Abstract:
Apparatus and methods are provided for automated semiconductor device probing. The apparatus includes a probe assembly; a machine vision system; and a semiconductor support fixture. A method includes providing apparatus for automated semiconductor device probing; locating the semiconductor device positioned on the semiconductor support fixture with the machine vision system; guiding the movement of at least one of the probe assembly and the semiconductor support fixture so as to position a contact portion of the semiconductor device and the electrical probe in alignment with one another; and moving at least one of the probe assembly and the semiconductor support fixture toward the other of the at least one of the probe assembly and the semiconductor support fixture so as to position the electrical probe and the contact portion of the semiconductor device in electrical connection with one another.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
     This patent application claims benefit of prior U.S. Provisional Patent Application Ser. No. 60/212,711, filed Jun. 20, 2000 by Yakov Kogan et al. for AUTOMATED SEMICONDUCTOR PROBING DEVICE, which patent application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to semiconductor chip testing apparatus and methods in general, and more particularly to apparatus and methods for automated semiconductor chip testing. 
     BACKGROUND OF THE INVENTION 
     Semiconductor devices, such as wafer chips, often require testing and/or assembly with electrical probes attached thereto. These processes may simultaneously require precise optical alignment and electrical connection. This can be especially important during chip-level testing and assembly of opto-electronic devices. 
     In addition, semiconductor device testing and/or assembly may require movement of the device with electrical probes attached thereto. Such a freedom of motion may significantly increase the efficiency of the testing and/or assembly of the device. 
     In known testing and assembly systems, this range of motion is typically achieved by taking advantage of the compliance of the electrical probes. However, such compliance is typically quite limited and does not permit movement of any significant distance. The optical alignment and electrical connection of the device may also be adversely affected by using the compliance of the electrical probes to achieve a range of motion. 
     SUMMARY OF THE INVENTION 
     Accordingly, one object of the present invention is to provide a device for precisely placing an electrical probe on a semiconductor chip. 
     Another object of the invention is to provide a device for automatically and precisely placing an electrical probe on a semiconductor chip. 
     A further object of the invention is to provide a device for automatically and precisely placing an electrical probe on a semiconductor chip that allows movement of the chip with the probes attached thereto. 
     A still further object of the invention is to provide a method for automatically and precisely placing an electrical probe on a semiconductor chip that allows movement of the chip with the probes attached thereto. 
     With the above and other objects in view, as will hereinafter appear, there is provided an apparatus for automated semiconductor device probing, the apparatus comprising: a probe assembly including an electrical probe for making an electrical connection with a semiconductor device, the probe assembly having a first surface and a second surface in opposition to one another; a machine vision system having a camera for locating the semiconductor device, the machine vision system having a first contact surface adjacent the first surface of the probe assembly, the first contact surface having a first attachment mechanism to selectively attach together the probe assembly and the machine vision system; and a semiconductor support fixture for positioning the semiconductor device, the semiconductor support fixture having a second contact surface adjacent the second surface of the probe assembly, the second contact surface having a second attachment mechanism to selectively attach together the probe assembly and the semiconductor support fixture. 
     In accordance with a further feature of the invention there is provided a method for automated semiconductor device probing, the method comprising: 
     providing apparatus for automated semiconductor device probing, the apparatus comprising: a probe assembly including an electrical probe for making an electrical connection with a semiconductor device, the probe assembly having a first surface and a second surface in opposition to one another; a machine vision system having a camera for locating the semiconductor device, the machine vision system having a first contact surface adjacent the first surface of the probe assembly, the first contact surface having a first ale attachment mechanism to selectively attach together the probe assembly and the machine vision system; and a semiconductor support fixture for positioning the semiconductor device, the semiconductor support fixture having a second contact surface adjacent the second surface of the probe assembly, the second contact surface having a second attachment mechanism to selectively attach together the probe assembly and the semiconductor support fixture; 
     locating the semiconductor device positioned on the semiconductor support fixture with the machine vision system; 
     guiding the movement of at least one of the probe assembly and the semiconductor support fixture so as to position a contact portion of the semiconductor device and said electrical probe in alignment with one another; and 
     moving at least one of the probe assembly and the semiconductor support fixture toward the other of the at least one of the probe assembly and the semiconductor support fixture so as to position the electrical probe and the contact portion of the semiconductor device in electrical connection with one another. 
     The above and other features of the invention, including various novel details of construction and combinations of parts and method steps, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular devices and method steps embodying the invention are shown by way of illustration only and not as limitations of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will be more fully disclosed by the following detailed description of the preferred embodiments of the invention, which are to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
     FIG. 1 is a diagrammatic illustration of an automated semiconductor probing device, with the device being shown with its probe assembly in contact with the machine vision system; 
     FIG. 2 is a diagrammatic illustration of an automated semiconductor probing device, with the device being shown with its probe assembly in contact with both the machine vision system and the semiconductor support system; 
     FIG. 3 is a diagrammatic illustration of an automated semiconductor probing device, with the device being shown with its probe assembly in contact with the semiconductor device; and 
     FIG. 4 is a schematic top view of a semiconductor device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention is shown in FIGS. 1-3. More particularly, there is shown an automated semiconductor probing device  5  which generally comprises a probe assembly  10 , a semiconductor support fixture  15 , and a machine vision system  20 . A semiconductor device  25  is shown supported on semiconductor support fixture  15 . Machine vision system  20  is used to locate semiconductor device  25  in relation to probe assembly  10 . Semiconductor support fixture  15  and/or probe assembly  10  are moved as guided by machine vision system  20  to precisely align semiconductor device  25  with probe assembly  10 . Semiconductor support fixture  15  and/or machine vision system  20  are then moved toward the other such that probe assembly  10  makes an electrical connection with a contact portion of semiconductor device  25 . Probe assembly  10  is then transferred from machine vision system  20  to semiconductor support fixture  15 , where the probe assembly remains as the semiconductor support fixture  15  moves away from machine vision system  20 . Thereafter, probe assembly  10  may be transferred back to machine vision system  20  for use on a subsequent chip. 
     Referring again to FIGS. 1-3, in a preferred embodiment of the invention, semiconductor device  25  is a wafer chip that contains a pair of contact pads  30 . In other preferred embodiments of the present invention (not shown), semiconductor device  25  may contain a single contact pad where another electrical connection is made at its bottom surface or on a side portion. Alternatively, semiconductor device  25  may have more than two contact pads thereon. 
     Still looking at FIGS. 1-3, in a preferred embodiment of the invention, probe assembly  10  is shown with a pair of electrical probes  35 . Electrical probes  35  are configured to selectively make contact with the two contact pads  30 . Of course, where appropriate, probe assembly  10  may have more or less than two electrical probes  35 . More particularly, in other preferred embodiments of the present invention (not shown), a probe assembly may have a single electrical probe or multiple probes. These probes can be configured to selectively make contact with a single contact pad or multiple contact pads of a semiconductor device. 
     Looking now in FIGS. 1-3, an opening  40  is provided in probe assembly  10  so as to create an optical path, along an optical axis  45 , formed between machine vision system  20  and semiconductor support fixture  15 . 
     Referring again to FIGS. 1-3, in the preferred embodiment of the present invention, machine vision system  20  is shown including a first attachment mechanism  50 . Probe assembly  10  may be selectively attached to first attachment mechanism  50 . For example, this attachment may include the use of an electromagnet, vacuum force or a mechanical connection. In use, first attachment mechanism  50  the electromagnet may be actuated by electrical current to attach probe assembly  10  thereto. Additionally the attachment mechanism may provide a fail safe mechanism to prevent probe assembly  10  from becoming released from machine vision system  20  during a loss of power. As such, in the event of power loss, probe assembly  10  is retained to machine vision system  20  in the absence of electrical current. 
     Still looking at FIGS. 1-3, in a preferred embodiment of the present invention, semiconductor support fixture  15  is shown positioned on a motion stage  55 . Motion stage  55  is used to move semiconductor support fixture  15  and, in turn, semiconductor device  25  relative to probe assembly  10  in the X-direction, the Y-direction and the Z-direction. Motion stage  55  is also guided by machine vision system  20 . 
     Referring again to FIGS. 1 and 2, machine vision system  20  is shown including a camera  60  in attachment to a support  65 . Support  65  is shown with a first attachment mechanism  50 . Camera  60  is configured to locate the position of semiconductor device  25  in relation to the position of probe assembly  10 . More particularly, camera  60  locates the position of contact pads  30  in relation to electrical probes  35 . Using this location information, machine vision system  20  guides motion stage  55  so as to position semiconductor support  15  in the X-direction and/or the Y-direction. This positioning is continued until contact pads  30  are positioned in alignment with electrical probes  35 . 
     Still looking at FIGS. 1-3, semiconductor support fixture  15  is shown including a second attachment mechanism  70 . Probe assembly  10  may be selectively attached to second mechanism  70 . For example, this attachment may include the use of an electromagnet, vacuum force or a mechanical connection. The attachment mechanism  70  may be actuated by an electrical current to attach probe assembly  10  thereto after alignment of contact pads  30  and electrical probes  35 . 
     Now looking at FIG. 1, semiconductor probing device  5  is shown with probe assembly  10  in attachment to first attachment mechanism  50 . In this configuration, probe assembly  10  and/or semiconductor support fixture  15  may be moved relative to one another such that electrical probes  35  and contact pads  30  may be aligned with one another. After aligning electrical probes  35  and contact pads  30 , probe assembly and semiconductor support fixture  15  are locked into this position relative to one another. In a preferred embodiment of the present invention, semiconductor support fixture  15  is then moved in the Z-direction toward probe assembly  10  until electronic probes  35  make electrical connection with contact pads  30 . See FIG.  2 . At this point, an electric signal may be applied to, and/or read back from, semiconductor device  25 . 
     Now looking at FIG. 2, in a preferred embodiment of the present invention, probe assembly  10  is adjacent to second attachment mechanism  70  as electronic probes  35  simultaneously become electrically connected with contact pads  30 . In addition, second attachment mechanism  70  may be activated to attach probe assembly  10  and semiconductor support fixture  15  to one another. This attachment acts to preserve the alignment of, and electrical connection between, electronic probes  35  and contact pads  30 . 
     Furthermore, first attachment mechanism  50  may be deactivated to detach probe assembly  10  and support  65  from one another. Upon this deactivation, probe assembly  10  and semiconductor support fixture  15  are left in attachment to one another, effectively forming a single unit  75 . Accordingly, probe assembly  10  is no longer secured to machine vision system  20 . Single unit  75 , on motion stage  55 , can now be moved a significant distance, in any direction, from machine vision system  20 . See FIG.  3 . This motion permits more extensive manipulation of semiconductor device  25  at the chip level allowing precise optical alignment while maintaining electrical connection to semiconductor device  25 . As such, the probe assembly  10  can remain mated to semiconductor device  25  while tests and operations are performed on the semiconductor device  25 , e.g. calibration, optical alignment, laser trimming, etc. 
     After testing and/or assembly is completed on semiconductor device  25 , single unit  75  is returned to interface with machine vision system  20  at first attachment mechanism  50 . This is done by appropriately moving motion stage  55  first in the X and Y directions, and then in the Z direction. See FIG.  2 . First attachment mechanism  50  is then activated once more to attach probe assembly  10  and semiconductor support fixture  15  to one another. Then second attachment mechanism  70  is deactivated so as to detach probe assembly  10  and semiconductor support fixture  15  from one another. Upon this deactivation, semiconductor support fixture  15  may be then be moved away from probe assembly  10  to permit removal of semiconductor device  25 . See FIG.  1 . Another semiconductor device (not shown) may then be positioned on semiconductor support fixture  15  for automated semiconductor device probing as described herein. 
     In addition, an alignment mechanism (not shown) may be provided to align probe assembly  10  and machine vision system  20  to one another during engagement with one another. This alignment mechanism (not shown) may include in intermeshing surfaces on probe assembly  10  and machine vision System  20 . This alignment mechanism (not shown) may be provided to prevent incremental misalignment between probe assembly  10  and machine vision system  20  over time, as probe assembly  10  is repeatedly redocked to machine vision system  20 . 
     In another preferred embodiment of the invention (not shown), multiple semiconductor devices  25  can be positioned at a single time on semiconductor support fixture  15 . Machine vision system  20  and probe assembly  10  can then be sequentially used on each of semiconductor devices  25  as described herein. 
     Looking now at FIGS. 1 and 4, in another preferred embodiment of the present invention, semiconductor device  25  is shown positioned on semiconductor support fixture  15  at an angle θ (FIG. 4) with respect to the X, Y plane of probe apparatus  10  and machine vision system  20  (FIG.  1 ). 
     One method to compensate for this angle θ is to employ the machine vision system  20  to determine this angle θ and adjust the position of probe assembly  10  with respect to semiconductor device  25 . This adjustment can be made by rotating first attachment mechanism  50  and probe assembly  10  as guided by machine vision system  20 . More particularly, a rotatable mount  66  may be included between first attachment mechanism  50  and support  65 . As such, the rotatable mount  66  turns probe assembly  10  to angle θ with respect to machine vision system  20 , aligning electronic probes  35  with contact pads  30 . Once this alignment is made, the automatic probing process continues as described herein. This rotary orientation serves to correct any angular deviation between contact pads  30  and electronic probes  35  in the horizontal plane. This may be important to allow automated probing of “randomly” positioned semiconductor devices  25  on semiconductor support fixture  15 . 
     In another preferred embodiment of the invention (not shown), a precision mount (not shown) may be used to rotate motion stage  55 , As such, a rotational deviation between a semiconductor device  25  and a probe assembly  10 , shown as angle θ in FIG. 4, may be corrected by rotating motion stage  55 .