1. Technical Field
The present invention relates to probe assemblies in general, and in particular to a probing assembly for testing integrated circuits fabricated on a wafer.
2. Description of Related Art
After integrated circuits (ICs) have been fabricated on a wafer, the wafer can be divided into multiple rectangular-shaped chips. Each chip has a rectangular (or other regular) arrangement of metallic contact pads through which electrical connections can be made. For efficiency sake, the testing of the chips is preferably performed while the chips are still joined together on the wafer. One typical procedure is to support the wafer on a flat stage or “chuck” and to move the wafer in X, Y and Z directions relative to the head of a probing assembly so that contacts on the probing assembly move relative to the surface of the wafer for consecutive engagement with the bond pads of one or more of test structures on the wafer. Various conductors that interconnect the test instrumentation with the contacts on the probing system enable each chip on the wafer to be sequentially connected to the test instrumentation and be tested.
The contacts of a conventional probing system include a beam affixed to the lower surface of a membrane assembly and is conductively interconnected with corresponding traces located on the surface of a membrane of the membrane assembly. A contact bump for engaging a bond pad of a device-under-test (DUT) is affixed to one end of the beam. When the contact bump is pressed against the bond pad of the DUT, the membrane assembly is deflected, compressing a portion of the elastomeric layer proximate the end of the beam to which the contact bump is affixed. The compliance of the elastomeric layer enables relative displacement of the respective contact bumps and facilitates simultaneous engagement with multiple bond pads that may have respective contact surfaces that lie in different planes. The resilience of an elastomeric layer of the membrane assembly controls the force exerted by the contacts and returns the contacts to the at-rest position when the probe is withdrawn from pressing engagement with the DUT. In order to maintain good compliance, more forces need to be exerted on the membrane assembly, which can shortened the service life of the membrane assembly.
Consequently, it would be desirable to provide an improved probing assembly.
In accordance with a preferred embodiment of the present invention, a probing assembly includes an interface board, a structural support element, a trace support element and a probe support element. The structural support element provides structural and mechanical support to the trace support element. The trace support element includes a body and multiple trace lines located on the body. The probe support element includes a plate having multiple guide holes in which micro probes are inserted. At least one of the micro pins is in contact with one of the trace lines within the trace support element. A set of rails are utilized to secure the probe support element, the trace support element and the structural support element to the interface board.
All features and advantages of the present invention will become apparent in the following detailed written description.
The invention itself, as well as a preferred mode of use, further objects, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
a-3b are an isometric view and a cross-sectional view of a probe support element within the membrane probing assembly from
a-5b show the actuation of the micro probes within the membrane probing assembly from
Referring now to the drawings and in particular to
Preferably, structural support element 120 has the shape of a pyramid with a flat or truncated top. Structural support element 120 is preferably made of an electrical insulating material such as Torlon® polyamide-imide manufactured by Quadrant Engineering or polyetheretherketone (PEEK)—a heat-resistant thermoplastic. Structural support element 120 is preferably rigid in order to provide structural and mechanical support for trace support element 130. Structural support element 120 and trace support element 130 can be detachably connected to one side of interface board 110 by means of a set of rails 150 and multiple screws 160. Probe support element 140 can be detachably connected to structural support element 120 and trace support element 130 via a screw through the center of probe support element 140.
With reference now to
Referring now to
The vertical distance that each of micro probes 142 may travel within its guide hole is controlled by a prober (not shown). Once an initial electrical contact is made with a DUT, the probing over-travel is controlled by a setting in the prober software. This over-travel is measured in microns and a typical setting would be approximately 125 microns.
Each of micro probes 142 includes an upper contact tip 401. Preferably, upper contact tip 401 is configured to provide electrical contact to one of trace lines 132 from
With reference now to
Within opening 133 of trace support element 130, each of trace lines 132 from trace support element 130 is in direct contact with an upper contact tip 401 of a corresponding micro probe 142.
Referring now to
b shows micro probe 142 being in contact with micro bump 502 of DUT 501. Micro bump 502 initially contacts lower contact tip 402 of micro probe 142, and further upward vertical motion of DUT 501 causes micro probe 142 to move up through the guide hole in plate 141, thereby flexing trace lines 132 which increases the corresponding gram (or spring) force micro probe 142 exerts on micro bump 502.
The compliance of each of micro probes 142 in plate 141 is independent. Also, thicker micro probes 142 can be utilized for a given pitch, which can increase the current carrying capacity of micro probes 142. Additionally, the gram force of micro probes 142 applied on micro bump 502 can be easily adjusted by changing the length of trace lines 132 extended beyond membrane 131 into opening 133 (i.e., distance x shown in
As has been described, the present invention provides an improved probing assembly for testing integrated circuits on a wafer.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Number | Name | Date | Kind |
---|---|---|---|
4563640 | Hasegawa | Jan 1986 | A |
5416429 | McQuade et al. | May 1995 | A |
20040086424 | Schembri | May 2004 | A1 |
20050209627 | Kick et al. | Sep 2005 | A1 |
Number | Date | Country | |
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20130249586 A1 | Sep 2013 | US |