Shielded probe for testing a device under test

• US 7,501,842 B2
• Filed: 10/19/2007
• Issued: 03/10/2009
• Est. Priority Date: 05/23/2003
• Status: Expired due to Fees

• Current Assignee: Cascade Microtech Incorporated (FormFactor Incorporated)
• Original Assignee: Cascade Microtech Incorporated (FormFactor Incorporated)
• Inventors: Gleason, K. Reed, Andrews, Mike, Martin, John, Lesher, Tim
• Primary Examiner(s): Nguyen; Vinh P
• Application Number:
  US11/975,471
• Publication Number:
  US 20080042671A1
• Time in Patent Office: 508 Days
• Field of Search: None
• US Class Current: 324/755.07
• CPC Class Codes: G01R 1/06738 related to tip portion
• CPC Class Codes: G01R 1/06772 High frequency probes
• CPC Class Codes: G01R 1/07342 the body of the probe being at an angle other than perpendicular to test object, e.g. probe card

Abstract

A probe for measuring the electrical characteristics of integrated circuits or other microelectronic devices at high frequencies may include a dielectric substrate that supports a signal path interconnecting test instrumentation and a probe tip and a ground path that shields both the signal path and the probe tip.

Claims

1. A probe comprising:

(a) at least one selected from a flexible or a semi-flexible substrate;

(b) an elongate conductor suitable to be electrically interconnected to a test signal supported by said substrate;

(c) a conductive member suitable to be electrically interconnected to a ground signal supported by said substrate wherein said conductive member and said elongate conductor form a controlled impedance structure;

(d) a conductive path between said first side of said substrate and said second side of said substrate in a manner free from an air gap between the conductive path and an edge of said substrate for at least a majority of the thickness of said substrate and said conductive path electrically connected to said elongate conductor and free from electrical interconnection with said conductive member; and

(e) a contact electrically interconnected to said conductive path for testing a device under test.

2. The probe of claim 1 wherein said elongate conductor is electrically interconnected to a central conductor of a coaxial cable.

3. The probe of claim 2 wherein said conductive member is electrically connected to a conductor surrounding said central conductor of said coaxial cable.

4. The probe of claim 3 wherein said substrate is supported by said coaxial cable.

5. The probe of claim 4 wherein said substrate is supported by a shelf of said coaxial cable.

6. The probe of claim 1 wherein said conductive member is substantially planar.

7. The probe of claim 1 further comprising a second conductive member suitable for electrical interconnection to a ground signal, said second conductive member supported on a side of said elongate conductor opposite said substrate.

8. The probe of claim 7 wherein a dielectric separates said second conductive member and said elongate conductor.

9. The probe of claim 1 wherein said substrate has a dielectric constant less than 7.

10. The probe of claim 1 wherein said substrate has a dielectric constant less than 5.

11. The probe of claim 1 wherein said substrate has a dielectric constant less than 4.

12. The probe of claim 1 wherein said substrate has a dielectric constant less than 2.

13. The probe of claim 1 wherein said ground signal is zero volts.

14. The probe of claim 1 wherein said conductive member covers greater than 50% of said second side of said substrate.

15. The probe of claim 1 wherein said conductive member covers greater than 60% of said second side of said substrate.

16. The probe of claim 1 wherein said conductive member covers greater than 70% of said second side of said substrate.

17. The probe of claim 1 wherein said conductive member covers greater than 80% of said second side of said substrate.

18. The probe of claim 1 wherein said conductive member covers greater than 90% of said second side of said substrate.

19. The probe of claim 1 wherein said conductive member, said elongate conductor, and said substrate collectively form a microstrip transmission structure.

20. The probe of claim 1 wherein said conductive path is a via through said substrate.

21. The probe of claim 1 wherein said conductive member laterally surrounds at least 50% of said contact.

22. The probe of claim 1 wherein said conductive member laterally surrounds at least 75% of said contact.

23. The probe of claim 1 wherein said conductive member laterally surrounds at least 100% of said contact.

24. The probe of claim 1 wherein said contact is in the form of a bump.

25. The probe of claim 1 wherein said substrate has a thickness less than 40 microns.

26. The probe of claim 1 wherein said substrate has a thickness less than 30 microns.

27. The probe of claim 1 wherein said substrate has a thickness less than 20 microns.

28. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 10 times the distance between said elongate conductor and said shield member.

29. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 7 times the distance between said elongate conductor and said shield member.

30. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 5 times the distance between said elongate conductor and said shield member.

31. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 4 times the distance between said elongate conductor and said shield member.

32. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 2 times the distance between said elongate conductor and said shield member.

33. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 10 times the distance between said elongate conductor and said shield member.

34. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 7 times the distance between said elongate conductor and said shield member.

35. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 5 times the distance between said elongate conductor and said shield member.

36. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 4 times the distance between said elongate conductor and said shield member.

37. The probe of claim 1 further comprising a conductive shield member arranged proximate said elongate conductor on a side of said elongate conductor opposite of said conductive member and suitable to be electrically interconnected to a ground signal, wherein a distance between said elongate conductor and said conductive member is less than 2 times the distance between said elongate conductor and said shield member.

38. A probe comprising:

(a) a non-rigid substrate supporting an elongate conductor on a first side of said substrate and a conductive member supported by a second side of said substrate wherein said conductive member and said elongate conductor form a controlled impedance structure;

(b) a conductive path between said first side of said substrate and said second side of said substrate in a region within the periphery of said substrate for at least a majority of the thickness of said substrate and said conductive path electrically connected to said elongate conductor and free from electrical interconnection with said conductive member; and

(c) a contact electrically interconnected to said conductive path for testing a device under test.

39. The probe of claim 38 wherein said elongate conductor is electrically interconnected to a central conductor of a coaxial cable.

40. The probe of claim 39 wherein said conductive member is electrically connected to a conductor surrounding said central conductor of said coaxial cable.

41. The probe of claim 38 wherein said dielectric substrate has a dielectric constant less than 7.

42. The probe of claim 38 wherein said dielectric substrate has a dielectric constant less than 5.

43. The probe of claim 38 wherein said dielectric substrate has a dielectric constant less than 4.

44. The probe of claim 38 wherein said dielectric substrate has a dielectric constant less than 2.

45. The probe of claim 38 wherein said conductive member covers greater than 50% of said second side of said substrate.

46. The probe of claim 38 wherein said conductive member covers greater than 60% of said second side of said substrate.

47. The probe of claim 38 wherein said conductive member covers greater than 70% of said second side of said substrate.

48. The probe of claim 38 wherein said conductive member covers greater than 80% of said second side of said substrate.

49. The probe of claim 38 wherein said conductive member covers greater than 90% of said second side of said substrate.

50. The probe of claim 38 wherein said conductive member, said elongate conductor, and said substrate collectively form a microstrip transmission structure.

51. The probe of claim 38 wherein said substrate has a thickness less than 40 microns.

52. The probe of claim 38 wherein said substrate has a thickness less than 20 microns.

53. The probe of claim 38 wherein said substrate has a thickness less than 10 microns.