Abstract:
An apparatus and method for cleaning needle probe tips includes a spray nozzle that is shaped to fit in a needle-tip aperture formed by a plurality of needle probes. The spray nozzle includes a plurality of openings through which a fluid can be sprayed onto the probe tips to blast debris off of the probe tips. The openings preferably spray fluid at differing angles to ensure that debris is removed from the entire probe tip surface.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to cleaning electrical probes, and more particularly to an on-board cleaning method and apparatus for removing debris from electrical probe needles.  
           [0003]    2. Description of the Related Art  
           [0004]    In the semiconductor industry, integrated circuits (ICs) typically undergo basic functional testing on a wafer before they are mounted onto a device that will connect the circuitry to electronic equipment. This testing process often involves using probe machines and probe cards to check numerous dies (ranging from 200 to 2,000, or more) on a silicon wafer. The dies, if they are not rejected, are cut apart and mounted on package devices.  
           [0005]    Many conventional testing machines use a probe card that contacts the silicon wafer circuitry during basic functional testing. The probe card typically contains 16 to 500 or more probe needles set at an angle relative to the plane defined by the surface of the wafer. The wafer is mounted on a chuck and is contacted by the probe card. This contact and other environmental factors introduce debris, such as metal, polymers and organo-metallic materials, into the probe card. As debris accumulates, the performance of the probe card can be adversely affected. More particularly, the build-up of debris on the probe needles may lead to high contact resistance and false test results, causing good dies to be discarded unnecessarily and resulting in decreased yields. Thus, to maintain proper functioning of the probe card, the probe needle tips should be cleaned periodically to remove any accumulated debris.  
           [0006]    Burnishing is one method for removing debris from needle probes and involves rubbing or scraping the needle probes to dislodge debris. In some conventional probe polishing assemblies, a chuck descends and a stage holding the chuck and the probe polishing assembly moves to place a burnishing pad under the probe card. The burnishing pad is then placed on a position suitable for polishing the probe needles. The burnishing pad then burnishes the probe needle tips by moving the burnishing pad against the XY-plane of the contact surface between the pad and the probe needle tips. After the probe card needle tips are polished, the burnishing assembly and the stage return to their original position, allowing wafer probing to continue.  
           [0007]    Using a burnishing pad for debris removal does have some limitations, however. Because debris tends to collect on the front of the probe needle tips, typical burnishing pads are not be able to reach all of the surfaces where debris has collected. As a result, the only currently known way to completely remove debris is to interrupt the testing process, remove the probe card from the testing device and immerse the probe needles in a solution, such as isopropyl alcohol, in an ultrasonic bath or manually brush the needle probes. Removing the probe card is a time-consuming procedure and increases the likelihood of small deformations in the probe needles. Further, burnishing pads require precise alignment between the pad and the needle probe to ensure that the burnishing process removes debris without bending the needle probes. This alignment process is time-consuming and further increases the down-time of the testing equipment. Additionally, burnishing friction may wear the probe needle tips, shortening the life of the probe card.  
           [0008]    There is a need for a probe cleaning assembly and method that does not encounter the problems noted above with previously known cleaning systems.  
         SUMMARY OF THE INVENTION  
         [0009]    Accordingly, the present invention is directed to an apparatus for removing debris from one or more probe needle tips, comprising a spray nozzle having a plurality of openings disposed on the spray nozzle through which a spray fluid is output onto the probe needle tips to remove debris. In one embodiment, the spray fluid is sprayed in different directions along the spray nozzle to ensure spray uniformity.  
           [0010]    The invention is also directed to a method for removing debris from a plurality of probe needles grouped to form a needle-tip aperture, comprising the steps of positioning a spray nozzle in the needle tip aperture and spraying a spray fluid through a plurality of apertures in a shaft portion of the spray nozzle. As a result, the invention provides thorough cleaning of the needle probe surfaces without relying on physical contact between the cleaning apparatus and the surface, ensuring that debris is removed from the entire probe needle tip to minimize false test results. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a perspective view of a system incorporating the inventive cleaning apparatus;  
         [0012]    [0012]FIGS. 2A and 2B are top and side views, respectively, of the inventive cleaning apparatus;  
         [0013]    [0013]FIG. 3 is a cross-sectional view of the inventive cleaning apparatus taken along line  3 - 3  in FIG. 2A; and  
         [0014]    [0014]FIGS. 4A and 4B are representative diagrams illustrating the operation of the inventive cleaning apparatus. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    [0015]FIG. 1 is a perspective view of an assembly incorporating a probe card needle cleaning apparatus  100  according to the present invention, and FIGS. 2A and 2B are top and side views, respectively, of the probe card needle cleaning apparatus  100 . As can be seen in the Figures, the cleaning apparatus  100  is disposed on a support arm  102  that is connected to a chuck  104  disposed underneath the wafer  106  to be tested. The apparatus includes a spray nozzle  108  supported by a nozzle holder  110 , which is in turn contained in a housing  112  on the support arm  102 . A pneumatic cylinder  113  is disposed below the housing  112  so that the apparatus  100  can be raised and lowered with respect to the probe needles to be cleaned All of the components are supported on a stage  114  so that the chuck  104  and components connected to the chuck  104  can be moved relative to the wafer  106  by the stage  114 .  
         [0016]    [0016]FIG. 3 is a side cross-sectional view of the inventive apparatus  100  when it is positioned for cleaning a plurality of probe needles  115 . As can be seen in the Figure, the plurality of probe needles  115  together form a needle tip aperture  116 . The spray nozzle  108  fits in the needle tip aperture  116  during the cleaning process. Also, as can be seen in the figure, the nozzle holder  110  has an optional recessed portion  118  to capture debris as it is removed from the probe needles  115 . To ease in cleaning the apparatus  100 , a capturing device  120 , such as a removable debris-capturing pad, can be placed in the recessed portion  118  to trap the debris. Alternatively, a suction attachment (not shown), such as a suction tube with one opening disposed in the recessed portion  118  and a conduit similar to the fluid conduit described below can be used to remove debris from the recessed portion  118 .  
         [0017]    To secure the spray nozzle  108  to the chuck  104 , the nozzle holder  110  is placed in the housing  112  and secured with set screws  122  as well as a vertical screw  124  that descends into the housing  112 . The nozzle holder  110  is preferably made of a rigid material, such as ceramic, and shaped in the form of a truncated sphere to provide a convex surface that makes more optimal contact with concave surfaces formed in the distal ends of the set screws  122  to minimize any slippage.  
         [0018]    A conduit  126  connects the spray nozzle  108  with an fluid source (not shown) so that fluid can be forced through openings in the nozzle  108 . The fluid can be either liquid or vapor, and can be, for example, a cleaning fluid or pressurized vapor. The specific fluid reservoirs, pump mechanisms, and valve layouts that can be used with the spray nozzle  108  do not form a part of the invention and can have any configuration desired by the user.  
         [0019]    [0019]FIGS. 4A and 4B are simplified diagrams illustrating the manner in which the inventive spray nozzle  108  operates. For clarification purposes only, FIGS. 4A and 4B show the process for cleaning a single probe needle  115 ; however, in practice, the inventive apparatus  100  can clean multiple probe needles  115  simultaneously. As can be seen in the Figures, debris  125  tends to accumulate on the needle aperture side of the probe needle tip  115 . The spray nozzle  108  has a plurality of spray holes  124  that are disposed primarily on a shaft portion  126  of the nozzle  108 . The spray holes  124  can be in any desired arrangement; however, a helical or spiral arrangement is preferred. Additionally, the angle in which the spray holes  124  are cut into the shaft portion can direct the spray angle of the fluid output through the holes. In one embodiment, the spray holes  124  that lie closer to the tip  128  of the spray nozzle  108  are cut to spray in a downward direction, while the spray holes  124  that are further down the shaft portion  126  are cut to spray in an upward direction. By angling the spray holes  124  to focus the spray direction toward a more central location, the resulting spray pattern from the spray nozzle  108  is aimed toward the critical surfaces on the probe needles  115  that collect debris  125 . A multi-directional spray pattern ensures that the spray will reach all debris-covered surfaces on the probe needles  115 . During the cleaning process, the spray nozzle  108  itself does not physically touch any portion of the probe needles  115 , making precise alignment between the spray nozzle  108  and the probe needles  115  unnecessary.  
         [0020]    Note that the invention is not limited to the above-described spray hole and spray angle configuration and can be customized according to the user&#39;s preferences. Further, the spray nozzle  108  itself does not have to be cylindrical, as shown in the Figure, but can have any desired shape desired by the user. In addition, the shape of the other components in the assembly  100  can be modified to provide additional functional characteristics. For example, the walls of the spray nozzle holder  110  can have a tapered shape to catch and contain the spray material  130  as it is output from the spray holes  124 .  
         [0021]    To clean a probe card, the chuck  104  descends and the stage  114  moves to place the cleaning assembly  100  under the probe card. The pneumatic cylinder  113  then lifts the spray nozzle  108  to a position suitable for cleaning the probe needles  115 , such as in the needle tip aperture  116 . A spray fluid  130 , such as pressurized vapor or liquid, is then output through the spray holes  124  onto the probe needle surfaces, as shown in FIG. 4B, to dislodge and remove debris  125  from the surfaces. During the spraying process, the spray nozzle  108  can be programmed or otherwise controlled to move up and down (in the Z-direction) relative to the probe needles  115  to provide further cleaning action. Because the spray angle of the spray holes  124  along the shaft  126  vary, the vertical movements of the spray nozzle  108  ensures that the fluid  130  is sprayed uniformly over the probe needle surface  115 . The debris that is blasted off of the probe needles  115  by the spray  130  is caught by the filter  120  in the spray nozzle holder  110 , which is periodically removed and cleaned or replaced.  
         [0022]    As a result, the invention provides thorough cleaning of the probe needle tips without requiring direct contact between the cleaning apparatus and the probe needle. The invention can be adapted for cleaning multiple probe cards, if desired.  
         [0023]    While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.