Through-wafer interconnection

• US 9,224,648 B2
• Filed: 01/12/2012
• Issued: 12/29/2015
• Est. Priority Date: 05/18/2005
• Status: Active Grant

• Current Assignee: Kolo Medical, Ltd.
• Original Assignee: Kolo Technologies, Inc.
• Inventors: Huang, Yongli
• Primary Examiner(s): STARK, JARRETT J
• Application Number:
  US13/349,436
• Publication Number:
  US 20120112324A1
• Time in Patent Office: 1,447 Days
• US Class Current: 1/1
• 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 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

A through-wafer interconnect and a method for fabricating the same are disclosed. The method starts with a conductive wafer to form a patterned trench by removing material of the conductive wafer. The patterned trench extends in depth from the front side to the backside of the wafer, and has an annular opening generally dividing the conductive wafer into an inner portion and an outer portion whereby the inner portion of the conductive wafer is insulated from the outer portion and serves as a through-wafer conductor. A dielectric material is formed or added into the patterned trench mechanical to support and electrically insulate the through-wafer conductor. Multiple conductors can be formed in an array.

Claims

1. A through-wafer interconnect which provides electrically conductive interconnection between electric contacts on a front side and a backside of a wafer in a microelectronic structure, the through-wafer interconnect comprising:

a through-wafer conductor passing through the front side of the wafer to the backside of the wafer;

an insulator surrounding at least a main body portion of the conductor, wherein the insulator comprises a top portion and a bottom portion that are different from each other in at least one aspect of cross-sectional size or material property; and

a frame surrounding the through-wafer conductor and the insulator, wherein at least a portion of the through-wafer conductor and a respective surrounding portion of the frame each comprise a native material of the wafer.

2. The through-wafer interconnect of claim 1 wherein the wafer is a conductive wafer.

3. The through-wafer interconnect of claim 1 wherein the through-wafer conductor comprises a top portion and a bottom portion which are different from each other in at least one aspect of cross-sectional size and material property.

4. The through-wafer interconnect of claim 1 wherein:

the wafer comprises a first conductive wafer bonded to a second conductive wafer;

a first portion of a patterned trench is formed through a top side of the first conductive wafer to form a first part of the conductor; and

a second portion of the patterned trench is formed through a backside of the second conductive wafer to form a second part of the.

5. The through-wafer interconnect of claim 1 wherein:

the wafer comprises a top layer and a bottom layer bonded together;

a first part of the conductor comprises the native material of the first layer; and

a second part of the conductor comprises the native material of the second layer.

6. The through-wafer interconnect of claim 1 wherein the insulator comprises a dielectric material added to an annular trench formed in the wafer by removing native material of the wafer.

7. The through-wafer interconnect of claim 1 wherein the insulator comprises lines of unremoved native material of the wafer patterned in an annular trench.

8. The through-wafer interconnect of claim 7 wherein the lines of unremoved native material of the wafer form a supporting framework between the conductor and the frame.

9. The through-wafer interconnect of claim 7 further comprising a filler material filled between the lines of unremoved native material of the wafer patterned in the annular trench.

10. The through-wafer interconnect of claim 7 wherein at least part of the lines of unremoved native material is oxidized.

11. The through-wafer interconnect of claim 7 wherein at least part of the lines of unremoved native material of the wafer is completely oxidized.

12. The through-wafer interconnect of claim 1 wherein the insulator comprises a filler material filled in a trench.

13. The through-wafer interconnect of claim 1 wherein the frame comprises a zigzag shaped wall which is flexible through stretching or compressing.

14. A through-wafer interconnect component comprising:

a plurality of conductors arranged in an array, each conductor passing through a front side of a conductive wafer to a backside of the wafer, each conductor having a center spaced apart from centers of adjacent conductors in the array;

an insulator surrounding each conductor, wherein the insulator passes between and is in contact with at least two adjacent conductors in the array; and

a frame supporting the plurality of conductors and the insulator, wherein at least a portion of each conductor and a portion of the frame each comprise a native material of the wafer.

15. The through-wafer interconnect of claim 14 wherein the insulator is disposed in a plurality of annular trenches each surrounding a respective conductor, the annular trenches being formed by removing a native material of the wafer.

16. The through-wafer interconnect of claim 14 wherein the frame has an outer peripheral wall and a plurality of inter-conductor walls, the outer peripheral wall defining a general area where the plurality of conductors and the insulator are disposed, and the plurality of inter-conductor walls dividing the general area into a plurality of sub-areas each containing one of the conductors and a respective portion of the insulator surrounding the conductor, wherein the inter-conductor walls are lower than the outer peripheral wall.

17. The through-wafer interconnect of claim 16 wherein the inter-conductor walls of the frame comprise the native material of the conductive wafer and are able to function as a decoupling conductor between the plurality of conductors.

18. The through-wafer interconnect of claim 14, further comprising lines of unremoved conductive wafer material that form a framework between the plurality of conductors and the frame to connect and support the conductors with respect to the frame.

19. The through-wafer interconnect of claim 14 wherein the frame comprises a zigzag shaped wall which is flexible through stretching or compressing.

20. A through-wafer interconnect comprising:

a conductive wafer including a top conductive wafer bonded to a bottom conductive wafer, the conductive wafer having a front side and a backside;

a patterned trench formed in the conductive wafer, the patterned trench having an annular trench opening dividing the conductive wafer along the annular trench opening into an inner portion and an outer portion, wherein a top portion of the patterned trench is formed in the top conductive wafer and a bottom portion of the patterned trench is formed in the bottom conductive wafer; and

a support material within the patterned trench connecting the inner portion and the outer portion, wherein;

the support material including an oxidized portion of an unremoved conductive wafer material and/or an added dielectric filler material, such that the inner portion of the conductive wafer is insulated from the outer portion and serves as a through-wafer conductor; and

a top portion of the through-wafer conductor corresponding to the top portion of the patterned trench has a cross-sectional size significantly different from that of a bottom portion of the through-wafer conductor corresponding to the bottom portion of the patterned trench.

21. The through-wafer interconnect of claim 20 wherein the support material comprises a plurality of lines of unremoved conductive wafer material formed within the patterned trench as a result of fine-patterning the trench.

22. The through-wafer interconnect of claim 21 wherein at least part of the plurality of lines of unremoved conductive wafer material are oxidized.

23. The through-wafer interconnect of claim 20 wherein the support material forms a framework between the inner portion and the outer portion of the conductive wafer to physically connect and support the inner portion with respect to the outer portion.

24. The through-wafer interconnect of claim 20 wherein the support material comprises a plurality of lines of unremoved conductive wafer material formed within the patterned trench as a result of fine-patterning the trench, and the filler material is disposed between the plurality of lines of unremoved conductive wafer material.

25. The through-wafer interconnect of claim 20, wherein the support material comprises

a first dielectric material in a top portion of the patterned trench;

and

a second dielectric material in a bottom portion of the patterned trench.

26. The through-wafer interconnect of claim 20 further comprising an etch stop layer, wherein a portion of the patterned trench extends from the backside to the etch stop layer.

27. The through-wafer interconnect of claim 20 further comprising a device formed on the top conductive wafer.

28. A through-wafer interconnect comprising:

a first conductive wafer bonded to a second conductive wafer between a bottom side of the first conductive wafer and a top side of the second conductive wafer;

a first portion of a patterned trench formed through a top side of the first conductive wafer; and

a second portion of the patterned trench formed through a backside of the second conductive wafer, wherein;

the first portion and the second portion of the patterned trench each have an annular circumferential opening generally dividing the respective conductive wafer into an inner portion and an outer portion;

the inner portion of the respective conductive wafer is insulated from the outer portion of the respective conductive wafer;

the inner portion of the first conductive wafer and the inner portion of the second conductive wafer are different from each other in at least one aspect of cross-sectional size or material property, and electrically connected to serve as a through-wafer conductor.

29. The through-wafer interconnect of claim 28, further comprising an intervening layer extending across a bonded joint between the first conductive wafer and the second conductive wafer.

30. The through-wafer interconnect of claim 29, the intervening layer comprising a cavity formed on the top side of the second conductive wafer, at least a bottom surface of the cavity being oxidized to form an etch stop layer thereon, wherein the bottom portion of the patterned trench extends through the backside of the second conductive wafer to the etch stop layer.

31. The through-wafer interconnect of claim 28, wherein there are a plurality of the through-wafer interconnects arranged in an array, wherein a center of each through-wafer interconnect in the array is spaced apart from centers of adjacent through-wafer interconnects in the array, further comprising a microelectronic device disposed on one of the first conductive wafer or the second conductive wafer and electrically connected to the through-wafer interconnects in the array.

32. The through-wafer interconnect of claim 28 wherein the second portion of the patterned trench has a trench opening that is broader than that of the first portion of the patterned trench, whereby a second portion of the through-wafer conductor surrounded and defined by the second portion of the patterned trench has a smaller cross-sectional size than a first portion of the through-wafer conductor surrounded and defined by the second portion of the patterned trench.

33. The through-wafer interconnect of claim 28 wherein at least one of the first conductive wafer or the second conductive wafer is either pre-fabricated to contain at least part of a microelectronic device or allows fabricating a microelectronic device thereon after being bonded to the other one of the first conductive wafer or the second conductive wafer.

34. The through-wafer interconnect of claim 28 wherein the second portion of the patterned trench is fine-patterned within the trench opening with a plurality of open passages interlined with a plurality of lines of unremoved conductive wafer material that connect between a wall of the trench and the through-wafer interconnect.

35. The through-wafer interconnect of claim 34 wherein the plurality of lines of unremoved conductive wafer material form a framework between the inner portion and the outer portion of the conductive wafer to connect and support the through-wafer interconnect.

36. The through-wafer interconnect of claim 35 wherein at least part of individual lines of the plurality of lines of unremoved conductive wafer material are oxidized such that the framework is electrically insulative between the inner portion and the outer portion of the conductive wafer.

37. A through-wafer interconnect comprising:

a first conductive wafer bonded to a second conductive wafer such that a bottom side of the first conductive wafer contacts a top side of the second conductive wafer;

a first portion of a patterned trench formed through a top side of the first conductive wafer; and

a second portion of the patterned trench formed through a backside of the second conductive wafer, wherein;

the first portion and the second portion of the patterned trench each have an annular circumferential opening generally dividing the respective conductive wafer into an inner portion and an outer portion;

the inner portion of the respective conductive wafer is insulated from the outer portion of the respective conductive wafer;

the inner portion of the first conductive wafer and the inner portion of the second conductive wafer are electrically connected to serve as a through-wafer conductor; and

a first portion of the through-wafer conductor surrounded and defined by the first portion of the patterned trench has a different cross-sectional size than a second portion of the through-wafer conductor surrounded and defined by the second portion of the patterned trench.

38. The through-wafer interconnect of claim 37 wherein the first conductive wafer and the second conductive wafer are bonded together with an intervening layer therebetween.

39. The through-wafer interconnect of claim 37 further comprising a cavity formed on the top side of the second conductive wafer, at least a bottom surface of the cavity being oxidized to form an etch stop layer thereon, wherein the bottom portion of the patterned trench extends through the backside of the second conductive wafer to the etch stop layer.

40. The through-wafer interconnect of claim 37 wherein the second portion of the patterned trench is fine-patterned within the trench opening with a plurality of open passages interlined with a plurality of lines of unremoved conductive wafer material that connect between a wall of the trench and the through-wafer interconnect.