Integrated magnetic inductors

Abstract

An integrated magnetic inductor is provided with an inductor coil, magnetic film, and a substrate. The magnetic film can be placed between the neighboring inductor coils, and the thickness of the magnetic film is greater than the coil thickness. In addition, the magnetic film includes exchange-coupled magnetic materials. The exchange-coupled magnetic materials provide improved permeability and f.sub.FMR at the frequency of interest for the integrated magnetic inductor.

Claims

1. A magnetic inductor comprising: a substrate; a coil mounted on the substrate, the coil having a plurality of segments; a magnetic film mounted on the substrate between segments of the plurality of segments of the coil, wherein the magnetic film is an exchange-coupled magnetic material comprising a soft magnetic phase material and a hard magnetic phase material; and wherein the coil has a first thickness and the magnetic film has a second thickness greater than the first thickness.

2. The magnetic inductor of claim 1, wherein the magnetic film is positioned in contact with at least a portion of the coil.

3. The magnetic inductor of claim 1, wherein the exchange-coupled magnetic material has a preselected volume fraction of the hard magnetic phase material to provide a predetermined saturation magnetization and magnetic anisotropy field.

4. The magnetic inductor of claim 1, wherein the soft magnetic phase material includes at least one of spinel NiZnCo, NiCo, NiZn, MnZn, NiZnCu ferrites, BaZnFe10O27, Ba3ME2Fe24O41 (ME=Co, Ni, Zn, Cu), NiFe, FeAlO, FeHfO, FeSmO, CoFeHfO, FeSiAl, CoZrTa, FeAlN, FeZrN, FeCoB, FeCoBSi, FeCoN, FeSi, NiFeCo, or FeAl.

5. The magnetic inductor of claim 1, wherein the hard magnetic phase material includes at least one of CoFe2O4, BaFe12O19, SrFe12O19, MnBi, MnAl, NdFeB, SmCo, FePt, SmFeN, FeCrCoMo, MnAlC, AlNiCo, PtCo, SmCoFeCu, or FeCrCo.

6. The magnetic inductor of claim 1, wherein the exchange-coupled magnetic material comprises a composite of the soft magnetic phase material and the hard magnetic phase material.

7. The magnetic inductor of claim 6, wherein the soft magnetic phase material is in a matrix of the hard magnetic phase material.

8. The magnetic inductor of claim 6, wherein the hard magnetic phase material is in a matrix of the soft magnetic phase material.

9. The magnetic inductor of claim 1, wherein the exchange-coupled magnetic material comprises one or more layers of the soft magnetic phase material and one or more layers of the hard magnetic phase material.

10. The magnetic inductor of claim 9, wherein the one or more layers of the soft magnetic phase material have a thickness less than the one or more layers of the hard magnetic phase material.

11. The magnetic inductor of claim 1, wherein the magnetic film is spaced a predetermined distance from the segments of the plurality of segments of the coil.

12. A magnetic inductor comprising: a substrate; a coil mounted on the substrate, the coil having a plurality of segments arranged to form at least one spiral turn; a magnetic film mounted on the substrate and positioned at an inner side and an outer side of each segment of the plurality of segments of the coil; and wherein the magnetic film is an exchange-coupled magnetic material comprising a soft magnetic phase material and a hard magnetic phase material.

13. The magnetic inductor of claim 12, wherein the coil has a first thickness and the magnetic film has a second thickness greater than the first thickness.

14. The magnetic inductor of claim 13, wherein the second thickness is at least two times greater than the first thickness.

15. The magnetic inductor of claim 12, wherein the magnetic film is spaced a predetermined distance from both the inner side and the outer side of each segment of the plurality of segments of the coil.

16. The magnetic inductor of claim 12, wherein the exchange-coupled magnetic material comprises a composite of the soft magnetic phase material and the hard magnetic phase material.

17. The magnetic inductor of claim 16, wherein the soft magnetic phase material is in a matrix of the hard magnetic phase material.

18. The magnetic inductor of claim 16, wherein the hard magnetic phase material is in a matrix of the soft magnetic phase material.

19. The magnetic inductor of claim 12, wherein the exchange-coupled magnetic material comprises at least one layer of a soft magnetic phase material positioned on at least one layer of a hard magnetic phase material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A-1D show examples of prior art inductors.

(2) FIG. 2 is a top view of an embodiment of an integrated magnetic inductor.

(3) FIG. 3 is a cross-sectional view of the inductor of FIG. 2 taken along line 3-3.

(4) FIGS. 4-6 are cross-sectional views of embodiments of the magnetic film of FIG. 2.

(5) FIG. 7 shows a graph of the complex permeability of the magnetic film in one embodiment.

(6) FIGS. 8 and 9 show graphs of inductance and quality factor in terms of frequency for different inductors.

(7) FIG. 10 is a top view of another embodiment of an integrated inductor.

(8) FIGS. 11 and 12 show graphs of inductance and quality factor in terms of frequency for the inductor of FIG. 10 and a similarly configured air-core inductor.

(9) FIG. 13 shows a graph of the calculated M.sub.s and H.sub.k of the exchange-coupled magnetic material in terms of volume fractions of the hard magnetic phase.

(10) FIG. 14 shows a graph of the calculated complex permeability in terms of frequency for exchange-coupled magnetic materials having different volume fractions of the hard magnetic phase.

(11) Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts.

DETAILED DESCRIPTION

(12) FIGS. 2 and 3 show an embodiment of an integrated magnetic inductor 100. The inductor 100 includes an inductor coil 102 and a magnetic film 104 mounted on a substrate 106. The magnetic film 104 can be located on each side, i.e., on an inner and outer side, of each segment of the inductor coil 102. In addition, as shown in FIG. 2, the magnetic film 104 can also occupy the space at the center of the inductor coil 102. The magnetic film 104 can be spaced a predetermined distance g (see e.g., FIG. 3) from each side of the inductor coil 102. In another embodiment, the magnetic film 104 can be in contact with one or more sides of one or more segments of the inductor coil 102. The magnetic film 104 can have a predetermined thickness t (see e.g., FIG. 3) that is greater than the predetermined thickness h (see e.g., FIG. 3) of the inductor coil 102. In one embodiment, t can be two or more times greater than h, but can be less than two times, e.g., 1.5 times, greater than h. The increased thickness in the magnetic film 104 to be greater than the thickness of the inductor coil 102 contributes to an increase in L due to a reduction in proximity effect and improved magnetic flux density.

(13) In one embodiment, the magnetic film 104 can be made from an exchange-coupled magnetic material(s). The exchange-coupled magnetic material can include magnetically soft and hard phases. The soft magnetic phase has higher saturation magnetization (M.sub.s) and smaller magnetic anisotropy field (H.sub.k) than the M.sub.s and H.sub.k of the hard magnetic phase. The exchange-coupled magnetic material used in the magnetic film 104 can be in the form of a composite or a film. The soft magnetic phase can include spinel NiZnCo, NiCo, NiZn, MnZn, NiZnCu ferrites, BaZnFe.sub.10O.sub.27, Ba.sub.3ME.sub.2Fe.sub.24O.sub.41 (ME=Co, Ni, Zn, Cu), NiFe, FeAlO, FeHfO, FeSmO, CoFeHfO, FeSiAl, CoZrTa, FeAlN, FeZrN, FeCoB, FeCoBSi, FeCoN, FeSi, NiFeCo, or FeAl. The hard magnetic phase includes CoFe.sub.2O.sub.4, BaFe.sub.12O.sub.19, SrFe.sub.12O.sub.19, MnBi, MnAl, NdFeB, SmCo, FePt, SmFeN, FeCrCoMo, MnAlC, AlNiCo, PtCo, SmCoFeCu or FeCrCo.

(14) An example of an exchange-coupled magnetic material that can be used with the present application is described in commonly-assigned U.S. patent application Ser. No. 14/941,201, entitled Methods for Manufacturing Core-Shell Exchange Coupled Magnetic Particles and filed on Nov. 13, 2015, which is incorporated herein by reference. In another embodiment, the exchange-coupled magnetic material can include single-phase ferromagnetic materials, single-phase ferrimagnetic materials and combinations thereof. However, in still other embodiments, other types of exchange-coupled magnetic materials can be used.

(15) As shown in FIGS. 4 and 5, the exchange-coupled magnetic material can be a composite with a soft magnetic phase material 112 in a matrix of hard magnetic phase material 114 (see e.g., FIG. 4) or a composite with a hard magnetic phase material 114 in a matrix of soft magnetic phase material 112 (see e.g., FIG. 5). Alternatively, as shown in FIG. 6, the exchange-coupled magnetic material can include one or more layers of a soft phase magnetic material 112 on a hard phase magnetic material 114. In one embodiment, the thickness of the hard phase magnetic material .sub.hard can be greater than the thickness of the soft phase magnetic material .sub.soft. However, in other embodiments, the thickness of the hard phase magnetic material .sub.hard can be less than or equal to the thickness of the soft phase magnetic material .sub.soft. By controlling a volume fraction of the hard (or soft) magnetic phase in the exchange-coupled magnetic materials of FIGS. 4-6, high M.sub.s and large H.sub.k can be simultaneously achieved. In one embodiment, the volume fraction can be controllable by the ratio of hard phase (or soft phase) to soft phase (or hard phase) to obtain a desired magnetic characteristic. As an example, a volume fraction of 0.3 indicates that hard and soft phases occupy 30% and 70%, respectively, in an exchange-coupled magnetic material.

(16) In one embodiment of the inductor 100, the coil 102 can have 2.5 spiral turns, a coil area of 11 mm.sup.2, a coil width of 50 m, a space of 50 m between the coil segments, and a thickness of 7 m; the substrate 106 can be glass having a .sub.r=5.5, a tan .sub.=0 and a =0 S/m; and the magnetic film 104 can have a thickness of 50 m, a at 1 GHz of 11.8, a at 2 GHz of 13.3, a loss (tan .sub.) at 1 GHz of 0.03 and a loss (tan .sub.) at 2 GHz of 0.07. FIG. 7 shows a graph of the complex permeability of the magnetic film 104 in one embodiment. However, in other embodiments, the coil 102 can have a greater or lesser number of spiral turns, a greater or lesser coil area, a greater or lesser coil width, a greater or lesser spacing and a greater or lesser thickness; the substrate 106 can incorporate different materials with different electrical and magnetic properties; and the magnetic film 104 can have a greater or lesser thickness, a greater or lesser p and a greater or lesser loss (tan .sub.p).

(17) FIGS. 8 and 9 show the simulated (using the ANSYS high frequency structure simulator) L and Q factor of the inductor 100 as compared to the air-core and magnetic inductors of FIGS. 1A-1D. The air-core inductor of FIG. 1A showed L of 9.28 nH and Q factor of 51.26 at 1 GHz. An L at 1 GHz of the double-side inductor of FIG. 1D, the top-type inductor of FIG. 1B, the bottom-type inductor of FIG. 1C, and the inductor 100 is 23.41, 13.19, 12.22, and 11.66 nH, respectively. However, the Q factors at 1 GHz of the double-side inductor of FIG. 1D, the top-type inductor of FIG. 1B, the bottom-type inductor of FIG. 1C are 31.60, 47.81, and 45.00, respectively, which are much lower than 63.15 Q factor at 1 GHz for of the inductor 100. The Q factor for the inductor 100 increased about 23.2% as compared to the air-core inductor of FIG. 1A. The simulated electrical characteristics of the inductors (with comparison to the air-core inductor of FIG. 1A) are summarized in Table 1.

(18) TABLE-US-00001 TABLE 1 L (nH) at 1 GHz Q at 1 GHz Q at 2 GHZ Magnetic Double-side 23.47 31.60 10.53 (+152.3%) (38.3%) (82.3%) Top-type 13.19 47.81 36.98 (+42.1%) (6.7%) (38.0%) Bottom-type 12.22 45.00 39.47 (+31.7%) (12.2%) (33.8%) Inductor 100 11.66 63.15 60.00 (+25.6%) (+23.2%) (+0.6%) Air-Core 9.28 51.26 59.66

(19) FIG. 10 shows another embodiment of an integrated magnetic inductor 200. In this embodiment, the inductor 200 can have a coil 102 with 3.5 spiral turns, a coil width of 15 m, space of 15 m between coil segments, and a coil area of 0.280.28 mm.sup.2, and the substrate 106 can be a GaAs substrate. FIGS. 11 and 12 show the simulated L and Q factor of the inductor 200 and a similarly configured air-core inductor. The L and Q factor at 5 GHz of the inductor 200 are 3.58 nH and 32.7, respectively, which are higher than the L and Q factor at 5 GHz of 2.88 nH and 25.2, respectively, of the air-core inductor. The L and Q factor of the inductor 200 are 24.3% and 29.7% increases as compared to those of the air-core inductor.

(20) In one embodiment, to characterize the magnetic properties of the exchange-coupled magnetic material used in the magnetic film 104, the calculated M.sub.s and H.sub.k of the exchange-coupled magnetic material are shown in FIG. 13 in terms of volume fractions of hard magnetic phase (f.sub.hard) Equations (1) and (2) were used to calculate M.sub.s and H.sub.k.
M.sub.s=M.sub.hardf.sub.hard+M.sub.softf.sub.soft(1)

(21) $\begin{array}{cc}{H}_k=2\frac{K_{\mathrm{hard}}{f}_{\mathrm{hard}}+K_{\mathrm{soft}}{f}_{\mathrm{soft}}}{M_{\mathrm{hard}}{f}_{\mathrm{hard}}+M_{\mathrm{soft}}{f}_{\mathrm{soft}}}=\frac{M_{\mathrm{hard}}{H}_{\mathrm{hard}}{f}_{\mathrm{hard}}+M_{\mathrm{soft}}{H}_{\mathrm{soft}}{f}_{\mathrm{soft}}}{M_{\mathrm{hard}}{f}_{\mathrm{hard}}+M_{\mathrm{soft}}{f}_{\mathrm{soft}}}& \left(2\right)\end{array}$

(22) M.sub.s and H.sub.k: Saturation magnetization and anisotropy field of the exchange-coupled magnetic material, respectively

(23) M.sub.soft/hard and K.sub.soft/hard: Saturation magnetization and anisotropy constant of soft/hard magnetic phases, respectively

(24) H.sub.soft/hard and f.sub.soft/hard: Anisotropy field and volume fraction of soft/hard magnetic phases, respectively

(25) For example, CoFe.sub.2O.sub.4 ferrite and Fe.sub.40Co.sub.60 were used as the magnetic hard and soft phases, respectively, of the exchange-coupled magnetic material. For the single-phase CoFe.sub.2O.sub.4, i.e., an f.sub.hard of 1, the M.sub.s and H.sub.k are 5,300 Gauss and 9,400 Oe. For the single-phase Fe.sub.40Co.sub.60, i.e., an f.sub.hard of 0, the M.sub.s and H.sub.k are 23,000 Gauss and 20 Oe. The calculated results show that both M.sub.s and H.sub.k are controllable with different volume fractions of f.sub.hard of the CoFe.sub.2O.sub.4, the hard magnetic phase material. The calculated results of M.sub.s and H.sub.k for different f.sub.hard are summarized in Table 2.

(26) TABLE-US-00002 TABLE 2 f.sub.hard M.sub.s (Gauss) H.sub.k (Oe) 0 23000 20 0.09 21407 229 0.12 20876 305 1 5300 9400

(27) The calculated M.sub.s and H.sub.k of the exchange-coupled magnetic material in FIG. 13 can be applied to equation (3) in order to determine the frequency-dependent complex permeability.

(28) $\begin{array}{cc}={}^{}-j{}^{}=1+\frac{4M_s}{H_k+j}\left[1+\frac{{}^2}{\left(H_k+4M_s+j\right)\left(H_k+j\right)-{}^2}\right]& \left(3\right)\end{array}$

(29) where is the real part and is the imaginary part of permeability, is the angular driving frequency, is the gyromagnetic constant (1.76107 rad/Oe.Math.s), and is the damping constant

(30) FIG. 14 shows the calculated complex permeability of the exchange-coupled magnetic material in terms of f.sub.hard. As f.sub.hard changes from 0 to 1, i.e., the percentage of hard magnetic phase material goes from 0% to 100%, the varies from 1280 to 1.6, while f.sub.FMR increases from 1.8 to 19.7 GHz. The and f.sub.FMR of the exchange-coupled magnetic material are summarized in Table 3.

(31) TABLE-US-00003 TABLE 3 f.sub.hard at 1 Ghz f.sub.FMR (GHz) 0 1280 1.8 0.09 97 6.2 0.12 71 7.1 1 1.6 19.7

(32) It is noted that the of the exchange-coupled magnetic materials, e.g., f.sub.hard of 0.09 or 0.12, is higher than that of the single phase CoFe.sub.2O.sub.4, i.e., an f.sub.hard of 1, and the f.sub.FMR is larger than that of the single phase Fe.sub.40Co.sub.60, i.e., an f.sub.hard of 0. Accordingly, the exchange-coupled magnetic material improves the and f.sub.FMR over single phase magnetic materials.

(33) It should be understood that the identified embodiments are offered by way of example only. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the embodiments without departing from the scope of the present application. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the application. It should also be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting.