Flex dot wafer probe

• US 4,899,099 A
• Filed: 05/19/1988
• Issued: 02/06/1990
• Est. Priority Date: 05/19/1988
• Status: Expired due to Fees

• Current Assignee: Augat, Inc. (TE Connectivity Limited)
• Original Assignee: Augat, Inc. (TE Connectivity Limited)
• Inventors: Goff, Jay T., Mendenhall, David W.
• Primary Examiner(s): Karlsen, Ernest F.
• Assistant Examiner(s): Burns, W.
• Application Number:
  US07/196,048
• Time in Patent Office: 628 Days
• Field of Search: 324/158 P, 324/158 F, 324/73 R, 324/72.5, 324/73 PC
• US Class Current: 324/750.23
• CPC Class Codes: G01R 1/0735 arranged on a flexible frame or film

Abstract

A flex dot wafer probe having utility as an electrical interface between semiconductor wafers and electronic test systems for determining the electrical integrity and performance of integrated circuits. The wafer probe comprises a wafer probe head having a preformed resilient, bendable, formable film mounted on a support member for flexible movement. The wafer probe head is integrated with a probe board which interfaces with an external test system. Wafer contact pads and protrusions are formed on the film in "mirror-image" patterns corresponding to the contact elements of the integrated circuits and interface contact pads of the probe board, respectively. Coplanar line conductors, formed to control the characteristic impedance of the wafer probe head, provide electrical continuity between the wafer contact pads and the protrusions. The conductive protrusions formed on the wafer contact pads and the film physically and electrically engage the contact elements of the integrated circuits and the probe board, respectively, thereby providing electrical paths for test signals between the external test system and the integrated circuits. The flexible configuration of the wafer probe head ensures that all protrusions are forcibly urged into physical and electrical engagement with the corresponding external contact elements at an acceptable force level which precludes deformation of the protrusions.

Claims

1. For use in testing the electrical integrity and performance of at least one integrated circuit formed on a semiconductor wafer, a wafer probe test system including a flex dot wafer probe and external test equipment having signal transmitting elements disposed in a predetermined pattern for providing electrical test signals to test the electrical integrity and performance of each integrated circuit, and wherein each integrated circuit to be tested includes a predetermined pattern of contact elements adapted to receive the electrical test signals, said flex dot wafer probe comprising;

probe board means having test equipment contact elements for electrically interfacing with corresponding signal transmitting elements of the external test equipment, said probe board means further including interface contact pads arranged in a predetermined pattern; and

wafer probe head means disposed in combination with said probe board means for interfacing between said probe board means and each integrated circuit to be tested, said wafer probe head means including

film means configured for resiliently interfacing between the interface contact pads of said probe board means and the contact elements of each integrated circuit to be tested to provide electrical continuity therebetween for the electrical test signals, said film means configured to include a base plane and at least one tab extending from said base plane in a U-shaped profile such that said at least one tab is approximately parallel to said base plane, and

support member means having first and second major surfaces for mounting said film means wherein said base plane of said film means is mounted on said first major surface and each said at least one tab is mounted on said second major surface,

said film means further including

a plurality of protrusions formed one each said at least one tab of said film means in a mirror-image pattern corresponding to said predetermined pattern of said interface contact pads, said protrusions being forcibly urged into physical and electrical engagement with said interface contact pads in a nondeformable manner to provide electrical continuity therebetween for the electrical test signals,

a plurality of wafer contact pads formed on said base planes of said film means in a mirror-image pattern corresponding to the predetermined pattern of the contact elements of each integrated circuit to be tested, said wafer contact pads being forcibly urged into physical and electrical engagement with corresponding contact elements of each integrated circuit to be tested in a scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals, and

coplanar line conductor means formed on said film means for electrically interconnecting said protrusions to corresponding ones of said wafer contact pads to provide electrical continuity between said probe board means and the integrated circuit chip to be tested wherein electrical test signals from the test equipment are transmitted to said probe board means and to said wafer probe head means via said forcibly engaged interface contact pads and said protrusions, and wherein the electrical test signals are further transmitted from said protrusions via said coplanar line conductor means to said plurality of wafer contact pads and through said forcibly engaged wafer contact pads and the contact elements of the integrated circuit to be tested to the integrated circuit to determine the electrical integrity and performance of the integrated circuit.

2. The flex dot wafer probe of claim 1 wherein each of said plurality of wafer contact pads further includes a protrusion depending therefrom, each said protrusion physically and electrically engaging corresponding contact elements of each integrated circuit to be tested in said scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals to determine the electrical integrity and performance of the integrated circuit.

3. The flex dot wafer probe of claim 1 wherein each of said plurality of protrusions includes a planar contact pad formed on each said at least one tab of said film means.

4. The flex dot wafer probe of claim 1 further comprising reference mark means operative in combination with external edges of each integrated circuit to be tested for visually aligning said wafer contact pads of said wafer probe head means with corresponding contact elements of each integrated circuit chip to be tested wherein said wafer contact pads and the contact elements are aligned in physical and electrical registration for testing by relative coplanar shifting therebetween.

5. The flex dot wafer probe of claim 4 wherein the integrated circuit to be tested has external edges of predetermined dimensions, the contact elements of the integrated circuit having a known positional relation to the external edges thereof, and

wherein said reference mark means comprises a triangular wafer alignment aperture having a first side, a second side projecting from said first side at approximately ninety degrees and a hypotenuse connecting said first and second sides, said first and second side having predetermined lengths, and wherein said first and second sides of said triangular wafer alignment aperture are aligned with corresponding edges of the integrated circuit to be tested and algebraic equations based upon said predetermined lengths of said first and second sides and the predetermined dimensions of the integrated circuit to be tested are solved to provide Δ

X, Δ

Y and Δ

θ

values to align said wafer contact pads and the contact elements in registration for testing by relative coplanar shifting therebetween.

6. The flex dot wafer probe of claim 4 wherein the integrated circuit to be tested has external edges of predetermined dimensions, the contact elements of the integrated circuit having a known positional relation to the external edges thereof, and

wherein said reference mark means comprises at least a first, a second and a third wafer alignment apertures, said first wafer alignment aperture defining an apex of a right angle and said second and third wafer alignment apertures being disposed a predetermined distance from said first wafer alignment aperture along the defined right angle, wherein said first, second and third wafer alignment apertures are aligned with corresponding edges of the integrated circuit to be tested and algebraic equations based upon said predetermined distances and the predetermined dimensions of the integrated circuit to be tested are solved to provide Δ

X, Δ

Y and Δ

θ

values to align said wafer contact pads and the contact elements in registration for testing by relative coplanar shifting therebetween.

7. The flex dot wafer probe of claim 1 wherein said support member means is operative for controlling flexile movement of said film means with said wafer contact pads forcibly urged into physical and electrical engagement with corresponding contact elements of each integrated circuit to be tested in said scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals.

8. The flex dot wafer probe of claim 2 wherein said support member means is operative for controlling flexile movement of said film means with said protrusions depending from said wafer contact pads forcibly urged into physical and electrical engagement with corresponding contact elements of each integrated circuit to be tested in said scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals.

9. The flex dot wafer probe of claim 7 wherein said support member means includes resilient pressure pad means formed on said first and second major surfaces thereof for interacting with said film means for controlling flexile movement of said film means wherein said wafer contact pads are forcibly urged into physical and electrical engagement with corresponding contact elements of each integrated circuit to be tested in said scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals, and wherein said resilient pressure pad means is aligned in registration with said protrusions and said wafer contact pads of said flex film means.

10. The flex dot wafer probe of claim 7 wherein said probe board means includes clearance openings to facilitate alignment and mating of said wafer probe head means in combination with said probe board means to form said flex dot wafer probe, and wherein said film means comprises

a resilient bendable film having said base plane and said at least one extending from said base plane with the extremity thereof disposed approximately planar to said base plane, and wherein said plurality of protrusions are formed on each said at least one in said mirror-image pattern corresponding to said predetermined pattern of said interface contact pads, said plurality of wafer contact pads are formed on said base plane in said mirror-image pattern corresponding to the predetermined pattern of the contact elements of the integrated circuit to be tested, and said coplanar line conductor means is formed on said base plane and each said at least one tab to provide electrical continuity between said probe board means and the integrated chip to be tested, and

said extremity of each said at least one and said base plane having alignment apertures formed therethrough, and wherein

said support member means includes a plurality of alignment pins disposed in a predetermined pattern corresponding to said alignment apertures of said resilient bendable film, said alignment pins inserted in corresponding ones of said plurality of alignment apertures to mount said resilient bendable film in proper orientation to form said probe head means, and further wherein selected ones of said plurality of alignment pins are inserted in said clearance openings of said probe board means to properly align said wafer probe head means in combination therewith.

11. The flex dot wafer probe of claim 1 wherein said coplanar line conductor means formed on said film means comprises a plurality of line conductors formed in a predetermined configuration and disposed in a predetermined pattern to define a characteristic impedance of said flex dot wafer probe at a predetermined value.

12. For use in testing the electrical integrity of at least one integrated circuit formed on a semiconductor wafer, a probe test system including a flex dot wafer probe and external test equipment having signal transmitting elements disposed in a predetermined pattern for providing electrical test signals to test the electrical integrity and performance of each integrated circuit, and wherein each integrated circuit includes a predetermined pattern of contact elements adapted to receive the electrical test signals, said flex dot wafer probe comprising:

a probe board for interfacing with the external test equipment, said probe board including

interface contact pads having a predetermined pattern,

means for electrically interfacing with the signal transmitting elements of the external test equipment, and

means for electrically interconnecting said interface contact pads and said electrical interface means;

a wafer probe head configured to be forcibly urged into physical and electrical engagement with said probe board and to interface with each integrated circuit to be tested, said wafer probe head including

a resilient bendable film having a base plane and at least one tab extending from said base plane with the extremity thereof disposed approximately planar to said base plane,

a plurality of protrusions formed on each said at least one tab in a mirror-image pattern corresponding to said predetermined pattern of said interface contact pads of said probe board, said plurality of protrusions being forcibly urged into physical and electrical engagement with said interface contact pads in a nondeformable manner to provide electrical continuity therebetween for the electrical test signals,

a plurality of wafer contact pads formed on said base plane in a mirror-image pattern corresponding to said predetermined pattern of the contact elements of each integrated circuit to be tested, said wafer contact pads being forcibly urged into physical and electrical engagement with corresponding contact elements of each integrated circuit to be tested in a scrubbing and nondeformable manner to provide enhanced electrically continuity therebetween for the electrical test signals, and

a plurality of coplanar line conductors formed on said base plane and said tabs to electrically interconnect corresponding ones of said plurality of protrusions and said plurality of wafer contact pads wherein the electrical test signals are transmitted from said interface contact pads to said plurality of protrusions, from said plurality of protrusions to said wafer contact pads via said plurality of coplanar line conductors and from said wafer contact pads to the contact elements of the integrated circuit to be tested to determine the electrical integrity and performance of the integrated circuit.

14. The flex dot wafer probe of claim 12 wherein each of said plurality of protrusions includes a planar contact pad formed on said first surface of said film means.

15. The flex dot wafer probe of claim 12 wherein each of said plurality of wafer contact pads further includes a protrusion depending therefrom, each said protrusion physically and electrically engaging corresponding contact elements of each integrated circuit to be tested in said scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals to determine the electrical integrity and performance of the integrated circuit.

18. The flex dot wafer probe of claim 12 wherein said plurality of coplanar line conductors have a predetermined configuration and are disposed in a predetermined pattern to define a characteristic impedance of said flex dot wafer probe at a predetermined value.

13. For use in testing the electrical integrity of at least one integrated circuit formed on a semiconductor wafer, a probe test system including a flex dot wafer probe and external test equipment having signal transmitting elements disposed in a predetermined pattern for providing electrical test signals to test the electrical integrity and performance of each integrated circuit, and wherein each integrated circuit includes a predetermined pattern of contact elements adapted to receive the electrical test signals, said flex dot wafer probe comprising:

a probe board for interfacing with the external test equipment, said probe board including

interface contact pads having a predetermined pattern,

means for electrically interfacing with the signal transmitting elements of the external test equipment, and

means for electrically interconnecting said interface contact pads and said electrical interface means;

a wafer probe head configured to be physically and electrically integrated with said probe board and to interface with each integrated circuit to be tested, said wafer probe head including

a resilient bendable film having a base plane and tabs extending from said base plane with extremities thereof disposed approximately planar said base plane,

a plurality of protrusions formed on said tabs in a mirror-image pattern corresponding to said predetermined pattern of said interface contact pads of said probe board, said plurality of protrusions physically and electrically engaging said interface contact pads in a nondeformable manner to provide electrical continuity therebetween for the electrical test signals,

a plurality of wafer contact pads formed on said base plane in a mirror-image pattern corresponding to said predetermined pattern of the contact elements of each integrated circuit to be tested, said wafer contact pads physically and electrically engaging corresponding contact elements of each integrated circuit to be tested in a scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals,

a plurality of coplanar line conductors formed on said base plane and said tabs to electrically interconnect corresponding ones of said plurality of protrusions and said plurality of wafer contact pads wherein the electrical test signals are transmitted from said interface contact pads to said plurality of protrusions, from said plurality of protrusions to said wafer contact pads via said plurality of coplanar line conductors and from said wafer contact pads to the contact elements of the integrated circuit to be tested to determine the electrical integrity and performance of the integrated circuit, and

a support member having first and second major surfaces, said film being mounted on said support member to have said base plane adjacent said first major surface and said tabs adjacent said second major surface, said support member further including resilient pressure pads disposed on said first and second major surfaces in registration with said plurality of wafer contact pads and said plurality of protrusions, respectively, to control flexile movement of said film wherein said plurality of wafer contact pads engage corresponding contact elements of each integrated circuit to be tested in said scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals and said plurality of protrusions engage corresponding interface contact pads of said probe board said nondeformable manner to provide electrical continuity therebetween for the electrical test signals and said plurality of protrusions.

16. The flex dot wafer probe of claim 13 wherein the integrated circuit to be tested has external edges of predetermined dimensions, the contact elements of the integrated circuit having a known positional relation to the external edges thereof,

said support member has a central aperture extending therethrough, and

said probe board includes an orientation aperture extending therethrough, and wherein said wafer probe head further comprises

a triangular wafer alignment aperture having a first side, a second side projecting from said first side at approximately ninety degrees and a hypotenuse connecting said first and second sides, said first and second side having predetermined lengths, and wherein said first and second sides of said triangular wafer alignment aperture are aligned with corresponding edges of the integrated circuit to be tested and algebraic equations based upon said predetermined lengths of said first and second sides and the predetermined dimensions of the integrated circuit to be tested are solved to provide Δ

X, Δ

Y and Δ

θ

values to align said wafer contact pads and the contact elements in registration for testing by relative coplanar shifting therebetween, said orientation aperture, said triangular alignment aperture and said central aperture being coaxially aligned along the Z-axis of said flex dot wafer probe to provide an unobstructed line-of-sight of the integrated circuit to be tested.

17. The flex dot wafer probe of claim 13 wherein the integrated circuit to be tested has external edges of predetermined dimensions, the contact elements of the integrated circuit having a known positional relation to the external edges thereof,

said support member has a central aperture extending therethrough, and

said probe board includes an orientation aperture extending therethrough, and wherein said wafer probe head has

at least first, second and third wafer alignment apertures, said first wafer alignment aperture defining an apex of a right angle, and said second and third wafer alignment apertures being disposed a predetermined distance from said first wafer alignment aperture along the defined right angle, wherein said first, second and third wafer alignment apertures are aligned with corresponding edges of the integrated circuit to be tested and algebraic equations based upon said predetermined distances and the predetermined dimensions of the integrated circuit to be tested are solved to provide Δ

X, Δ

Y and Δ

θ

values to align said wafer contact pads and the contact elements in registration for testing by relative coplanar shifting therebetween, said orientation aperture, said triangular alignment aperture and said central aperture being coaxially aligned along the Z-axis of said flex dot wafer probe to provide an unobstructed line-of-sight of the integrated circuit to be tested.

19. A method for testing the electrical integrity and performance of at least one integrated circuit formed on a semiconductor wafer using external test equipment having signal transmitting elements disposed in a predetermined pattern to provide electrical test signals to test the electrical integrity and performance of each integrated circuit, and wherein each integrated circuit to be tested includes a predetermined pattern of contact elements adapted to receive the electrical test signals, comprising the steps of:

forming a flex dot wafer probe for electrically interfacing between the external test equipment and the integrated circuit to be tested, said flex dot wafer probe including a probe board for interfacing with the external test equipment, said probe board having an orientation aperture formed therethrough and further including interface contact pads having a predetermined pattern, means for electrically interfacing with the signal transmitting elements of the external test equipment, and means for electrically interconnecting said interface contact pads and said electrical interface means, a wafer probe head physically and electrically integrated with said probe board and interfacing with each integrated circuit to be tested, said wafer probe head including a support member having first and second major surfaces and a central aperture formed therethrough, a resilient bendable film having a base plane and tabs extending from said base plane with extremities thereof disposed approximately planar said base plane and wafer alignment means formed therethrough for aligning said flex dot wafer probe with the integrated circuit to be tested, said wafer alignment means in combination with said orientation aperture and said central aperture forming an unobstructed line-of-sight through said flex dot wafer probe along the Z-axis thereof, said film being mounted on said support member to have said base plane adjacent said first major surface and said tabs adjacent said second major surface, a plurality of protrusions formed on said tabs in a mirror-image pattern corresponding to said predetermined pattern of said interface contact pads of said probe board, said plurality of protrusions physically and electrically engaging said interface contact pads in a nondeformable manner to provide electrical continuity therebetween for the electrical test signals, a plurality of wafer contact pads formed on said base plane in a mirror-image pattern corresponding to said predetermined pattern of the contact elements of each integrated circuit to be tested, said wafer contact pads physically and electrically engaging corresponding contact elements of each integrated circuit to be tested in a scrubbing and nondeformable manner to provide enhanced electrical continuity therebetween for the electrical test signals, and a plurality of coplanar line conductors formed on said base plane and said tabs to electrically interconnect corresponding ones of said plurality of protrusions and said plurality of wafer contact pads;

aligning said flex dot wafer probe with the integrated circuit to be tested by

positioning said wafer alignment means along edges of the integrated circuit to be tested,

solving equations based upon known dimensions of said wafer alignment means, said wafer contact pads, the edges of the integrated circuit to be tested and the contact elements of the integrated circuit to be tested to generate Δ

X, Δ

Y and Δ

θ

values to align said wafer contact pads and the contact elements in registration for testing, and

effecting relative coplanar shifting between said wafer contact pads and the contact elements of the integrated circuit to be tested for registration thereof;

effecting Z-axis movement of said flex dot wafer probe to bring said wafer contact pads and the contact elements of the integrated circuit to be tested in physical and electrical engagement in a nondeformable manner to provide electrical continuity therebetween for the electrical test signals;

effecting relative micromovement between said physically engaged wafer contact pads and the contact elements to scrub oxide films therefrom to enhance the electrical continuity therebetween; and

providing electrical test signals from the external test equipment to the signal transmitting elements, the electrical test signals being transmitted to said interface contact pads, from said interface contact pads to said plurality of protrusions, from said plurality of protrusions to said wafer contact pads via said plurality of coplanar line conductors and from said wafer contact pads to the contact elements of the integrated circuit to be tested to determine the electrical integrity and performance of each integrated circuit to be tested.