Differential waveguide probe

• US 7,876,114 B2
• Filed: 08/07/2008
• Issued: 01/25/2011
• Est. Priority Date: 08/08/2007
• Status: Expired due to Fees

• Current Assignee: Cascade Microtech Incorporated (FormFactor Incorporated)
• Original Assignee: Cascade Microtech Incorporated (FormFactor Incorporated)
• Inventors: Campbell, Richard L., Andrews, Michael
• Primary Examiner(s): Hollington; Jermele M
• Application Number:
  US12/221,828
• Publication Number:
  US 20090189623A1
• Time in Patent Office: 901 Days
• Field of Search: None
• US Class Current: 324/754.06
• CPC Class Codes: G01R 1/06772 High frequency probes

Abstract

A wafer probe comprises a contact conductively interconnected with the wall of a waveguide channel and supported by a substrate that projects from an end of a waveguide channel.

Claims

1. An apparatus for probing a device under test;

said apparatus comprising;

(a) an elongate waveguide comprising a waveguide wall including a waveguide end portion and a surface defining a waveguide channel, said waveguide channel defined by a major dimension and a shorter minor dimension, said major dimension and said minor dimension measured substantially normal to a longitudinal axis of said waveguide channel;

(b) a dielectric substrate comprising a first substrate portion affixed to said waveguide wall adjacent a bisector of said major dimension of said waveguide channel and extending from a point of attachment to said waveguide wall toward an opposing side of said waveguide channel and a second substrate portion supported by said first substrate portion and extending from said waveguide channel a distance beyond said waveguide end portion;

(c) a contact supported by said substrate and engageable with a probe pad of a device under test; and

(d) an electrical conductor conductively interconnected with said contact and including a conductor end portion supported by a surface of said substrate, said conductor end portion conductively interconnected with said waveguide wall proximate said bisector of said major dimension of said waveguide channel.

2. The apparatus for probing a device under test of claim 1 wherein said conductor end portion is interconnected with said waveguide wall at a distance from said waveguide end portion that is no greater than one-half of a wave length of a signal to be transmitted in said waveguide.

3. The apparatus for probing a device under test of claim 1 wherein said waveguide channel is substantially rectangular in cross-section.

4. The apparatus for probing a device under test of claim 3 wherein said waveguide wall further includes substantially circular exterior surface.

5. The apparatus for probing a device under test of claim 1 wherein said a waveguide channel has a substantially elliptical cross-section.

6. The apparatus for probing a device under test of claim 1 further comprising a shorting plate occluding a portion of said waveguide channel at said waveguide end portion.

7. The apparatus for probing a device under test of claim 6 wherein said shorting plate includes a substantially planar surface that intersects said longitudinal axis of said waveguide channel at an oblique angle.

8. The apparatus for probing a device under test of claim 7 further comprising a second shorting plate including a substantially planar surface that intersects said longitudinal axis of said waveguide channel at a second oblique angle.

9. The apparatus for probing a device under test of claim 1 wherein said substrate is flexible.

10. The apparatus for probing a device under test of claim 1 further comprising:

(a) a second contact supported by said substrate and engageable with a second probe pad of said device under test; and

(b) a second conductor conductively interconnected with said second contact and including a second conductor end portion supported by a surface of said substrate, said second conductor end portion conductively interconnected with said waveguide wall proximate said bisector of said major dimension of said waveguide channel.

11. The apparatus for probing a device under test of claim 10 wherein at least one said first contact and said second contact is conductively interconnected with said waveguide wall at a distance from said waveguide end portion no greater than one-half of a wave length of a signal to be transmitted in said waveguide.

12. An apparatus for probing a device under test;

said apparatus comprising;

(a) an elongate waveguide comprising a waveguide wall including a waveguide end portion and a surface defining a waveguide channel, said waveguide channel defined by a major dimension and a shorter minor dimension, said major dimension and said minor dimension measured substantially normal to a longitudinal axis of said waveguide channel;

(b) a dielectric substrate comprising a first substrate portion affixed to said waveguide wall adjacent a bisector of said major dimension of said waveguide channel and extending from a point of attachment to said waveguide wall to a second point of attachment on an opposing side of said waveguide channel and a second substrate portion extending from said first substrate portion beyond said waveguide end portion;

(c) a first electrical contact supported by said substrate and arranged for engagement with a first probe pad of a device under test;

(d) a first conductor conductively interconnected with said first contact and including a first conductor end portion supported by a surface of said substrate, said first conductor end portion conductively interconnected with said waveguide wall proximate said bisector of said major dimension of said waveguide channel;

(e) a second electrical contact supported by said substrate and arranged for engagement with a second probe pad of said device under test; and

(f) a second conductor conductively interconnected with said second contact and including a second conductor end portion supported by a surface of said substrate, said second conductor end portion conductively interconnected with a surface of said waveguide channel at a location opposing said interconnection of said first conductor with said waveguide wall and proximate said bisector of said major dimension of said waveguide channel.

13. The apparatus for probing a device under test of claim 12 wherein said conductor end portion is interconnected with said waveguide wall at a distance from said waveguide end portion that is no greater than one-half of a wave length of a signal to be transmitted in said waveguide.

14. The apparatus for probing a device under test of claim 12 wherein said waveguide channel is substantially rectangular in cross-section.

15. The apparatus for probing a device under test of claim 14 wherein said waveguide wall further includes substantially circular exterior surface.

16. The apparatus for probing a device under test of claim 12 wherein said a waveguide channel has a substantially elliptical cross-section.

17. The apparatus for probing a device under test of claim 12 further comprising a shorting plate occluding a portion of said waveguide channel at said waveguide end portion.

18. The apparatus for probing a device under test of claim 17 wherein said shorting plate includes a substantially planar surface that intersects said longitudinal axis of said waveguide channel at an oblique angle.

19. The apparatus for probing a device under test of claim 18 further comprising a second shorting plate including a substantially planar surface that intersects said longitudinal axis of said waveguide channel at a second oblique angle.

20. The apparatus for probing a device under test of claim 12 wherein said substrate is flexible.