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Wafers handling robotics arms

  1. Sep 14, 2014 #1

    iii

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    Hi to all the forum members, my questions for this tread are correlated to the robotics arms for wafers like the robotics arms that are in this website:
    www.kensingtonlabs.com
    1. why is so important to build very very accuracy robotics arms, Wafer Handling Systems , in the machines of semiconductors industry that arrive to 1 micro meter accuracy? in other words why the semiconductors industries invest a lot of money in research and development of very very accuracy robotics arms? and how it will make the chips for the CPU of the computers or smartphones better?
    2. If the wafer that the robotics arm move was have 300 millimeters diameter and now the wafer diameter enlarge to 450 millimeters so the wafer became to be heavier and bigger so what need to change in the robotics arm for wafers with 300 millimeters diameters that it will continue to be very very accuracy also for wafers with 450 millimeters diameter?

    I think, but I am not sure, maybe the answer can be correlated also to very very accuracy machines productions or Hard Disk Drivers that are also very very accuracy.
    I also will be happy to receive from the forum members links to article websites or relevant books like from google books or relevant lectures like from youtube education that are correlated to these questions, thank you.
     
  2. jcsd
  3. Sep 14, 2014 #2

    Integral

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    So much depends upon the process that it is difficult to give specific answers to your questions.

    Si wafers tend to be fragile so accurate placement is essential. In the systems I worked on we used a Genmark robot to pick up a wafer from a cassette, then flip the wafer over and placed it on a Aerotech stage, which then did the precision movements necessary to process the wafer. When the process was complete the robot retrieved the wafer from the process chamber and returned it to the cassette.

    The accuracy required for this robot was on the order of 10s of microns. Correct placement was essential, a broken wafer due to robot handling errors was frowned on by management.

    Changing wafer size can mean a complete retooling of the fab, this is VERY expensive, in capital costs and production time lost. I was involved in the retooling to process 8" wafers up from 6". This took a better part of a year from start to end.

    Oh yeah, as a side note I worked for HP making ink jet print cartridges.
     
    Last edited: Sep 14, 2014
  4. Sep 14, 2014 #3

    jedishrfu

    Staff: Mentor

    Wafer testing requires accurate wafer placement. Test machines walk from site to site dropping a test down on the wafer. It must have good contact in order to test the chip on the wafer prior to slice and dice of the wafer.
     
  5. Sep 15, 2014 #4

    iii

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    Thank you for yours replies.
    Integral I have some question for you and I will glad if you can replay to one or more of them:
    1. How can error of several houndres microns in the placement of the wafer will frowned and broke the wafer?
    2. What can be others reasons (beside broken) for the necessary to the precision movement in putting the wafer on the Aerotech stage?
    3. What take a lot of energy and time for changing the robotic arm from working in 6" wafer diameter to 8" wafer diameter?
    4. I don't understand why ink jet print cartridges need this technology?
    jedishrfu, I will glad if you can explain what are these test machines?
     
  6. Sep 15, 2014 #5

    jedishrfu

    Staff: Mentor

    The test machines test the chip on the wafer. They injection patterns and capture output that is compared to expected output. Errors are reported to the operator. Chips are tested and several operating temperatures. The test head provides the power, input and output channels.

    For logic chips designers follow this strategy:

    http://en.m.wikipedia.org/wiki/Design_for_testing

    http://www.ece.uc.edu/~wjone/intro.pdf
     
  7. Sep 15, 2014 #6

    Bandit127

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    Take variation in to account when you think about this.

    Most chip fabrication plants aim for single parts per million defects. If you require pacement to be within (say) 100 microns reliably over millions of wafers you might decide the expense of robots capable of 1 micron reloution is worth the money.

    1 micron accuracy does not necessarily mean 1 micron repeatability. It is more likely to mean 1 micron resolution. The two are not the same.
     
  8. Sep 15, 2014 #7

    Integral

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    Once the wafer was placed on the stage and clamped into place a vision system had to locate fiducials printed on the wafer. If these spots were not in or near the field of view the system could not align the wafer, therefore it could not be processed. The initial placement of the wafer was important for that and clamping. The clamps should not move the wafer but just hold its position. So accurate placement on the stage is critical.

    Once in place a 30W laser begins cutting slots through (or into) the wafer. In modern ink jet cartridges the ink nozzles are printed on the wafer in the thin film processes this gives the position accuracy required to print your beautiful pics. We can then with the laser we cut from the back side to something less then 100 microns from breaking through. When removing a wafer with hundreds of slots cut into it from the stage you must handle it very carefully as it is extremely fragile. Thus accurate robot motions are critical. After the laser is done the wafers are moved to a wet bench where chemicals finish the slots through to the nozzles. The wafer then goes to saw and is cut into the individual die, which then are attached to the cartridge you buy in the store.

    There is much more to a wafer size change then the robot end effector. First off, before you can do that, you have to have a robot with the new range of motion needed. Then there are many other fab tools which must be modified or replaced. There are some tools which can be adapted to different wafer sizes and others which cannot. This is a major change in any fab and not something that is done casually.
     
  9. Sep 16, 2014 #8

    iii

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    Thank you for your replies, I have some questions about your replies and I will glad if you can replay one or more answers from these questions:
    Integral, you wrote about some processes that are important that the robotic arm will be very accuracy like for laser cutting, nozzle the thin films and put the wafer in the carriage I will glad to know if there are more processes that are important robot will be very accuracy?
    What can be the parts that need to change or add or modify for for change the robotics arm from wafers that have 300 millimeter diameter to wafer that have 450 millimeter diameter?
    Bendit127, I don't understand why if the robotic arm handling is more accurate than the wafer will have less defects?
    jedishrfu, thank you for explain me about the test machines.
    I want to read some articles or books in this area, do you know about good articles or books that you can recommend me?
     
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