Magnetic core with hard ferromagnetic bias layer and structure including the magnetic core

Abstract

[Solution] The planar magnetic core includes a plurality of ferromagnetic layers, including a plurality of hard ferromagnetic bias layers and a plurality of soft ferromagnetic layers. Each ferromagnetic layer has one soft ferromagnetic layer or one hard ferromagnetic bias layer. Each hard ferromagnetic bias layer is a ferromagnetic layer adjacent to at least one soft ferromagnetic layer. The planar magnetic core also includes a plurality of insulating layers, each insulating layer disposed between adjacent ferromagnetic layers. Each ferromagnetic layer has an easy axis of magnetization parallel to a major surface of the planar magnetic core and aligned with one another. Each hard ferromagnetic layer is magnetized to generate an in-plane bias magnetic flux passing through the hard ferromagnetic layer in a first direction parallel to the easy axis of magnetization and forming a closed path through adjacent soft ferromagnetic layers in a second direction parallel to the first direction.

Description

[Technical Field]

[0001] This application claims priority to U.S. patent application Ser. No. 17 / 108,096, filed December 1, 2020, and entitled "Magnetic Core with Hard Ferromagnetic Biasing Layers and Structures Containing Same," the contents of which are incorporated herein by reference.

[0002] This application relates to magnetic cores and devices that include magnetic cores, such as inductors. [Background technology]

[0003] Inductors for microelectronics include alternating soft ferromagnetic and insulating layers. Figure 1A shows a typical example of a horizontally stacked magnetic core 10. The core includes soft ferromagnetic layers 100 and insulating layers 110 disposed between adjacent soft ferromagnetic layers 100. A coil is configured to generate magnetic flux through the soft ferromagnetic layers 100, resulting in alternating magnetization states 120, as indicated by the arrows.

[0004] One problem with this configuration is that some of the magnetic flux forms a closed circuit within a given layer in addition to forming a closed circuit in adjacent layers. The formation of a closed circuit within a given layer results in multiple magnetic domains 130 with antiparallel magnetization states 135, minimizing the energy of the intralayer closed circuit, as shown, for example, in FIG. 1B, which is a top view of the top soft ferromagnetic layer 100 in the core 10. The top insulator 110 is not shown in FIG. 1B for clarity. Domain walls 140 form between the magnetic domains 130, where a portion of the magnetic moment 145 is not aligned with any of the domains 130. An applied magnetic field from the inductor coil reorients the magnetic moments 145, which causes both hysteresis and power loss due to eddy currents.

[0005] It would be desirable to overcome the above and / or other deficiencies in the art. The prior art documents relevant to the invention of this application are as follows (including documents cited in the international phase after the international filing date and documents cited when the application entered the national phase in other countries). (Prior art document) (Patent document) (Patent Document 1) U.S. Patent No. 9,647,053 (Patent Document 2) U.S. Patent Application Publication No. 2007 / 218273 (Patent Document 3) U.S. Patent Application Publication No. 2018 / 295724 (Patent Document 4) U.S. Patent Application Publication No. 2013 / 0134534 (Patent Document 5) U.S. Patent Application Publication No. 2015 / 0171157 (Patent Document 6) Chinese Patent Application Publication No. 101840993 (Patent Document 7) U.S. Patent No. 9,679,958 (Patent Document 8) U.S. Patent Application Publication No. 2017 / 0250133 (Patent Document 9) U.S. Patent Application Publication No. 2020 / 0152364 (Patent Document 10) U.S. Patent Application Publication No. 2016 / 0126008 (Patent Document 11) US Patent Application Publication No. 2015 / 0036308 Summary of the Invention [Means for solving the problem]

[0006] Although the exemplary embodiments described herein possess novel features, no single embodiment is essential, nor does a single embodiment alone contribute to preferred features. The following description and drawings detail specific exemplary implementations of the present disclosure, illustrating some exemplary aspects for implementing various principles of the present disclosure. However, these specific examples are not intended to be exhaustive of the various embodiments possible in the present disclosure. Without limiting the scope of the claims, a summary of advantageous features is provided below. Other objectives and other advantageous and novel features of the present disclosure are described in the following detailed description of the present disclosure with reference to the drawings, which are intended to illustrate, but not limit, the present invention.

[0007] One aspect of the present invention relates to a horizontally stacked planar magnetic core having a plurality of ferromagnetic layers, including a plurality of hard ferromagnetic layers and a plurality of soft ferromagnetic layers, each ferromagnetic layer comprising one of the soft ferromagnetic layers or one of the hard ferromagnetic layers, each hard ferromagnetic layer being adjacent to at least one soft ferromagnetic layer, the horizontally stacked planar magnetic core further comprising a plurality of insulating layers, each insulating layer disposed between adjacent ferromagnetic layers, each ferromagnetic layer having an easy axis of magnetization parallel to a major surface of the planar magnetic core, the easy axes being aligned with one another.

[0008] In one or more embodiments, the ferromagnetic layers are stacked along the height of the planar magnetic core. In one or more embodiments, the plurality of hard ferromagnetic layers includes a top hard ferromagnetic layer disposed as a top ferromagnetic layer. In one or more embodiments, the plurality of hard ferromagnetic layers includes a bottom hard ferromagnetic layer disposed as a bottom ferromagnetic layer. In one or more embodiments, the plurality of soft ferromagnetic layers are disposed between the top and bottom hard ferromagnetic layers. In one or more embodiments, the plurality of soft ferromagnetic layers includes N soft ferromagnetic layers, where N is an odd integer greater than or equal to 3.

[0009] In one or more embodiments, the soft ferromagnetic layer thickness of each soft ferromagnetic layer is the same, and the hard ferromagnetic layer thickness of each hard ferromagnetic layer is the same, and the hard ferromagnetic layer thickness is related to the soft ferromagnetic layer thickness. In one or more embodiments, the ratio of the hard ferromagnetic layer thickness to the soft ferromagnetic layer thickness is:

[0010]

number

[0011] In one or more embodiments, each of the top and bottom hard ferromagnetic layers is magnetized to generate a bias flux passing through each of the hard ferromagnetic layers in a first direction parallel to the easy axis of the hard ferromagnetic layer. In one or more embodiments, the bias flux passing through the top hard ferromagnetic layer forms a closed path through a first adjacent soft ferromagnetic layer, and the bias flux passing through the bottom hard ferromagnetic layer forms a closed path through a second adjacent soft ferromagnetic layer, and each of the bias fluxes passes through the first and second adjacent soft ferromagnetic layers in a second direction opposite the first direction. In one or more embodiments, the bias magnetic flux passing through the first and second adjacent soft ferromagnetic layers each induces a magnetic flux passing through the first and second adjacent soft ferromagnetic layers in the second direction, the induced magnetic flux passing through the first adjacent soft ferromagnetic layer forms a closed path passing through the third adjacent soft ferromagnetic layer in the first direction, the induced magnetic flux passing through the second adjacent soft ferromagnetic layer forms a closed path passing through the fourth adjacent soft ferromagnetic layer in the first direction, the top hard ferromagnetic layer and the third adjacent soft ferromagnetic layer are ferromagnetic layers adjacent to the first adjacent soft ferromagnetic layer, and the bottom hard ferromagnetic layer and the fourth adjacent soft ferromagnetic layer are ferromagnetic layers adjacent to the second adjacent soft ferromagnetic layer.

[0012] In one or more embodiments, the hard ferromagnetic layer and the soft ferromagnetic layer comprise cobalt, iron, and / or nickel. In one or more embodiments, the insulating layer comprises (a) aluminum, cobalt, chromium, silicon, tantalum, titanium, and / or zirconium, or (b) a compound of (1) aluminum, cobalt, chromium, silicon, tantalum, titanium, and / or zirconium and (2) oxygen and / or nitrogen. In one or more embodiments, each hard ferromagnetic layer has a coercivity greater than 50 Oe, and each soft ferromagnetic layer has a coercivity less than 1 Oe. In one or more embodiments, the thickness of each ferromagnetic layer ranges from about 10 nm to about 1,000 nm, the thickness of each ferromagnetic layer being measured along an axis perpendicular to a major surface of the planar magnetic core. In one or more embodiments, the thickness of each insulating layer ranges from about 1 nm to about 50 nm, the thickness of each insulating layer being measured along the axis. In one or more embodiments, the planar magnetic core has a total thickness of 100,000 nm or less, the total thickness being measured along the axis.

[0013] Another aspect of the present invention relates to a horizontally stacked planar magnetic core having a plurality of soft-hard ferromagnetic layer pairs, each soft-hard ferromagnetic layer pair including one soft ferromagnetic layer and one hard ferromagnetic layer, an intra-pair spacer layer disposed between the soft ferromagnetic layer and the hard ferromagnetic layer of each soft-hard ferromagnetic layer pair, and an inter-pair spacer layer disposed between adjacent soft-hard ferromagnetic layer pairs, wherein the inter-pair spacer layer thickness of each inter-pair spacer layer is greater than the intra-pair spacer layer thickness of each intra-pair spacer layer, and the inter-pair spacer layer thicknesses and the intra-pair spacer layer thicknesses are measured along an axis perpendicular to a major surface of the planar magnetic core.

[0014] In one or more embodiments, for each soft-hard ferromagnetic layer pair, the relative position of the soft ferromagnetic layer with respect to the hard ferromagnetic layer is the same. In one or more embodiments, for each soft-hard ferromagnetic layer pair, the soft ferromagnetic layer is disposed below the hard ferromagnetic layer.

[0015] In one or more embodiments, the horizontally stacked planar magnetic core further includes a first inter-pair spacer layer disposed between the first soft-hard ferromagnetic layer pair and the second soft-hard ferromagnetic layer pair, and a second inter-pair spacer layer disposed between the second soft-hard ferromagnetic layer pair and a third soft-hard ferromagnetic layer pair, the second soft-hard ferromagnetic layer pair being disposed between the first soft-hard ferromagnetic layer pair and the third soft-hard ferromagnetic layer pair.

[0016] In one or more embodiments, each soft ferromagnetic layer has the same soft ferromagnetic layer thickness, each hard ferromagnetic layer has the same hard ferromagnetic layer thickness, the soft ferromagnetic layer thickness and the hard ferromagnetic layer thickness are measured along the axis, and the hard ferromagnetic layer thickness is related to the soft ferromagnetic layer thickness. In one or more embodiments, in each soft-hard ferromagnetic layer pair, the hard ferromagnetic layer is magnetized to generate a bias flux that passes through the hard ferromagnetic layer in a first direction parallel to an easy axis of magnetization in a major plane of the hard ferromagnetic layer, and the bias flux forms a closed loop that passes through the soft ferromagnetic layer only in a second direction parallel to the easy axis of magnetization in a major plane of the soft ferromagnetic layer. In one or more embodiments, in each soft-hard ferromagnetic layer pair, the bias magnetic flux passing through the soft ferromagnetic layer induces magnetic flux passing through the soft ferromagnetic layer in the second direction, and the induced magnetic flux forms a closed loop passing through the hard ferromagnetic layer only in the first direction.

[0017] In one or more embodiments, the ratio of the hard ferromagnetic layer thickness to the soft ferromagnetic layer thickness is:

[0018]

number

[0019] In yet another aspect of the present invention, an inductor includes a horizontally stacked planar magnetic core having a plurality of ferromagnetic layers including a plurality of hard ferromagnetic layers and a plurality of soft ferromagnetic layers, each ferromagnetic layer comprising one of the soft ferromagnetic layers or one of the hard ferromagnetic layers, each hard ferromagnetic layer being a ferromagnetic layer adjacent to at least one soft ferromagnetic layer. The inductor further includes a plurality of insulating layers, each insulating layer disposed between adjacent ferromagnetic layers. Each ferromagnetic layer has an easy axis of magnetization parallel to a major surface of the planar magnetic core, the easy axes being aligned with one another. The inductor further includes a conductive winding wound generally helically around the outside of the planar magnetic core.

[0020] In one or more embodiments, each ferromagnetic layer has a hard axis in a major plane of the ferromagnetic layer that is perpendicular to the easy axis, the hard axes being aligned with one another, and the conductive windings are configured to generate inductor coil flux in each ferromagnetic layer that passes through the horizontally laminated planar magnetic core in a direction parallel to the hard axis. In one or more embodiments, the plurality of hard ferromagnetic layers includes a top hard ferromagnetic layer disposed as a top ferromagnetic layer and a bottom hard ferromagnetic layer disposed as a bottom ferromagnetic layer, and the plurality of soft ferromagnetic layers are disposed between the top and bottom hard ferromagnetic layers, and each of the top and bottom hard ferromagnetic layers is magnetized to generate a bias magnetic flux passing through each of the hard ferromagnetic layers in a first direction parallel to the easy axis of the hard ferromagnetic layer, the bias magnetic flux passing through the top hard ferromagnetic layer forming a closed path through a first adjacent soft ferromagnetic layer, and the bias magnetic flux passing through the bottom hard ferromagnetic layer forming a closed path through a second adjacent soft ferromagnetic layer, and each of the bias magnetic flux passing through the first and second adjacent soft ferromagnetic layers in a second direction opposite to the first direction. In one or more embodiments, the bias magnetic flux passing through the first and second adjacent soft ferromagnetic layers each induces a magnetic flux passing through the first and second adjacent soft ferromagnetic layers in the second direction, the induced magnetic flux passing through the first adjacent soft ferromagnetic layer forms a closed path passing through the third adjacent soft ferromagnetic layer in the first direction, the induced magnetic flux passing through the second adjacent soft ferromagnetic layer forms a closed path passing through the fourth adjacent soft ferromagnetic layer in the first direction, the top hard ferromagnetic layer and the third adjacent soft ferromagnetic layer are ferromagnetic layers adjacent to the first adjacent soft ferromagnetic layer, and the bottom hard ferromagnetic layer and the fourth adjacent soft ferromagnetic layer are ferromagnetic layers adjacent to the second adjacent soft ferromagnetic layer.

[0021] Another aspect of the present invention relates to a structure having a semiconductor integrated circuit with a multi-layer wiring network formed on a substrate, the inductor being incorporated into the multi-layer wiring network.

[0022] Yet another aspect of the present invention relates to a method of manufacturing a semiconductor substrate comprising depositing a plurality of ferromagnetic layers, including a plurality of hard ferromagnetic layers and a plurality of soft ferromagnetic layers, each ferromagnetic layer comprising one of the soft ferromagnetic layers or one of the hard ferromagnetic layers, each hard ferromagnetic layer being a ferromagnetic layer adjacent to at least one soft ferromagnetic layer, depositing an insulating layer between adjacent ferromagnetic layers, inducing easy axes in each ferromagnetic layer, the easy axes being aligned with each other and parallel to a top plane of the semiconductor substrate, magnetizing each of the hard ferromagnetic layers to generate a bias flux passing through the hard ferromagnetic layer in a first direction, the bias flux being parallel to the easy axis in each hard ferromagnetic layer, and defining a horizontally stacked planar magnetic core comprising the plurality of ferromagnetic layers and the insulating layer.

[0023] In one or more embodiments, the method further includes defining a hard axis in each ferromagnetic layer, the hard axis being perpendicular to the easy axis in a major plane of each ferromagnetic layer, and forming a conductive winding around the horizontally laminated planar magnetic core, the conductive winding configured to generate inductor coil flux in each ferromagnetic layer, the inductor coil flux passing through the horizontally laminated planar magnetic core in a direction parallel to the hard axis.

[0024] In one or more embodiments, the manufacturing method further includes depositing a top hard ferromagnetic layer as the top ferromagnetic layer, depositing a bottom hard ferromagnetic layer as the bottom ferromagnetic layer, and depositing the plurality of soft ferromagnetic layers between the bottom and top hard ferromagnetic layers.

[0025] In one or more embodiments, the ratio of the hard ferromagnetic layer thickness of each hard ferromagnetic layer to the soft ferromagnetic layer thickness of each soft ferromagnetic layer is:

[0026]

number

[0027] In one or more embodiments, the manufacturing method further includes depositing a plurality of soft-hard ferromagnetic layer pairs, each soft-hard ferromagnetic layer pair including one of the soft ferromagnetic layers and one of the hard ferromagnetic layers; depositing an intra-pair spacer layer between the soft ferromagnetic layer and the hard ferromagnetic layer of each soft-hard ferromagnetic layer pair; and depositing an inter-pair spacer layer between adjacent soft-hard ferromagnetic layer pairs, each insulating layer comprising one of the intra-pair spacer layer or the inter-pair spacer layer, the inter-pair spacer layer thickness of each inter-pair spacer layer being greater than the intra-pair spacer layer thickness of each intra-pair spacer layer, the inter-pair spacer layer thickness and the intra-pair spacer layer thickness being measured along an axis perpendicular to a top plane of the semiconductor substrate. In one or more embodiments, the ratio of the hard ferromagnetic layer thickness of each hard ferromagnetic layer to the soft ferromagnetic layer thickness of each soft ferromagnetic layer is:

[0028]

number

[0029] For a full understanding of the gist and advantages of the present concepts, reference is made to the following detailed description of the preferred embodiments and the accompanying drawings. [Figure 1A] FIG. 1A is a cross-sectional view of a conventional horizontally stacked magnetic core. [Figure 1B] FIG. 1B is a plan view of the horizontally stacked magnetic core shown in FIG. 1A. [Figure 2] FIG. 2 is a cross-sectional view of a planar magnetic core according to one embodiment. [Figure 3] FIG. 3 is an exploded perspective view of the planar magnetic core shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of a planar magnetic core according to another embodiment. [Figure 5] FIG. 5 is a cross-sectional view of a planar magnetic core according to another embodiment. [Figure 6] FIG. 6 is an exploded perspective view of the planar magnetic core shown in FIG. [Figure 7] FIG. 7 is a flow diagram of a method for manufacturing a semiconductor device, according to one embodiment. [Figure 8] FIG. 8 is a representative cross-sectional view of a magnetic core inductor incorporated into a semiconductor device on a substrate, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] The horizontally stacked planar magnetic core includes a plurality of ferromagnetic layers, including a plurality of hard ferromagnetic bias layers and a plurality of soft ferromagnetic layers. At least one soft ferromagnetic layer is adjacent to each hard ferromagnetic bias layer. Each hard ferromagnetic bias layer is magnetized to generate an in-plane bias flux passing through the hard ferromagnetic bias layer in a first direction. The bias flux forms a closed path by passing through adjacent soft ferromagnetic layers in a second direction opposite to the first direction (e.g., the first and second directions are antiparallel). The ferromagnetic layers have anisotropy such that their easy axes are parallel to each other and parallel to the first and second directions. The hard axes of the ferromagnetic layers are perpendicular to the easy axes in the major plane of each ferromagnetic layer.

[0031] The bias flux passing through the adjacent soft ferromagnetic layer sets a preferred direction of magnetization of the magnetic moment of the soft ferromagnetic layer, thereby forming an interlayer closed path for the magnetic flux between the hard ferromagnetic bias layer and the soft ferromagnetic layer(s). This allows the magnetic flux to form a closed path within the adjacent hard ferromagnetic bias layer, rather than passing through the soft ferromagnetic layer again to form a closed path (which would result in the formation of new magnetic domains magnetized in both the first and second directions), thereby reducing the number of magnetic domain walls formed within the soft ferromagnetic layer. The elimination of magnetic domains and associated magnetic domain walls caused by the bias flux in the hard ferromagnetic bias layer reduces hysteresis and eddy current power losses in the inductor compared to using an inductor core that does not include a hard ferromagnetic bias layer.

[0032] A horizontally stacked planar magnetic core can be used to form an inductor, and the inductor coil can be configured to generate an inductor coil flux that passes through the ferromagnetic layers in a direction parallel to the hard axis.

[0033] 2 is a cross-sectional view of one embodiment of a horizontally stacked planar magnetic core 20. The planar magnetic core 20 can be fabricated on a substrate 250 and / or incorporated into a multi-layer wiring structure on the substrate 250 to form an inductor.

[0034] The magnetic core 20 includes multiple ferromagnetic layers 200 and insulating layers 210. Each ferromagnetic layer 200 is either a soft ferromagnetic layer 202 or a hard ferromagnetic bias layer 204. The ferromagnetic layers 200 include multiple soft ferromagnetic layers 202 and multiple hard ferromagnetic bias layers 204, with the ferromagnetic layers being arranged in alternating order of (a) soft ferromagnetic layers 202 and (b) hard ferromagnetic bias layers 204. The ferromagnetic layers 204 are stacked along the height of the core 20 (e.g., along the "z" axis).

[0035] Each hard ferromagnetic bias layer 204 is a ferromagnetic layer 200 adjacent to at least one soft ferromagnetic layer 202. For example, in Figure 2, the top ferromagnetic layer 200A in the stack of ferromagnetic layers 200 is the top hard ferromagnetic bias layer 204. The ferromagnetic layer adjacent to layer 200A is ferromagnetic layer 200B, which is soft ferromagnetic layer 202. In another example, the ferromagnetic layers adjacent to hard ferromagnetic bias layer 200C are soft ferromagnetic layers 200B and 200D.

[0036] Each ferromagnetic layer 200 has anisotropy, with its easy axis 220 parallel to the "x" axis and its hard axis 222 parallel to the "y" axis. For example, within the major plane of the ferromagnetic layer 200, the hard axis 222 is perpendicular to the easy axis 220. The major plane of the ferromagnetic layer 200 corresponds to the xy plane (e.g., the length (x) and width (y) of the ferromagnetic layer 200, and the thickness (z) of the ferromagnetic layer 200 is perpendicular to the xy plane). In some embodiments, the anisotropy of the ferromagnetic layer 200 is induced during fabrication to permanently or semi-permanently set the hard and easy axes. For example, the easy axis 220 can be set by applying a bias field parallel to the desired easy axis 220 during or after deposition of each ferromagnetic layer 200, followed by an annealing process.

[0037] Each ferromagnetic layer 200 may include cobalt, iron, and / or nickel, or a compound or alloy containing cobalt, iron, and / or nickel. In one example, the soft ferromagnetic layer 202 is made of Co, where x and y are about 0.915 and about 0.04, respectively. x Zr y Ta 1-x-y In another example, the soft ferromagnetic layer 202 can be composed of CoZrTa-B (or CoZrTaB), CoNiFe, NiFe, CoFe, and / or CoFeB, or an alloy containing any of the above compounds. The hard ferromagnetic bias layer 204 can be composed of AlNiCo, NdFeB, SmCo, Fe x O y The alloy may be composed of a ferritic alloy (containing one or more metals such as Co, Sr, and / or Ba), or an alloy containing any of the above compounds.

[0038] Insulator layer 210 can be composed of (a) aluminum, cobalt, chromium, silicon, tantalum, titanium, and / or zirconium, or (b) compounds of (1) aluminum, cobalt, chromium, silicon, tantalum, titanium, and / or zirconium and (2) oxygen and / or nitrogen. For example, insulator layer 210 can be composed of silicon dioxide (SiO), aluminum oxide (Al x O y ), chromium oxide (Cr x O y ), cobalt oxide (Co x O y ), tantalum oxide (Ta x O y ), titanium oxide (Ti x O y ), silicon nitride (Si x N y ), aluminum nitride (Al x N y ), tantalum nitride (Ta x N y), or a combination of two or more of the above. In some embodiments, the insulator layer 210 can function as a spacer layer between adjacent ferromagnetic layers 200. The thickness of each spacer layer is related to the energy state for forming a closed magnetic field loop in adjacent soft and hard ferromagnetic layers 202, 204. In some embodiments, the thickness of the spacer layer can be adjusted to promote a closed magnetic field loop in the pair of soft and hard ferromagnetic layers 202, 204, for example, as described below in connection with FIG. 4.

[0039] At the top layer of core 20, insulator layer 210 can function as cap layer 212. At the bottom layer of core 20, insulator layer 210 can function as adhesion layer 214. Of course, the terms "top layer" and "bottom layer" are not applicable because magnetic core 20 can be flipped or rotated, but the layers maintain the same relative positions to each other.

[0040] The hard ferromagnetic bias layers 204 are magnetized to generate a corresponding bias field. The in-plane bias flux 230 resulting from the bias field passes through the hard ferromagnetic bias layers 204 in a first direction parallel to the easy axis 220 (e.g., from right to left as shown by the arrows in FIG. 2 ). The bias flux 230 passing through each hard ferromagnetic bias layer 204 passes through the adjacent soft ferromagnetic layer(s) 202, as shown by the curved arrows 235, to form a closed bias field loop. The bias flux 230 passing through each soft ferromagnetic layer 202 passes in a second direction opposite (e.g., anti-parallel to) the first direction (e.g., from left to right). The second direction is parallel to the easy axis 220.

[0041] When the bias flux 230 passes through adjacent hard ferromagnetic bias layer(s) 204 to form a closed loop (as indicated by curved arrows 235), it has lower energy than when it passes through the same soft ferromagnetic layer 202 and returns again to form a closed loop (e.g., forming a domain wall within each soft ferromagnetic layer 202). For example, the hard ferromagnetic layers 204 have a higher magnetic permeability than the soft ferromagnetic layers 202.

[0042] The bias flux 230 passing through the soft ferromagnetic layer 202 generates a magnetic moment and an induced flux 240 passing in a second direction through the soft ferromagnetic layer 202. Like the bias flux 230, when the induced flux 240 passes through adjacent hard ferromagnetic bias layer(s) 204 to form a closed loop (as indicated by curved arrows 235), it has lower energy than when it passes through the same soft ferromagnetic layer 202 and back again to form a closed loop (e.g., forming a domain wall within each soft ferromagnetic layer 202).

[0043] When core 20 is incorporated into an inductor operating at high frequencies (e.g., at least 1 MHz), reducing the domain walls in soft ferromagnetic layer 202 can improve the efficiency of core 20 (e.g., by lowering the coercivity of laminated core 20 compared to when core 20 does not include hard ferromagnetic bias layer 204). For example, core 20 can reduce hysteresis and eddy current power losses compared to when core 20 does not include hard ferromagnetic bias layer 204.

[0044] Each hard ferromagnetic bias layer 204 can have a coercivity greater than about 50 Oe, for example, in the range of about 50 Oe to about 1,000 Oe, including about 250 Oe, about 500 Oe, about 750 Oe, and any range or value between any two of the foregoing coercivities. Each soft ferromagnetic layer 204 can have a coercivity less than about 1 Oe, for example, in the range of about 0.01 Oe to 1 Oe, including about 0.1 Oe, about 0.25 Oe, about 0.5 Oe, about 0.75 Oe, and any range or value between any two of the foregoing coercivities.

[0045] The thickness of each ferromagnetic layer 200 can be from about 10 nm to about 1,000 nm, and the thickness of each insulating layer 210 can be from about 1 nm to about 50 nm. The total thickness of core 20 can be less than about 100,000 nm (i.e., 100 microns). The thicknesses of ferromagnetic layer 200, insulating layer 210, and core 20 are measured along the "z" axis, which is perpendicular to the major surface of core 20.

[0046] When core 20 is incorporated into a multi-layer wiring structure to form an inductor, the inductor coil is preferably constructed and oriented so that its magnetic flux passes through ferromagnetic layer 200 in a direction parallel to hard axis 222 .

[0047] FIG. 3 is an exploded perspective view of the planar magnetic core 20 shown in FIG. 2. The cap layer 212 is not shown in FIG. 3 for clarity. FIG. 3 further illustrates that magnetic flux lines 230, 240 pass through the hard ferromagnetic bias layer 204 in a first direction and through the soft ferromagnetic layer 202 in a second direction (i.e., from left to right and right to left in FIG. 3 ), and extend between the soft and hard ferromagnetic layers 202, 204. Thus, the magnetic flux has a closed path passing through the soft and hard ferromagnetic layers 202, 204. The magnetic flux lines 230, 240 passing through the soft and hard ferromagnetic layers 202, 204 are parallel or substantially parallel (e.g., within 10 degrees) to the easy axis 220. Furthermore, the magnetic flux lines 230, 240 passing through the soft and hard ferromagnetic layers 202, 204 are perpendicular or substantially perpendicular (ie, within 10 degrees) to the hard axis 222 in each major plane of the soft and hard ferromagnetic layers 202, 204.

[0048] FIG. 4 is a cross-sectional view of a planar magnetic core according to another embodiment. Core 40 is identical to core 20, except as described below. In FIG. 4, the soft and hard ferromagnetic layers 202, 204 are labeled 202A, 202B, ... 202N, 204A, 204B, ... 204N, respectively, for ease of illustration. The thicknesses of the soft and hard ferromagnetic layers 202, 204 in core 40 are related (e.g., co-optimized) to equalize the magnetic flux passing through adjacent pairs of soft and hard ferromagnetic layers 202, 204. That is,

[0049]

number

[0050]

number

[0051] According to equations (1) and (2), in order for the magnetic fluxes passing through an adjacent pair of soft and hard ferromagnetic layers 202 and 204 to be equal, the ratio of the thickness of the hard ferromagnetic bias layer 204 to the thickness of the soft ferromagnetic layer 202 must be:

[0052]

number

[0053]

number

[0054] The thickness of the insulator layer 210 can be adjusted to facilitate a closed magnetic field loop between the pair of soft and hard ferromagnetic layers 202, 204. Typically, the core 40 has N soft-hard ferromagnetic layer pairs 440, each of which has one soft ferromagnetic layer 202 and one hard ferromagnetic bias layer 204. The N soft-hard ferromagnetic layer pairs 440 are repeating units in which the relative positions of the soft and hard ferromagnetic layers 202, 204 are the same across each soft-hard ferromagnetic layer pair 440. For example, if the soft ferromagnetic layer 202 is located above the hard ferromagnetic bias layer 204 in one pair of soft-hard ferromagnetic layers 440, then the soft ferromagnetic layer 202 is located above the hard ferromagnetic bias layer 204 in all of the N soft-hard ferromagnetic layer pairs 440. Similarly, if the soft ferromagnetic layer 202 is located below the hard ferromagnetic bias layer 204 in a pair of soft-hard ferromagnetic layers 440, then the soft ferromagnetic layer 202 is located below the hard ferromagnetic bias layer 204 in all N soft-hard ferromagnetic layer pairs 440.

[0055] When the soft ferromagnetic layer 202 has two adjacent hard ferromagnetic bias layers 204, the thickness of the first insulator 210 disposed between the soft ferromagnetic layer 202 and the first adjacent hard ferromagnetic bias layer 204 (e.g., the hard ferromagnetic bias layer 204 in the adjacent pair of soft-hard ferromagnetic layers 440) can be greater than the thickness of the second insulator 210 disposed between the soft ferromagnetic layer 202 and the second adjacent hard ferromagnetic bias layer 204 (e.g., the hard ferromagnetic bias layer 204 in the pair of soft-hard ferromagnetic layers 440 of the soft ferromagnetic layer 202). Taking the soft ferromagnetic layer 202A as an example, the thickness of the insulator layer 210B is greater than the thickness of the insulator layer 210A. The thicker insulator layer (e.g., the insulator layer 210B) is called an inter-pair spacer layer 400. The thinner insulator layer (eg, insulator layer 210A) is referred to as an intra-pair spacer layer 410.

[0056] The inter-pair spacer layer 400 may be about 2 to about 10 times the thickness of the intra-pair spacer layer 410. The thickness of the intra-pair spacer layer 410 may be about 1 nm to about 50 nm, including about 10 nm, about 20 nm, about 30 nm, about 40 nm, and any value or range between any two of the aforementioned thicknesses. Thus, the thickness of the inter-pair spacer layer 400 is greater than the thickness of the intra-pair spacer layer 410. The thickness of each layer (e.g., the ferromagnetic layer 200 and the insulator layer 210) is measured along the "z" axis, which is perpendicular to the top and bottom planes of the substrate 250 and the major surface of the core 40.

[0057] This difference in insulating layer thickness causes the bias and induction fluxes 230, 240 to pass through the soft ferromagnetic layer 202A and form a return path through the hard ferromagnetic bias layer 204A with lower energy than the return path through the hard ferromagnetic bias layer 204B. Thus, all or substantially all of the magnetic flux (e.g., bias and induction fluxes 230, 240) passing through the soft ferromagnetic layer 202A forms a closed loop through the hard ferromagnetic bias layer 204A, as indicated by curved arrow 435. Furthermore, all or substantially all of the magnetic flux (e.g., bias and induction fluxes 230, 240) passing through the hard ferromagnetic bias layer 204A forms a closed loop through the soft ferromagnetic layer 202A, as indicated by curved arrow 437.

[0058] Typically, for each soft ferromagnetic layer 202 having two adjacent hard ferromagnetic bias layers 204, an inter-pair spacer layer 400 is disposed on (e.g., in direct physical contact with) a first side 420 of each soft ferromagnetic layer 202, and an intra-pair spacer layer 410 is disposed on (e.g., in direct physical contact with) a second side 425 of each soft ferromagnetic layer 202. The first and second sides 420, 425 are on opposite sides of the soft ferromagnetic layer 202. In FIG. 4 , the first side 420 is at the bottom of each soft ferromagnetic layer 202, which is closer to the substrate 250 than the top. Because only one hard ferromagnetic bias layer 204N is adjacent to the bottommost soft ferromagnetic layer 202N of the core 40, a thicker inter-pair spacer layer 400 is not needed below the bottom surface of that soft ferromagnetic layer 202N to set its magnetization. Instead, a thinner adhesion layer 214 is formed below the soft ferromagnetic layer 202N. The thickness of the adhesion layer 214 and the cap layer 212 may be the same as the thickness of the in-pair spacer layer 410.

[0059] In an alternative embodiment, for each soft ferromagnetic layer 202 having two adjacent hard ferromagnetic bias layers 204, the inter-pair spacer layer 400 is disposed above (e.g., in direct physical contact with) the second side 425 of each soft ferromagnetic layer 202, and the intra-pair spacer layer 410 is disposed below (e.g., in direct physical contact with) the first side 425 of each soft ferromagnetic layer on the top surface of each soft ferromagnetic layer 202. This corresponds to rotating FIG. 4 180 degrees so that the hard ferromagnetic bias layer 204A is the “bottom layer” of the core 40.

[0060] The advantage of pairing the soft and hard ferromagnetic layers 202, 204 is that all or substantially all of the bias flux 230 passing through one hard ferromagnetic bias layer 204 is directed to pass through the corresponding soft ferromagnetic layer 202 of the soft-hard ferromagnetic layer pair 440, thereby minimizing the formation of domain walls in each soft ferromagnetic layer 202.

[0061] It should be noted that even when interlayer flux closure occurs, there will typically be some domain walls in the soft ferromagnetic layer 202. However, the number of domain walls will be reduced compared to when flux is primarily confined within the individual magnetic layers, such as when the hard ferromagnetic bias layer 204 is removed from the core 40. This is advantageous because (1) the domain walls can move when the core is exposed to alternating magnetic fields, which can cause power losses, and (2) the pattern of domain walls formed when flux is confined within the individual magnetic layers can reduce the total capacitance of the magnetic material that responds to alternating magnetic fields, thereby reducing the maximum achievable inductance.

[0062] When the core 40 is incorporated into a multi-layer wiring structure to form an inductor, it is preferable to configure and orient the inductor coil so that the magnetic flux of the inductor coil passes through the soft and hard ferromagnetic layers 202, 204 in a direction parallel to the hard axis 222.

[0063] 5 is a cross-sectional view of a planar magnetic core 50 according to another embodiment. The planar magnetic core 50 can be fabricated on a substrate 550 and / or incorporated into a multi-layer wiring structure on the substrate 550 to form an inductor.

[0064] The core 50 includes multiple ferromagnetic layers 500A-G (collectively, ferromagnetic layers 500) and an insulator layer 510. The core 50 also includes a cap layer 212 and an adhesion layer 214. Each ferromagnetic layer 500 is either a soft ferromagnetic layer 502 or a hard ferromagnetic bias layer 504. Each ferromagnetic layer 500 has anisotropy, with its easy axis 520 parallel to the "x" axis and its hard axis 522 parallel to the "y" axis. Thus, within the major plane of the ferromagnetic layer 500, the hard axis is perpendicular to the easy axis 520. The soft and hard ferromagnetic layers 502, 504 may be the same as the soft and hard ferromagnetic layers 202, 204, respectively. The insulator layer 510 may be the same as the insulator layer 210 and / or the in-pair spacer layer 410.

[0065] The top and bottom (or first and last, respectively) ferromagnetic layers 500 (e.g., layers 500A and 500G) are hard ferromagnetic bias layers 504 (e.g., top and bottom hard ferromagnetic bias layers). The hard ferromagnetic bias layers 504 are configured to generate a bias field 540 in a first direction (e.g., from right to left) parallel to the easy axis 520. All of the ferromagnetic layers 500 between the top and bottom hard ferromagnetic bias layers 504 are soft ferromagnetic layers 502. The core 50 is configured such that half of the magnetic flux passing through each soft ferromagnetic layer 502 forms a closed path passing through each adjacent ferromagnetic layer 500.

[0066] In the top layer of the core 50, the bias flux 530 passes through the hard ferromagnetic bias layer 500A in a first direction (e.g., from right to left) parallel to the easy axis 520. The bias flux 530 has a return path that passes through the soft ferromagnetic layer 500B in a second direction (e.g., from left to right) parallel to the easy axis 520 to form a closed loop. When the bias flux 530 passes through the soft ferromagnetic layer 500B and then through the hard ferromagnetic bias layer 500A to form a closed loop, it is in a lower energy state than when the bias flux 530 passes through the same soft ferromagnetic layer 500B and then returns again to form a closed loop (e.g., forming a domain wall).

[0067] The bias flux 530 passing through the soft ferromagnetic layer 500B generates a magnetic moment and an induced flux 540 passing through the soft ferromagnetic layer 500B in a second direction. The magnitude of the induced flux 540 is equal to or approximately equal to the magnitude of the bias flux 530. The induced flux 540 passing through the soft ferromagnetic layer 500B (e.g., in the second direction) forms a closed loop that passes through the soft ferromagnetic layer 500C (e.g., in the first direction), where the induced flux 540 functions as a bias flux 530′. When the induced flux 540 passing through the soft ferromagnetic layer 500B passes through the soft ferromagnetic layer 500C (e.g., as bias flux 530′) to form a closed loop, it is in a lower energy state than when the induced flux 540 passes through the soft ferromagnetic layer 500B and returns to form a closed loop (e.g., forming a domain wall). In this manner, half of the magnetic flux passing through soft ferromagnetic layer 500B (e.g., bias magnetic flux 530) forms a closed loop passing through hard ferromagnetic bias layer 500A, and the other half of the magnetic flux passing through soft ferromagnetic layer 500B (e.g., induced magnetic flux 540) forms a closed loop passing through soft ferromagnetic layer 500C (e.g., as bias magnetic flux 530').

[0068] This is repeated for all soft ferromagnetic layers 502 (e.g., soft ferromagnetic layers 500C-500F). For example, bias flux 530' passing through soft ferromagnetic layer 500C generates an additional magnetic moment and induced flux 540 passing through soft ferromagnetic layer 500C. The magnitude of induced flux 540 is approximately equal to the magnitude of bias flux 530'. Inductive flux 540 passing through soft ferromagnetic layer 500C (e.g., in a first direction) forms a closed loop passing through soft ferromagnetic layer 500D (e.g., in a second direction), where induced flux 540 functions as bias flux 530'. When the induced flux 540 passing through the soft ferromagnetic layer 500C passes through the soft ferromagnetic layer 500D (e.g., as bias flux 530') to form a closed loop, it is in a lower energy state than when it passes through the soft ferromagnetic layer 500C and returns again to form a closed loop (e.g., forming a domain wall). Thus, half of the flux passing through the soft ferromagnetic layer 500C (e.g., bias flux 530') forms a closed loop through the soft ferromagnetic layer 500B (as induced flux 540), and the other half of the flux passing through the soft ferromagnetic layer 500C (e.g., induced flux 540) forms a closed loop through the soft ferromagnetic layer 500D (e.g., as bias flux 530').

[0069] At the bottom of the core 50, the bias flux 530 passes through the hard ferromagnetic bias layer 500G in a first direction (e.g., from right to left) parallel to the easy axis 520. The bias flux 530 has a return path that passes through the soft ferromagnetic layer 500F in a second direction (e.g., from left to right) parallel to the easy axis 520 to form a closed loop. When the induced flux 540 passes through the soft ferromagnetic layer 500F and then passes through the hard ferromagnetic bias layer 500G to form a closed loop, it is in a lower energy state than when it passes through the same soft ferromagnetic layer 500F and returns again to form a closed loop (e.g., forming a domain wall).

[0070] The bias flux 530 passing through the soft ferromagnetic layer 500F generates a magnetic moment and an induced flux 540 passing through the soft ferromagnetic layer 500F in a second direction. The magnitude of the induced flux 540 passing through the soft ferromagnetic layer 500F is equal to or approximately equal to the magnitude of the bias flux 530 passing through the soft ferromagnetic layer 500F.

[0071] The induced magnetic flux 540 passing through the soft ferromagnetic layer 500F (e.g., in a second direction) forms a closed loop passing through the soft ferromagnetic layer 500E (e.g., in a first direction), where the induced magnetic flux 540 acts as the bias magnetic flux 530'. When the induced magnetic flux 540 passing through the soft ferromagnetic layer 500F passes through the soft ferromagnetic layer 500E (e.g., as the bias magnetic flux 530') to form a closed loop, it is in a lower energy state than when the induced magnetic flux 540 passes through the soft ferromagnetic layer 500F and returns again to form a closed loop (e.g., forming a domain wall). In this way, half of the magnetic flux passing through the soft ferromagnetic layer 500F (e.g., bias magnetic flux 530) forms a closed loop passing through the hard ferromagnetic bias layer 500G, and the other half of the magnetic flux passing through the soft ferromagnetic layer 500F (e.g., induced magnetic flux 540) forms a closed loop passing through the soft ferromagnetic layer 500E (e.g., as bias magnetic flux 530').

[0072] The thicknesses of the soft and hard ferromagnetic layers 502, 504 are jointly optimized for interlayer flux closure. As shown, the magnitude of the magnetic flux passing through the hard ferromagnetic bias layer 504 is equal to or approximately equal to half the magnitude of the magnetic flux passing through the soft ferromagnetic layer 502. Therefore, the flux balance equation (1) can be rewritten as:

[0073]

number

[0074] For the magnetic flux passing through the adjacent soft and hard ferromagnetic layers 502, 504 to be equal, the ratio of the thickness of the hard ferromagnetic bias layer 504 to the thickness of the soft ferromagnetic layer 502 should be:

[0075]

number

[0076]

number

[0077] When core 50 is incorporated into a multi-layer wiring structure to form an inductor, the inductor coil is preferably configured and oriented so that the magnetic flux of the inductor coil passes through ferromagnetic layer 500 in a direction parallel to hard axis 522 .

[0078] Typically, the core 50 includes N ferromagnetic layers 500, where N is an odd integer greater than or equal to 3. That is, the core 50 includes top and bottom hard ferromagnetic bias layers 504 and an odd integer number of soft ferromagnetic layers 502 disposed between the top and bottom hard ferromagnetic bias layers 504. By including an odd integer number of soft ferromagnetic layers 502, accumulation of induced magnetic flux 540 in the core 50 can be prevented.

[0079] Figure 6 is an exploded perspective view of the planar magnetic core 50 shown in Figure 5. The cap layer 212 is not shown in Figure 6 for clarity. Figure 6 also shows magnetic flux lines 530, 530', 540 in the ferromagnetic layer 500. The magnetic flux lines 530, 530', 540 passing through the soft and hard ferromagnetic layers 502, 504 are parallel or substantially parallel (e.g., within 10 degrees) to the easy axis 520. Furthermore, the magnetic flux lines 530 and / or 540 passing through the soft and hard ferromagnetic layers 502, 504 are perpendicular or substantially perpendicular (i.e., within 10 degrees) to the hard axis 522 in each major plane of the soft and hard ferromagnetic layers 502, 504.

[0080] FIG. 7 is a flow diagram of a method for fabricating a semiconductor device according to one embodiment. In step 700, ferromagnetic layers and insulating layers are alternately deposited. The ferromagnetic layers include multiple hard ferromagnetic layers and multiple soft ferromagnetic layers, each of which can be either a soft ferromagnetic layer or a hard ferromagnetic layer. Furthermore, each hard ferromagnetic layer is adjacent to at least one (i.e., one or two) adjacent soft ferromagnetic layers. For example, each hard ferromagnetic layer can be the top or bottom ferromagnetic layer of a horizontally stacked magnetic core. In this case, each hard ferromagnetic layer is adjacent to only one soft ferromagnetic layer (e.g., the top hard ferromagnetic layer of the core has a soft ferromagnetic layer adjacent to the bottom of the top hard ferromagnetic layer, and the bottom hard ferromagnetic layer of the core has a soft ferromagnetic layer adjacent to the top of the bottom hard ferromagnetic bias layer). In another example, the hard ferromagnetic layer is disposed between a top and bottom ferromagnetic layer, in which case the hard ferromagnetic layer has two adjacent soft ferromagnetic layers (one above and one below the hard ferromagnetic bias layer). In some embodiments, the ferromagnetic layers can be deposited in soft-hard ferromagnetic layer pairs.

[0081] In step 710, a magnetic easy axis is induced in each ferromagnetic layer. The magnetic easy axis is parallel to the top plane of the semiconductor substrate on which the semiconductor device is formed and lies within a major surface of each ferromagnetic layer. The magnetic easy axis can be induced during or after deposition of the ferromagnetic layer (step 700). For example, a bias magnetic field can be applied during deposition of the ferromagnetic layer (such as by electrodeposition and / or sputter deposition). To form the magnetic easy axis, the bias magnetic field is configured to pass through the ferromagnetic layer in a direction parallel to the top plane of the semiconductor substrate during deposition. Additionally or alternatively, the bias magnetic field can be applied during a post-deposition annealing process.

[0082] An easy axis is induced in each ferromagnetic layer, which in turn induces a hard axis in each ferromagnetic layer. The hard axis is perpendicular to the easy axis in the major plane of each ferromagnetic layer. For example, the easy axis can be parallel to the "x" axis, the hard axis can be parallel to the "y" axis, and the ferromagnetic layers can be deposited along the "z" axis.

[0083] In step 720, each hard ferromagnetic layer is magnetized to form a respective hard ferromagnetic bias layer. Each hard ferromagnetic bias layer generates an in-plane bias flux that passes through the respective hard ferromagnetic bias layer in a first direction parallel to the magnetic easy axis of the respective ferromagnetic layer (e.g., induced in step 710). The bias flux has a magnetization state oriented in the first direction. The bias flux forms a closed path by passing through an adjacent soft ferromagnetic layer in a second direction opposite the first direction. Each hard ferromagnetic layer can be magnetized during deposition of the hard ferromagnetic layer, during a post-deposition anneal (e.g., in the presence of an in-plane magnetic field of sufficient strength), and / or during induction of the magnetic easy axis in the hard ferromagnetic layer (e.g., in step 710). In some embodiments, steps 710 and 720 are performed simultaneously.

[0084] In step 730, a horizontally laminated planar magnetic core comprising ferromagnetic and insulating layers is defined, such as by photolithography and etching.

[0085] In some embodiments, the method includes forming a conductive winding around a horizontally stacked planar magnetic core to form an inductor, the conductive winding being configured to form a magnetic field of an inductor coil that passes through adjacent soft ferromagnetic layers in a direction parallel to the hard axis of at least one adjacent soft ferromagnetic layer, e.g., to avoid domain wall motion and associated energy losses.

[0086] In one embodiment, the uppermost ferromagnetic layer of the plurality of ferromagnetic layers is a hard ferromagnetic bias layer (e.g., the uppermost hard ferromagnetic bias layer). Additionally or alternatively, the lowermost ferromagnetic layer of the plurality of ferromagnetic layers is a hard ferromagnetic bias layer (e.g., the lowermost hard ferromagnetic bias layer). When the uppermost ferromagnetic layer and the lowermost ferromagnetic layer are each hard ferromagnetic bias layers, the other ferromagnetic layers may be only soft ferromagnetic layers (e.g., odd-integer soft ferromagnetic layers). In this embodiment, the ratio of the hard ferromagnetic layer thickness of each hard ferromagnetic bias layer to the soft ferromagnetic layer thickness of each soft ferromagnetic layer is, as described above,

[0087]

number

[0088] In another embodiment, the ferromagnetic layers are deposited as soft-hard ferromagnetic layer pairs, each having one soft ferromagnetic layer and one hard ferromagnetic bias layer. An intra-pair spacer layer is deposited between the soft ferromagnetic layer and the hard ferromagnetic bias layer of each soft-hard ferromagnetic layer pair, and an inter-pair spacer layer is deposited between adjacent soft-hard ferromagnetic layer pairs. The inter-layer spacer and intra-layer spacer are insulating layers, and the inter-pair spacer thickness of each inter-pair spacer layer is greater than the inter-pair spacer thickness of each intra-pair spacer layer. In this embodiment, the ratio of the hard ferromagnetic layer thickness of each hard ferromagnetic bias layer to the soft ferromagnetic layer thickness of each soft ferromagnetic layer is:

[0089]

number

[0090] 8 is a representative cross-sectional view of a magnetic core inductor 800 integrated into a semiconductor device on a substrate 810, according to one embodiment. The inductor 800 includes a horizontally stacked magnetic core 820 and conductive windings 830.

[0091] The conductive windings 830 are integrated into a multi-layer wiring network 835 that provides electrical connections between PMOS and NMOS transistor gates 862, 864, the inductor 800, and an integrated circuit (IC) chip contact structure 832. The PMOS and NMOS transistor gates 862, 864 are fabricated on a semiconductor substrate 810 (e.g., silicon, silicon-on-insulator, or other semiconductor substrate). The IC chip contact structure 832 may consist of C4 contacts, solder bumps, or copper pillars, although any other contacts for external communication of the semiconductor device are acceptable, without limitation.

[0092] The multi-layer wiring network 835 is arranged in the form of wiring planes 820. Each wiring plane 820 includes wiring segments 850. Electrical connections between the wiring segments 850 of different wiring planes 837 are provided by conductive vias (VIAs) 840. The spaces in the multi-layer wiring network 835 are filled with a dielectric insulating material 860, such as SiO2.

[0093] Inductor 800 is integrated into the top layer of multilayer wiring network 835. Conductive winding 830 is piecewise composed of wiring segments 850′ and vias 840′ disposed in at least two integration planes 839 on the top layer of multilayer wiring network 835. Vias 840′ forming part of conductive winding 830 are perpendicular or orthogonal to major surface 875 and electrically interconnect wiring segments 850′ in the two integration planes 839. In another embodiment, inductor 800 can be integrated into multilayer wiring network 835 instead of in an integration plane 830 above multilayer wiring network 835.

[0094] Magnetic core 820 can be configured as any of the magnetic cores described herein. For example, magnetic core 820 can be the same as or configured as core 20, core 40, or core 50. Conductive winding 830 is configured and / or arranged to generate an inductor coil magnetic field that generates inductor coil flux through soft ferromagnetic layers in core 820. The inductor coil flux is parallel to the hard axis of magnetization in each soft ferromagnetic layer. The inductor coil flux passing through the soft ferromagnetic layers and the easy axis of magnetization in the soft ferromagnetic layers are parallel and / or substantially parallel to a major surface 875 of planar magnetic core 820, which is also parallel and / or substantially parallel to wiring plane 837 and top surface 812 of semiconductor substrate 810.

[0095] Inductor 800 may be a component of a power converter, such as a switched inductor DC-DC power converter. In some embodiments, the power converter can include multiple inductors, each of which is the same as or similar to inductor 800. The inductors can be arranged electrically in parallel with each other, electrically in series with each other, or a combination thereof. Multiple inductors can be integrated on the same integration or wiring plane or on different integration or wiring planes.

[0096] The present invention should not be understood as being limited to the particular embodiments described above, but rather as embracing all aspects of the invention fairly defined in the appended claims. Various modifications, equivalent processes, and various structures to which the present invention may be applicable will be apparent to those skilled in the art to which the present invention pertains upon review of this disclosure. The claims are intended to cover such modifications and equivalents.

Claims

1. A horizontally stacked planar magnetic core, a plurality of ferromagnetic layers including a plurality of hard ferromagnetic layers and a plurality of soft ferromagnetic layers, each ferromagnetic layer comprises one of the soft ferromagnetic layers or one of the hard ferromagnetic layers; Each hard ferromagnetic layer is a ferromagnetic layer adjacent to at least one soft ferromagnetic layer; the plurality of ferromagnetic layers; a plurality of insulating layers, each insulating layer being disposed between adjacent ferromagnetic layers; and and each ferromagnetic layer having an easy axis of magnetization parallel to a major surface of the planar magnetic core and aligned with each other; Planar magnetic core.

2. 2. The planar magnetic core of claim 1, wherein the ferromagnetic layers are stacked along the height of the planar magnetic core.

3. 2. The planar magnetic core of claim 1, wherein the plurality of hard ferromagnetic layers includes a top hard ferromagnetic layer disposed as a top ferromagnetic layer.

4. 4. The planar magnetic core of claim 3, wherein the plurality of hard ferromagnetic layers includes a bottom hard ferromagnetic layer disposed as a bottom ferromagnetic layer.

5. 5. The planar magnetic core of claim 4, wherein the plurality of soft ferromagnetic layers are disposed between the top and bottom hard ferromagnetic layers.

6. 6. The planar magnetic core of claim 5, wherein the plurality of soft ferromagnetic layers comprises N soft ferromagnetic layers, where N is an odd integer greater than or equal to 3.

7. 5. The planar magnetic core according to claim 4, The thickness of each soft ferromagnetic layer is the same, The hard ferromagnetic layers have the same thickness, the hard ferromagnetic layer thickness is related to the soft ferromagnetic layer thickness; Planar magnetic core.

8. 8. The planar magnetic core of claim 7, wherein the ratio of the thickness of the hard ferromagnetic layer to the thickness of the soft ferromagnetic layer is: [0014] wherein M Ｓ＿ｓｏｆｔ is the saturation magnetization of each soft ferromagnetic layer, and M Ｓ＿ｈａｒｄ is the saturation magnetization of each hard ferromagnetic layer, Planar magnetic core.

9. 6. The planar magnetic core according to claim 5, a planar magnetic core, wherein each of the top and bottom hard ferromagnetic layers is magnetized to generate a bias magnetic flux passing through each of the hard ferromagnetic layers in a first direction parallel to the easy axis of the hard ferromagnetic layer.

10. 10. The planar magnetic core of claim 9, the bias magnetic flux passing through the top hard ferromagnetic layer forms a closed path passing through a first adjacent soft ferromagnetic layer; the bias magnetic flux passing through the bottom hard ferromagnetic layer forms a closed path passing through a second adjacent soft ferromagnetic layer; each of the bias magnetic fluxes passing through the first and second adjacent soft ferromagnetic layers in a second direction opposite to the first direction; Planar magnetic core.

11. 11. The planar magnetic core of claim 10, each of the bias magnetic fluxes passing through the first and second adjacent soft ferromagnetic layers induces a magnetic flux passing through the first and second adjacent soft ferromagnetic layers in the second direction; an induced magnetic flux passing through the first adjacent soft ferromagnetic layer forms a closed path passing through a third adjacent soft ferromagnetic layer in the first direction; an induced magnetic flux passing through the second adjacent soft ferromagnetic layer forms a closed path passing through the fourth adjacent soft ferromagnetic layer in the first direction; the uppermost hard ferromagnetic layer and the third adjacent soft ferromagnetic layer are ferromagnetic layers adjacent to the first adjacent soft ferromagnetic layer; the bottom hard ferromagnetic layer and the fourth adjacent soft ferromagnetic layer are ferromagnetic layers adjacent to the second adjacent soft ferromagnetic layer; Planar magnetic core.

12. 10. The planar magnetic core of claim 1, wherein the hard ferromagnetic layer and the soft ferromagnetic layer comprise cobalt, iron, and / or nickel.

13. 2. The planar magnetic core of claim 1, wherein the insulating layer comprises: (a) aluminum, cobalt, chromium, silicon, tantalum, titanium, and / or zirconium, or (b) Compounds of (1) aluminum, cobalt, chromium, silicon, tantalum, titanium, and / or zirconium and (2) oxygen and / or nitrogen A planar magnetic core having a

14. 2. The planar magnetic core according to claim 1, each hard ferromagnetic layer has a coercivity greater than 50 Oe; A planar magnetic core, wherein each soft ferromagnetic layer has a coercivity of less than 1 Oe.

15. 10. The planar magnetic core of claim 1, wherein the thickness of each ferromagnetic layer ranges from about 10 nm to about 1,000 nm, and the thickness of each ferromagnetic layer is measured along an axis perpendicular to a major surface of the planar magnetic core.

16. 16. The planar magnetic core of claim 15, wherein the thickness of each insulating layer ranges from about 1 nm to about 50 nm, the thickness of each insulating layer being measured along the axis.

17. 17. The planar magnetic core of claim 16, wherein the planar magnetic core has a total thickness of 100,000 nm or less, said total thickness being measured along said axis.

18. A horizontally stacked planar magnetic core, a plurality of soft-hard ferromagnetic layer pairs, each of which includes one soft ferromagnetic layer and one hard ferromagnetic layer; an inter-pair spacer layer disposed between the soft ferromagnetic layer and the hard ferromagnetic layer of each soft-hard ferromagnetic layer pair; an inter-pair spacer layer disposed between adjacent pairs of soft and hard ferromagnetic layers; and an inter-pair spacer layer thickness of each inter-pair spacer layer being greater than an intra-pair spacer layer thickness of each intra-pair spacer layer; the inter-pair spacer layer thickness and the intra-pair spacer layer thickness are measured along an axis perpendicular to a major surface of the planar magnetic core; each soft ferromagnetic layer and each hard ferromagnetic layer having an easy axis of magnetization parallel to a major surface of the planar magnetic core and aligned with each other; Planar magnetic core.

19. 20. The planar magnetic core of claim 18, A planar magnetic core wherein for each soft-hard ferromagnetic layer pair, the relative position of the soft ferromagnetic layer with respect to the hard ferromagnetic layer is the same.

20. 20. The planar magnetic core of claim 19, A planar magnetic core wherein for each soft-hard ferromagnetic layer pair, the soft ferromagnetic layer is disposed below the hard ferromagnetic layer.

21. 20. The planar magnetic core of claim 18, a first interpair spacer layer disposed between the first soft-hard ferromagnetic layer pair and the second soft-hard ferromagnetic layer pair; a second inter-pair spacer layer disposed between the second soft-hard ferromagnetic layer pair and the third soft-hard ferromagnetic layer pair; and the second soft-hard ferromagnetic layer pair is disposed between the first soft-hard ferromagnetic layer pair and the third soft-hard ferromagnetic layer pair; Planar magnetic core.

22. 20. The planar magnetic core of claim 18, The thickness of each soft ferromagnetic layer is the same, The hard ferromagnetic layers have the same thickness, the soft ferromagnetic layer thickness and the hard ferromagnetic layer thickness are measured along the axis; the hard ferromagnetic layer thickness is related to the soft ferromagnetic layer thickness; Planar magnetic core.

23. 23. The planar magnetic core of claim 22, In each soft-hard ferromagnetic layer pair, the hard ferromagnetic layer is magnetized to generate a bias magnetic flux passing through the hard ferromagnetic layer in a first direction parallel to an easy axis of magnetization in a major surface of the hard ferromagnetic layer; the bias magnetic flux forms a closed loop passing through the soft ferromagnetic layer only in a second direction parallel to an easy axis of magnetization in a major surface of the soft ferromagnetic layer; Planar magnetic core.

24. 24. The planar magnetic core of claim 23, In each soft-hard ferromagnetic layer pair, the bias magnetic flux passing through the soft ferromagnetic layer induces an induced magnetic flux passing through the soft ferromagnetic layer in the second direction; the induced magnetic flux forms a closed loop passing through the hard ferromagnetic layer only in the first direction; Planar magnetic core.

25. 25. The planar magnetic core of claim 24, The ratio of the hard ferromagnetic layer thickness to the soft ferromagnetic layer thickness is: [Equation 15] wherein M Ｓ＿ｓｏｆｔ is the saturation magnetization of each soft ferromagnetic layer, and M Ｓ＿ｈａｒｄ is the saturation magnetization of each hard ferromagnetic layer, Planar magnetic core.

26. 26. The planar magnetic core of claim 25, the first and second inter-pair spacer layers have the same inter-pair spacer layer thickness; The inner spacer layers have the same inner spacer layer thickness; the thickness of the inter-pair spacer layer is in the range of 2 to 10 times the thickness of the intra-pair spacer layer; Planar magnetic core.

27. 20. The planar magnetic core of claim 18, wherein the inter-pair spacer layer and the intra-pair spacer layer comprise an insulating material.

28. An inductor, A horizontally stacked planar magnetic core, a plurality of ferromagnetic layers including a plurality of hard ferromagnetic layers and a plurality of soft ferromagnetic layers, each ferromagnetic layer comprises one of the soft ferromagnetic layers or one of the hard ferromagnetic layers; Each hard ferromagnetic layer is a ferromagnetic layer adjacent to at least one soft ferromagnetic layer; the plurality of ferromagnetic layers; a plurality of insulating layers, each insulating layer being disposed between adjacent ferromagnetic layers; and and each ferromagnetic layer having an easy axis of magnetization parallel to a major surface of the planar magnetic core and aligned with each other; the planar magnetic core; a conductive winding wound generally spirally around the outside of the planar magnetic core; An inductor having

29. 29. The inductor of claim 28, each ferromagnetic layer has a hard axis of magnetization perpendicular to the easy axis of magnetization and aligned with each other in a major plane of the ferromagnetic layer; the conductive winding is configured to generate an inductor coil flux in each ferromagnetic layer, the inductor coil flux passing through the horizontally stacked planar magnetic core in a direction parallel to the hard axis of magnetization; Inductor.

30. 29. The inductor of claim 28, the plurality of hard ferromagnetic layers include a top hard ferromagnetic layer disposed as a top ferromagnetic layer and a bottom hard ferromagnetic layer disposed as a bottom ferromagnetic layer, the plurality of soft ferromagnetic layers are disposed between the top and bottom hard ferromagnetic layers; each of the top and bottom hard ferromagnetic layers is magnetized to generate a bias magnetic flux passing through each of the hard ferromagnetic layers in a first direction parallel to an easy axis of magnetization of the hard ferromagnetic layer; the bias magnetic flux passing through the top hard ferromagnetic layer forms a closed path passing through a first adjacent soft ferromagnetic layer; the bias magnetic flux passing through the bottom hard ferromagnetic layer forms a closed path passing through a second adjacent soft ferromagnetic layer; each of the bias magnetic fluxes passing through the first and second adjacent soft ferromagnetic layers in a second direction opposite to the first direction; Inductor.

31. 31. The inductor of claim 30, each of the bias magnetic fluxes passing through the first and second adjacent soft ferromagnetic layers induces a magnetic flux passing through the first and second adjacent soft ferromagnetic layers in the second direction; an induced magnetic flux passing through the first adjacent soft ferromagnetic layer forms a closed path passing through a third adjacent soft ferromagnetic layer in the first direction; an induced magnetic flux passing through the second adjacent soft ferromagnetic layer forms a closed path passing through the fourth adjacent soft ferromagnetic layer in the first direction; the uppermost hard ferromagnetic layer and the third adjacent soft ferromagnetic layer are ferromagnetic layers adjacent to the first adjacent soft ferromagnetic layer; the bottom hard ferromagnetic layer and the fourth adjacent soft ferromagnetic layer are ferromagnetic layers adjacent to the second adjacent soft ferromagnetic layer; Inductor.

32. A structure comprising: a semiconductor integrated circuit having a multilayer wiring network formed on a substrate; The inductor according to claim 28 is incorporated into the multilayer wiring network. structure.

33. A manufacturing method comprising: Depositing a plurality of ferromagnetic layers, including a plurality of hard ferromagnetic layers and a plurality of soft ferromagnetic layers, on a semiconductor substrate, each ferromagnetic layer comprises one of the soft ferromagnetic layers or one of the hard ferromagnetic layers; Each hard ferromagnetic layer is a ferromagnetic layer adjacent to at least one soft ferromagnetic layer; depositing the plurality of ferromagnetic layers; depositing an insulating layer between adjacent ferromagnetic layers; inducing easy axes of magnetization in each ferromagnetic layer, the easy axes being aligned with each other and parallel to a top plane of the semiconductor substrate; magnetizing each of the hard ferromagnetic layers to generate a bias flux passing through the hard ferromagnetic layer in a first direction, the bias flux being parallel to an easy axis of magnetization within each hard ferromagnetic layer; defining a horizontally stacked planar magnetic core having the plurality of ferromagnetic layers and the insulating layer; A manufacturing method comprising the steps of:

34. The manufacturing method according to claim 30, further comprising: defining a hard axis in each ferromagnetic layer, the hard axis being perpendicular to the easy axis in a major plane of each ferromagnetic layer; forming a conductive winding around a horizontally laminated planar magnetic core, the conductive winding configured to generate an inductor coil flux in each ferromagnetic layer, the inductor coil flux passing through the horizontally laminated planar magnetic core in a direction parallel to the hard axis; The manufacturing method of the present invention.

35. The manufacturing method according to claim 33, further comprising: depositing a top hard ferromagnetic layer as a top ferromagnetic layer; depositing a bottom hard ferromagnetic layer as a bottom ferromagnetic layer; depositing the plurality of soft ferromagnetic layers between the bottom and top hard ferromagnetic layers; The manufacturing method of the present invention.

36. 36. The method of claim 35, The ratio of the thickness of each hard ferromagnetic layer to the thickness of each soft ferromagnetic layer is: [0016] wherein M Ｓ＿ｓｏｆｔ is the saturation magnetization of each soft ferromagnetic layer, and M Ｓ＿ｈａｒｄ is the saturation magnetization of each hard ferromagnetic layer, the soft ferromagnetic layer thickness and the hard ferromagnetic layer thickness are measured along an axis perpendicular to a top plane of the semiconductor substrate; Manufacturing method.

37. The manufacturing method according to claim 33, further comprising: depositing a plurality of soft-hard ferromagnetic layer pairs, each soft-hard ferromagnetic layer pair including one of the soft ferromagnetic layers and one of the hard ferromagnetic layers; depositing an intra-pair spacer layer between the soft ferromagnetic layer and the hard ferromagnetic layer of each soft-hard ferromagnetic layer pair; depositing an interpair spacer layer between adjacent pairs of soft and hard ferromagnetic layers; and each insulating layer having one of the intra-pair spacer layer or the inter-pair spacer layer; an inter-pair spacer layer thickness of each inter-pair spacer layer being greater than an intra-pair spacer layer thickness of each intra-pair spacer layer; the inter-pair spacer layer thickness and the intra-pair spacer layer thickness are measured along an axis perpendicular to a top plane of the semiconductor substrate; Manufacturing method.

38. 38. The method of claim 37, The ratio of the thickness of each hard ferromagnetic layer to the thickness of each soft ferromagnetic layer is: [Equation 17] wherein M Ｓ＿ｓｏｆｔ is the saturation magnetization of each soft ferromagnetic layer, and M Ｓ＿ｈａｒｄ is the saturation magnetization of each hard ferromagnetic layer, the soft ferromagnetic layer thickness and the hard ferromagnetic layer thickness are measured along the axis; Manufacturing method.

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