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Difference between layer number & stream number in technology file

VEERA PRAMOD

 I would like to know the difference between layer number & stream number in technology file.

 

Thank you.

Veera Pramodu Kotrika 

  • Hi Veera,

    The CAD layer number is the number prescribed by the given process/foundary that must be used in the gds database. The stream number is the number sequence assigned to that layer for the stream out process. One the foundry receives the gds file it then has to transfer those cad layer numbers to the MASK numbers used for data prep that defines the field for clear/dark. Hope that helps !!

  • I don't think that was quite the question, so the answer is not quite right.

    The Cadence database actually stores data on layers using a numerical layer number and purpose number. The tech file associates names with these numbered layers/purposes, but really it's stored as a number.

    The numbers chosen are to some extent arbitrary, although sometimes people try to align them with the numbers used in the stream (aka GDS) files.

    The streamLayers information in the tech file (if present) controls the mapping of these Cadence layer numbers to stream layer numbers. In the absence of streamLayers in the tech file or a layer mapping file, the stream file gets written using the Cadence layer numbers.

    Hope that's clearer?

    Regards,

    Andrew
  • Much clearer !! Thanks Andrew.


    David M Parmeter
    IC Layout Engineer
    Skyworks Solutions

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