Fabricating interconnects and tips using sacrificial substrates

• US 5,994,152 A
• Filed: 01/24/1997
• Issued: 11/30/1999
• Est. Priority Date: 02/21/1996
• Status: Expired due to Term

• Current Assignee: FormFactor Incorporated
• Original Assignee: FormFactor Incorporated
• Inventors: Mathieu, Gaetan L., Eldridge, Benjamin N., Khandros, Igor Y.
• Primary Examiner(s): Picardat, Kevin M.
• Application Number:
  US08/788,740
• Time in Patent Office: 1,040 Days
• Field of Search: 438/117, 438/14, 438/15, 438/17, 438/611, 438/617
• US Class Current: 438/617
• CPC Class Codes: H01L 21/44 Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/38 - H01L21/428

Abstract

Interconnection elements and/or tip structures for interconnection elements may first be fabricated upon sacrificial substrates for subsequent mounting to electronic components. In this manner, the electronic components are not `at risk` during the fabrication process. The sacrificial substrate establishes a predetermined spatial relationship between the interconnection elements which may be composite interconnection elements having a relatively soft elongate element as a core and a relatively hard (springy material) overcoat. Tip structures fabricated on sacrificial substrates may be provided with a surface texture optimized for mounting to any interconnection elements for making pressure connections to terminals of electronic components. Interconnection elements may be fabricated upon such tip structures, or may first be mounted to the electronic component and the tip structures joined to the free-ends of the interconnection elements. Tip structures formed as cantilever beams are described.

Claims

1. A method of an fabricating interconnection element, comprising:

fabricating an interconnection component, including a connection region,

fabricating a cantilever structure on a sacrificial substrate;

mounting the cantilever structure to the connection region of the interconnection component; and

releasing the cantilever structure from the sacrificial substrate by removing at least a portion of the sacrificial substrate.

2. The method, according to claim 1, characterized in that:

the interconnection component is elongate.

3. The method, according to claim 1, characterized in that:

the interconnection component is a composite interconnection element.

4. The method, according to claim 1, characterized in that:

the interconnection component is a monolithic interconnection element.

5. The method, according to claim 1, characterized in that:

the interconnection component is a contact bump of a membrane probe.

6. The method, according to claim 1, characterized in that:

the cantilever structure has a surface texture.

7. The method, according to claim 1, characterized in that:

the cantilever structure is brazed or soldered to the interconnection component.

8. The method, according to claim 1, characterized in that:

a plurality of cantilever structures are lithographically defined on the sacrificial substrate.

9. The method, according to claim 1, characterized in that:

the interconnection component is an element on a second substrate.

10. The method, according to claim 1, characterized in that:

the cantilever structure is formed by providing a masking layer on the sacrificial substrate, forming an opening in the masking layer, and depositing spring material in the opening.

11. The method, according to claim 1, characterized in that:

the cantilever structure is tapered from a one end to an opposite end thereof.

12. The method, according to claim 1, characterized in that:

the interconnection component is resident on an electronic component.

13. The method, according to claim 1, characterized in that:

the interconnection component is fabricated upon the cantilever structure while the cantilever structure is resident on the sacrificial substrate.

14. The method, according to claim 1, wherein:

the sacrificial substrate comprises a sheet of metal.

15. The method, according to claim 1, wherein:

the sacrificial substrate comprises a silicon wafer.

16. A method of fabricating an elongate interconnection element, comprising:

mounting an elongate interconnection element at a selected area on a surface of a sacrificial substrate; and

releasing the elongate interconnection element from the sacrificial substrate by removing at least a portion of the sacrificial substrate.

17. The method, according to claim 16, further comprising:

prior to removing the at least a portion of the sacrificial substrate, attaching a first region of the elongate interconnection element to an electronic component.

18. The method, according to claim 16, further comprising:

prior to mounting the elongate interconnection element, fabricating a cantilever structure at the selected area.

19. The method, according to claim 16, wherein:

the elongate interconnection element is a composite interconnection element.

20. The method, according to claim 16, wherein:

the elongate interconnection element is a monolithic interconnection element.

21. A method of forming a cantilever element, comprising:

providing a support substrate,

applying a release material on a first side of the support substrate, the release material suitable for destructive removal,

applying a masking material on the first side of the support substrate and masking at least a portion of the release material,

patterning the masking material to expose a selected portion through the masking layer, and

depositing spring material in the selected portion to form a cantilever element.

22. The method of claim 21 further comprising releasing the cantilever element by removing at least a portion of the release material.

23. The method of claim 21 wherein the support substrate is silicon.

24. The method of claim 21 wherein the support substrate is a portion of a silicon wafer.

25. The method of claim 21 wherein the release material is conductive.

26. The method of claim 21 wherein the release material is aluminum.

27. The method of claim 21 wherein the release material is copper.

28. The method of claim 21 wherein the release material is removed by etching.

29. The method of claim 21 wherein the release material covers the first surface of the support substrate.

30. The method of claim 21 wherein the masking material is photoresist.

31. The method of claim 21 wherein the spring material comprises nickel.

32. The method of claim 21 wherein the spring material comprises cobalt.

33. The method of claim 21 wherein the spring material comprises one or more materials with final material properties and dimensions sufficient to form a resilient member after being released from the support substrate.

34. The method of claim 21 wherein the spring material is deposited by electroplating.

35. The method of claim 21 wherein the spring material is deposited by a method selected from the group consisting of plating, electroless plating, chemical vapor deposition, physical vapor deposition, and sputtering.

36. The method of claim 21 wherein the spring material is deposited to a thickness in the range of about 25 microns to about 75 microns.

37. The method of claim 21 further comprising applying a first compatibility material on the first side of the support substrate, covering at least a portion of the release material.

38. The method of claim 37 further comprising applying the masking material to mask at least a portion of the first compatibility material.

39. The method of claim 38 further comprising patterning the masking material so the selected portion exposes a portion of the first compatibility material.

40. The method of claim 37 wherein the first compatibility material comprises a material which promotes adhesion of the release material and the spring material.

41. The method of claim 37 wherein the first compatibility material comprises a material which forms a more stable interface with one or both of the release material or the spring material as compared to the interface directly between the release material and the spring material.

42. The method of claim 37 wherein the first compatibility material comprises a material which a good electrical contact material.

43. The method of claim 37 wherein the first compatibility material is selected from the group consisting of gold, rhodium, palladium, copper and cobalt.

44. The method of claim 21 further comprising applying a second compatibility material on the first side of the support substrate to cover at least a portion of the spring material.

45. The method of claim 44 wherein the second compatibility material comprises a material to promote connection or the spring material to an interconnection element.

46. The method of claim 44 wherein the second compatibility material comprises a material which forms a more stable interface with one or both of the spring material and the interconnection element.

47. The method of claim 21 further comprising shaping the support substrate to define at least partially a feature on the cantilever element.

48. The method of claim 47 further comprising etching a trench in the support substrate before applying the release material.

49. The method of claim 48 further comprising patterning the masking material so that the trench leads to the formation of a ridge on the cantilever element.

50. The method of claim 49 further comprising patterning the masking material so that the ridge is near an end of the cantilever element.

51. The method of claim 21 further comprising

providing an interconnection element, and

securing the interconnection element to the cantilever element.

52. The method of claim 51 further comprising securing the interconnection element to a second substrate.

53. The method of claim 51 wherein the interconnection element is a rigid structure with a connection region suitable to be secured to the cantilever element.

54. The method of claim 51 wherein the interconnection element is a post secured to a second substrate.

55. The method of claim 51 wherein the interconnection element is a resilient structure with a connection region suitable to be secured to the cantilever element.

56. The method of claim 51 wherein the interconnection element is a flexible member which is secured to the cantilever element.

57. The method of claim 51 wherein the interconnection element is a flexible member which is secured to the cantilever element and further comprising plating the flexible element so that it becomes a resilient structure.

58. The method of claim 51 wherein the securing comprises brazing.

59. The method of claim 51 wherein the securing comprises soldering.

60. The method of claim 51 wherein the securing comprises reflowing a eutectic material.