Monolithic magnetic induction device

• US 9,287,344 B2
• Filed: 08/23/2011
• Issued: 03/15/2016
• Est. Priority Date: 08/23/2010
• Status: Active Grant

• Current Assignee: Hong Kong University of Science and Technology
• Original Assignee: Hong Kong University of Science and Technology
• Inventors: Sin, Johnny Kin On, Wu, Rongxiang, Hui, Ron Shu Yuen
• Primary Examiner(s): Kraig, William F
• Assistant Examiner(s): Malek, Maliheh
• Application Number:
  US13/215,350
• Publication Number:
  US 20120068301A1
• Time in Patent Office: 1,666 Days
• US Class Current: 1/1
• CPC Class Codes: H01F 27/28 Coils; Windings; Conductive connections
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• CPC Class Codes: H01L 23/481 Internal lead connections, e.g. via connections, feedthrough structures
• CPC Class Codes: H01L 23/645 Inductive arrangements H01L23/647, H01L23/66 take precedence
• CPC Class Codes: H01L 28/10 Inductors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

Providing for a monolithic magnetic induction device having low DC resistance and small surface area is described herein. By way of example, the magnetic induction device can comprise a substrate (e.g., a semiconductor substrate) having trenches formed in a bottom layer of the substrate, and holes formed in the substrate between the trenches and an upper layer of the substrate. Additionally, the magnetic induction device can comprise a conductive coil embedded or deposited within the trenches. The magnetic induction device can further comprise a set of conductive vias formed in the holes that electrically connect the bottom layer of the substrate with the upper layer. Further, one or more integrated circuit components, such as active devices, can be formed in the upper layer, at least in part above the conductive coil. The vias can be utilized to connect to integrated circuit components with the conductive coil, where suitable.

Claims

1. A magnetic induction device for an integrated circuit, comprising:

a semiconductor substrate having a first surface, and a second surface opposite the first surface, wherein a distance from the first surface to the second surface is equal to a thickness of the semiconductor substrate;

a conducting coil that forms a set of turns embedded within the semiconductor substrate and that extends from the first surface to a first depth within the semiconductor substrate that is less than the thickness of the semiconductor substrate; and

one or more conductive vias, that substantially fills one or more respective holes in the semiconductor substrate, and that extends from the second surface to the first depth, a first end of at least one of the one or more conductive vias being embedded within the semiconductor substrate at the first depth and in physical contact with the conducting coil, to a second end at the second surface of the semiconductor substrate;

wherein the set of turns embedded within the semiconductor substrate formed by the conductive coil is exclusive of the one or more conductive vias.

2. The magnetic induction device of claim 1, further comprising one or more integrated circuit (IC) components formed at least in part within or above the second surface of the semiconductor substrate, wherein the at least one of the one or more conductive vias electrically connects the conducting coil at a first end of the at least one of the one or more conductive vias with at least a subset of the one or more IC components at a second end of the at least one of the one or more conductive vias.

3. The magnetic induction device of claim 2, the magnetic induction device is a monolithic device and the conducting coil, one or more conductive vias and one or more IC components are embedded substantially within the semiconductor substrate.

4. The magnetic induction device of claim 1, the conducting coil has a thickness of about 200 micrometers (μ

m).

5. The magnetic induction device of claim 1, the conducting coil has a thickness of greater than 100 μ

m.

6. The magnetic induction device of claim 1, the semiconductor substrate is comprised of silicon.

7. The magnetic induction device of claim 1, further comprising an insulating layer between the conducting coil and an IC component at least in part on or above the second surface, or between the conducting coil and the semiconductor substrate.

8. The magnetic induction device of claim 7, the insulating layer is formed with a complementary metal oxide semiconductor (CMOS) compatible deposition process.

9. The magnetic induction device of claim 1, the conducting coil has a DC resistance of about 100 milliohms or less.

10. The magnetic induction device of claim 1, the conducting coil has a quality factor of about 3.9 at 100 megahertz.

11. The magnetic induction device of claim 1, the one or more conductive vias is formed with a batch formation process.

12. The magnetic induction device of claim 1, the one or more conductive vias is formed with a plasma etching process.

13. The magnetic induction device of claim 1, the semiconductor substrate having a thickness greater than 200 micrometers (μ

m).

14. The magnetic induction device of claim 1, the semiconductor substrate having an area about 1 square millimeter or less.

15. The magnetic induction device of claim 1, having an inductor efficiency of about 90 percent or greater.

16. The magnetic induction device of claim 1, the conducting coil having a current capacity of at least about 0.5 amps.

17. The magnetic induction device of claim 1, having no magnetic core.

18. The magnetic induction device of claim 1, having an operating frequency of about 100 megahertz or less.

19. The magnetic induction device of claim 1, the conducting coil comprising copper metal and having:

a radius of about 450 μ

m;

7 turns;

a coil thickness of about 200 μ

m;

a track width of about 30 μ

m;

a track spacing between coil turns of about 15 μ

m; and

a width of the via of about 10 μ

m.

20. The magnetic induction device of claim 19, having a DC resistance of about 87 milliohms at an operating current of about 100 milliamps, and a DC resistance of about 96 milliohms at an operating current of about 2 amps.

21. The magnetic induction device of claim 1, the conducting coil comprising copper metal and having:

a coil thickness of about 100 μ

m;

a track width of about 15 μ

m;

a track spacing between coil turns of about 10 μ

m; and

a width of the via of about 30 μ

m.

22. The magnetic induction device of claim 21, the conducting coil further having:

a radius of about 330 μ

m; and

2 turns.

23. The magnetic induction device of claim 22, having primary DC resistance of about 105 milliohms and secondary DC resistance of about 110 milliohms.

24. The magnetic induction device of claim 21, the conducting coil further having:

a radius of about 700 μ

m; and

5 turns.

25. The magnetic induction device of claim 24, wherein the magnetic induction device is a two-phase coupled inductor or a monolithic transformer having primary DC resistance of about 0.44 ohms and secondary DC resistance of about 0.45 ohms.

26. A monolithic magnetic induction device, comprising:

a silicon substrate having a top surface and a thickness of at least 300 μ

m, a surface area of about 1 square millimeter or less, a wafer resistivity of greater than about 6 ohm-centimeters;

a copper coil within the silicon substrate having a thickness greater than about 50 μ

m and less than 300 μ

m, a radius of less than about 700 μ

m, a track width below about 30 μ

m, a track spacing below about 15 μ

m, between 2 and about 7 turns, and an insulation layer between at least 2 of the turns providing an isolation thickness of about 3 μ

m or greater;

an integrated circuit (IC) component formed at least in part on the top surface or within the silicon substrate; and

at least one via that substantially fills one or more respective holes that extends through a portion of the silicon substrate and electrically connects at least a part of the IC component and at least a part of the copper coil.

27. The monolithic magnetic induction device of claim 26, wherein the IC component overlies the copper coil in a cross-section.

28. The monolithic magnetic induction device of claim 26, the copper coil formed at least in part from a set of trench lines generating between 2 and about 7 turns.

29. The monolithic magnetic induction device of claim 26, the copper coil formed at least in part from a set of trench lines are formed with an etching process and filled with copper material post-etch.

30. The monolithic magnetic induction device of claim 29, wherein a copper electroplating process is utilized to fill the set of trench lines with the copper.

31. The monolithic magnetic induction device of claim 30, wherein the silicon substrate serves as a molding material layer for the copper electroplating process.

32. The monolithic magnetic induction device of claim 26, the copper coil being formed from a single patterned metal layer.

33. The monolithic magnetic induction device of claim 26, the IC component is formed at least in part on or above a top exterior surface of the silicon substrate.

34. The monolithic magnetic induction device of claim 26, the copper coil comprising a magnetic flux in a direction substantially parallel to a normal vector of the top exterior surface.

35. The monolithic magnetic induction device of claim 26, the copper coil comprising a non-metallic core.

36. The monolithic magnetic induction device of claim 26, the non-metallic core being silicon.

37. The monolithic magnetic induction device of claim 26, comprising an operating frequency of about 100 megahertz or less.

38. The monolithic magnetic induction device of claim 26, the copper coil having a current capacity of at least about 0.5 amps.

39. The monolithic magnetic induction device of claim 26, comprising an inductor efficiency of about 90 percent or greater.

40. The monolithic magnetic induction device of claim 26, the copper coil has a DC resistance of about 100 milliohms or less.

41. The monolithic magnetic induction device of claim 26, the copper coil has a quality factor of about 3.9 at 100 megahertz.