Core substrate and interposer

Abstract

A first conductor portion (201) comprises a sintered body and passes through a ceramic substrate (100) in the thickness direction. A first magnetic body portion (301) for increasing the inductance of the first conductor portion (201) is embedded in the ceramic substrate (100) and comprises a ceramic. In at least one cross-sectional view of the first magnetic body portion (301) perpendicular thickness direction, the first conductor portion (201) is offset from the center (CM1) of the first magnetic body portion (301).

Description

Core substrate and interposer

[0001] The present invention relates to a core substrate and an interposer, and more particularly to a core substrate having at least one built-in inductor for constituting an interposer on which a semiconductor element is mounted.

[0002] According to Japanese Patent Laid-Open Publication No. 2019-179792 (Patent Document 1), in a semiconductor device, an interposer is disposed between a semiconductor element and a motherboard. The semiconductor element and the motherboard are each connected to the interposer using solder balls. The interposer is shown to be a multilayer printed wiring board, which includes a core substrate, three conductor circuit layers stacked on the core substrate so as to face the semiconductor element, and three conductor circuit layers stacked on the core substrate so as to face the motherboard. On the semiconductor element mounting side of the interposer, the wiring dimensions are gradually reduced by passing through the three conductor circuit layers.

[0003] Efficient power management is sometimes required for semiconductor devices such as integrated circuits (ICs). Typically, a voltage regulator controls the supply voltage to each of multiple computing cores in a processor chip (semiconductor device) depending on the processor's processing power, etc. A voltage regulator typically requires switches, capacitors, and inductors. Controlling the supply voltage for each computing core requires a separate switch, capacitor, and inductor for each computing core. In particular, inductors are difficult to incorporate into semiconductor devices and are typically prepared separately from the semiconductor device. High-performance processors, particularly those for data servers, have many computing cores to enhance their processing power, and correspondingly, the inductance required per unit area of ​​the processor chip is increasing. The inductance of an inductor can be increased by increasing the magnetic permeability near the inductor's current path. It is widely known to use magnetic materials for this purpose.

[0004] U.S. Patent Application Publication No. 2019 / 0279806 (Patent Document 2) discloses a package substrate (interposer) with an embedded inductor that is disposed between a die (semiconductor element) and a board (motherboard). The specification exemplifies forming a substrate core primarily made of organic material with conductive through-holes (conductor portions) and a magnetic coating (magnetic material portion) containing magnetic particles and disposed around the conductor portions. In this case, the magnetic material portion must be formed at a temperature equal to or lower than the heat resistance temperature of the organic material of the substrate core. A typical method for achieving this is to solidify a resin in which magnetic particles are dispersed. However, when the magnetic material portion is formed from magnetic particles dispersed in a resin, it is difficult to ensure a sufficiently high magnetic permeability due to limitations on the magnetic particle filling rate (the proportion of magnetic particles per volume).

[0005] International Publication No. 2022 / 163588 (Patent Document 3) discloses a core substrate with an inductor built in for forming an interposer on which a semiconductor element is mounted. The core substrate includes a ceramic substrate, a conductor portion, and a magnetic material portion. The ceramic substrate has a first surface and a second surface opposite the first surface in the thickness direction, and a through hole between the first surface and the second surface. The conductor portion passes through the through hole. The conductor portion is made of sintered metal. The magnetic material portion surrounds the conductor portion at the through hole. The magnetic material portion is made of ceramics rather than resin with dispersed magnetic particles. By densely sintering the ceramics, the magnetic permeability of the magnetic material portion can be sufficiently increased. Therefore, the core substrate can incorporate an inductor with a large inductance per unit area.

[0006] JP 2019-179792 A U.S. Patent Application Publication No. 2019 / 0279806 WO 2022 / 163588

[0007] Generally, as the DC bias current applied to an inductor increases from zero, the magnetic material of the magnetic body approaches magnetic saturation, and therefore its permeability decreases. As a result, the inductance of the inductor decreases. This characteristic is called the DC bias characteristic. The smaller the rate of decrease, the better the DC bias characteristic. If a magnetic material with high permeability is used with the intention of increasing the inductance, the DC bias characteristic tends to deteriorate.

[0008] According to the technology disclosed in WO 2022 / 163588, an inductor having a large inductance per unit area can be built into a core substrate. However, the inventors have found that, according to this technology, the DC superposition characteristics of the inductor built into the core substrate tend to be insufficient when a large current flows, such as when power is supplied to a semiconductor element.

[0009] The present invention has been made to solve the above problems, and one object of the present invention is to provide a core substrate in which an inductor built therein has a sufficiently large inductance per unit area while also having sufficiently good DC bias characteristics. Another object of the present invention is to provide an interposer in which a semiconductor element is to be mounted, in which an inductor built in a core substrate of the interposer has a sufficiently large inductance per unit area while also having sufficiently good DC bias characteristics.

[0010] Aspect 1 is a core substrate having at least one built-in inductor for forming an interposer on which a semiconductor element is mounted, comprising: a ceramic substrate having a thickness direction; a first conductor portion made of a sintered body and penetrating the ceramic substrate in the thickness direction; and a first magnetic material portion made of ceramic and embedded in the ceramic substrate for increasing the inductance of the first conductor portion, wherein in at least one cross-sectional view perpendicular to the thickness direction so that the first magnetic material portion appears, the first conductor portion is offset from the center of the first magnetic material portion.

[0011] A second aspect of the present invention is the core substrate according to the first aspect, wherein the first conductor portion is in contact with the first magnetic portion.

[0012] Aspect 3 is the core substrate according to aspect 2, wherein the first conductor portion is in contact with the ceramic substrate.

[0013] Aspect 4 is a core substrate described in aspect 3, wherein in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion protrudes toward the ceramic substrate across a tangent to the boundary between the first magnetic material portion and the ceramic substrate.

[0014] Aspect 5 is a core substrate described in aspect 2, wherein in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion is in contact with the ceramic substrate without crossing the tangent to the boundary between the first magnetic material portion and the ceramic substrate.

[0015] Aspect 6 is the core substrate according to aspect 2, wherein in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion is spaced apart from the ceramic substrate.

[0016] A seventh aspect is the core substrate according to the first aspect, wherein the first conductor portion is spaced from the first magnetic portion and in contact with the ceramic substrate.

[0017] Aspect 8 is a core substrate described in any one of aspects 1 to 7, wherein in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the center of the first conductor portion is away from the center of the first magnetic material portion by more than 10% of the diameter of a circle having the area of ​​the first magnetic material portion.

[0018] Aspect 9 is a core substrate according to any one of aspects 1 to 8, wherein the at least one cross-sectional view includes any cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears.

[0019] A tenth aspect of the present invention is the core substrate according to any one of the first to ninth aspects, wherein the first conductor portion is a solid body.

[0020] Aspect 11 is the core substrate according to any one of aspects 1 to 10, wherein the ceramic substrate is made of low-temperature co-fired ceramics or a composite material of glass and alumina.

[0021] A twelfth aspect of the present invention is the core substrate according to any one of the first to eleventh aspects, wherein a sintered interface is formed between the first conductor portion and a portion of the core substrate other than the first conductor portion.

[0022] Aspect 13 is a core substrate described in any one of aspects 1 to 12, which is made of a sintered body and comprises a second conductor portion that penetrates the ceramic substrate in the thickness direction, and a second magnetic material portion that is embedded in the ceramic substrate and increases the inductance of the second conductor portion, wherein in at least one cross-sectional view perpendicular to the thickness direction so that the first magnetic material portion and the second magnetic material portion appear, the first conductor portion is offset from the center of the first magnetic material portion, the second conductor portion is offset from the center of the second magnetic material portion, and the distance between the center of the first conductor portion and the center of the second conductor portion is greater than the distance between the center of the first magnetic material portion and the center of the second magnetic material portion.

[0023] A fourteenth aspect of the present invention is the core substrate according to the thirteenth aspect, wherein the first conductor portion and the second conductor portion form a series circuit.

[0024] Aspect 15 is a core substrate according to aspect 14, wherein the ceramic substrate has a surface to which an end of the first conductor portion and an end of the second conductor portion reach, and further includes a connection portion that electrically connects the end of the first conductor portion and the end of the second conductor portion to each other.

[0025] Aspect 16 is a core substrate described in any one of aspects 1 to 15, wherein the at least one inductor includes a first inductor and a second inductor, the core substrate has, within the ceramic substrate, a first structure constituting at least the first inductor and a second structure constituting at least the second inductor, the first structure and the second structure being separated from each other, each of the first structure and the second structure comprising the first conductor portion and the first magnetic material portion, the core substrate further comprising at least one magnetic shield portion for suppressing magnetic interference between the first inductor and the second inductor, and the at least one magnetic shield portion being separated from the first conductor portion and the first magnetic material portion of each of the first structure and the second structure.

[0026] Aspect 17 is a core substrate described in Aspect 16, wherein the at least one magnetic shield portion includes a magnetic shield portion having a first interface facing the first conductor portion of the first structure, and the first interface includes a sintered interface.

[0027] Aspect 18 is the core substrate according to aspect 17, wherein the one magnetic shield portion has a second interface opposite the first interface, and the second interface includes a sintered interface.

[0028] Aspect 19 is a core substrate described in any one of aspects 16 to 18, wherein, in at least one cross-sectional view perpendicular to the thickness direction, the at least one magnetic shield portion blocks the gap between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure.

[0029] Aspect 20 is a core substrate described in Aspect 19, wherein the at least one magnetic shield portion that shields the space between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure is a single magnetic shield portion.

[0030] Aspect 21 is a core substrate described in any one of aspects 16 to 20, wherein the at least one magnetic shield portion has a portion that surrounds the first structure without surrounding the second structure, and a portion that surrounds the second structure without surrounding the first structure.

[0031] Aspect 22 is an interposer comprising a core substrate according to any one of aspects 1 to 21, and a wiring layer laminated on the core substrate, the wiring layer having a mounting surface on which a semiconductor element is to be mounted.

[0032] Aspect 23 is a core substrate having at least one built-in inductor for forming an interposer on which a semiconductor element is mounted, comprising: a ceramic substrate having a thickness direction; first to n-th conductor portions (n ​​is an integer of 2 or more) made of a sintered body and penetrating the ceramic substrate in the thickness direction; and magnetic material portions made of ceramic and embedded in the ceramic substrate for increasing the inductance of the first to n-th conductor portions, wherein, in at least one cross-sectional view perpendicular to the thickness direction in which the magnetic material portions appear, first to n-th regions into which the magnetic material portions are virtually divided are defined so that a position belonging to the k-th region (k is an integer of 1 to n) is located closest to the center of the k-th conductor portion among the centers of the first to n-th conductor portions, and the k-th conductor portion is positioned away from the center of the k-th region toward the edge of the magnetic material portion.

[0033] Aspect 24 is a core substrate described in Aspect 23, wherein the at least one inductor includes a first inductor and a second inductor, the core substrate has, within the ceramic substrate, a first structure constituting at least the first inductor and a second structure constituting at least the second inductor, the first structure and the second structure being separated from each other, each of the first structure and the second structure comprising the first to nth conductor portions and the magnetic material portion, the core substrate further comprising at least one magnetic shield portion for suppressing magnetic interference between the first inductor and the second inductor, and the at least one magnetic shield portion being separated from the first to nth conductor portions and the magnetic material portion of each of the first structure and the second structure.

[0034] Aspect 25 is a core substrate described in Aspect 24, wherein the at least one magnetic shield portion includes a magnetic shield portion having a first interface facing the first conductor portion of the first structure, and the first interface includes a sintered interface.

[0035] Aspect 26 is the core substrate according to aspect 25, wherein the one magnetic shield portion has a second interface opposite the first interface, and the second interface includes a sintered interface.

[0036] Aspect 27 is a core substrate described in any one of aspects 24 to 26, wherein, in at least one cross-sectional view perpendicular to the thickness direction, the at least one magnetic shield portion blocks the gap between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure.

[0037] Aspect 28 is a core substrate described in Aspect 27, wherein the at least one magnetic shield portion that shields the space between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure is a single magnetic shield portion.

[0038] Aspect 29 is a core substrate described in any one of aspects 24 to 28, wherein the at least one magnetic shield portion has a portion that surrounds the first structure without surrounding the second structure, and a portion that surrounds the second structure without surrounding the first structure.

[0039] According to the first aspect, first, the first magnetic material portion embedded in the ceramic substrate of the core substrate is made of ceramic. By densely sintering the ceramic of the first magnetic material portion, the magnetic permeability of the first magnetic material portion can be increased. Therefore, the inductor built into the core substrate can have a sufficiently large inductance per unit area. Second, in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion is offset from the center of the first magnetic material portion. This causes a bias in the magnetic field within the first magnetic material portion, resulting in fewer portions of the first magnetic body to which a high magnetic field is applied. Therefore, even if the current flowing through the first conductor portion increases, the entire first magnetic material portion is less likely to approach magnetic saturation in the cross-sectional view. This allows the inductor to have sufficiently good DC bias characteristics. From the above, the inductor built into the core substrate can have a sufficiently large inductance per unit area and sufficiently good DC bias characteristics.

[0040] According to the second aspect, the first conductor portion is in contact with the first magnetic material portion. This prevents the separation between the first conductor portion and the first magnetic material portion from acting as an air gap, thereby preventing the apparent decrease in magnetic permeability of the first magnetic material portion. This allows the inductance of the inductor formed by the first conductor portion to be increased.

[0041] According to the above-mentioned aspect 3, in order to increase the inductance, the first conductor portion is in contact with not only the first magnetic material portion as defined in the above-mentioned aspect 2, but also the ceramic substrate, which makes it easier to balance between obtaining a sufficiently large inductance and obtaining sufficiently good DC bias characteristics.

[0042] According to the above-mentioned Aspect 4, not only is the first conductor portion in contact with each of the first magnetic material portion and the ceramic substrate as defined in the above-mentioned Aspect 3, but in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion protrudes toward the ceramic substrate across a tangent to the boundary between the first magnetic material portion and the ceramic substrate. This allows for a balance between obtaining a sufficiently large inductance and obtaining sufficiently good DC bias characteristics to be achieved, while the above-mentioned Aspect 3 achieves a balance between obtaining a sufficiently large inductance and obtaining a sufficiently good DC bias characteristics, making it possible to place some emphasis on the DC bias characteristics.

[0043] According to the above-mentioned aspect 5, the first conductor portion not only contacts the first magnetic material portion as defined in the above-mentioned aspect 2 in order to increase the inductance, but also contacts the ceramic substrate without crossing the tangent line of the boundary between the first magnetic material portion and the ceramic substrate, thereby achieving a balance between obtaining a sufficiently large inductance and obtaining sufficiently good DC bias characteristics, and making it possible to place a slightly greater emphasis on the magnitude of the inductance than in the above-mentioned aspect 4.

[0044] According to the above-mentioned aspect 6, the first conductor portion is not only in contact with the first magnetic material portion as defined in the above-mentioned aspect 2, but is also spaced apart from the ceramic substrate, which allows greater emphasis to be placed on the magnitude of inductance compared to the above-mentioned aspect 3.

[0045] According to the seventh aspect, the first conductor portion is spaced from the first magnetic portion and is in contact with the ceramic substrate, which allows for greater emphasis on good DC bias characteristics than in the second aspect.

[0046] According to the eighth aspect, in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the center of the first conductor portion is spaced from the center of the first magnetic material portion by 10% or more of the diameter of a circle having the area of ​​the first magnetic material portion, thereby making it possible to more reliably obtain sufficiently good DC bias characteristics.

[0047] According to the above-mentioned Aspect 9, in each of the above-mentioned aspects, at least one cross-sectional view includes any cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears. This makes it possible to more fully obtain the effects of each aspect.

[0048] According to the tenth aspect, the first conductor is solid. This prevents an increase in electrical resistance due to a hollow portion, thereby reducing the electrical resistance of the first conductor.

[0049] According to the eleventh aspect, the ceramic substrate is made of low-temperature co-fired ceramics or a composite material of glass and alumina, which makes it easier to form the ceramic substrate and the first conductors by co-firing in manufacturing the core substrate.

[0050] According to the twelfth aspect, the core substrate has a sintered interface between the first conductor and the portion of the core substrate other than the first conductor. This prevents the heat resistance of the core substrate from being reduced due to the low heat resistance of the organic adhesive, unlike when the first conductor is bonded to the portion of the core substrate other than the first conductor via an organic adhesive. This improves the heat resistance of the core substrate.

[0051] According to the thirteenth aspect, the distance between the center of the first conductor portion and the center of the second conductor portion is greater than the distance between the center of the first magnetic material portion and the center of the second magnetic material portion, so that when the magnetic fields caused by the currents flowing through the first conductor portion and the second conductor portion reinforce each other between the first conductor portion and the second conductor portion, magnetic saturation due to the reinforced magnetic fields can be suppressed.

[0052] According to the above-mentioned Aspect 14, the first conductor portion and the second conductor portion form a series circuit. As a result, first, by connecting the first conductor portion and the second conductor portion in series, approximately twice the inductance can be obtained. Second, in this series circuit, the magnetic field caused by the current flowing through the first conductor portion and the magnetic field caused by the current flowing through the second conductor portion may reinforce each other between the first conductor portion and the second conductor portion. In such a case, as described in relation to the above-mentioned Aspect 13, magnetic saturation due to the mutually reinforced magnetic fields can be suppressed.

[0053] According to the above-described aspect 15, the core substrate is provided with a connection portion that electrically connects the end of the first conductor portion and the end of the second conductor portion. As a result, in a series circuit of the first conductor portion and the second conductor portion, the current flowing through the first conductor portion and the current flowing through the second conductor portion are approximately opposite in direction. Therefore, the magnetic fields caused by the current flowing through the first conductor portion and the magnetic fields caused by the current flowing through the second conductor portion reinforce each other between the first conductor portion and the second conductor portion. Magnetic saturation due to this mutually enhancing magnetic fields can be suppressed, as described in relation to the above-described aspect 13.

[0054] According to the sixteenth aspect, at least one magnetic shield portion suppresses magnetic interference between the first inductor and the second inductor, thereby suppressing crosstalk between the first inductor and the second inductor.

[0055] According to the seventeenth aspect, the at least one magnetic shield portion includes a sintered interface, which allows the at least one magnetic shield portion to be fixed to the core substrate by sintering.

[0056] According to the eighteenth aspect, the first interface and the second interface opposite the first interface of the at least one magnetic shield portion each include a sintered interface. This allows the at least one magnetic shield portion to be formed by co-firing with its surrounding structure. This allows the core substrate to be manufactured efficiently.

[0057] According to the above-described aspect 19, at least one magnetic shield portion shields the gap between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure, thereby effectively suppressing crosstalk between the first conductor portion of the first structure and the first conductor portion of the second structure.

[0058] According to the above-described aspect 20, the at least one magnetic shield portion that shields the gap between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure is a single magnetic shield portion, which further simplifies the configuration of the core substrate.

[0059] According to the above-mentioned aspect 21, at least one magnetic shield portion has a portion that surrounds the first structure without surrounding the second structure, and a portion that surrounds the second structure without surrounding the first structure, thereby making it possible to more reliably suppress crosstalk between the first structure and the second structure.

[0060] According to the above-mentioned aspect 22, first, the first magnetic material portion embedded in the ceramic substrate of the core substrate is made of ceramic. This allows the ceramic of the first magnetic material portion to be densely sintered, thereby increasing the magnetic permeability of the first magnetic material portion. Therefore, the inductor built into the core substrate can have a sufficiently large inductance per unit area. Second, in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion is offset from the center of the first magnetic material portion. This makes it difficult for the entire first magnetic material portion to approach a magnetic saturation state in the cross-sectional view, even if the current flowing through the first conductor portion increases. This allows the inductor to have sufficiently good DC bias characteristics. From the above, in an interposer on which a semiconductor element is to be mounted, the inductor built into the core substrate of the interposer can have a sufficiently large inductance per unit area and sufficiently good DC bias characteristics.

[0061] According to the above-mentioned aspect 23, first, the magnetic body portion embedded in the ceramic substrate of the core substrate is made of ceramic. This allows the ceramic of the magnetic body portion to be densely sintered, thereby increasing the magnetic permeability of the magnetic body portion. Therefore, the inductor built into the core substrate can have a sufficiently large inductance per unit area. Second, in at least one cross-sectional view perpendicular to the thickness direction in which the magnetic body portion appears, the kth conductor portion is positioned away from the center of the kth region of the magnetic body portion toward the edge of the magnetic body portion. This makes it difficult for the entire kth region of the magnetic body portion to approach magnetic saturation in the cross-sectional view, even if the current flowing through the kth conductor portion increases. Therefore, the DC bias characteristics of the inductor can be sufficiently improved. From the above, the inductor built into the core substrate can have a sufficiently large inductance per unit area and sufficiently good DC bias characteristics.

[0062] According to the twenty-fourth aspect, at least one magnetic shield portion suppresses magnetic interference between the first inductor and the second inductor, thereby suppressing crosstalk between the first inductor and the second inductor.

[0063] According to the twenty-fifth aspect, the at least one magnetic shield portion includes a sintered interface, which allows the at least one magnetic shield portion to be fixed to the core substrate by using sintering.

[0064] According to the above-mentioned aspect 26, the first interface and the second interface opposite to the first interface of the at least one magnetic shield portion each include a sintered interface. This allows the at least one magnetic shield portion to be formed by co-firing with its surrounding structure. This allows the core substrate to be manufactured efficiently.

[0065] According to the above-described aspect 27, at least one magnetic shield portion shields the gap between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure, thereby effectively suppressing crosstalk between the first conductor portion of the first structure and the first conductor portion of the second structure.

[0066] According to the above-mentioned aspect 28, the at least one magnetic shield portion that shields the gap between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure is a single magnetic shield portion, which can further simplify the configuration of the core substrate.

[0067] According to Aspect 29, at least one magnetic shield portion has a portion that surrounds the first structure without surrounding the second structure, and a portion that surrounds the second structure without surrounding the first structure, thereby making it possible to more reliably suppress crosstalk between the first structure and the second structure.

[0068] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

[0069] FIG. 1 is a cross-sectional view schematically showing the configuration of an electronic device having an interposer. FIG. 2 is a schematic view showing an example of the configuration of a wiring layer provided on a surface of a core substrate of an interposer that faces a semiconductor element. FIG. 3 is a schematic view showing an example of the configuration of a wiring layer provided on a surface of a core substrate of an interposer opposite to the surface facing the semiconductor element. FIG. 4 is a cross-sectional view showing an electronic device of a modified example of FIG. 1. FIG. 5 is a schematic view showing the configuration of an inductor built into a core substrate. FIG. 6 is a circuit diagram showing an example of electrical connection of the first inductor and the second inductor shown in FIG. 5. FIG. 7 is a partial cross-sectional view schematically showing the configuration of a core substrate of a comparative example. FIG. 8 is a diagram schematically showing the configuration of a core substrate in the first embodiment, and is a partial cross-sectional view taken along line VIII-VIII in FIG. 9. FIG. 9 is a partial cross-sectional view taken along line IX-IX in FIG. 8. FIG. 10 is a partial cross-sectional view schematically showing a core substrate of a first modified example of the first embodiment. FIG. 11 is a partial cross-sectional view schematically showing a core substrate of a second modified example of the first embodiment. FIG. 12 is a partial cross-sectional view schematically showing a core substrate according to a third modified example of the first embodiment. FIG. 13 is a partial cross-sectional view schematically showing a core substrate according to a fourth modified example of the first embodiment. FIG. 14 is a partial cross-sectional view schematically showing a configuration of a core substrate according to the second embodiment. FIG. 15 is a partial cross-sectional view schematically showing a core substrate according to a first modified example of the second embodiment. FIG. 16 is a partial cross-sectional view schematically showing a core substrate according to a second modified example of the second embodiment. FIG. 17 is a partial cross-sectional view schematically showing a core substrate according to a third modified example of the second embodiment. FIG. 18 is a partial cross-sectional view schematically showing a core substrate according to a fourth modified example of the second embodiment. FIG. 19 is a partial cross-sectional view schematically showing a configuration of a core substrate according to the third embodiment. FIG. 20 is a schematic diagram showing an example of electrical connections of a plurality of inductors built in a core substrate according to the fourth embodiment. FIG. 21 is a partial cross-sectional view schematically showing a configuration of a core substrate according to the fourth embodiment. FIG. 22 is a partial cross-sectional view schematically showing a step of a manufacturing method of a core substrate according to a first modified example of the fourth embodiment. FIG. 23 is a partial cross-sectional view schematically showing a configuration of a core substrate according to a second modified example of the fourth embodiment. FIG. 24 is a schematic diagram showing an example of electrical connections between a plurality of inductors built into a core substrate according to the fifth embodiment.Fig. 25 is a partial cross-sectional view schematically showing the configuration of a core substrate in embodiment 5. Fig. 26 is a diagram showing simulation results of inductance and DC superposition characteristics when the deviation rate S is changed for a pair of inductors built into the core substrate and connected in series with each other.

[0070] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0071] First Embodiment FIG. 1 is a cross-sectional view schematically illustrating the configuration of electronic device 901 according to the first embodiment. Electronic device 901 includes interposer 700, semiconductor element 811, motherboard 812, and package substrate 813. Interposer 700 includes core substrate 601, wiring layer 791, and wiring layer 792. Wiring layer 791 and wiring layer 792 are laminated on first surface SF1 and second surface SF2 of core substrate 601, respectively. In other words, wiring layer 791 is provided on the surface of core substrate 601 facing semiconductor element 811, and wiring layer 792 is provided on the surface of core substrate 601 opposite to the surface facing semiconductor element 811. Wiring layer 791 and wiring layer 792 may be laminated on core substrate 601 by a build-up method, a sputtering method, or the like, or may be bonded as separate wiring boards.

[0072] 2 is a schematic diagram showing an example of the configuration of the wiring layer 791. The wiring layer 791 has a stacking surface SG2 and a mounting surface SC that are opposite to each other. The stacking surface SG2 is stacked on the second surface SF2 of the core substrate 601. A semiconductor element 811 is mounted on the mounting surface SC. The wiring layer 791 also has an insulating portion 791i and a wiring portion 791j. The wiring portion 791j electrically connects the stacking surface SG2 and the mounting surface SC. The wiring portion 791j has a wiring group W1a that reaches the stacking surface SG2, a wiring group W1b that reaches the mounting surface SC, and wiring (not shown) that connects the wiring group W1a and the wiring group W1b.

[0073] The wiring layer 791 is preferably a multi-layer wiring layer configured so that the wiring dimensions (e.g., line and space (L / S) dimensions) are reduced from the stacking surface SG2 to the mounting surface SC. This makes it possible to configure an interposer 700 that can mount a semiconductor element 811 having a small terminal pitch even if the wiring dimensions (L / S) of the core substrate 601 are not particularly high. Specifically, the wiring layer 791 may be a laminate of a normal wiring layer facing the core substrate 601 and a fine wiring layer facing the semiconductor element 811. In this case, the wiring group W1a belongs to the normal wiring layer, and the wiring group W1b belongs to the fine wiring layer.

[0074] A typical wiring layer may be formed by providing a wiring structure on a plate-shaped organic material (e.g., an epoxy-based member) or inorganic material (e.g., low temperature co-fired ceramics (LTCC) or a non-magnetic ferrite material). To form the wiring structure on this organic material, for example, Cu plating is used. To form the wiring structure on an inorganic material, when the inorganic material is formed by a firing process, the wiring structure is simultaneously formed by firing Ag (silver) or Cu (copper). From the viewpoint of ease of forming fine wiring, it is preferable that a fine wiring layer be formed by providing a wiring structure on a plate-shaped organic material (e.g., an epoxy-based or polyimide-based member). To form the wiring structure on this organic material, for example, Cu plating is used.

[0075] FIG. 3 is a schematic diagram showing an example of the configuration of the wiring layer 792. The wiring layer 792 has a stacking surface SG1 and a bottom surface SB that are opposite to each other. The stacking surface SG1 is stacked on the first surface SF1 of the core substrate 601. In the electronic device 901 of FIG. 3, the bottom surface SB faces the package substrate 813. The wiring layer 792 also has an insulating portion 792i and a wiring portion 792j. The wiring portion 792j electrically connects the stacking surface SG1 and the bottom surface SB. The wiring portion 792j has a wiring group W2a that reaches the bottom surface SB, a wiring group W2b that reaches the stacking surface SG1, and wiring (not shown) that connects the wiring group W2a and the wiring group W2b.

[0076] The semiconductor element 811 is connected to the wiring layer 791 of the interposer 700 by, for example, solder balls 821. The semiconductor element 811 may be an IC (Integrated Circuit) chip. In particular, when the IC chip is a processor chip having multiple processing cores, the voltage regulator described above can be configured using an inductor, which will be described later.

[0077] The interposer 700 is mounted on the package substrate 813 by bonding the wiring layer 792 to the package substrate 813. This bonding is performed, for example, by solder balls 823. The package substrate 813 is mounted on the motherboard 812, and this bonding is performed, for example, by using solder balls 822.

[0078] In the wiring layer 791 (FIG. 2), the pitch of the terminal group connected to the wiring group W1b on the mounting surface SC may be smaller than the pitch of the terminal group connected to the wiring group W1a on the stacking surface SG2, and in this case, the interposer 700 (FIG. 1) has the function of converting the terminal pitch. As a modified example, depending on the application of the interposer, either or both of the wiring layer 791 and the wiring layer 792 may be omitted.

[0079] 4 is a cross-sectional view showing an electronic device 902, which is a modified example of the electronic device 901 (FIG. 1). In the electronic device 902, the interposer 700 is bonded to the motherboard 812 without the package substrate 813 (FIG. 1), and this bonding is performed by, for example, solder balls 822.

[0080] 5 is a schematic diagram showing the configuration of inductors L1 to L6 built into core substrate 601. Core substrate 601 has multiple inductors L1 and L2 built into it, and may also have additional inductors L3 to L6 built into it, with any number of inductors. Note that, although the configurations of inductors L1 and L2 will be described in detail below, other inductors may have similar configurations.

[0081] FIG. 6 is a circuit diagram showing an example of the electrical connection of inductor L1 and inductor L2 shown in FIG. 5. In this embodiment, the series connection of inductor L1 and inductor L2 forms an inductor having a combined inductance greater than the inductance of each of the inductors, and both ends of the inductor are disposed on the second surface SF2 that faces the semiconductor element 811 ( FIG. 1 ). This allows an inductor having a sufficiently large inductance to be easily connected to the semiconductor element 811. Note that the electrical connections between the multiple inductors built into the core substrate are not limited to those shown in FIG. 6 and may be designed appropriately depending on the application of the core substrate. This may form a series structure of any number of inductors, a parallel structure of any number of inductors, or a combination thereof.

[0082] FIG. 7 is a partial cross-sectional view showing the configuration of a core substrate 690 of a comparative example. In the core substrate 690, a first magnetic material portion 391 and a first conductor portion 291 are formed in this order on the side wall of one through hole of a resin substrate 190 made of glass epoxy resin. The first conductor portion 291 has a hollow structure filled with a resin material 281. Similarly, a second magnetic material portion 392 and a second conductor portion 292 are formed in this order on the side wall of another through hole of the resin substrate 190. The second conductor portion 292 has a hollow structure filled with a resin material 282. The first conductor portion 291 and the second conductor portion 292 form inductors L1 and L2, respectively. The first conductor portion 291 and the second conductor portion are connected to each other by a connecting portion 450, thereby forming a series circuit of inductors L1 and L2. The first conductor portion 291 and the second conductor portion 292 are also collectively referred to as conductor portions 290.

[0083] As described above, the first magnetic material portion 391 and the second magnetic material portion 392 (collectively referred to as the magnetic material portion 390) are formed within the resin substrate 190. Therefore, the process of forming the magnetic material portion 390 must be performed at a temperature below the heat resistance temperature of the resin substrate 190. Due to this constraint, the magnetic material portion 390 is made of a resin in which magnetic particles are dispersed, rather than a sintered ceramic body. In this case, the gaps between the magnetic particles in the magnetic material portion 390 are filled with resin, and it is generally difficult to increase this filling rate to 70% or more. As a result, it is difficult to increase the relative permeability of the first magnetic material portion 391 and the second magnetic material portion 392 compared to the first magnetic material portion 301 and the second magnetic material portion 302 ( FIG. 8 ), and the relative permeability is, for example, approximately 6.

[0084] A design example of the core substrate 690 is described below. The resin substrate 190 has a square shape with sides of 50 mm in the in-plane direction and a dimension of 1000 μm in the thickness direction. The multiple through holes described above are arranged at a pitch of 500 μm. Each of the magnetic material portions 390 has an outer diameter of 400 μm and an inner diameter of 200 μm. Each of the conductor portions 290 has an outer diameter of 200 μm. The conductor portions 290 are formed by Cu plating. The magnetic material portions 390 are made of resin with dispersed magnetic particles, and their relative permeability is estimated to be 6. In this case, the inductance of one inductor (e.g., inductor L1) is estimated by the inventor to be approximately 1 nH at 140 MHz.

[0085] FIG. 8 is a diagram schematically illustrating the configuration of the core substrate 601 in the first embodiment, and is a partial cross-sectional view taken along line VIII-VIII in FIG. 9 . FIG. 9 is a partial cross-sectional view taken along line IX-IX in FIG. 8 . Specifically, FIG. 9 shows a cross-sectional view perpendicular to the thickness direction, in which the first magnetic material portion 301 appears. FIG. 9 also shows a cross-sectional view perpendicular to the thickness direction, in which the first magnetic material portion 301 and the second magnetic material portion 302 appear. Note that the core substrate 601 may be manufactured using multilayer ceramic technology, and in FIG. 8 , the boundaries between layers in the multilayer structure are indicated by dashed lines.

[0086] As described above, the core substrate 601 is used to form the interposer 700 (FIG. 1) on which the semiconductor element 811 is mounted, and has multiple inductors built in. In FIGS. 8 and 9, the multiple inductors are shown as inductor L1 and inductor L2.

[0087] The core substrate 601 has a ceramic substrate 100. The ceramic substrate 100 forms a first surface SF1 and a second surface SF2 of the core substrate 601. The first surface SF1 and the second surface SF2 are surfaces of the ceramic substrate 100 that are opposite to each other in the thickness direction (the vertical direction in FIG. 8 ).

[0088] The core substrate 601 has a first conductor portion 201 that constitutes the inductor L1 and a first magnetic material portion 301 that increases the inductance of the first conductor portion 201. The first conductor portion 201 penetrates the ceramic substrate 100 in the thickness direction. Unlike the hollow first conductor portion 291 ( FIG. 7 (comparative example)), the first conductor portion 201 may be a solid body. In other words, the first conductor portion 201 does not need to have a hollow space inside. The first magnetic material portion 301 is embedded in the ceramic substrate 100 and penetrates the ceramic substrate 100 in the example shown in FIG. 8.

[0089] In the core substrate 601, the first conductor portion 201 is in contact with the first magnetic material portion 301. The first conductor portion 201 is spaced apart from the ceramic substrate 100 in the cross-sectional view of Fig. 9. The first magnetic material portion 301 may surround the first conductor portion 201 at one through-hole of the ceramic substrate 100 in the cross-sectional view of Fig. 9.

[0090] The ceramic substrate 100 is a substrate made of a sintered body. The ceramic sintered body is substantially free of organic components and may contain glass components. In other words, the ceramic substrate 100 may be made of a composite material of glass and ceramics, specifically a composite material of glass and alumina. The ceramic substrate 100 is preferably made of LTCC. LTCC is a ceramic that can be sintered at approximately 900°C or less, well below the melting point of Ag or Cu. This allows for the simultaneous sintering of a low-electrical-resistance conductor primarily composed of Ag or Cu. The ceramic substrate 100 has multiple through-holes between the first surface SF1 and the second surface SF2, in which the inductors L1 and L2 are embedded. The ceramic substrate 100 preferably has a thermal expansion coefficient of 4 ppm / °C or more and 16 ppm / °C or less. The ceramic substrate 100 preferably has a relative dielectric constant of 8 or less and a dielectric loss tangent of 0.01 or less at 1 GHz.

[0091] The first conductor 201 is made of a sintered body and is made of, for example, Ag and / or Cu.

[0092] The first magnetic body portion 301 is made of ceramics. Therefore, the first magnetic body portion 301 is made of a sintered body and does not contain organic components. In order to reduce the volume of the inductor, the magnetic material constituting the first magnetic body portion 301 preferably has high magnetic permeability, and the first magnetic body portion 301 preferably has a density of 70% or more. In order to reduce the electrical loss of the inductor, the magnetic material constituting the first magnetic body portion 301 is preferably a soft magnetic material with low magnetic loss at high frequencies. For example, a soft magnetic material with a magnetic loss tangent of 0.1 or less at a frequency of 100 MHz is preferably used. In order to reduce magnetic loss at high frequencies, the magnetic material constituting the first magnetic body portion 301 preferably has a high volume electrical resistivity, and specifically, is preferably an electrical insulator. The first magnetic body 301 is preferably made of a ferrite-based material, and the crystal structure of the material is preferably a spinel structure from the viewpoint of ease of manufacturing, for example, Ni-Zn ferrite or Ni-Zn-Cu ferrite, and from the viewpoint of high magnetic permeability, it is preferably a hexagonal structure with c-axis orientation along the thickness direction (vertical direction in Figure 8).

[0093] The core substrate 601 also has a second conductor portion 202 that constitutes the inductor L2, and a second magnetic material portion 302 that increases the inductance of the second conductor portion 202. The configurations of the second conductor portion 202 and the second magnetic material portion 302 are substantially the same as the configurations of the first conductor portion 201 and the first magnetic material portion, respectively, and therefore detailed description thereof will not be repeated.

[0094] The first conductor portion 201 and the second conductor portion 202 each have a center CC1 and a center CC2. In the example shown in FIG. 9 , the first conductor portion 201 and the second conductor portion 202 have a circular shape, and the centers CC1 and CC2 are the centers of the circles. As a modified example, an ellipse may be used instead of the circle. The first conductor portion 201 and the second conductor portion 202 may have any shape other than a circle or an ellipse, and in that case, the center of the shape may be defined by the center of gravity. The first magnetic material portion 301 and the second magnetic material portion 302 each have a center CM1 and a center CM2. In the example shown in FIG. 9 , the outer edges of the first magnetic material portion 301 and the second magnetic material portion 302 have a circular shape, and the centers CM1 and CM2 are the centers of the circles. As a modified example, an ellipse may be used instead of the circle. The shape of the outer edges of the first magnetic material part 301 and the second magnetic material part 302 may be any shape other than a circle or an ellipse, and in that case, the center of the shape may be defined by the center of gravity.

[0095] In the cross-sectional view of FIG. 9 , the first conductor portion 201 is offset from the center CM1 of the first magnetic material portion 301. Preferably, the center CC1 of the first conductor portion 201 is spaced from the center CM1 of the first magnetic material portion 301 by 10% or more of the diameter of a circle having the area of ​​the first magnetic material portion 301. Similarly, the second conductor portion 202 is offset from the center CM2 of the second magnetic material portion 302. Preferably, the center CC2 of the second conductor portion 202 is spaced from the center CM2 of the second magnetic material portion 302 by 10% or more of the diameter of a circle having the area of ​​the second magnetic material portion 302. Preferably, the distance between the center CC1 of the first conductor portion 201 and the center CC2 of the second conductor portion 202 is greater than the distance between the center CM1 of the first magnetic material portion 301 and the center CM2 of the second magnetic material portion 302. In particular, in the example shown in FIG. 9, the centers CC1, CM1, CM2, and CC2 are arranged in this order on an imaginary line, thereby satisfying the distance condition described above.

[0096] 9 (one of the cross-sectional views perpendicular to the thickness direction in which the first magnetic material portion 301 appears) may be present in any cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion 301 appears, thereby making it possible to more fully obtain the effects associated with each of the features.

[0097] The manufacturing method of the core substrate 601 may include a firing step as described above. This firing step may fire the first conductor portion 201, the second conductor portion 202, the first magnetic material portion 301, and the second magnetic material portion 302 simultaneously with the ceramic substrate 100. In this case, the core substrate 601 has a sintered interface between the first conductor portion 201 and a portion of the core substrate 601 other than the first conductor portion 201. In other words, the first conductor portion 201 and the other portion are sintered to each other. Specifically, in FIG. 8 , the core substrate 601 has a sintered interface between the first conductor portion 201 and the first magnetic material portion 301. In other words, the first conductor portion 201 and the first magnetic material portion 301 are sintered to each other. The core substrate 601 also has a sintered interface between the first magnetic material portion 301 and the ceramic substrate 100. In other words, the first magnetic material portion 301 and the ceramic substrate 100 are sintered to each other. These interfaces do not contain organic materials and are formed by bonds between inorganic materials, in other words, these interfaces are formed by inorganic bonds.

[0098] 8, the ends of the first conductor portion 201 and the second conductor portion 202 reach the first surface SF1 of the ceramic substrate 100, and the core substrate 601 has a connection portion 450 that electrically connects these portions to each other. As a result, the first conductor portion 201 of the inductor L1 and the second conductor portion 202 of the inductor L2 form a series circuit as shown in FIG.

[0099] A design example of the core substrate 601 (FIGS. 8 and 9) is described below. The ceramic substrate 100 has a square shape with sides of 50 mm in the in-plane direction and a thickness dimension of 550 μm. The through holes provided in the ceramic substrate 100 are arranged at a pitch of 450 μm. The ceramic substrate 100 is formed, for example, from LTCC primarily composed of Ba-Si-Al-O elements or a composite material of glass and alumina. The first magnetic material portion 301 and the second magnetic material portion 302 (FIG. 8) each have an outer diameter of 350 μm and an inner diameter of 100 μm. The first conductor portion 201 and the second conductor portion 202 each have an outer diameter of 100 μm. The first conductor portion 201 and the second conductor portion 202 are formed by sintering Ag powder. The first magnetic material part 301 and the second magnetic material part 302 are made of sintered ferrite, and the relative permeability thereof can be estimated to be about 16. In this case, the inductance of each of the inductors L1 and L2 is estimated by the inventors to be about 2 nH at 140 MHz.

[0100] According to this embodiment, first, the first magnetic material portion 301 embedded in the ceramic substrate 100 of the core substrate 601 is made of ceramic. By densely sintering the ceramic of the first magnetic material portion 301, the magnetic permeability of the first magnetic material portion 301 can be increased. Therefore, the inductor built into the core substrate 601 can have a sufficiently large inductance per unit area. Second, in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion 301 appears, the first conductor portion 201 is offset from the center CM1 of the first magnetic material portion 301. This causes a bias in the magnetic field within the first magnetic material portion 301, resulting in fewer portions of the first magnetic material portion 301 to which a high magnetic field is applied. Therefore, even if the current flowing through the first conductor portion 201 increases, the entire first magnetic material portion 301 is less likely to approach magnetic saturation in the cross-sectional view. This allows the inductor to have sufficiently good DC superposition characteristics. From the above, the inductor built into the core substrate 601 can have a sufficiently large inductance per unit area and also have sufficiently good DC superposition characteristics.

[0101] Because the first conductor portion 201 is in contact with the first magnetic material portion 301, the separation between the first conductor portion 201 and the first magnetic material portion 301 acts like an air gap, which prevents the apparent decrease in magnetic permeability of the first magnetic material portion. This makes it possible to increase the inductance of the inductor formed by the first conductor portion 201. Furthermore, because the first conductor portion 201 is separated from the ceramic substrate 100, greater emphasis can be placed on the magnitude of inductance compared to the core substrates 602 to 604 (FIGS. 10 to 12).

[0102] 9, the center CC1 of the first conductor portion 201 may be spaced apart from the center CM1 of the first magnetic material portion 301 by 10% or more of the diameter of a circle having the area of ​​the first magnetic material portion 301. This makes it possible to more reliably obtain sufficiently good DC superposition characteristics.

[0103] The first conductor 201 may be solid, which prevents an increase in electrical resistance due to a hollow portion, thereby reducing the electrical resistance of the first conductor 201.

[0104] The ceramic substrate 100 may be made of low-temperature co-fired ceramics or glass alumina. This makes it easier to form the ceramic substrate 100 and the first conductor 201 by co-firing during the manufacture of the core substrate 601. The core substrate 601 may have a sintered interface between the first conductor 201 and the portion of the core substrate 601 other than the first conductor 201. This prevents the heat resistance of the core substrate 601 from being reduced due to the low heat resistance of the organic adhesive, unlike when the first conductor 201 is bonded to the portion of the core substrate 601 other than the first conductor 201 via an organic adhesive. This therefore improves the heat resistance of the core substrate 601.

[0105] The distance between the center CC1 of the first conductor portion 201 and the center CC2 of the second conductor portion 202 may be greater than the distance between the center CM1 of the first magnetic material portion 301 and the center CM2 of the second magnetic material portion 302. This makes it possible to suppress magnetic saturation caused by the mutually enhancing magnetic fields when the magnetic fields caused by the currents flowing through the first conductor portion 201 and the second conductor portion 202 enhance each other between the first conductor portion 201 and the second conductor portion 202.

[0106] The first conductor portion 201 of the inductor L1 and the second conductor portion 202 of the inductor L2 may form a series circuit. This provides, first, an inductance that is approximately twice as large as the inductance of inductor L1 or inductor L2 alone. Second, in this series circuit, the magnetic field caused by the current flowing through the first conductor portion 201 and the magnetic field caused by the current flowing through the second conductor portion 202 may reinforce each other between the first conductor portion 201 and the second conductor portion 202. In such cases, as described above, magnetic saturation due to the mutually reinforcing magnetic fields can be suppressed.

[0107] The core substrate 601 may be provided with a connection portion 450 that electrically connects the end of the first conductor portion 201 and the end of the second conductor portion 202 to each other. As a result, in a series circuit of the first conductor portion 201 and the second conductor portion 202, the current flowing through the first conductor portion 201 and the current flowing through the second conductor portion 202 are in roughly opposite directions. Therefore, the magnetic field caused by the current flowing through the first conductor portion 201 and the magnetic field caused by the current flowing through the second conductor portion 202 reinforce each other between the first conductor portion 201 and the second conductor portion 202. As described above, magnetic saturation due to this mutually reinforced magnetic field can be suppressed.

[0108] <Modifications of First Embodiment> The cross-sectional views of Fig. 10 to Fig. 12 respectively correspond to the first to third modified examples of the cross-sectional view of Fig. 9. Specifically, in the configurations shown in the cross-sectional views of Fig. 10 to Fig. 12, the deviation of the center CC1 of the first conductor 201 from the center CM1 of the first magnetic material portion 301 and the deviation of the center CC2 of the second conductor 202 from the center CM2 of the second magnetic material portion 302 are made larger than the configuration shown in the cross-sectional view of Fig. 9 (first embodiment).

[0109] 10 and 11 , in the core substrates 602 and 603 of the first and second modifications, the first conductor portion 201 is in contact with the first magnetic material portion 301, as in the first embodiment ( FIG. 9 ). This makes it easier to ensure a sufficiently large inductance. Meanwhile, in the core substrates 602 and 603 of the first and second modifications, the first conductor portion 201 is also in contact with the ceramic substrate 100 in the cross-sectional view. This makes it easier to achieve a balance between obtaining a sufficiently large inductance and obtaining sufficiently good DC superposition characteristics, as described above.

[0110] In the core substrate 602, in the cross-sectional view of Fig. 10 , the first conductor portion 201 contacts the ceramic substrate 100 without crossing the tangent line LT of the boundary between the first magnetic material portion 301 and the ceramic substrate 100. This allows a balance between obtaining a sufficiently large inductance and obtaining sufficiently good DC bias characteristics, while placing a slightly higher priority on the magnitude of inductance than in the core substrate 603 ( Fig. 11 ). On the other hand, in the core substrate 603, in the cross-sectional view of Fig. 11 , the first conductor portion 201 protrudes toward the ceramic substrate 100, crossing the tangent line LT of the boundary between the first magnetic material portion 301 and the ceramic substrate 100. This allows a balance between obtaining a sufficiently large inductance and obtaining sufficiently good DC bias characteristics, while placing a slightly higher priority on the DC bias characteristics than in the core substrate 602 ( Fig. 10 ).

[0111] In the core substrate 604, in the cross-sectional view of FIG. 12 , the first conductor portion 201 is spaced apart from the first magnetic material portion 301 and is in contact with the ceramic substrate 100. This allows for greater emphasis on excellent DC superposition characteristics compared to the core substrates 601-603. On the other hand, if the first conductor portion 201 is too far away from the first magnetic material portion, the inductance of the inductor L1 formed by the first conductor portion 201 may become excessively small. To avoid this, if the first conductor portion 201 has a circular shape, the distance DO between the first conductor portion 201 and the first magnetic material portion 301 is preferably equal to or less than the diameter of the circle. If the first conductor portion has a shape other than a circle, the diameter of a circle having the same area as the shape is defined as the equivalent diameter, and the distance DO between the first conductor portion 201 and the first magnetic material portion 301 is preferably equal to or less than the equivalent diameter.

[0112] The cross-sectional view of FIG. 13 corresponds to the fourth modified example of the cross-sectional view of FIG. 9 described above. Specifically, the configuration shown in the cross-sectional view of FIG. 13 differs from the configuration shown in the cross-sectional view of FIG. 9 (first embodiment) in that the direction from center CM1 to center CC1 is different from the direction from center CM2 to center CC2. As a result, the imaginary line passing through center CC1 and center CM1 and the imaginary line passing through center CM2 and center CC2 are different imaginary lines rather than a common imaginary curve. In this modified example, the effects of the first conductor portion 201 being offset from the center CM1 of the first magnetic material portion 301 and the second conductor portion 202 being offset from the center CM2 of the second magnetic material portion 302 are obtained in substantially the same manner as in the first embodiment. Furthermore, if the distance between the center CC1 of the first conductor portion 201 and the center CC2 of the second conductor portion 202 is greater than the distance between the center CM1 of the first magnetic material portion 301 and the center CM2 of the second magnetic material portion 302, the resulting effect can be obtained in substantially the same manner as in the configuration shown in Fig. 9 (Embodiment 1). However, the difference in these distances is easier to ensure with the configuration shown in Fig. 9, and therefore the resulting effect can be made greater.

[0113] <Embodiment 2> Embodiment 2 (Fig. 14) differs from embodiment 1 (Fig. 9) in that it has a configuration in which multiple conductor portions penetrate one magnetic material portion. In the following, this configuration will be mainly described, and the other configuration is substantially the same as the configuration of embodiment 1 described above. Therefore, the same or corresponding elements are denoted by the same reference numerals, and the description thereof will not be repeated.

[0114] Fig. 14 is a partial cross-sectional view schematically showing the core substrate 611 of the second embodiment in the same field of view as Fig. 9 (first embodiment). Specifically, Fig. 14 shows one cross-sectional view perpendicular to the thickness direction, in which the magnetic material part 300 appears.

[0115] The core substrate 611 has first to n-th conductor portions (n ​​is an integer of 2 or greater) and a magnetic material portion 300 for increasing the inductance of the first to n-th conductor portions. In the present embodiment, n=2, and therefore the core substrate 611 has a first conductor portion 201 and a second conductor portion 202. As in the first embodiment, the first conductor portion 201 and the second conductor portion 202 are made of a sintered body and penetrate the ceramic substrate 100 in the thickness direction. As in the first magnetic material portion 301 (first embodiment), the magnetic material portion 300 is embedded in the ceramic substrate 100 and is made of ceramic. The material of the magnetic material portion 300 may also be the same as the material of the first magnetic material portion 301 (first embodiment).

[0116] 14 , first to n-th regions into which the magnetic material part 300 is virtually divided are defined so that a position belonging to the k-th region (k is an integer between 1 and n) is located closest to the center of the k-th conductor part among the centers of the first to n-th conductor parts. Any position belonging to the k-th region according to this definition is located closest to the center of the k-th conductor part among the centers of the first to n-th conductor parts. In the present embodiment, n=2, and a first region RG1 and a second region RG2 are defined. Specifically, the first region RG1 and the second region RG2 into which the magnetic material part 300 is virtually divided are defined so that the position belonging to the first region RG1 is located closest to the center of the kth conductor part out of the center CC1 of the first conductor part 201 and the center CC2 of the second conductor part 202, and the position belonging to the second region RG2 is located closest to the center CC2 of the second conductor part 202 out of the center CC1 of the second conductor part 202 and the center CC2 of the second conductor part 202.

[0117] Furthermore, the center of gravity of the k-th region is defined as the center of the k-th region (k is an integer between 1 and n). In this embodiment, n=2, so the center CM1 of the first region RG1 is the center of gravity of the first region RG1, and the center CM2 of the second region RG2 is the center of gravity of the second region RG2.

[0118] The k-th conductor portion is disposed away from the center of the k-th region toward the edge of the magnetic material portion 300 (k is an integer greater than or equal to 1 and less than or equal to n). In the present embodiment, n=2, and therefore the first conductor portion 201 is disposed away from the center CM1 of the first region RG1 toward the edge of the magnetic material portion 300, and the second conductor portion 202 is disposed away from the center CM2 of the second region RG2 toward the edge of the magnetic material portion 300.

[0119] 14, the outer edge of the magnetic material portion 300 of the core substrate 611 has a pair of linear portions extending parallel to each other with a gap therebetween and a pair of arcuate portions connecting the linear portions. The boundary between the first region and the second region RG2 may be a perpendicular bisector for each of the pair of linear portions. Furthermore, centers CC1, CM1, CM2, and CC2 may be located in this order on the perpendicular bisector of the boundary.

[0120] According to this embodiment, firstly, the magnetic material part 300 embedded in the ceramic substrate 100 of the core substrate 611 is made of ceramic. This allows the ceramic of the magnetic material part 300 to be densely sintered, thereby increasing the magnetic permeability of the magnetic material part 300. Therefore, the inductor built into the core substrate 611 can have a sufficiently large inductance per unit area.

[0121] 14 , the first conductor portion 201 and the second conductor portion 202 are disposed toward the edge of the magnetic body portion 300, away from the center CM1 of the first region RG1 and the center CM2 of the second region RG2 of the magnetic body portion 300. As a result, even if the current flowing through the first conductor portion 201 increases, the entire first region RG1 of the magnetic body portion 300 is less likely to approach a magnetic saturation state in the cross-sectional view. Similarly, even if the current flowing through the second conductor portion 202 increases, the entire second region RG2 of the magnetic body portion 300 is less likely to approach a magnetic saturation state in the cross-sectional view. Therefore, the DC superposition characteristics of the inductor can be sufficiently improved.

[0122] From the above, the inductor built into the core substrate 611 can have a sufficiently large inductance per unit area and also have sufficiently good DC bias characteristics. Note that this effect is not limited to when n=2, but can also be obtained when n is 3 or more.

[0123] <Modification of Second Embodiment> The shape of the outer edge of the magnetic material portion 300 of the core substrate 611 is not limited to that shown in FIG. 14 and may be, for example, the shape shown in FIG. 15 or FIG. 16 described below. Referring to FIG. 15 , in the core substrate 612, the outer edge of the magnetic material portion 300 has an elliptical shape. The boundary between the first region RG1 and the second region RG2 (indicated by the dashed line in the figure) may correspond to the minor axis of the ellipse. Centers CC1, CM1, CM2, and CC2 may be located on the major axis of the ellipse, in this order. Referring to FIG. 16 , in the core substrate 613, the outer edge of the magnetic material portion 300 has a rectangular shape. The boundary between the first region RG1 and the second region RG2 may be the perpendicular bisector of each of a pair of long sides of the rectangle. Centers CC1, CM1, CM2, and CC2 may be located on the perpendicular bisector of the boundary, in this order.

[0124] The second embodiment and its first and second modifications described above correspond to the case where n = 2. However, as mentioned above, n is not limited to 2 and may be 3 or greater. FIG. 17 is a partial cross-sectional view schematically illustrating a core substrate 614 of a third modification corresponding to n = 4. The core substrate 614 has a first conductor portion 201 to a fourth conductor portion 204. The first conductor portion 201 to the fourth conductor portion 204 each have a center CC1 to CC4. In the core substrate 614, the magnetic material portion 300 is virtually divided into a first region RG1 to a fourth region RG4. The first region RG1 to the fourth region RG4 each have a center CM1 to CM4. The first conductor portion 201 is disposed toward the edge of the magnetic material portion 300, away from the center CM1 of the first region RG1. The second conductor 202 is disposed offset from the center CM2 of the second region RG2 toward the edge of the magnetic material part 300. The third conductor 203 is disposed offset from the center CM3 of the third region RG3 toward the edge of the magnetic material part 300. The fourth conductor 204 is disposed offset from the center CM4 of the fourth region RG4 toward the edge of the magnetic material part 300.

[0125] In the cross-sectional view of FIG. 17 , each of the first to fourth conductor portions 201 to 204 is spaced apart from the ceramic substrate 100. However, the arrangement of the first to fourth conductor portions 201 to 204 is not limited to this. In the cross-sectional view of FIG. 18 , a core substrate 615 of the fourth modification has a configuration similar to that of the core substrate 603 ( FIG. 11 ), in which each of the first to fourth conductor portions 201 to 204 protrudes toward the ceramic substrate 100, crossing a tangent line (not shown) at the boundary between the magnetic material portion 300 and the ceramic substrate 100. As another modification, similar to the core substrate 602 ( FIG. 10 ), each of the first to fourth conductor portions 201 to 204 may be in contact with the ceramic substrate 100 without crossing the tangent line. As yet another modification, similar to the core substrate 604 ( FIG. 12 ), each of the first to fourth conductor portions 201 to 204 may be spaced apart from the magnetic material portion 300.

[0126] Third Embodiment Figure 19 is a partial cross-sectional view schematically illustrating the configuration of a core substrate 621 according to a third embodiment. The core substrate 621 has a configuration that combines a plurality of configurations, each of which corresponds to the second embodiment. Figure 19 illustrates two configurations included in the plurality of configurations. Of these two configurations, the first configuration includes a magnetic material portion 300A and a first conductor portion 201A and a second conductor portion 202A as a plurality of conductor portions. The second configuration includes a magnetic material portion 300B and a first conductor portion 201B and a second conductor portion 202B as a plurality of conductor portions. The first and second configurations are separated by a ceramic substrate 100.

[0127] The first configuration and the second configuration may be symmetrical with respect to an imaginary line (not shown) along the first direction (the vertical direction in FIG. 19 ). The distance between the imaginary line and the center CC1 of the first conductor portion 201A may be greater than the distance between the imaginary line and the center CM1 of the first region RG1 of the magnetic material portion 300A. The distance between the imaginary line and the center CC2 of the second conductor portion 202A may be greater than the distance between the imaginary line and the center CM2 of the second region RG2 of the magnetic material portion 300A. The distance between the imaginary line and the center CC1 of the first conductor portion 201B may be greater than the distance between the imaginary line and the center CM1 of the first region RG1 of the magnetic material portion 300B. The distance between the imaginary line and the center CC2 of the second conductor portion 202B may be greater than the distance between the imaginary line and the center CM2 of the second region RG2 of the magnetic material portion 300B. When the distance between each conductor portion and the virtual straight line is increased as described above, it is possible to suppress adverse effects due to magnetic interference between the first configuration and the second configuration.

[0128] <Fourth Embodiment> Fig. 20 is a schematic diagram showing an example of electrical connection of a plurality of inductors L1 to L4, L1a to L4a built into a core substrate 631 according to the fourth embodiment. Fig. 21 is a partial cross-sectional view schematically showing the configuration of core substrate 631 in the same field of view as Fig. 18 (fourth modification of the second embodiment).

[0129] The core substrate 631 has a first structure ST and a second structure STa within a ceramic substrate 100. The first structure ST forms at least an inductor L1 (first inductor), specifically inductors L1 to L4. The second structure STa forms at least an inductor L1a (second inductor), specifically inductors L1a to L4a. The first structure ST and the second structure STa are separated from each other, specifically separated from each other by the ceramic substrate 100. Each of the first structure ST and the second structure STa has first to n-th conductor portions and a magnetic material portion. Specifically, the first structure ST has first to fourth conductor portions 201 to 204 and a magnetic material portion 300, and the second structure STa has first to fourth conductor portions 201a to 204a and a magnetic material portion 300a.

[0130] The core substrate 631 has at least one magnetic shield portion, specifically, magnetic shield portions 401 and 402. The magnetic shield portions 401 and 402 are intended to suppress magnetic interference between at least the inductor L1 of the first structure ST and at least the inductor L1a of the second structure STa. The magnetic shield portions 401 and 402 are embedded in the ceramic substrate 100. The magnetic shield portions 401 and 402 are separated from the first conductor portion 201 to the fourth conductor portion 204 and the magnetic material portion 300 of the first structure ST, and are also separated from the first conductor portion 201a to the fourth conductor portion 204a and the magnetic material portion 300a of the second structure STa.

[0131] The magnetic shield portion 401 has a first interface IS1 facing the first conductor portion 201 of the first structure ST, and this first interface IS1 includes a sintered interface. The first structure ST, the magnetic shield portion 401, and at least a portion of the ceramic substrate 100 between the first structure ST and the magnetic shield portion 401 may be formed by co-firing, in which case the sintered interface is formed between the magnetic shield portion 401 and the ceramic substrate 100. A similar sintered interface may also be formed in the magnetic shield portion 402.

[0132] In addition to the first interface IS1, the magnetic shield portion 401 has a second interface IS2 opposite to the first interface IS1. The second interface IS2 faces the first conductor portion 201a of the second structure STa. In this embodiment, the second interface IS2 includes a sintered interface. The first structure ST, the magnetic shield portion 401, and the entire ceramic substrate 100 may be formed by co-firing, in which case the sintered interface is formed between the magnetic shield portion 401 and the ceramic substrate 100. A similar sintered interface may also be formed in the magnetic shield portion 402.

[0133] 21 (at least one cross-sectional view perpendicular to the thickness direction), the magnetic shield portion 401 shields the gap between the center CC1 of the first conductor portion 201 of the first structure ST and the center CC1a of the first conductor portion 201a of the second structure STa. Specifically, on a line LC passing through the center CC1 and the center CC1a, the magnetic shield portion 401 shields the gap between the center CC1 and the center CC1a. Similarly, the magnetic shield portion 402 may shield the gap between the center CC1 and the center CC1a.

[0134] The magnetic shield portion 401 (as part of the magnetic shield portions 401, 402) may surround the first conductor portion 201 of the first structure ST without surrounding the first conductor portion 201 a of the second structure STa. Also, the magnetic shield portion 402 (as part of the magnetic shield portions 401, 402) may surround the first conductor portion 201 a of the second structure STa without surrounding the first conductor portion 201 of the first structure ST.

[0135] The material of the magnetic shields 401 and 402 may be iron, ferrite, or an alloy, such as permalloy, permendur, or Sendust (registered trademark). The magnetic shields 401 and 402 may be any of a conductor, a semiconductor, and an insulator.

[0136] Note that, other than the above, the configuration is substantially the same as that of core substrate 615 (FIG. 18: fourth modified example of embodiment 2), and therefore the same or corresponding elements are denoted by the same reference numerals, and the description thereof will not be repeated. Furthermore, magnetic shield units 401, 402 of embodiment 4 can be applied to any of embodiment 2 and the multiple modified examples described in connection therewith.

[0137] According to this embodiment, the magnetic shield portions 401 and 402 suppress magnetic interference between the inductor L1 of the first structure ST and the inductor L1a of the second structure STa, thereby suppressing crosstalk therebetween.

[0138] In the core substrate 631 ( FIG. 21 ), the first conductor portion 201 of the inductor L1 is in contact with the ceramic substrate 100, similar to the core substrate 615 ( FIG. 18 ). In this case, the first conductor portion 201 is not completely surrounded by the magnetic material portion 300 in a cross-sectional view perpendicular to the thickness direction, as in FIGS. 18 and 21 . This makes magnetic interference more likely to occur between the first conductor portion 201 of the first structure ST and the first conductor portion 201 a of the second structure STa. However, this magnetic interference can be effectively suppressed by the magnetic shield portions 401 and 402. Furthermore, as described in the fourth modification of the second embodiment, the first conductor portion 201 protrudes toward the ceramic substrate 100, crossing the tangent to the boundary between the magnetic material portion 300 and the ceramic substrate 100, which further increases the magnetic interference. This magnetic interference can be effectively suppressed by the magnetic shield portions 401 and 402. As a modified example, when the first conductor portion 201 is farther away from the magnetic material portion 300, the magnetic interference becomes even greater, but this magnetic interference can be effectively suppressed by the magnetic shield portions 401 and 402.

[0139] The magnetic shield portion 401 includes a sintered interface. This allows the magnetic shield portion 401 to be fixed to the core substrate 631 by using sintering. Furthermore, the first interface IS1 and the second interface IS2 of the magnetic shield portion 401 may each include a sintered interface. This allows the magnetic shield portion 401 to be formed by simultaneous firing with its surrounding structure. This allows the core substrate 631 to be manufactured efficiently.

[0140] The magnetic shield portion 401 shields the gap between the center CC1 of the first conductor portion 201 of the first structure ST and the center CC1a of the first conductor portion 201a of the second structure STa, thereby effectively suppressing crosstalk between the first conductor portion 201 of the first structure ST and the first conductor portion 201a of the second structure STa.

[0141] The magnetic shield portions 401 and 402 may include the magnetic shield portion 401 as a portion that surrounds the first structure ST without surrounding the second structure STa, and the magnetic shield portion 402 as a portion that surrounds the second structure STa without surrounding the first structure ST, thereby more reliably suppressing crosstalk between the first structure ST and the second structure STa.

[0142] <First Modification of Fourth Embodiment> FIG. 22 is a partial cross-sectional view schematically illustrating a step in a manufacturing method of a core substrate according to a first modification of the fourth embodiment. The core substrate according to this modification is formed by attaching inductor units to through holes HL and HLa of a ceramic substrate 100F, which is a part of the ceramic substrate 100. Specifically, an inductor unit UT is attached to the through hole HL, and another similar inductor unit UT is attached to the through hole HLa. The inductor units may be fixed to the ceramic substrate 100F by adhesive bonding, press fitting, or shrink fitting. In this case, the second interface IS2 ( FIG. 21 ) in the finally obtained core substrate does not need to include a sintered interface.

[0143] The inductor unit UT has a first structure ST, a magnetic shielding portion 401, and a ceramic substrate 100M therebetween. The ceramic substrate 100M forms a part of the ceramic substrate 100 in the core substrate.

[0144] Next, an example of a method for forming the inductor unit UT will be described below. First, a sintered body having the first structure ST and the ceramic substrate 100M is formed by co-firing. Next, with the upper and lower surfaces of this sintered body, which are opposite to each other in the thickness direction, masked, a magnetic shield portion 401 is formed on the side surface of the sintered body by sputtering. After that, the masking is removed. In this manner, the inductor unit UT is obtained.

[0145] In this modification, the ceramic unit UT is prepared separately from the ceramic substrate 100F. Furthermore, the second interface IS2 does not need to include a sintered interface in the core substrate. Therefore, a non-ceramic substrate having through holes HL and HLa can be used instead of the ceramic substrate 100F. The non-ceramic substrate 100F may be a resin substrate.

[0146] <Second Modification of Fourth Embodiment> Figure 23 is a partial cross-sectional view schematically illustrating the configuration of a core substrate 632 according to a second modification of the fourth embodiment, taken in the same field of view as Figure 21. The core substrate 632 has a magnetic shield portion 400 instead of the magnetic shield portions 401, 402 (Figure 21). While the center CC1 of the first conductor portion 201 of the first structure ST and the center CC1a of the first conductor portion 201a of the second structure STa are shielded by multiple magnetic shield portions 401, 402 in the core substrate 631 (Figure 21), the distance between these two is shielded by a single magnetic shield portion 400 in the core substrate 632 (Figure 23) of this modification. The magnetic shield portion 400 may have a portion that surrounds the first structure ST without surrounding the second structure STa (the portion included in region DA in the figure) and a portion that surrounds the second structure STa without surrounding the first structure ST (the portion included in region DB in the figure).

[0147] According to this modification, the configuration of the core substrate can be further simplified, and the core substrate can be more easily made smaller.

[0148] 24 is a schematic diagram showing an example of electrical connection of a plurality of inductors L1, L2, L1a, and L2a built into a core substrate 641 according to embodiment 5. Fig. 25 is a partial cross-sectional view schematically showing the configuration of core substrate 641 in the same field of view as Fig. 11 (second modified example of embodiment 1).

[0149] The core substrate 641 includes a first structure ST and a second structure STa within a ceramic substrate 100. The first structure ST includes at least an inductor L1 (first inductor), specifically inductors L1 and L2. The second structure STa includes at least an inductor L1a (second inductor), specifically inductors L1a and L2a. The first structure ST and the second structure STa are separated from each other, specifically by the ceramic substrate 100. Each of the first structure ST and the second structure STa includes a first conductor portion and a first magnetic material portion. Specifically, the first structure ST includes a first conductor portion 201 and a first magnetic material portion 301, and the second structure STa includes a first conductor portion 201a and a first magnetic material portion 301a. Furthermore, each of the first structure ST and the second structure STa may include a second conductor portion and a second magnetic material portion. Specifically, the first structure ST has a second conductor portion 202 and a second magnetic material portion 302, and the second structure STa has a second conductor portion 202a and a second magnetic material portion 302a.

[0150] The core substrate 631 has at least one magnetic shield portion, specifically, magnetic shield portions 401 and 402. The magnetic shield portions 401 and 402 are intended to suppress magnetic interference between at least the inductor L1 of the first structure ST and at least the inductor L1a of the second structure STa. The magnetic shield portions 401 and 402 are embedded in the ceramic substrate 100. The magnetic shield portions 401 and 402 are separated from the first conductor portion 201 and the first magnetic material portion 301 of the first structure ST, and also from the first conductor portion 201a and the first magnetic material portion 301a of the second structure STa. The magnetic shield portions 401 and 402 are further separated from the second conductor portion 202 and the second magnetic material portion 302 of the first structure ST, and also from the second conductor portion 202a and the second magnetic material portion 302a of the second structure STa.

[0151] Note that the configuration other than that described above is substantially the same as that of core substrate 603 ( FIG. 11 : second modified example of embodiment 1) or core substrate 631 ( FIG. 21 : embodiment 4), and therefore the same or corresponding elements are denoted by the same reference numerals, and their description will not be repeated. Furthermore, magnetic shield sections 401 and 402 of embodiment 4 can be applied to both embodiment 1 and the multiple modified examples described in relation thereto. Furthermore, modifications similar to those to embodiment 4 described above may also be applied to embodiment 5.

[0152] According to the fifth embodiment, with respect to the core substrate 641 having the first structure ST and the second structure STa shown in FIG. 24, substantially the same effects as those described in the fourth embodiment can be obtained. Note that in this embodiment, the case where the first structure ST is similar to the core substrate 603 (FIG. 11) has been described in detail, but the first structure ST may be similar to the core substrates 601, 602, 604, etc. Generally speaking, the above-mentioned effects are greater when similar to the core substrate 602 than when similar to the core substrate 601, greater when similar to the core substrate 603 than when similar to the core substrate 602, and greater when similar to the core substrate 604 than when similar to the core substrate 603. The same applies to the fourth embodiment described above.

[0153] <Simulation> Generally, the inductance characteristics of DC superposition when a DC current is superposed decreases from the initial inductance (i.e., the inductance when the DC current is zero) as the DC current increases. According to estimates by the inventors, for an inductor for a semiconductor device mounted on an interposer, it is desirable that the inductance decrease by less than 60% when the DC current increases to 8 A.

[0154] FIG. 26 shows the results of a simulation of the dependence of the DC bias characteristics of the inductance of the core substrate on the deviation ratio S. Specifically, the DC bias characteristics were evaluated as the rate of reduction in inductance when a DC current of up to 8 A was applied. For the simulation conditions, the ceramic substrate 100 was provided with an inductor formed by the first conductor portion 201 and the first magnetic material portion 301, and an inductor formed by the second conductor portion 202 and the second magnetic material portion 302. The former inductor and the latter inductor constituted a series circuit as shown in FIG. 6. The deviation ratio S was defined for each inductor as the deviation between the center of the conductor portion and the center of the magnetic material portion divided by the diameter of the conductor portion. In this simulation, it was assumed that the first conductor portion 201 and the second conductor portion 202 each had a common first circular shape, and the first magnetic material portion 301 and the second magnetic material portion 302 each had a common second circular shape, with the diameter of the second circle being three times the diameter of the first circle. Therefore, when the deviation rate S is greater than 50%, the conductor portion deviates from the center of the magnetic material portion. When the deviation rate S is 0%, the inductance reduction rate is 60%, which is considered excessive. In contrast, when the deviation rate S is 56% and 84%, the inductance reduction rate can be reduced to 50% and 40%, respectively, and the inductance sacrifice is relatively small. When the deviation rate S is 110% and 140%, respectively, the inductance reduction rate can be further reduced, and the inductance sacrifice is not significant. When the deviation rate S is 230%, the inductance reduction rate can be significantly reduced, and the inductance sacrifice is not significant.

[0155] The above-described embodiments and modifications may be freely combined with each other. Although the present invention has been described in detail, the above description is illustrative in all respects and does not limit the present invention. It is understood that countless modifications not illustrated can be envisioned without departing from the scope of the present invention.

[0156] 100: Ceramic substrate 201, 201A, 201a, 201B: First conductor portion 202, 202A, 202a, 202B: Second conductor portion 203, 203a: Third conductor portion 204, 204a: Fourth conductor portion 300, 300A, 300a, 300B: Magnetic material portion 301, 301a: First magnetic material portion 302, 302a: Second magnetic material portion 450: Connection portion 601 to 604, 611 to 615, 621, 631, 632, 641: Core substrate 700: Interposer 791: Wiring layer 811: Semiconductor element 400 to 402: Magnetic shield portion

Claims

1. A core substrate having at least one built-in inductor for forming an interposer on which a semiconductor element is mounted, comprising: a ceramic substrate having a thickness direction; a first conductor portion made of a sintered body and penetrating the ceramic substrate in the thickness direction; and a first magnetic material portion made of ceramic and embedded in the ceramic substrate for increasing the inductance of the first conductor portion, wherein the first conductor portion is offset from the center of the first magnetic material portion in at least one cross-sectional view perpendicular to the thickness direction so that the first magnetic material portion appears.

2. A core substrate according to claim 1, wherein the first conductor portion is in contact with the first magnetic portion.

3. A core substrate according to claim 2, wherein the first conductor portion is in contact with the ceramic substrate.

4. A core substrate as claimed in claim 3, wherein in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion protrudes towards the ceramic substrate, crossing the tangent to the boundary between the first magnetic material portion and the ceramic substrate.

5. A core substrate as described in claim 2, wherein, in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion is in contact with the ceramic substrate without crossing the tangent to the boundary between the first magnetic material portion and the ceramic substrate.

6. A core substrate according to claim 2, wherein, in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the first conductor portion is spaced apart from the ceramic substrate.

7. A core substrate according to claim 1, wherein the first conductor portion is spaced from the first magnetic portion and in contact with the ceramic substrate.

8. A core substrate according to any one of claims 1 to 7, wherein in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears, the center of the first conductor portion is spaced from the center of the first magnetic material portion by 10% or more of the diameter of a circle having the area of ​​the first magnetic material portion.

9. A core substrate according to any one of claims 1 to 7, wherein the at least one cross-sectional view includes any cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion appears.

10. A core substrate according to any one of claims 1 to 7, wherein the first conductor portion is a solid body.

11. A core substrate according to any one of claims 1 to 7, wherein the ceramic substrate is made of low-temperature co-fired ceramics or a composite material of glass and alumina.

12. A core substrate according to any one of claims 1 to 7, wherein a sintered interface is formed between the first conductor portion and a portion of the core substrate other than the first conductor portion.

13. A core substrate as claimed in any one of claims 1 to 7, comprising: a second conductor portion made of a sintered body and penetrating the ceramic substrate in the thickness direction; and a second magnetic material portion embedded in the ceramic substrate for increasing the inductance of the second conductor portion, wherein in at least one cross-sectional view perpendicular to the thickness direction in which the first magnetic material portion and the second magnetic material portion appear, the first conductor portion is offset from the center of the first magnetic material portion, the second conductor portion is offset from the center of the second magnetic material portion, and the distance between the center of the first conductor portion and the center of the second conductor portion is greater than the distance between the center of the first magnetic material portion and the center of the second magnetic material portion.

14. A core substrate according to claim 13, wherein the first conductor portion and the second conductor portion form a series circuit.

15. A core substrate according to claim 14, wherein the ceramic substrate has a surface to which an end of the first conductor portion and an end of the second conductor portion reach, and further comprises a connection portion that electrically connects the end of the first conductor portion and the end of the second conductor portion to each other.

16. A core substrate according to any one of claims 1 to 7, wherein the at least one inductor includes a first inductor and a second inductor, the core substrate has, within the ceramic substrate, a first structure constituting at least the first inductor and a second structure constituting at least the second inductor, the first structure and the second structure being spaced apart from each other, the first structure and the second structure each comprising the first conductor portion and the first magnetic material portion, the core substrate further comprising at least one magnetic shield portion for suppressing magnetic interference between the first inductor and the second inductor, the at least one magnetic shield portion being spaced apart from the first conductor portion and the first magnetic material portion of each of the first structure and the second structure.

17. A core substrate according to claim 16, wherein the at least one magnetic shield portion includes a magnetic shield portion having a first interface facing the first conductor portion of the first structure, the first interface including a sintered interface.

18. A core substrate according to claim 17, wherein the one magnetic shield portion has a second interface opposite the first interface, and the second interface includes a sintered interface.

19. A core substrate as described in claim 16, wherein, in at least one cross-sectional view perpendicular to the thickness direction, the at least one magnetic shield portion blocks the gap between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure.

20. A core substrate according to claim 19, wherein the at least one magnetic shield section that shields the space between the center of the first conductor section of the first structure and the center of the first conductor section of the second structure is a single magnetic shield section.

21. A core substrate according to claim 16, wherein the at least one magnetic shielding portion has a portion that surrounds the first structure without surrounding the second structure, and a portion that surrounds the second structure without surrounding the first structure.

22. An interposer comprising: a core substrate according to any one of claims 1 to 7; and a wiring layer laminated on the core substrate, the wiring layer having a mounting surface on which a semiconductor element is to be mounted.

23. A core substrate having at least one built-in inductor for forming an interposer on which a semiconductor element is mounted, comprising: a ceramic substrate having a thickness direction; first to n-th conductor portions (n ​​is an integer of 2 or more) made of a sintered body and penetrating the ceramic substrate in the thickness direction; and magnetic material portions made of ceramic and embedded in the ceramic substrate for increasing the inductance of the first to n-th conductor portions, wherein, in at least one cross-sectional view perpendicular to the thickness direction in which the magnetic material portions appear, first to n-th regions into which the magnetic material portions are virtually divided are defined so that a position belonging to the k-th region (k is an integer of 1 to n) is located closest to the center of the k-th conductor portion among the centers of the first to n-th conductor portions, and the k-th conductor portion is arranged away from the center of the k-th region toward the edge of the magnetic material portion.

24. A core substrate according to claim 23, wherein the at least one inductor includes a first inductor and a second inductor, the core substrate has, within the ceramic substrate, a first structure constituting at least the first inductor and a second structure constituting at least the second inductor, the first structure and the second structure being spaced apart from each other, the first structure and the second structure each comprising the first to n-th conductor portions and the magnetic material portion, the core substrate further comprising at least one magnetic shield portion for suppressing magnetic interference between the first inductor and the second inductor, the at least one magnetic shield portion being spaced apart from the first to n-th conductor portions and the magnetic material portion of each of the first structure and the second structure.

25. A core substrate according to claim 24, wherein the at least one magnetic shield portion includes a magnetic shield portion having a first interface facing the first conductor portion of the first structure, the first interface including a sintered interface.

26. A core substrate according to claim 25, wherein the one magnetic shield portion has a second interface opposite the first interface, and the second interface includes a sintered interface.

27. A core substrate as described in claim 24, wherein, in at least one cross-sectional view perpendicular to the thickness direction, the at least one magnetic shield portion blocks the gap between the center of the first conductor portion of the first structure and the center of the first conductor portion of the second structure.

28. A core substrate according to claim 27, wherein the at least one magnetic shield section that shields the space between the center of the first conductor section of the first structure and the center of the first conductor section of the second structure is a single magnetic shield section.

29. A core substrate according to claim 24, wherein the at least one magnetic shield portion has a portion that surrounds the first structure without surrounding the second structure, and a portion that surrounds the second structure without surrounding the first structure.

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