Integrated circuit inductor with a magnetic core

• US 6,853,288 B2
• Filed: 11/21/2003
• Issued: 02/08/2005
• Est. Priority Date: 03/10/2000
• Status: Expired due to Fees

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Ahn, Kie Y., Forbes, Leonard
• Primary Examiner(s): MAI, ANH T
• Application Number:
  US10/719,501
• Publication Number:
  US 20040113738A1
• Time in Patent Office: 445 Days
• Field of Search: 336/200, 336/232, 336/223, 296/021, 296/05
• US Class Current: 336/200
• CPC Class Codes: H01F 17/0033 with the coil helically wound around a magnetic core
• CPC Class Codes: H01F 17/045 with core of cylindric geometry and coil wound along its longitudinal axis, i.e. rod or drum core
• CPC Class Codes: H01F 41/046 structurally combined with ferromagnetic material
• CPC Class Codes: H01F 5/003 Printed circuit coils
• CPC Class Codes: H01L 28/10 Inductors
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

An inductor is fabricated on a substrate having a top surface and a bottom surface. The inductor includes a plurality of holes extending through the substrate, wherein the plurality of holes interconnect the top surface and the bottom surface of the substrate. The inductor also includes a plurality of conductive posts formed in the plurality of holes and a plurality of conductive segments formed on the top surface and on the bottom surface that interconnect the conductive posts such that a continuous conductive coil is formed. The inductor also includes a magnetic core that occupies substantially the entire volume enclosed by the conductive coil.

Claims

1. A method of fabricating an inductor comprising:

forming a plurality of vias in a substrate;

forming a magnetic core within the substrate;

depositing a first metallic material into the vias to form a plurality of metallic posts; and

fabricating a plurality of conductive segments that interconnect the plurality of metallic posts to form a conductive coil surrounding the magnetic core.

2. The method of claim 1, wherein forming the plurality of vias comprises extending the vias entirely through the substrate.

3. The method of claim 1, wherein forming the plurality of vias comprises forming two substantially parallel rows of vias extending through the substrate.

4. The method of claim 1, wherein forming the plurality of vias comprises using an etching process.

5. The method of claim 1, wherein forming the plurality of vias comprises using a laser.

6. The method of claim 1, wherein the substrate comprises a semiconductor wafer.

7. The method of claim 1, wherein the substrate comprises silicon.

8. The method of claim 1, wherein the substrate comprises silicon carbide.

9. The method of claim 1, wherein the substrate comprises germanium.

10. The method of claim 1, wherein forming the magnetic core comprises depositing a magnetic oxide.

11. The method of claim 1, wherein forming the magnetic core comprises depositing ferromagnetic material by chemical vapor deposition.

12. The method of claim 1, wherein forming a magnetic core comprises:

forming a porous region in the substrate; and

depositing a ferromagnetic material in the porous region.

13. The method of claim 1, wherein forming the conductive coil comprises depositing copper.

14. The method of claim 1, wherein forming the conductive coil comprises depositing gold.

15. The method of claim 1, wherein fabricating the plurality of conductive segments comprises forming a plurality of conductive straps interconnecting the metallic posts to form the conductive coil.

16. The method of claim 15, wherein forming the plurality of conductive straps comprises using a second metallic material, wherein the first metallic material is not the same as the second metallic material.

17. The method of claim 15, wherein the metallic posts are configured in two substantially parallel rows.

18. The method of claim 1, wherein the substrate has at least two substantially parallel surfaces, and wherein the metallic posts are substantially perpendicular to the parallel surfaces.

19. The method of claim 1, wherein the metallic posts have circular cross-sections.

20. The method of claim 1, wherein the metallic posts are at least partially surrounded by an insulating material.

21. The method of claim 20, wherein the insulating material comprises polyimide.

22. The method of claim 1, wherein the inductor has an inductance of at least 1 nanohenry.

23. The method of claim 1, further comprising covering the conductive coil with a passivation layer.

24. The method of claim 23, wherein the passivation layer is configured to electrically insulate the inductor and to protect the inductor from physical damage.

25. The method of claim 1, further comprising operatively coupling the inductor to an integrated circuit formed on the substrate.

26. The method of claim 25, wherein the integrated circuit is a computer memory circuit.

27. An inductor comprising:

a substrate;

a magnetic core formed within the substrate;

a plurality of vias filled with a metallic material providing a plurality of metallic posts through the substrate; and

a plurality of conductive segments interconnecting the plurality of conductive posts to form a conductive coil surrounding the magnetic core.

28. The inductor of claim 27, wherein the substrate comprises a semiconductor wafer.

29. The inductor of claim 27, wherein the substrate comprises silicon.

30. The inductor of claim 27, wherein the magnetic core comprises a porous region of the substrate treated with a ferromagnetic material.

31. The inductor of claim 27, wherein the metallic material in the vias comprises copper.