xsection bug - etch does not work unless performed twice

edited September 13 in General

Hi all,
I encountered a strange bug that in a recent xsection update some steps etch does not work unless it is done twice.

For example here I am emulating wet etch hardmask removal, and it only works if done twice, despite the thickness of the hardmask being only 0.5um.

  _depth = 3
  _bias = 3
  etch(_depth, _bias, :into => [@SiOx,@SiNx])
  #bugs out and does not work without the second etch
  etch(_depth, _bias, :into => [@SiOx,@SiNx])

If I increase depth to 6 then it still does not work with only one etch. Only the second etch works.

Any idea of what is going on?

//Btw, xsection is an amazing process visualization tool!


  • Hi @ResuS,

    Thanks for your feedback :) Actually, the xsection script does not really belong here as it is a separate project (https://github.com/klayoutmatthias/xsection). However, I do not actively maintain it and it is pretty much frozen. The reason is that it is already beyond what is reasonable - it is amazingly useful but also is quick to lead you to wrong conclusions and people are raising feature requests that I consider inappropriate for this simple concept. So use on your own risk. I mean that.

    If you want to learn more about this: I gave a talk 2022 in Paris about XSection and why I do not really like it. You can watch it here: https://peertube.f-si.org/videos/watch/25b56a31-7357-468c-a9fd-8938e6005fe4

    About your specific problem: Did you properly set "depth" (see here: https://klayoutmatthias.github.io/xsection/DocReference)? The default depth is only 2µm (fitting to a planar CMOS process for example), but you are using values much bigger that this. Try a depth of 10µm for example and don't forget to set a larger height too.

    With just a small snippet it's impossible to debug the issue. If you find "depth" does not help, please try to paste a stripped down sample and attach some test layout (.zip it to attach it).


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