MEMS power inductor with magnetic laminations formed in a crack resistant high aspect ratio structure

• US 8,466,537 B1
• Filed: 12/30/2011
• Issued: 06/18/2013
• Est. Priority Date: 12/30/2011
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Papou, Andrei, French, William, Hopper, Peter J.
• Primary Examiner(s): YUSHIN, NIKOLAY K
• Application Number:
  US13/340,849
• Publication Number:
  US 20130168808A1
• Time in Patent Office: 536 Days
• Field of Search: 257/531, 257/628, 257/277, 257/E21.022, 296/021, 296/00, 295/921
• US Class Current: 257/531
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 2017/0066 with a magnetic layer
• CPC Class Codes: H01F 41/046 structurally combined with ferromagnetic material
• CPC Class Codes: H01L 23/5227 Inductive arrangements or effects of, or between, wiring layers other inductive arrangements H01L23/645
• 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

Magnetic laminations are formed in the openings of a first non-conductive structure, which is formed in the opening of a second non-conductive structure that has a maximum aspect ratio that is less than the maximum aspect ratio of the first non-conductive structure. The second non-conductive structure is more crack resistant than the first non-conductive structure, and thereby protects the first non-conductive structure and the magnetic laminations from environmental contaminants.

Claims

1. A semiconductor inductor comprising:

a first structure being non-conductive and having a top surface;

a second structure being non-conductive and having a top surface, a side wall surface, and a bottom surface, the bottom surface touching the top surface of the first structure;

a third structure being non-conductive and having a top surface, a side wall surface, and a bottom surface, the bottom surface of the third structure touching the top surface of the first structure, the side wall surface of the third structure touching the side wall surface of the second structure, the second structure and the third structure having different material characteristics;

a plurality of lower magnetic structures that touch the first and third structures, each lower magnetic structure having a top surface, and being spaced apart and electrically isolated from each other lower magnetic structure;

a fourth structure being non-conductive and having a top surface, and a bottom surface, the bottom surface of the fourth structure touching the top surfaces of the second structure, the third structure, and each lower magnetic structure; and

a conductive trace having a top surface, touching the fourth structure, and lying directly over and spaced apart from each of the lower magnetic structures.

2. The semiconductor inductor of claim 1 wherein the conductive trace has a number of loops.

3. The semiconductor inductor of claim 1 wherein the plurality of lower magnetic structures are spaced apart from the second non-conductive structure.

4. The semiconductor inductor of claim 1 wherein:

the first, second, and fourth structures each has a low intrinsic stress and a low Young'"'"'s modulus; and

the third structure has a high intrinsic stress and a high Young'"'"'s modulus.

5. The semiconductor inductor of claim 1 wherein the first, second, and fourth structures have a maximum aspect ratio that is less than a maximum aspect ratio of the second structure.

6. The semiconductor inductor of claim 1 wherein the plurality of lower magnetic structures each includes NiFe.

7. The semiconductor inductor of claim 1 wherein the conductive trace includes copper.

8. The semiconductor inductor of claim 1 wherein the top surfaces of second structure, the third structure, and each of the plurality of lower magnetic structures lie substantially in a single plane.

9. The semiconductor inductor of claim 1 and further comprising a fifth structure being non-conductive and having a low intrinsic stress, a top surface, and a bottom surface, the bottom surface of the fifth structure touching the top surfaces of the fourth structure and the conductive trace.

10. The semiconductor inductor of claim 9 and further comprising:

a sixth structure being non-conductive and having a low intrinsic stress, a top surface, a side wall surface, and a bottom surface, the bottom surface of the sixth structure touching the top surface of the fifth structure; and

a seventh structure being non-conductive and having a high intrinsic stress, a top surface, a side wall surface, and a bottom surface, the bottom surface of the seventh structure touching the top surface of the fifth structure, the side wall surface of the seventh structure touching the side wall surface of the sixth structure.

11. The semiconductor inductor of claim 10 and further comprising a plurality of upper magnetic structures that touch the fifth and seventh structures, each upper magnetic structure having a top surface, and being spaced apart and electrically isolated from each other upper magnetic structure.

12. The semiconductor inductor of claim 11 wherein each lower magnetic structure lines a lower lamination opening, no lower magnetic structure filling a lamination opening.

13. The semiconductor inductor of claim 12 wherein each upper magnetic structure lines an upper lamination opening, no lower magnetic structure filling an upper lamination opening.

14. The semiconductor inductor of claim 11 wherein each upper magnetic structure lies horizontally adjacent to and spaced apart from the conductive trace.

15. The semiconductor inductor of claim 11 and further comprising an eighth structure being non-conductive and having a low intrinsic stress, a top surface, and a bottom surface, the bottom surface of the eighth structure touching the top surfaces of the sixth structure, the seventh structure, and each upper magnetic structure.

16. The semiconductor inductor of claim 11 wherein each upper magnetic structure lies directly vertically above a corresponding lower magnetic structure.

17. The semiconductor inductor of claim 16 wherein each upper magnetic structure is spaced apart from the corresponding lower magnetic structure.

18. The semiconductor inductor of claim 16 wherein each upper magnetic structure touches the corresponding lower magnetic structure.

19. The semiconductor inductor of claim 11 wherein the top surfaces of sixth structure, the seventh structure, and each of the plurality of upper magnetic structures lie substantially in a single plane.

20. A method of forming a semiconductor inductor comprising:

forming a first structure being non-conductive and having a top surface;

forming a second structure being non-conductive and having a top surface, a side wall surface, and a bottom surface, the bottom surface touching the top surface of the first structure;

forming a third structure being non-conductive and having a top surface, a side wall surface, and a bottom surface, the bottom surface of the third structure touching the top surface of the first structure, the side wall surface of the third structure touching the side wall surface of the second structure, the second structure and the third structure having different material characteristics;

forming a plurality of lower magnetic structures that touch the first and third structures, each lower magnetic structure having a top surface, and being spaced apart and electrically isolated from each other lower magnetic structure;

forming a fourth structure being non-conductive and having a top surface, and a bottom surface, the bottom surface of the fourth structure touching the top surfaces of the second structure, the third structure, and each lower magnetic structure; and

forming a conductive trace having a top surface, touching the fourth structure, and lying directly over and spaced apart from each of the lower magnetic structures.