0 Replies Latest reply on Sep 25, 2009 8:44 AM by vigen_boyajyan

    Library analysis flow, when to use it?

    vigen_boyajyan

      Standard cells are frequently used elements in every design and it is a very important to validate standard cell library not only in terms of area, power consumption and timing, but also in terms of CA too, since standard cells are the primary contributor to the overall yield loss. You can use the mentioned flow to compare different libraries for the same technology node or to qualify all elements from the library before moving into P&R stage.

       

      Calibre Yield Analyzer supports Standard cell library analysis flow and it is easy to invoke the flow through Calibre Interactive; you need only standard cell library in any supported format (gds or oasis), and defect statistics from foundry or manually created based on MGC format. Output will be a characterization results per cell with errors per each defect mechanism (open, short, via failure). Layout engineers will get a right direction to optimize cells; standard cell users can validate different libraries.

      Output data:

      1)      Total YSI values per cell (combination of short, open and via failure), to be able to catch the worst cells in terms of yield from particular library

      2)      Based on YSI values user can start debugging standard cell to figure out which mechanism is a top contributor (open, short or via failure)

      3)      Two useful features are available to figure out the location of errors per each mechanism and number of failures per particle size (histogram and color maps).

      4)      Layout engineer can do slight modifications of standard cell on-the-fly and re-run the flow to get the new values.

      Also the worst standard cells in particular design can be determined by the following formula:

       

      YSI TOTAL = YSI (one cell) X N; where N – is number of instantiation in particular design

       

      Library Analysis flow also takes into account surrounding affects to provide more accurate and reliable values.

      This feature available for all supported defect statistics format: TSMC, UMC and MGC.

      To invoke and get correct and reliable results frame layer should be added in caa_layer.txt file, this layer is required for Library analysis flow to generate 3x1 and 3x3 matrixes.