 10_b.

It should be noted that this application does not limit a quantity of turns of the coil obtained through winding the conducting wire <NUM>. For the thin film inductor <NUM> shown in <FIG>, the quantity of turns of the coil obtained through winding the conducting wire <NUM> may be designed based on an inductance required by the thin film inductor <NUM>.

A larger quantity of turns of the coil indicates a larger inductance of the thin film inductor <NUM>, and a smaller quantity of turns of the coil indicates a smaller inductance of the thin film inductor <NUM>.

In addition, the thin film inductor <NUM> is applied to a power delivery circuit of a power supply. When the power delivery circuit of the power supply supplies a small current, an inductance of the thin film inductor <NUM> needs to be set relatively large. When the power delivery circuit of the power supply supplies a large current, an inductance of the thin film inductor <NUM> needs to be set relatively small. On this basis, as shown in <FIG>, the film inductor <NUM> further includes an insulating isolation film <NUM>. The insulating isolation film <NUM> is disposed on two sides of the conductor <NUM>, and is located in a gap (gap) between the first magnetic film <NUM> and the second magnetic film <NUM>. A lower surface and an upper surface of the insulating isolation film <NUM> are respectively in contact with the first magnetic film <NUM> and the second magnetic film <NUM>.

It should be noted that the two sides of the conductor <NUM> indicate two sides of the conductor <NUM> in a signal transmission direction (for example, the Z direction in <FIG>).

The insulating isolation film <NUM> separates the first magnetic film <NUM> from the second magnetic film <NUM>, to prevent the first magnetic film <NUM> from being electrically connected to the second magnetic film <NUM>. In addition, a thickness of the insulating isolation film <NUM> is thin. For example, the thickness may be about <NUM>. Therefore, a magnetic line in the first magnetic film <NUM> can enter the second magnetic film <NUM> through the insulating isolation film <NUM>, or a magnetic line in the second magnetic film <NUM> can enter the first magnetic film <NUM> through the insulating isolation film <NUM>.

It may be learned from the foregoing that, to increase the inductance per unit area of the thin film inductor <NUM>, a magnetic material with a relatively high magnetic permeability and a relatively good saturation characteristic may be used to form the first magnetic film <NUM> and the second magnetic film <NUM>. However, in this case, a resistivity of the thin film inductor <NUM> is relatively small. When a switch frequency of a switch transistor in a voltage conversion circuit is relatively high, relatively large loss may occur to an eddy current generated in the thin film inductor <NUM>. In this way, the inductance of the thin film inductor <NUM> is reduced. In addition, the relatively large loss of the eddy current causes heat emitting of the thin film inductor <NUM>, thereby reducing an inductance value Q and reducing conversion efficiency of the voltage conversion circuit.

To resolve the foregoing problem, as shown in <FIG>, the first magnetic film <NUM> and the second magnetic film <NUM> each include magnetic sub-films <NUM> and insulating sub-films <NUM>.

In the first magnetic film <NUM>, the magnetic sub-films <NUM> and the insulating sub-films <NUM> are alternately disposed. In the second magnetic film <NUM>, the magnetic sub-films <NUM> and the insulating sub-films <NUM> are alternately disposed.

In this case, the first magnetic film <NUM> and the second magnetic film <NUM> are in a structure of a plurality of laminated (laminated) layers of thin films.

In this case, after the conductor <NUM> in the thin film inductor <NUM> is powered on, as shown in <FIG>, a direction of magnetic lines (indicated by using black arrows in the figure) of an alternating magnetic field generated by the thin film inductor <NUM> may be clockwise.

Alternatively, after a direction of a current flowing into the conductor <NUM> is changed, as shown in <FIG>, a direction of magnetic lines of an alternating magnetic field generated by the thin film inductor <NUM> is counterclockwise.

In the first magnetic film <NUM> and the second magnetic film <NUM>, a closed loop current, that is, the eddy current is induced in the alternating magnetic field at a section perpendicular to the direction of the magnetic lines. Generation of the eddy current causes additional loss, thereby weakening the magnetic field.

On this basis, in <FIG> and <FIG>, in the first magnetic film <NUM> and the second magnetic film <NUM>, a loop current is induced in the alternating magnetic field at a section perpendicular to horizontal (X direction) magnetic lines. The loop current is a longitudinal eddy current.

It may be learned from the foregoing that because the first magnetic film <NUM> and the second magnetic film <NUM> include the insulating magnetic sub-films <NUM>. Therefore, as shown in <FIG>, the longitudinal eddy current formed at the section perpendicular to the X direction is separated into a plurality of sub-eddies M1 by the layers of magnetic sub-films <NUM> in the first magnetic film <NUM> and the second magnetic film <NUM>. Each sub-eddy current M1 is limited to a long and narrow loop of each magnetic sub-film <NUM>. In this way, a resistance on a path of the eddy current is increased, to reduce loss of the eddy current.

It should be noted that a magnetic field generated by the eddy current is a change to an original magnetic field generated when the first magnetic film <NUM> and the second magnetic film <NUM> are powered on.

For example, as shown in <FIG>, a direction H of the original magnetic field generated when the first magnetic film <NUM> and the second magnetic film <NUM> are powered on is from inside to outside, and a direction of the eddy current is clockwise during the original magnetic field is being enhanced.

Alternatively, a direction H of the original magnetic field generated when the first magnetic film <NUM> and the second magnetic film <NUM> are powered on is from inside to outside, and a direction of the eddy current is counterclockwise during the magnetic field is being weakened.

In addition, when the switch frequency in the circuit is a low frequency, each sub-eddy current M1 is easily limited to each layer of magnetic sub-film <NUM>. However, when the switch frequency in the circuit is a high frequency, because a capacitance effect exists between the layers of magnetic sub-films <NUM>, that is, a higher frequency indicates a smaller impedance of a capacitor, the sub-eddy currents M1 in the magnetic sub-films <NUM> more easily pass through the insulating sub-films <NUM> and converge, to form a large eddy current path. In this way, an effect of the loss of the eddy current is reduced.

In this case, when the switch frequency in the circuit is a high frequency, to increase the impedance of the capacitor, a thickness of the insulating sub-film <NUM> may be appropriately increased.

For example, a thickness d of each layer of insulating sub-film <NUM> may be from <NUM> to <NUM>. When the thickness d of the insulating sub-film <NUM> is less than <NUM>, and the switch frequency in the circuit is a high frequency, the impedance of the capacitor formed between the layers of magnetic sub-films <NUM> is relatively small, so that sub-eddy currents M1 in the magnetic sub-films <NUM> easily pass through the insulating sub-films <NUM> and converge, to reduce the effect of the loss of the eddy current.

In addition, when the thickness d of the insulating sub-film <NUM> is greater than <NUM>, if the first magnetic film <NUM> or the second magnetic film <NUM> is fixed, a proportion of a thickness of the magnetic sub-films <NUM> in a thickness of the first magnetic film <NUM> or the second magnetic film <NUM> decreases, thereby reducing an effective magnetic permeability of the thin film inductor <NUM>.

In some embodiments of this application, the thickness d of the insulating sub-film <NUM> may be <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>.

The insulating sub-film <NUM> is made of an insulating inorganic or organic material.

In addition, a thickness t of each layer of magnetic sub-film <NUM> may be from <NUM> to <NUM>. When the thickness t of the magnetic sub-film <NUM> is less than <NUM>, the thickness t of the magnetic sub-film <NUM> is quite small. This does not facilitate improving the effective magnetic permeability of the thin film inductor <NUM>.

When the thickness t of the magnetic sub-film <NUM> is greater than <NUM>, if the first magnetic film <NUM> or the second magnetic film <NUM> is fixed, a proportion of the thickness of the insulating sub-films <NUM> in the thickness of the first magnetic film <NUM> or the second magnetic film <NUM> decreases, so that the sub-eddy currents M1 in the magnetic sub-films <NUM> easily pass through the insulating sub-films <NUM> and converge, thereby reducing the effect of the loss of the eddy current. In addition, when the thickness t of the magnetic sub-film <NUM> is greater than <NUM>, and the switch frequency in the circuit is a high frequency, an impedance of an eddy current path of the thin film inductor <NUM> decreases. This does not facilitate limiting each sub-eddy current M1 to a long and narrow loop of the magnetic sub-film <NUM>.

In some embodiments of this application, the thickness t of the magnetic sub-film <NUM> may be <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>.

The magnetic sub-film <NUM> is made of the foregoing magnetic material.

In addition, as shown in <FIG> or <FIG>, at the insulating isolation film <NUM> of the thin film inductor <NUM>, the magnetic lines are perpendicular to a magnetic film surface of the first magnetic film <NUM>. In this case, in the first magnetic film <NUM> or the second magnetic film <NUM>, a closed loop current is induced in the alternating magnetic field at a section perpendicular to a direction (Y direction) of a vertical magnetic line. The loop current is a lateral eddy current M2 that is shown in <FIG> and that is parallel to a film surface B of the first magnetic film <NUM>.

As described above, a direction of the eddy current in <FIG> is related to the original magnetic field generated when the first magnetic film <NUM> and the second magnetic film <NUM> are powered on.

A plane in which the lateral eddy current M2 is located is parallel to the magnetic sub-films <NUM> in the first magnetic film <NUM> or the second magnetic film <NUM>. Therefore, the lateral eddy current M2 cannot be separated by the plurality of layers magnetic sub-films <NUM>. In this case, loss of the eddy current at a position of the insulating isolation film <NUM> cannot be effectively reduced.

To resolve the foregoing problem, in the thin film inductor <NUM> provided in this embodiment of this application, as shown in <FIG>, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> are exposed from a surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>, and/or, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the second magnetic film <NUM> are exposed from a surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>.

In this case, the magnetic sub-films <NUM> and the insulating sub-films <NUM> that are exposed from the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> and/or the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> intersect a plane in which an eddy current generated from magnetic lines passing through the insulating isolation film <NUM>.

In this way, the magnetic lines passing through the insulating isolation film <NUM> can enter the first magnetic film <NUM> and/or the magnetic sub-films <NUM> exposed from the surface in contact with the insulating isolation film <NUM>. In this case, the eddy current generated in the plane perpendicular to the magnetic lines is separated into the plurality of sub-eddy currents by the layers of magnetic sub-films <NUM>. As shown in <FIG>, each sub-eddy current enters one layer of magnetic sub-film <NUM>. In this case, each sub-eddy current can be limited to one layer of magnetic sub-film <NUM>, to reduce loss of the eddy current.

In the following, a structure of the magnetic core <NUM> can be described by using an example. In the structure of the magnetic core <NUM>, the magnetic sub-films <NUM> intersect the plane in which the eddy current generated from the magnetic lines passing through the insulating isolation film <NUM> is located.

In this example, as shown in <FIG>, the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> and the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> are inclined surfaces C with a same slope. In this case, a thickness of the insulating isolation film <NUM> is the same at all positions.

There is an included angle α between the inclined surface C and a lower surface D of the first magnetic film <NUM>. The included angle α may be an acute angle shown in <FIG>. Alternatively, as shown in <FIG>, the included angle α is an obtuse angle. This is not limited in this application.

It should be noted that the lower surface D of the first magnetic film <NUM> is a surface that is of the first magnetic film <NUM> and that is away from the second magnetic film <NUM>.

It may be learned from <FIG> and <FIG> that when the included angle α is an acute angle, an average thickness of the first magnetic film <NUM> is thinner, to facilitate implementing an ultra-thin design requirement of an electronic element. For ease of description, the following is described by using an example in which the included angle α is an acute angle.

In addition, as shown in <FIG>, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> are parallel to the lower surface D of the first magnetic film <NUM>.

In this case, in a process of preparing the first magnetic film <NUM>, first, a physical vapor deposition (Physical Vapor Deposition, PVD) process is applied on a bearing surface of a substrate for a plurality of times to implement alternately sputtering, to form the magnetic sub-films <NUM> and insulating sub-films <NUM> that are alternately disposed, thereby finally forming the first magnetic film <NUM>.

The magnetic sub-films <NUM> and the insulating sub-films <NUM> formed in the foregoing steps are parallel to the bearing surface of the substrate, so that the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> can be parallel to the lower surface D of the first magnetic film <NUM> (that is, the surface that is of the first magnetic film <NUM> and that is in contact with the bearing surface of the substrate).

In this way, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> intersect the inclined surface C, so that the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> can be exposed from the inclined surface C.

In some embodiments of this application, the inclined surface C may be prepared by using a lift-off (lift-off) process. The lift-off process is described in detail in the following description.

Next, the insulating isolation film <NUM> and the conductor <NUM> are prepared. The magnetic sub-films <NUM> and the insulating sub-films <NUM> in the second magnetic film <NUM> are parallel to the lower surface D of the first magnetic film <NUM>.

In addition, as shown in <FIG>, the inclined surface C may also be formed at the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>. In this way, the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> and the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> are the inclined surfaces C.

In the following, a specific structure of the thin film inductor <NUM> is described by using an example when the included angle α between the lower surface D of the first magnetic film <NUM> and each of the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> and the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> is an acute angle.

For example, the first magnetic film <NUM> shown in <FIG> may be a trapezoidal frustum shown in <FIG>.

An upper base E1 of the trapezoidal frustum is close to the second magnetic film <NUM>, and a lower base E2 is away from the second magnetic film <NUM>.

In addition, as shown in <FIG>, the thin film inductor <NUM> further includes a flattened dielectric layer <NUM>, a magnetic flux hole <NUM>, and an interlayer dielectric layer <NUM>.

The flattened dielectric layer <NUM> covers the upper base of the trapezoidal frustum, that is, the first magnetic film <NUM>, and a part of side surfaces F of the trapezoidal frustum.

In some embodiments of this application, when the flattened dielectric layer <NUM> is prepared, a dielectric layer may be first deposited on the substrate on which the first magnetic film <NUM> is prepared. A material of the dielectric layer may include at least one of Si<NUM>N<NUM> or SiO<NUM>. Then, a chemical mechanical planarization (Chemical Mechanical Planarization, CPM) process is used to grind an upper surface of the dielectric layer (a surface away from the first magnetic film <NUM>), so that the surface of the dielectric layer is flat, to achieve a flattening purpose.

A part of the material of the flattened dielectric layer <NUM> is etched, to form the magnetic flux hole <NUM>. The insulating isolation film <NUM> is located in the magnetic flux hole <NUM>, and covers the other part of the side surfaces F of the trapezoidal frustum.

It may be learned from <FIG> that the part of the side surfaces F of the trapezoidal frustum, that is, the first magnetic film <NUM> is covered by the insulating isolation film <NUM>, and the other part is covered by the flattened dielectric layer <NUM>.

The interlayer dielectric layer <NUM> covers an upper surface of the flattened dielectric layer <NUM> and a sidewall of the magnetic flux hole <NUM>.

The interlayer dielectric layer <NUM> and the insulating isolation film <NUM> are made of the same material. For example, the material may be at least one of Si<NUM>N<NUM> or SiO<NUM>. In addition, the interlayer dielectric layer <NUM> and the insulating isolation film <NUM> may be an integrated structure.

In this case, a dielectric layer may be deposited by using the same deposition process on the substrate on which the flattened dielectric layer <NUM> and the magnetic flux hole <NUM> are prepared. In this case, a part that is of the dielectric layer, that is located in the magnetic flux hole <NUM>, and that is in contact with the side surfaces of the trapezoidal frustum, that is, the first magnetic film <NUM> is the insulating isolation film <NUM>. Apart that is of the dielectric layer and that covers the upper surface of the flattened dielectric layer <NUM> and the sidewall of the magnetic flux hole <NUM> is the interlayer dielectric layer <NUM>.

On this basis, as shown in <FIG>, the flattened dielectric layer <NUM> and a part that is of the interlayer dielectric layer <NUM> and that covers the upper base E1 of the trapezoidal frustum, that is, the first magnetic film <NUM> serve as a lower support layer <NUM> for bearing the conductor <NUM>. It may be learned from the foregoing that the lower support layer <NUM> is made of an inorganic material, for example, mainly Si<NUM>N<NUM> and/or SiO<NUM>.

In addition, as shown in <FIG>, a tail <NUM> of the second magnetic film <NUM> covers the sidewall on a side that is of the magnetic flux hole <NUM> and that is away from the accommodation cavity <NUM>, and covers, after a turning, the upper surface of the interlayer dielectric layer <NUM> connected to the sidewall.

An end that is of the tail <NUM> of the second magnetic film <NUM> and that is away from the accommodation cavity <NUM> has a taper angle β.

The taper angle β is from <NUM>° to <NUM>°.

For example, in some embodiments of this disclosure, the taper angle β may be <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, or <NUM>°.

In addition, as shown in <FIG>, the thin film inductor <NUM> further includes a seed layer (Seed layer) <NUM>, an upper support layer <NUM>, and an adhesion layer (Adhesion layer) <NUM>.

The seed layer <NUM> is located in the accommodation cavity <NUM>. The seed layer <NUM> is in contact with a surface that is of the conductor <NUM> and that is close to the first magnetic film <NUM>.

A material forming the seed layer <NUM> includes at least one of titanium (Ti) or copper (Cu). When the conductor <NUM> is prepared by using an electroplating process, the conductor <NUM> may be disposed on an upper surface of the lower support layer <NUM> by using the seed layer <NUM>.

The upper support layer <NUM> is located in the accommodation cavity <NUM>. The upper support layer <NUM> covers surfaces of the conductor <NUM> except the surface in contact with the seed layer <NUM>.

A material forming the upper support layer <NUM> may be an organic macromolecular polymer (Polymer). In this way, the upper support layer <NUM> has a relatively large thickness relative to the lower support layer <NUM> (as shown in <FIG>), to support the second magnetic film <NUM>. In addition, the thickness of the upper support layer <NUM> is adjusted to adjust a height of the entire thin film inductor <NUM>.

On this basis, because of the relatively large thickness of the upper support layer <NUM>, when the first magnetic film <NUM> and the second magnetic film <NUM> are anisotropic, a film length of the second magnetic film <NUM> covering the upper support layer <NUM> is greater than a film length of the first magnetic film <NUM> covering the substrate in the X direction (in <FIG>, the hard axis of the film inductor <NUM>).

In addition, in this application, a film length of the second magnetic film <NUM> and a film length of the first magnetic film <NUM> are not limited in the Z direction (in <FIG>, the easy axis of the film inductor <NUM>). For example, the film length of the second magnetic film <NUM> may be greater than the film length of the first magnetic film <NUM>. Alternatively, the film length of the second magnetic film <NUM> may be less than the film length of the first magnetic film <NUM>.

In addition, the adhesion layer <NUM> is disposed on a surface that is of the second magnetic film <NUM> and that is close to the first magnetic film <NUM>.

A material forming the adhesion layer <NUM> includes at least one of tantalum (Ta), titanium (Ti), titanium nitride (TiN), or tantalum nitride (TaN). The adhesion layer <NUM> is configured to bond the second magnetic film <NUM> to the upper support layer <NUM>, a magnetic film air gap film layer <NUM>, and the interlayer dielectric layer <NUM>.

Alternatively, a specific structure of the thin film inductor <NUM> is shown in <FIG> when the included angle α between the lower surface D of the first magnetic film <NUM> and each of the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> and the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> is an acute angle. The first magnetic film <NUM> is the trapezoidal frustum shown in <FIG>. The upper base E1 of the trapezoidal frustum is close to the second magnetic film <NUM>, and the lower base E2 is away from the second magnetic film <NUM>.

A difference between the structure shown in <FIG> and that shown in <FIG> is that the side surfaces F of the trapezoidal frustum are fully covered by the insulating isolation film <NUM>.

In this case, the thin film inductor <NUM> shown in <FIG> further includes the flattened dielectric layer <NUM> and the interlayer dielectric layer <NUM>.

The flattened dielectric layer <NUM> covers the upper base E1 of the trapezoidal frustum. A material of the flattened dielectric layer <NUM> is the same as that described above.

In some embodiments of this application, when the flattened dielectric layer <NUM> shown in <FIG> is prepared, a dielectric layer may be first deposited on the substrate on which the first magnetic film <NUM> is prepared. A material of the dielectric layer may include Si<NUM>N<NUM> and/or SiO<NUM>.

Then, a chemical mechanical planarization (Chemical Mechanical Planarization, CPM) process is used to grind an upper surface of the dielectric layer (a surface away from the first magnetic film <NUM>), so that the surface of the dielectric layer is flat, to achieve a flattening purpose.

Next, an etching process is used to remove a part of the dielectric layer except the part covering the upper base E1 of the trapezoid frustum, to obtain the flattened dielectric layer <NUM> shown in <FIG>.

In addition, the interlayer dielectric layer <NUM> covers the flattened dielectric layer <NUM>. The interlayer dielectric layer <NUM> and the insulating isolation film <NUM> are made of the same material and are an integrated structure.

In this case, a dielectric layer may be deposited by using the same deposition process on the substrate on which the flattened dielectric layer <NUM> is prepared. In this case, a part that is of the dielectric layer and that covers the side surfaces of the trapezoid frustum, that is, the first magnetic film <NUM> serves as the insulating isolation film <NUM>. The remaining part of the dielectric layer is the interlayer dielectric layer <NUM>.

On this basis, as shown in <FIG>, the flattened dielectric layer <NUM> and the part that is of the interlayer dielectric layer <NUM> and that covers the upper base E1 of the trapezoidal frustum, that is, the first magnetic film <NUM> serve as the lower support layer <NUM> for bearing the conductor <NUM>. It may be learned from the foregoing that the lower support layer <NUM> is made of an inorganic material, for example, mainly Si<NUM>N<NUM> and/or SiO<NUM>.

In addition, an end that is away from the accommodation cavity <NUM> and that is of a part that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> has a taper angle β. The taper angle β is from <NUM>° to <NUM>°. For example, in some embodiments of this disclosure, the taper angle β may be <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, or <NUM>°.

It should be noted that the thin film inductor <NUM> shown in <FIG> also has the seed layer <NUM>, the upper support layer <NUM>, and the adhesion layer <NUM>. A manner of setting these thin film layers is the same as that described above.

The following uses the structure shown in <FIG> as an example to describe a process in which the inclined surfaces C can be used to reduce loss of the eddy current at the insulating isolation film <NUM> in the thin film inductor <NUM> when the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> and the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> are the inclined planes C.

In the following description, after the conductor <NUM> in the thin film inductor <NUM> is powered on, when the direction of the magnetic lines of the alternating magnetic field generated by the thin film inductor <NUM> is counterclockwise shown in <FIG>, the first magnetic film <NUM> in contact with the left-side insulating isolation film <NUM> in <FIG> or <FIG> serves as an example.

In this case, as shown in <FIG>, the magnetic lines passing through the insulating isolation film <NUM> are perpendicular to the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>, that is, the inclined surface C shown in <FIG>. In this case, the eddy current M is induced in the alternating magnetic field at the section perpendicular to the direction of the magnetic lines, that is, the section parallel to the inclined surface C.

In addition, because the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> are parallel to the lower surface D of the first magnetic film <NUM>, as shown in <FIG>, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> can be exposed from the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>, that is, the inclined surface C shown in <FIG>. In this case, the magnetic lines passing through the insulating isolation film <NUM> can enter the magnetic sub-films <NUM> in the first magnetic film <NUM> shown in <FIG>.

In this way, as shown in <FIG>, the eddy current M is separated into the plurality of sub-eddy currents M1 by the layers of magnetic sub-films <NUM>. In addition, each sub-eddy current M1 enters one layer of magnetic sub-film <NUM>. In this case, as shown in <FIG>, each sub-eddy current M1 can be limited to each layer of magnetic sub-film <NUM>, to reduce loss of the eddy current.

In this example, as shown in <FIG>, in the magnetic core <NUM>, only the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> is the inclined surface C.

On this basis, after the conductor <NUM> in the thin film inductor <NUM> is powered on, when the direction of the magnetic lines of the alternating magnetic field generated by the thin film inductor <NUM> is counterclockwise shown in <FIG>, the first magnetic film <NUM> in contact with the left-side insulating isolation film <NUM> in <FIG> is used as an example.

The magnetic lines passing through the insulating isolation film <NUM> are perpendicular to the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>, that is, the inclined surface C shown in <FIG>, so that the magnetic lines can enter the magnetic sub-films <NUM> in the first magnetic film <NUM>. This is the same as Example <NUM>. In this case, the eddy current M is induced in the alternating magnetic field at the section perpendicular to the direction of the magnetic lines, that is, the section parallel to the inclined surface C.

In addition, as shown in <FIG>, the eddy current M is separated into the plurality of sub-eddy currents M1 by the layers of magnetic sub-films <NUM>. In addition, each sub-eddy current M1 enters one layer of magnetic sub-film <NUM>. In this case, as shown in <FIG>, each sub-eddy current M1 can be limited to each layer of magnetic sub-film <NUM>, to reduce loss of the eddy current.

In this example, as shown in <FIG>, in the magnetic core <NUM>, only the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> is the inclined surface C.

In this case, after the conductor <NUM> in the thin film inductor <NUM> is powered on, when the direction of the magnetic lines of the alternating magnetic field generated by the thin film inductor <NUM> is clockwise shown in <FIG>, the second magnetic film <NUM> in contact with the left-side insulating isolation film <NUM> in <FIG> is used as an example.

The magnetic lines passing through the insulating isolation film <NUM> from the first magnetic film <NUM> are perpendicular to the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>, that is, the inclined surface C shown in <FIG>, so that the magnetic lines can enter the magnetic sub-films <NUM> in the second magnetic film <NUM> shown in <FIG>. This is the same as Example <NUM>. In this case, the eddy current M is induced in the alternating magnetic field at the section perpendicular to the direction of the magnetic lines, that is, the section parallel to the inclined surface C.

In this example, as shown in <FIG>, the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> and the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> are curved surfaces S with same curvature. In this case, a thickness of the insulating isolation film <NUM> is the same at all positions.

In addition, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> and the second magnetic film <NUM> are parallel to the lower surface D of the first magnetic film <NUM>.

In this case, as shown in <FIG>, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> are exposed from the curved surface S that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>.

In this case, as shown in <FIG>, the magnetic lines passing through the insulating isolation film <NUM> enter the magnetic sub-films <NUM> in the first magnetic film <NUM>.

In this case, the sub-eddy current M1 is induced in the alternating magnetic field at a section perpendicular to a direction of a magnetic line. In this way, as shown <FIG>, the sub-eddy currents M1 can be respectively limited to the magnetic sub-films <NUM>, to reduce loss of the eddy current.

It should be noted that when the thickness of the insulating isolation film <NUM> does not need to be the same at all positions, in the magnetic core <NUM>, only the surface that is of the second magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> may be set to the curved surface S. Alternatively, the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM> is set to the curved surface S. A process of reducing loss of the eddy current at the position of the insulating isolation film <NUM> by using the surface S may be obtained in the same manner.

It should be noted that the thin film inductor <NUM> shown in <FIG> also has the flattened dielectric layer <NUM>, the interlayer dielectric layer <NUM>, the seed layer <NUM>, the upper support layer <NUM>, and the adhesion layer <NUM>. A manner of setting these thin films is the same as that described above.

In this example, as shown in <FIG>, the thin film inductor <NUM> further includes a support pad <NUM>. The support pad <NUM> is located below the first magnetic film <NUM>, and corresponds to the position of the insulating isolation film <NUM>. A material forming the support pad <NUM> may be a non-magnetic material.

It should be noted that a part below the first magnetic film <NUM> is a side that is of the first magnetic film <NUM> and that is away from the second magnetic film <NUM>.

As shown in <FIG>, an upper surface G of the support pad <NUM> is in contact with the insulating isolation film <NUM>. In addition, the first magnetic film <NUM> covers two sides of the upper surface G of the support pad <NUM>. In the first magnetic film <NUM> covering the support pad <NUM>, the magnetic sub-films <NUM> and the insulating sub-films <NUM> are in contact with the insulating isolation film <NUM>.

In addition, the surface that is of the support pad <NUM> and that is in contact with the first magnetic film <NUM> is a curved surface. In this way, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> alternately cover the curved surface of the support pad <NUM>. In this way, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> are also in a curved state. A curvature of these sub-films is the same as or similar to a curvature of the curved surface of the support pad <NUM> covered by these sub-films.

It may be learned from the foregoing that the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> are in the curved state. Therefore, in the first magnetic film <NUM>, the magnetic sub-films <NUM> and the insulating sub-films <NUM> that cover the support pad <NUM> intersect a plane in which the insulating isolation film <NUM> is located. In this way, the magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> can be exposed from the surface that is of the first magnetic film <NUM> and that is in contact with the insulating isolation film <NUM>.

To simplify a process for preparing the support pad <NUM>, in some embodiments of this application, the surface that is of the support pad <NUM> and that is in contact with the first magnetic film <NUM> is an arc surface. To improve stability of the support pad <NUM> in the thin film inductor <NUM>, a lower surface of the support pad <NUM> is flush with the lower surface of the first magnetic film <NUM>.

On this basis, after the conductor <NUM> in the thin film inductor <NUM> is powered on, when the direction of the magnetic lines of the alternating magnetic field generated by the thin film inductor <NUM> is counterclockwise shown in <FIG>, in <FIG>, a partial structure of the thin film inductor <NUM> at the position of the left-side insulating isolation film <NUM> is used as an example.

In this case, as shown in <FIG>, a plurality of magnetic lines of the alternating magnetic field at the position of the insulating isolation film <NUM> pass through the insulating isolation film <NUM> from the second magnetic film <NUM>, then separately enter the curved magnetic sub-films <NUM> in the first magnetic film <NUM> covering the support pad <NUM>, and then go along a direction of laying the magnetic sub-films <NUM>.

The magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> covering the support pad <NUM> intersect the plane at which the insulating isolation film <NUM> is located. The plurality of magnetic lines passing through the insulating isolation film <NUM> can enter the layers of magnetic sub-films <NUM> in the first magnetic film <NUM>. Therefore, the sub-eddy currents M1 are induced in the alternating magnetic field at sections perpendicular to the magnetic lines. As shown in <FIG>, the sub-eddy current M1 is limited to the layers of magnetic sub-films <NUM>, thereby reducing loss of the eddy current.

An embodiment of this application provides an integrated circuit <NUM>. As shown in <FIG>, the integrated circuit <NUM> includes a silicon substrate <NUM> and any foregoing described thin film inductor <NUM> disposed on the silicon substrate <NUM>. The integrated circuit <NUM> has technical effects the same as the thin film inductor <NUM> provided in the foregoing embodiment.

The material forming the silicon substrate <NUM> includes Si and a polymer (polymer).

It should be noted that the integrated circuit <NUM> may be a System-on-Chip (SoC), a central processing unit (central processing unit, CPU), a graphics processing unit (graphics processing unit, GPU), or a power management integrated circuit (power management integrate circuit, PMIC).

In addition, as shown in <FIG>, the integrated circuit <NUM> further includes a circuit structure <NUM> disposed on the silicon substrate <NUM>, a circuit-inductor interconnection layer <NUM> sequentially covering the circuit structure <NUM>, and a chip encapsulation structure <NUM>.

The circuit structure <NUM> includes a plurality of transistors <NUM>, and a metal interconnection layer <NUM> configured to connect the plurality of transistors <NUM> together to form a circuit.

In this embodiment of this application, a type of the transistor <NUM> is not limited. The transistor <NUM> may be a transistor prepared by using a complementary metal oxide semiconductor (complementary metal oxide semiconductor, CMOS) process, a silicon germanium (SiGe) process, or a gallium nitride (GaN) process.

In addition, the metal interconnection layer <NUM> includes a plurality of dielectric layers or passivation layers (passivation layer), and a metal conducting wire embedded in the dielectric layers or the passivation layers. A material forming the dielectric layer or the passivation layer in the metal interconnection layer <NUM> includes any one of silicon dioxide (SiO<NUM>), silicon nitride (Si<NUM>N<NUM>), and polyimide (polyimide).

On this basis, as shown in <FIG>, the thin film inductor <NUM> is located between the circuit-inductor interconnection layer <NUM> and the chip encapsulation structure <NUM>. The circuit-inductor interconnection layer <NUM> is configured to electrically connect the thin film inductor <NUM> to the circuit structure <NUM> located below the thin film inductor <NUM>.

The manner of setting the thin film inductor <NUM> in the integrated circuit <NUM> may be that the first magnetic film <NUM> is closer to the silicon substrate <NUM> (the left-side thin film inductor <NUM>) than the second magnetic film <NUM>; or
the second magnetic film <NUM> in the thin film inductor <NUM> is closer to the silicon substrate <NUM> (the right-side thin film inductor <NUM>) than the first magnetic film <NUM>.

A package assembly structure configured to implement signal interconnection between a circuit and an inductor, for example, an interconnection path (Via), a solder pillar (solder pillar), a copper pillar (copper pillar), a micro bump (micro bump), or a lead bump (solder bump) is disposed in the circuit-inductor interconnection layer <NUM>.

In addition, the chip encapsulation structure <NUM> may be prepared by using a wafer-level packaging (wafer-level packaging, WLP) process. The chip encapsulation structure includes an encapsulation substrate and encapsulation cabling disposed inside the encapsulation substrate.

On this basis, a chip encapsulation pin <NUM> is disposed above the chip encapsulation structure <NUM>, so that the entire integrated circuit <NUM> can be connected to a printed circuit board (printed circuit board, PCB).

An embodiment of this application provides a terminal device. The terminal device includes at least one integrated circuit <NUM> described above.

On this basis, as shown in <FIG>, the mobile terminal <NUM> further includes a power management chip <NUM> and a power bus or a power delivery network of a power supply that is connected to the power management chip <NUM>.

In this case, the power management chip <NUM> includes the integrated circuit <NUM>, and the thin film inductor <NUM> is integrated into the integrated circuit <NUM>.

In this case, the power management chip <NUM> may provide working voltage to other components of the terminal device <NUM> by using the power bus, for example, a radio frequency transceiver (radio frequency module), a memory, a hard disk, a camera and an image processor (imaging processing module), an input/output (I/O) interface, and a man-machine interaction device.

In addition, in some embodiments of this disclosure, the mobile terminal <NUM> further includes a processor <NUM> and a data bus (Data bus) connected to the processor <NUM>. The processor <NUM> includes the integrated circuit <NUM>. When the integrated circuit <NUM> is an integrated power module, the thin film inductor <NUM> is integrated into the integrated power module.

In this case, the processor <NUM> may provide working voltage to other components of the terminal device <NUM> by using the power bus, for example, the radio frequency transceiver, the memory, the hard disk, the camera and the image processor, the input/output interface, and the man-machine interaction device.

It should be noted that the processor <NUM> may be any one of a SoC, a CPU, and a GPU.

In addition, the terminal device <NUM> has technical effects the same as the integrated circuit <NUM> provided in the foregoing embodiment.

An embodiment of this application provides a method for preparing the thin film inductor <NUM> shown in <FIG>. As shown in <FIG>, the method includes steps S101 to S105.

Form a first magnetic film <NUM> on a substrate by using a composition process.

The first magnetic film <NUM> is a trapezoid frustum. An upper base E1 of the trapezoidal frustum is away from the substrate, and a lower base E2 is close to the substrate. magnetic sub-films <NUM> and insulating sub-films <NUM> in the first magnetic film <NUM> are exposed from side surfaces F of the trapezoid frustum.

It should be noted that the composition process in this embodiment of this application includes a photolithography process, or includes a photolithography process and an etching step, or includes printing, ink jetting, another process for forming a predetermined pattern, or the like.

The photolithography process indicates a process that includes processes of film forming, exposing, developing, and the like and in which a photoresist, a mask reticle, an exposure machine, and the like are used to form a pattern.

On this basis, in some embodiments of this application, a preparing process of preparing the first magnetic film <NUM> by using the lift-off process is as follows:.

First, as shown in <FIG>, a photoresist <NUM> coats the substrate.

It should be noted that the photoresist <NUM> in this embodiment of this application may be a positive photoresist, or may be a negative photoresist. This is not limited in the present invention.

Next, as shown in <FIG>, a mask reticle <NUM> is configured to implement mask exposure on the photoresist <NUM>.

Then, as shown in <FIG>, a developing process is performed on the photoresist after the exposure performed by using the mask reticle. The photoresist shielded by the mask reticle <NUM> is not irradiated by light, and therefore is dissolved in a developing solution.

Afterwards, an adhesion layer (a black film layer in <FIG>) is deposited on the substrate on which the foregoing structures are formed. A physical vapor deposition process is used for a plurality of times to implement alternately sputtering, to form magnetic sub-films <NUM> and insulating sub-films <NUM> that are alternately disposed.

Finally, as shown in <FIG>, the photoresist <NUM> is lifted off, thereby forming the first magnetic film <NUM> in a trapezoidal frustum shape on the substrate.

Prepare a flattened dielectric layer <NUM> on the substrate on which the first magnetic film <NUM> is formed.

First, as shown in <FIG>, a first dielectric layer <NUM> is deposited. A CPM process is performed on the first dielectric layer <NUM>, so that an upper surface of the first dielectric layer <NUM> is flat to some extent as shown in <FIG>.

Next, as shown in <FIG>, the first dielectric layer <NUM> is exposed by using the mask reticle <NUM> and the photoresist <NUM>.

Then, the developing process is performed on the photoresist <NUM>. As shown in <FIG>, a part that is of the photoresist <NUM> and that is irradiated by light is dissolved in the developing solution.

Afterwards, a dry etching process is used to etch a part that is the first dielectric layer <NUM> and that is not covered by the photoresist <NUM>, to form a magnetic flux hole <NUM> shown in <FIG>. A part of a side surface F of the first magnetic film <NUM> in the trapezoidal frustum shape is exposed at a bottom of the magnetic flux hole <NUM>.

A size of an opening of the magnetic flux hole <NUM> is controlled, so that the first dielectric layer <NUM> can cover a part of the side surface of the trapezoid frustum. In this way, the part of the side surface F of the first magnetic film <NUM> in the trapezoidal frustum shape is exposed in the magnetic flux hole <NUM>, and the other part is covered by the first dielectric layer <NUM>.

In addition, as shown in <FIG>, the first dielectric layer <NUM> further covers the upper base of the trapezoidal frustum.

As shown in <FIG>, after the photoresist <NUM> on the first dielectric layer <NUM> is lifted off, the first dielectric layer <NUM> formed by using the composition process may serve as the flattened dielectric layer <NUM>.

Form an insulating isolation film <NUM> on the substrate on which the foregoing structures are formed.

As shown in <FIG>, a second dielectric layer <NUM> is deposited. The second dielectric layer <NUM> covers an upper surface of the first dielectric layer <NUM> and a side wall of the magnetic flux hole <NUM>, and is in contact with the other part of the side surface of the trapezoidal frustum by using the magnetic flux hole <NUM>.

A part that is of the second dielectric layer <NUM> and that is in contact with the side surface of the trapezoidal frustum serves as the insulating isolation film <NUM>.

Form a conductor <NUM> on the substrate on which the foregoing structures are formed.

First, as shown in <FIG>, the photoresist <NUM> above the upper base E1 of the trapezoidal frustum, that is, the first magnetic film <NUM> is formed by using the composition process, and the photoresist is exposed by using the mask reticle <NUM>.

Next, as shown in <FIG>, the developing process is used and performed on the photoresist <NUM> after the exposure, so that the photoresist <NUM> irradiated by light is removed through the developing process.

Afterwards, as shown in <FIG>, the conductor <NUM> is formed on the substrate on which the foregoing structures are formed. As shown in <FIG>, the photoresist <NUM> around the conductor <NUM> is lifted off. A material forming the conductor <NUM> may be at least one of copper (Cu), titanium (Ti), nickel (Ni), or gold (Au).

Form a second magnetic film <NUM> on the substrate on which the foregoing structures are formed.

An accommodation cavity <NUM> for accommodating the conductor <NUM> is formed between the first magnetic film <NUM> and the second magnetic film <NUM>.

For example, as shown in <FIG>, first, the photoresist <NUM> coats the structure of <FIG>. Because the photoresist <NUM> is used to form an upper support layer <NUM>, the photoresist <NUM> has a relatively large thickness. Then, the photoresist <NUM> is exposed by using the mask reticle <NUM>.

Next, as shown in <FIG>, the developing process is performed on the photoresist <NUM> after the exposure, and a thermal reflow (thermal reflow) process is performed on the photoresist <NUM> after the developing process, to form the upper support layer <NUM> shown in <FIG>.

Afterwards, as shown in <FIG>, the photoresist <NUM> coats the structure shown in <FIG>, and the photoresist <NUM> is exposed by using the mask reticle <NUM>.

As shown in <FIG>, the developing process is performed on the photoresist <NUM> after the exposure.

As shown in <FIG>, the physical vapor deposition process is used for a plurality of times to implement alternately sputtering, to form magnetic sub-films <NUM> and insulating sub-films <NUM> that are alternately disposed.

Finally, the remaining photoresist <NUM> is lifted off, to form the second magnetic film <NUM> shown in <FIG>.

It should be noted that, in the foregoing preparation method, because of a relatively small size of the opening of the magnetic flux hole <NUM>, as shown in <FIG>, a tail of the prepared second magnetic film <NUM> covers a sidewall on a side that is of the magnetic flux hole <NUM> and that is away from the accommodation cavity <NUM>, and covers, after a turning, an upper surface of the interlayer dielectric layer <NUM> connected to the sidewall.

In addition, an end that is of the tail <NUM> of the second magnetic film <NUM> and that is away from the accommodation cavity <NUM> has a taper angle β. The taper angle β is less than <NUM>°.

The method for preparing the thin film inductor <NUM> has technical effects the same as the magnetic film inductor <NUM> provided in the foregoing embodiment.

An embodiment of this application provides a method for preparing the thin film inductor <NUM> shown in <FIG>. The method still includes the foregoing steps S101 to S105. A structure of the thin film inductor <NUM> is different from the structure shown in <FIG>. Therefore, specific processes of some steps in the foregoing steps S101 to S105 are also different. The following describes in detail the specific processes of these steps.

First, step S101 is performed. A process of preparing the first magnetic film <NUM> is the same as the foregoing description.

In a process of performing step S102, first, steps in <FIG> and <FIG> are performed. The first dielectric layer <NUM> is deposited on the substrate on which the first magnetic film <NUM> is formed. A flattening process is performed on the first dielectric layer <NUM>.

Next, as shown in <FIG>, the photoresist <NUM> coats the substrate on which the foregoing structures are formed, and the photoresist <NUM> is exposed by using the mask reticle <NUM>. Then, as shown in <FIG>, the developing process is performed on the photoresist <NUM> after the exposure.

Afterwards, as shown in <FIG>, the first dielectric layer <NUM> that is not covered by the photoresist <NUM> is etched to form the flattened dielectric layer <NUM>. The first dielectric layer <NUM> formed by using the composition process, that is, the flattened dielectric layer <NUM> covers the upper base E1 of the trapezoid frustum. As shown in <FIG>, the photoresist on a surface of the flattened dielectric layer <NUM> is removed.

In a process of performing step S103, as shown in <FIG>, the second dielectric layer <NUM> is deposited on the substrate on which the foregoing structures are formed.

The second dielectric layer <NUM> covers the flattened dielectric layer <NUM>. In addition, a part that is of the second dielectric layer <NUM> and that fully covers the side surfaces of the trapezoid frustum, that is, the first magnetic film <NUM> serves as the insulating isolation film <NUM>.

In a process of performing step S104, as shown in <FIG>, the photoresist <NUM> coats the substrate on which the insulating isolation film <NUM> is formed, and the photoresist <NUM> is exposed by using the mask reticle <NUM>. As shown in <FIG>, the developing process is performed on the photoresist <NUM> after the exposure, to remove a part of the photoresist <NUM>. As shown in <FIG>, the conductor <NUM> located above the upper base E1 of the trapezoidal frustum is formed by using the composition process. Finally, as shown in <FIG>, the photoresist <NUM> on a surface of the conductor <NUM> is lifted off.

In a process of performing step S105, as described above, as shown in <FIG>, first, the photoresist <NUM> coats the structure of <FIG>. Because the photoresist <NUM> is used to form the upper support layer <NUM>, the photoresist <NUM> has a relatively large thickness. Next, the photoresist <NUM> is exposed by using the mask reticle <NUM>.

Then, as shown in <FIG>, the developing process is performed on the photoresist <NUM> after the exposure, and a thermal reflow process is performed on the photoresist <NUM> after the developing process, to form the upper support layer <NUM> shown in <FIG>.

As shown in <FIG>, the physical vapor deposition process is used for a plurality of times to implement alternately sputtering, to form the magnetic sub-films <NUM> and the insulating sub-films <NUM> that are laminated and alternately disposed.

It should be noted that in the foregoing preparation method, because the magnetic flux hole <NUM> does not need to be prepared at the first dielectric layer <NUM>, as shown in <FIG>, the tail of the prepared second magnetic film <NUM> flatly covers the upper surface of the insulating isolation film <NUM>. In addition, an end that is of the tail <NUM> of the second magnetic film <NUM> and that is away from the accommodation cavity <NUM> has a taper angle β. The taper angle β is less than <NUM>°.

This application provides a method for preparing a thin film inductor <NUM>. As shown in <FIG>, the method includes steps S201 to S207.

As shown in <FIG>, two spaced support pads <NUM> are disposed on a substrate <NUM>. A surface that is of the support pad <NUM> and that is away from the substrate <NUM> is a curved surface.

A material forming the support pad <NUM> may be a non-magnetic material.

It should be noted that when the thin film inductor <NUM> is integrated into an integrated circuit, the substrate <NUM> may be a silicon substrate.

In addition, to simplify a process of preparing the support pad <NUM>, in step S101, a surface that is of the support pad <NUM> and that is away from the substrate <NUM> is an arc surface.

As shown <FIG>, a first magnetic film <NUM> is formed by using a composition process on the substrate <NUM> on which the support pads <NUM> are formed.

The first magnetic film <NUM> includes magnetic sub-films <NUM> and insulating sub-films <NUM> that are alternately disposed. A method for preparing the first magnetic film <NUM> is the same as the method described above.

As shown in <FIG>, at positions of the support pads <NUM>, a part of a material in the first magnetic film <NUM> is removed, to expose upper surfaces G of the support pads <NUM>.

On the substrate <NUM> on which the foregoing structures are formed, as shown in <FIG>, a composition process is performed on a dielectric layer at the positions of the support pads <NUM>, for example, a dielectric layer with the same material as the second dielectric layer <NUM>, to form an insulating isolation film <NUM>.

As shown in <FIG>, the formed insulating isolation film <NUM> covers the upper surfaces of the support pads <NUM>, and sides of magnetic sub-films <NUM> and the insulating sub-films <NUM> in the first magnetic film <NUM> on two sides of the upper surfaces of the support pads <NUM>.

It should be noted that a part of the second dielectric layer <NUM> except the insulating isolation film <NUM> may be used as a lower support layer <NUM>.

As shown in <FIG>, a conductor <NUM> on the lower support layer <NUM> is formed on the substrate <NUM> on which the foregoing structures are formed. A process for preparing the conductor <NUM> is the same as the process described above.

As shown in <FIG>, an upper support layer <NUM> is formed on the substrate <NUM> on which the foregoing structures are formed. A process for preparing the upper support layer <NUM> is the same as the process described above.

As shown in <FIG>, a second magnetic film <NUM> is formed by using a composition process on the substrate <NUM> on which the foregoing structures are formed.

The second magnetic film <NUM> includes magnetic sub-films <NUM> and insulating sub-films <NUM> that are alternately disposed. A method for preparing the second magnetic film <NUM> is the same as the method described above.

The method for preparing the thin film inductor <NUM> has technical effects the same as the thin film inductor <NUM> provided in the foregoing embodiment.

Claim 1:
A thin film inductor, comprising:
a magnetic core (<NUM>), wherein the magnetic core (<NUM>) comprises a first magnetic film (<NUM>) and a second magnetic film (<NUM>), and an accommodation cavity (<NUM>) exists between the first magnetic film (<NUM>) and the second magnetic film (<NUM>);
a conductor (<NUM>), located in the accommodation cavity (<NUM>); and
an insulating isolation film (<NUM>), disposed on two sides of the conductor (<NUM>) and located between the first magnetic film (<NUM>) and the second magnetic film (<NUM>), wherein the insulating isolation film (<NUM>) is in contact with the first magnetic film (<NUM>) and the second magnetic film (<NUM>); wherein
the first magnetic film (<NUM>) and the second magnetic film (<NUM>) each comprise magnetic sub-films (<NUM>) and insulating sub-films (<NUM>);
in the first magnetic film (<NUM>), the magnetic sub-films (<NUM>) and the insulating sub-films (<NUM>) are alternately disposed;
in the second magnetic film (<NUM>), the magnetic sub-films (<NUM>) and the insulating sub-films (<NUM>) are alternately disposed;
characterized in that the magnetic sub-films (<NUM>) and the insulating sub-films (<NUM>) in the first magnetic film (<NUM>) are exposed from a surface that is of the first magnetic film (<NUM>) and that is in contact with the insulating isolation film (<NUM>); and/or, the magnetic sub-films (<NUM>) and the insulating sub-films (<NUM>) in the second magnetic film (<NUM>) are exposed from a surface that is of the second magnetic film (<NUM>) and that is in contact with the insulating isolation film (<NUM>).