Can I still do CAA if my foundry doesn't provide defect densities?

Discussion created by vigen_boyajyan on Sep 9, 2009

Yes, we still can do CAA analysis without defect density distribution provided by foundry, because CA(x) is only a function of the layout and the range of defect sizes (x) being considered. YSI = D0 x WCA, where WCA (Weighted Critical Area) depends on the defect density distribution. You need the distribution curve to calculate WCA, regardless of what you have for D0. For “generic” statistics, you can target a specific node by taking nominal min CDs as the min defect size, a fixed max defect size, and a standard fall power.


General guidelines for “generic” defect densities are the following:


  1. Contact to Diffusion should always be the #1 failure mode.
  2. For Opens and Shorts, the base layers (DIFF, POLY) should have higher failure rates than the metal layers.


We can use Calibre YieldAnalyzer with some “generic” defect densities to get the useful YSI and Yield values with MG statistics format; this is very useful for the following flows:

1)      Comparison of different standard cell Libraries for one particular technology node to choose the best on terms of Yield if other parameters like timing power and area pretty much the same.

2)      Two different place and route tools comparison in terms of Yield.

3)      Two different implementations of the same top cell (when sub cell placement and overall routing are different, but the functionality and area are the same).

4)      Memory cell comparison with and without redundancy.