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NanoRoute crash with incremental tech libraries in mixed signal flow

nevsan
I'm trying to create an incremental technology database tree for using the ARM 7-Track Standard Cell library for the Global Foundries 130nm BCDlite process. My metal stackup is 8 metal layers with two top metals. I only want to use 5 metal layers (all signal layers) for digital implementation, but want to embed it in a design using the real stackup.

For our pure digital flow, we typically load the ARM routing technology LEF (sc7_tech.lef) and the standard cell LEF (sc7_130bcdlite_base_rvt_w3.lef), and proceed with Encounter for full implementation. This works fine.

Now, following the guidance of the Mixed Signal Interoperability guide, I'm migrating these LEFs over to an incremental tech library in OA. First, I import from the ARM 7-track routing technology LEF:

lefin -lef sc7_tech.lef -lib sc7_tech -techRefs gf013hv30v -mapConflicts

This gives me a library sc7_tech that references gf013hv30v. I then do this for the 7-track standard cell library.

lefin -lef sc7_base_rvt_w3/r0p0/lef/sc7_130bcdlite_base_rvt_w3.lef -lib sc7_130bcdlite_base_rvt_w3 -techRefs sc7_tech

This gives me the standard cells. My hierarchy, is thus sc7_130bcdlite_base_rvt_w3 -> sc7_tech -> gf013hv30v (the base PDK).

I'm able to load this OA into Encounter instead of the LEFs and use it as normal. However, when I run routeDesign, encounter stops at "start initial detail routing ...", and begins to fill up all of the memory on my machine (all 64 GB) before crashing. The exact same flow with the LEF files works without any problems.

I would really like to figure out why this is happening, and am confused that trialRoute is able to work fine with the OA library. I can even save the trialRouted design into OA and open it with Virtuoso, remaster instances, etc. It's just routeDesign -globalDetail that crashes it.

Some things that I've tried
  • Modify the sc7_tech LEF file to match my metal stackup (it uses 6 metal layers, with 6 being a top metal), based on info from the gf013hv30v techFile.
  • Modify that modified LEF to not include any info for MET7 or MET8.
  • Pull in the routing tech LEF using -pnrLibDataOnly
I also tried importing in sc7_tech.lef without referencing the base PDK. This worked and was able to get through the same Encounter flow as before without a problem. The issue is, of course, that the resulting layout is not referencing the base PDK that the rest of the design is, so all of the non METAL/VIA layers are gone, and it doesn't exactly match my stackup (i.e. not very interoperable).

Please help. We're expecting to tapeout very soon and this is blocking us.

Thanks!

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