Abstract:
A system and method for cleaning a contactor device is presented. The cleaning system includes an automated testing handler and a handler controller for controlling the operation of the handler and facilitating user interaction with the handler. The handler further includes a contactor having a plurality of pins for establishing an electrical connection with one or more input devices. The handler is configured to house one or more input devices and one or more surrogate cleaning devices. The surrogate cleaning devices are configured to clean the pins of the contactor. A pick and place mechanism positioned in the handler is configured to transport both the input devices and the surrogate cleaning devices to the contactor.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This application claims priority from Provisional U.S. Application No. 60/817,532, filed Jun. 30, 2006, incorporated herein by reference in its entirety. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    The following description of the background of the invention is provided simply as an aid in understanding the invention and is not admitted to describe or constitute prior art to the invention. 
         [0003]    The present invention relates generally to the field of semiconductor device testing. Specifically, the present invention relates to a system and a method for cleaning a semiconductor device contactor in automated testing equipment (“ATE”). 
         [0004]    ATE is used in the semiconductor industry to test semiconductor devices. Generally, the automated testing equipment is configured to receive a batch or “lot” of semiconductor devices for testing. The ATE conducts testing based on predetermined settings which are dependent upon the characteristics of each device input into the ATE for testing. During actual testing, various testing systems configured to manipulate the input device&#39;s operating conditions are applied to the input device and the result is recorded. 
         [0005]    In general, to be tested, an input device is first connected to a contactor. The characteristics of the contactor used for testing affects the reproducibility of the test as well as the test yield. A poor contactor may cause invalid failures or test miscorrelations, which in turn can result in unwarranted machine downtimes, unexplained yield problems, and even customer returns. 
         [0006]    The contactor includes a set of pins. These pins come into contact with the leads or solder balls of the input device during electrical testing. Contact elements are commonly composed of a beryllium-copper base metal with gold-plating on the surface. The profile of a contact element is critical to contact integrity and life prolongation. 
         [0007]    During testing, each device must be inserted into the contactor for an electrical connection to the tester. Throughout the course of testing each device, pins on the contactor collect debris and other foreign substances. Foreign substances or debris cause the contactor to perform at less than optimal conditions. This may result in less than accurate testing results. Thus, the contactor pins must be cleaned at regular intervals. Currently, in most ATE the processing of equipment is halted in its entirety to clean the contactor pins. This method lengthens the time it takes to process and test a lot or batch of semiconductor devices. Accordingly, a system and method is needed to effectively clean contactors in ATE so that a lot of semiconductor devices may be processed efficiently. 
       SUMMARY OF THE INVENTION 
       [0008]    One embodiment of the invention relates to a system for cleaning a contactor device, including an automated testing handler. The handler further comprises a contactor having a plurality of pins for establishing an electrical connection with one or more input devices. The handler is configured to house one or more input devices and one or more surrogate cleaning devices, wherein the surrogate cleaning devices are configured to clean the pins of the contactor. A pick and place mechanism is positioned in the handler and is configured to transport both the input devices and the surrogate cleaning devices to the contactor. The system also includes a handler controller for controlling the operation of the handler and facilitating user interaction with the handler. 
         [0009]    According to another embodiment of the invention, a method for cleaning a contactor device in a handler includes providing one or more surrogate cleaning devices i housed in the handler, providing one or more input devices in the handler and determining whether the contactor requires cleaning. If the contactor requires cleaning, the method executes an auto cleaning cycle. If the contactor does not require cleaning, the method executes a device processing cycle. 
         [0010]    According to still another embodiment of the invention, the execution of the auto cleaning cycle includes the steps of determining whether a surrogate cleaning device is available for cleaning the contactor and inserting the surrogate cleaning device into the contactor in order to clean the contactor. 
         [0011]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    These and other features, aspects and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
           [0013]      FIG. 1  is a block diagram of a system for cleaning a contactor device according to one embodiment of the invention. 
           [0014]      FIG. 2  is a screenshot of a graphical user interface for a system for cleaning a contactor device according to one embodiment of the invention. 
           [0015]      FIG. 3  is a block diagram of an automated testing equipment handler according to one embodiment of the invention. 
           [0016]      FIG. 4  is a diagram of a surrogate cleaning device according to one embodiment of the present invention. 
           [0017]      FIG. 5  is a flowchart illustrating an initialization sequence for a method for cleaning a contactor device according to one embodiment of the invention. 
           [0018]      FIG. 6  is a flowchart illustrating the loading sequence for a method for cleaning a contactor device according to one embodiment of the invention. 
           [0019]      FIG. 7  is a flowchart illustrating an auto cleaning cycle sequence for a method for cleaning a contactor device according to one embodiment of the invention. 
           [0020]      FIG. 8  is a photograph of pogo pins for a contactor before being cleaned according to one embodiment of the invention. 
           [0021]      FIG. 9  is a photograph of pogo pins for a contactor after being cleaned according to one embodiment of the invention. 
           [0022]      FIG. 10  is a flowchart illustrating a post-cleaning sequence according to one embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    Embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the following description is intended to describe exemplary embodiments of the invention, and not to limit the invention. 
         [0024]      FIG. 1  shows a device cleaning system according to one embodiment of the invention. The device cleaning system includes a handler (ATE)  10  and a controller  20 . According to one embodiment of the invention, the controller  20  is a personal computer, workstation or server operably connected to the handler  10 . In another embodiment of the invention, the controller  20  may be integrated into the handler  10 . The controller  20  includes a processor and memory configured to run software for operation of the device cleaning system. The controller  20  also allows a user  30  to input commands for execution by the handler  10 . In addition, the controller  20  provides output to the user  30 . According to one embodiment of the invention, a user  30  may input commands and view output through the use of a graphical user interface  40  implemented by the controller  20 . 
         [0025]    An exemplary embodiment of the graphical user interface is shown in  FIG. 2 . A user  30  may input commands and establish and change settings for the device cleaning system using the GUI  40 . An example of the commands and settings a user  30  may establish using the GUI  40  will be discussed herein. These commands and settings can directly influence the handler&#39;s  10  operation and overall cleaning system performance. 
         [0026]    A block diagram of the handler  10  is shown in  FIG. 3 . The handler  30  includes at least one contactor  50 , a pick and place mechanism  60  having a shuttle  65  and a bin  70  that may be populated with one or more JEDEC trays  80 . The JEDEC trays include input devices  90  for testing. In addition, surrogate cleaning devices (SCD)  100  are housed in a standard JEDEC tray  110 . Preferably, a unique bin  70  is also identified by the device cleaning system for housing the SCD JEDEC tray  110 . The bin location is stored in a memory of controller  20  for the benefit of the device cleaning system software. 
         [0027]    Input devices  90  are placed in physical contact with the contactor  50  to be tested. The contactor  50  establishes an electrical connection with the input devices  90  in order to test desired characteristics of the input devices  90 . Generally, the configuration of the contactor  50  is dependent upon the input devices  90 . The configuration of the contactor  50  impacts test results including test yields, and the ability to reproduce testing results. 
         [0028]    The contactor  50  has a set of contacts called pogo pins  55 . The contacts  55  may also be referred to as contact fingers and/or contact elements. A pogo pin  55  is a type of nail affixed to the contactor to make contact with the input devices  90 . Generally, pogo pins  55  and like elements are composed of beryllium-copper based metal with gold plating on the surface. An enlarged view of pogo pins  55  is shown in  FIGS. 8 and 9 . The pogo pins  55  are preferably relatively clean (free from debris) in order to insure quality operation of the device cleaning system. The use of SCDs  100  by the device cleaning system ensures cleanliness of the pogo pins  55  and thus efficient operation of the handler  10 . Typically, for each group of contactors  50 , there are several times that amount of distinct SCDs  100  used to clean the contactors  50 . 
         [0029]    As shown in  FIG. 4 , according to one embodiment of the present invention, the SCD is composed of several layers. According to one embodiment of the invention, the SCD  100  is approximately 450 μm in thickness. Preferably the SCD  100  is within +/−0.010″ of the size of an input device  90 . Generally, the layers that form the SCD  100  are composed of debris capturing materials. For example, the base layer is comprised of an adhesive  101 . A PET film  102  is positioned on top of the adhesive  101 . A polyurethane foam  103  rests on top of the PET film  102 . The polyurethane foam  103  contains a resin  105  and an abrasive substance  104 . These substances enable cleaning of the contactor  50 , specifically the pogo pins  55 . 
         [0030]    Operation of the system will now be described.  FIG. 5  is a flowchart showing the power-on/initiation sequence for the device testing system according to one embodiment of the invention. First, the handler  10  is powered on (Step  1000 ). The controller  20  begins an initialization sequence for the handler  10  (Step  1010 ). According to one embodiment of the invention, one operation performed during the initialization sequence detects which devices are currently present in the handler  10  and possibly the current status of those devices. For example, the handler is capable of determining whether a new contactor  50  configuration is being used (Step  1020 ). If the contactor  50  configuration is new (meaning it was not used last time the handler  10  was powered on) the cleaning cycle count of the contactor  50  is reset (Step  1030 ). 
         [0031]    The cleaning cycle count indicates how many times the contactor  50  has been used to test an input device  90 . After a certain number of devices  90  have been tested the same contactor  50 , the system determines that the contactor  50  should be cleaned to continue effective processing operations. The cleaning cycle count is preset in the device cleaning software at a default amount. However, the user  30  may change the cleaning cycle count via the GUI interface  40 . Resetting the cleaning cycle count for the contactor  50  indicates that the current contactor  50  in use is clean and has not been used to test any input devices  50 . In the alternative, if the handler  10  determines that the contactor  50  configuration is not new, then the contactor cleaning cycle count is retrieved from the system memory (Step  1040 ). 
         [0032]    In addition, during the power on sequence the handler determines whether SCDs  100  are currently present (Step  1050 ). If SCDs  100  are present in the handler  10  during the power on, then the user  30  is prompted to remove the SCD  100  (Step  1060 ). The system requests removal of the SCDs  100  because there is no way to know how many of the SCD  100  are used (e.g., have already been used to clean parts) versus how many SCDs  100  are new. Preferably, because of the physical composition of the SCDs  100 , the SCDs  100  are used to clean a contactor  50  only once. After one use, a SCD  100  is less effective at cleaning a second contactor  50 . In the alternative, if SCDs  100  are not detected in the handler, the device testing system proceeds to its loading procedures (Step  1070 ). 
         [0033]    The loading and processing procedures for the device testing system will now be described with reference to  FIG. 6 . As stated above, preferably a designated bin  70  is used to house the SCD JEDEC tray  110 . Prior to loading, a user  30  may select a bin to house the SCD JEDEC tray  110 . According to one embodiment of the invention, the SCD JEDEC tray  110  is keyed/notched so that only the SCD JEDEC  110  can be placed into the designated bin. Generally, as shown in  FIG. 6 , SCDs  100  are loaded into the handler  10  after power-on and initialization (Step  2000 ). However, according to another embodiment of the invention, SCDs  100  may be loaded in the middle of lot processing depending upon the number of input devices  90  used. 
         [0034]    As further shown in  FIG. 6 , SCDs  100  and input devices  90  may be loaded into the handler  10  simultaneously (Steps  2000 ,  2010 ). A full or partial SCD JEDEC tray  110  may be loaded in a designated bin  70 . Generally, after loading is complete, the doors of the handler  10  are closed. Upon closing of the handler door (not shown), the system runs a self-test. For example, according to one embodiment of the invention, the device cleaning system checks to see if SCDs  100  are available after closing the handler door (Step  2012 ). If SCDs  100  are available, the device cleaning system proceeds to Step  2020  as shown in  FIG. 6 . If the device cleaning system determines that there are no SCDs  100  present in the handler  10 , then a warning message is displayed to the user  30  (Step  2014 ). Once the SCDs  100  and input devices  90  are placed in the handler  10 , the device cleaning system records the number of SCDs  100  and input devices  90  (Step  2020 ). Upon receiving an indication that the input devices  90  are ready for processing, the device cleaning system determines whether the contactors  50  populating the handler  10  need cleaning (Step  2030 ). Whether or not a contactor  50  needs cleaning depends upon the contactor&#39;s  50  cleaning cycle count, which was described above. If the contactor  50  needs cleaning, then the auto cleaning cycle is initiated. If the contactor  50  does not need cleaning, then device processing  2040  is initiated. 
         [0035]    In device processing  2040 , the input devices  90  are tested using the contactors  50  populating the handler  10 . During this process, the device cleaning system records the number of times each contactor  50  is used to test an input device, thus yielding a contactor  50  cleaning cycle count (Step  2050 ). As shown in  FIG. 6 , after the contactor cleaning cycle count is calculated, the device cleaning system again determines whether a contactor  50  needs cleaning (Step  2060 ). If the cleaning device system determines that the contactor  50  needs cleaning, then the auto cleaning cycle  3000  is initiated. If the contactor does not need to be cleaned, input device processing  2030  continues. According to one embodiment of the invention, in the alternative, a user  30  may input a clean contactor command  2070 . Once the clean contactor command  2070  is received the auto cleaning cycle is initiated (Step  3000 ). 
         [0036]      FIG. 7  illustrates an aspect of the auto cleaning cycle according to one embodiment of the invention. Generally, the auto cleaning cycle is implemented when the contactor cleaning cycle count has reached a testing threshold. In the alternative, the auto cleaning cycle may be initiated by a user  30 . For example, a user  30  may execute a clean contactor command to initiate the auto cleaning cycle (Step  3000 ). After the initialization of the cleaning cycle, the device cleaning system determines if SCDs  100  are available to carryout cleaning (Step  3010 ). If SCDs  100  are not available, then the auto cleaning cycle operation is halted (Step  3020 ). If there are SCDs  100  available in the handler  10 , then the auto cleaning cycle proceeds without halting. First, the device cleaning system activates the pick and place handler  60  in order to remove at least one SCD  100  from the SCD JEDEC tray  10  (Step  3030 ). Once removed, the SCDs  100  are placed into a shuttle  65  (Step  3040 ). The orientation and placement of the SCD  100  in the shuttle is dependent upon the configuration of the contactor  50  at a test site in the handler. For example, if the test site is configured in a 2×2 pattern then the orientation of the SCDs  100  in the shuttle  65  must also be 2×2. 
         [0037]    The shuttle  65  transports the SCDs  100  to the test site in the proximity of the contactor  50  (Step  3050 ). Next, the SCDs  100  are removed from the shuttle via the pick and place handler  60 . If the pick and place device  60  is unable to pick up the SCDs  100  (Step  3060 ) then the system implements a flush (Step  3070 ). If at any point, the handler  10  is unable to pickup an SCD  100  from the shuttle  65  or if an SCD  100  is dropped while a mechanism is moving, the entire lot of devices must be re-run because of SPC failure. In the event the SCD  100  can be picked up by the user  30  entering a retry command, a flush operation does not take place. According to another embodiment of the invention, the handler  10  includes a mechanism for determining whether the system is having difficulty picking up an SCD  100  or an input part  90 . 
         [0038]    However, if the pick and place mechanism is able to pick up the SCDs  100 , each SCD  100  is plunged into a contactor in order to clean the pogo pins  55  of the contactor  50  (Step  3080 ). According to an alternative embodiment, the SCDs  100  are positioned near the test site and accordingly do not need to be transported via a shuttle to the test site. According to one embodiment of the invention, all contactors  50  that are enabled are cleaned at the same time. Generally, a SCD  100  is inserted into the contactor and then the device cleaning system waits a predetermined, user defined period of time (e.g., 100 ms) before retracting the SCD  100 . This insertion step may be repeated a number of times based on the device testing settings. For example, the number of times an SCD  100  is inserted into a contactor  50  is dependent upon a variable set by the user  30  entitled “Insertions per Cleaning Cycle.” The user may set this variable using the GUI  40 . During cleaning, the system displays a message to the user  30  indicating that contactor cleaning is underway. Once the SCD  100  has been inserted into the contactor  50  a predetermined number of times, the SCD  100  is returned to a JEDEC tray. 
         [0039]    The SCD  100  effectively cleans and removes debris from the pogo pins  55  of the contactor  50 .  FIG. 8  shows multiple photographs of the pogo pins  55  of a contactor  50  covered in debris. The photograph was taken before cleaning. The debris may significantly affect the performance of the contactor  50  and thus the processing of multiple input devices  90 .  FIG. 9  shows multiple photographs of the same pogo pins  55  shown in  FIG. 8  after being cleaned by the insertion of an SCD  100  as described above. As shown in  FIG. 9 , debris is no longer present on the pogo pins  55 . Removal of debris in this manner maintains the performance of the contactor  50  during testing operations. 
         [0040]    As stated above, once the SCD  100  has been inserted into the contactor  50  a predetermined amount of times, the SCD  100  is returned to a JEDEC tray (Step  4000 ). In addition, the physical location of the SCD  100  in a JEDEC tray once it has been returned is recorded and stored in controller memory (Step  4010 ). Upon the return of the SCD  100 , the amount of times the SCD  100  was inserted into a contactor  50  is recorded and stored in controller memory (Step  4020 ). Based on the insertion count of the SCD  100 , the device cleaning system determines whether the device can continue to use the SCD  100  (Step  4030 ). The SCD insertion count is a user defined threshold. If the SCD  100  insertion count is greater than the threshold, then the system decrements the value of a variable used to track the number of units remaining until SCD depletion (“URSD”) (Step  4040 ). In the alternative, if the SCD  100  insertion count is less than a threshold amount, then the URSD number remains the same (Step  4050 ). After either step  4040  or  4050 , the value of the URSD is displayed to the user  30  (Step  4060 ). Further, after a URSD value is determined, the system determines whether that value is less than the number of untested input devices  90  remaining in the handler (Step  4070 ). In other words, the system determines whether there are enough SCDs  100  to test the remaining input devices  90 . If not, the operation of the handler is halted and a message is displayed to the user  30  (Step  4080 ). If the system detects that there are enough SCDs to test the remaining input devices  90 , then system operation continues normally (Step  4090 ). 
         [0041]    As set forth in the embodiments disclosed above several advantages of the invention are realized. For example, the present invention facilitates the cleaning of contactor devices while carrying out input device processing operations such as testing. The system cleans the contactor after the contactor has been used to test a set number of input devices. Depending on the characteristics of the input devices and the nature of the testing, this number can be adjusted so that the contactor operates at optimal levels. Moreover the system and method allows for cleaning of the contactor without significantly interrupting input device processing. Thus, the system and method allow for efficient and high quality testing of semiconductor devices. 
         [0042]    The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teaching or may be acquired from practice of the invention. The embodiment was chosen and described in order to explain the principles of the invention and as a practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modification are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.