Microelectronic contact structure

• US 8,033,838 B2
• Filed: 10/12/2009
• Issued: 10/11/2011
• Est. Priority Date: 02/21/1996
• Status: Expired due to Fees

• Current Assignee: FormFactor Incorporated
• Original Assignee: FormFactor Incorporated
• Inventors: Mathieu, Gaetan L., Eldridge, Benjamin N., Grube, Gary W., Khandros, Igor Y.
• Primary Examiner(s): Abrams; Neil
• Application Number:
  US12/577,444
• Publication Number:
  US 20100093229A1
• Time in Patent Office: 729 Days
• Field of Search: 439/81, 439/66, 324/762, 324/754
• US Class Current: 439/81
• CPC Class Codes: G01R 1/06727 Cantilever beams
• CPC Class Codes: G01R 1/06738 related to tip portion
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/68304 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/68359 used as a support during manufacture of interconnect decals or build up layers
• CPC Class Codes: H01L 2224/11003 for holding or transferring the bump preform
• CPC Class Codes: H01L 2224/111 Manufacture and pre-treatment of the bump connector preform
• CPC Class Codes: H01L 2224/11826 Physical vapour deposition [PVD], e.g. evaporation, or sputtering
• CPC Class Codes: H01L 2224/13017 being non uniform along the bump connector
• CPC Class Codes: H01L 2224/13018 comprising protrusions or indentations
• CPC Class Codes: H01L 2224/13019 at the bonding interface of the bump connector, i.e. on the surface of the bump connector
• CPC Class Codes: H01L 2224/13565 Only outside the bonding interface of the bump connector
• CPC Class Codes: H01L 2224/13582 Two-layer coating
• CPC Class Codes: H01L 2224/819 with the bump connector not providing any mechanical bonding
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01074 Tungsten [W]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/1433 Application-specific integrated circuit [ASIC]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding

Abstract

Spring contact elements are fabricated by depositing at least one layer of metallic material into openings defined on a sacrificial substrate. The openings may be within the surface of the substrate, or in one or more layers deposited on the surface of the sacrificial substrate. Each spring contact element has a base end portion, a contact end portion, and a central body portion. The contact end portion is offset in the z-axis (at a different height) than the central body portion. The base end portion is preferably offset in an opposite direction along the z-axis from the central body portion. In this manner, a plurality of spring contact elements are fabricated in a prescribed spatial relationship with one another on the sacrificial substrate. The spring contact elements are suitably mounted by their base end portions to corresponding terminals on an electronic component, such as a space transformer or a semiconductor device, whereupon the sacrificial substrate is removed so that the contact ends of the spring contact elements extend above the surface of the electronic component. In an exemplary use, the spring contact elements are thereby disposed on a space transformer component of a probe card assembly so that their contact ends effect pressure connections to corresponding terminals on another electronic component, for the purpose of probing the electronic component.

Claims

1. A microelectronic spring contact element, comprising:

an elongate member having a base portion, a contact portion opposite the base portion, and a central body portion connected at one end to the base portion and at an opposite end to the contact potion, wherein a width of the central body portion in a first plane tapers from the one end to the opposite end and a thickness of the central body portion in a second plane perpendicular to the first plane tapers from the one end to the opposite end;

an end of the contact portion is offset in a first direction from the central portion by a non-zero distance “

d1”

;

an end of the base portion is offset in a second direction opposite the first direction from the central portion by a non-zero distance “

d2”

;

wherein;

the end of the base portion is adapted in use to be mounted to a first electronic component; and

the end of the contact portion is adapted in use to make a pressure connection with a second electronic component,

wherein the end of the base portion and the end of the contact portion are substantially parallel to the central body portion.

2. The microelectronic spring contact element of claim 1, wherein the contact portion comprises a contact tip structure extending from the end of the contact portion.

3. The microelectronic spring contact element of claim 2, wherein the contact tip structure comprises a pyramid shape or a truncated pyramid shape.

4. The microelectronic spring contact element of claim 1, wherein the contact tip structure is attached to the end of the contact portion.

5. The microelectronic spring contact element of claim 1, wherein the contact structure is integrally formed with the contact portion.

6. The microelectronic spring contact element of claim 1, wherein a width in the first plane of the end of the base portion is greater than a width in the first plane of the end of the contact portion.

7. The microelectronic spring contact element of claim 6, wherein a thickness in the second plane of the end of the base portion is greater than a thickness in the second plane of the end of the contact portion.

8. The microelectronic spring contact element of claim 1, wherein a thickness in the second plane of the end of the base portion is greater than a thickness in the second plane of the end of the contact portion.

9. The microelectronic spring contact element of claim 1, wherein the thickness of the central body portion tapers from the one end to the opposite end at a taper angle of between 2-6 degrees.

10. The microelectronic spring contact element of claim 9, wherein the width of the central body portion tapers from the one end to the opposite end at a taper angle of between 2-6 degrees.

11. The microelectronic spring contact element of claim 1, wherein the width of the central body portion tapers from the one end to the opposite end at a taper angle of between 2-6 degrees.

12. The microelectronic spring contact element of claim 1, wherein a length parallel to the first plane of the elongate member from the base portion to the contact portion is greater than a height parallel to the second plane of the elongate member from the end of the base portion to the end of the contact portion.

13. The microelectronic spring contact element of claim 12, the length is at least five times the height.

14. The microelectronic spring contact element of claim 13, wherein the length is in a range of 40-500 mils.

15. The microelectronic spring contact element of claim 13, wherein the length is in a range of 60-100 mils.

16. The microelectronic spring contact element of claim 12, wherein the length is in a range of 40-500 mils.

17. The microelectronic spring contact element of claim 12, wherein the length is in a range of 60-100 mils.