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  1. #1
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    Analog Layout- Why CD KEY is Required ?

    Hi,

    Why CDKEY is required in an ic chip layout? what are the uses of CDKEY structure ?

    Thanks in advance.

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  2. #2
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    Re: Analog Layout- Why CD KEY is Required ?

    "CD" stands for "Critical Dimensions" and the CD "key" has
    all of the features that should be dimensionally controlled.
    It's not for your benefit, it's part of the "foundry dues" just
    like mask ID marks and alignment marks and WAT structures.

    CD measurement data is fed back through the SPC system
    to keep lithography on-center.

    CDs could be in the chip or in the scribe lanes. I prefer to
    see them on the chip, "just in case" something goes wrong.
    Just like I prefer to have "drop-in" PCMs rather than scribe
    linw WAT keys, because any wafer-processing-received
    insight is destroyed before you know you needed it.


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