Microinductor and fabrication method thereof

Abstract

A microinductor comprises a magnetic core and a coil which winds around the magnetic core. The magnetic core used in the microinductor is formed of FeCuNbCrSiB.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the present invention will be more apparent by describing certain exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

FIGS. 1A through 1D are graphs showing properties of a related art microinductor using a magnetic core formed of NiFe;

FIG. 2 is a simplified conceptual diagram of a microinductor according to an exemplary embodiment of the present invention;

FIG. 3 is a plane diagram of a microinductor according to an exemplary embodiment of the present invention;

FIG. 4 is a perspective view of the microinductor of FIG. 3;

FIG. 5 is a cross-sectional view taken along I-I of FIG. 3;

FIGS. 6, 7A, and 7B are conceptual diagrams of exemplary magnetic cores used in the microinductor of FIG. 3;

FIG. 8 is a conceptual diagram of a plurality of microinductors on a wafer according to an exemplary embodiment of the present invention;

FIGS. 9A through 9E are cross-sectional views showing a microinductor fabrication method according to an exemplary embodiment of the present invention;

FIGS. 10A through 10D are graphs showing microinductor properties according to an exemplary embodiment of the present invention;

FIGS. 11A through 11E are photos, taken by an electron microscope, of surface state of the magnetic core used in the microinductor according to an exemplary embodiment of the present invention;

FIGS. 12A through 12E are graphs of magnetic field-magnetic moment properties of the microinductor along a magnetization easy axis; and

FIGS. 13A through 13E are graphs of magnetic field-moment properties of the microinductor along a magnetization hard axis.

Claims

1. A microinductor comprising: a magnetic core which is formed of FeCuNbCrSiB; anda coil which winds around the magnetic core.

2. The microinductor of claim 1, further comprising: an insulator which insulates the magnetic core.

3. The microinductor of claim 2, wherein the insulator is aluminum oxide.

4. The microinductor of claim 2, wherein the insulator is polyimide.

5. The microinductor of claim 1, further comprising: a substrate which supports the magnetic core and the coil; anda plurality of pads which are located on the substrate and connected to the coil.

6. The microinductor of claim 5, wherein the coil comprises: a lower coil pattern which interposes between the substrate and the magnetic core;an upper coil pattern which is located on the magnetic core; anda via which connects the lower coil pattern to the upper coil pattern.

7. The microinductor of claim 5, wherein the magnetic core is a closed magnetic circuit which has two sides facing each other on the substrate.

8. The microinductor of claim 7, wherein the coil comprises: a first coil which winds around a first side of the two sides of the magnetic core; anda second coil which winds around a second side of the two sides of the magnetic core, the second coil connected to the first coil at one end.

9. The microinductor of claim 8, wherein one end of the first coil is connected to a first pad of the plurality of the pads, the other end of the first coil is connected to the one end of the second coil, and the other end of the second coil is connected to a second pad of the plurality of the pads.

10. The microinductor of claim 1, wherein a width of each winding of the coil is 20˜40 μm, a thickness of each winding is 5˜20 μm, and an interval between the windings is 20˜40 μm.

11. The microinductor of claim 10, wherein the magnetic core is a thin film type of thickness 2˜6 μm.

12. A fabrication method of a microinductor which comprises a magnetic core and a coil winding around the magnetic core, the method comprising: forming a lower coil pattern on a substrate;fabricating a magnetic core formed of FeCuNbCrSiB, in a pattern on the substrate where the lower coil pattern is formed;forming a via pattern connected to the lower coil pattern; andfabricating a coil to wind around the magnetic core by depositing an upper coil pattern being connected to the via pattern.

13. The fabrication method of claim 12, wherein the forming the lower coil pattern comprises: forming a seed layer on a surface of the substrate and forming an alignment mark on at least one surface of the substrate; andforming the lower coil pattern by plating along the seed layer, andthe fabricating the magnetic core, the forming the via pattern and the fabricating the coil are performed at a corresponding position based on the alignment mark.

14. The fabrication method of claim 12, wherein for the fabricating the magnetic core, the magnetic core is fabricated at a position apart from the lower coil by a distance, and the magnetic core is a closed magnetic circuit which has two sides facing each other.

15. The fabrication method of claim 12, wherein the fabricating the magnetic core comprises: depositing a FeCuNbCrSiB film on the substrate where the lower coil pattern is formed, by sputtering using a FeCuNbCrSiB sample; andfabricating the magnetic core by patterning the FeCuNbCrSiB film.

16. The fabrication Method of claim 12, wherein the forming the via pattern comprises: forming a pad together with the via pattern.

17. The fabrication method of claim 12, further comprising: annealing the microinductor in a vacuum furnace at a temperature while a magnetic field is applied.

18. The fabrication method of claim 15, wherein the sputtering process is conducted in a sputtering chamber in which the substrate having the lower coil pattern and the FeCuNbCrSiB sample are placed, under the following condition: gas in sputtering chamber: argonpressure in sputtering chamber: 4.2 Pasputtering time: 1˜2 hsputtering power: 600 Wflow rate: 13 SCCMmagnitude of magnetic field: 16 kA/mdirection of magnetic field: parallel with the substrate surface.