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VTH_P/VTH_N implant spacinfg rule violation prevention/fix

DavidBD

 Hello,

I and encounting a DRC rule violation related to VTH_N/VTH_P implant spacing rule.

I found that SOC have special placement flag to handle this rule  :

setPlaceMode -honorImplantSpacing true

When I use it I got the following error :

 **WARN: (SOCSP-300):    No layer1-to-layer2 spacing rule specified for any Implant
        layer in-use. Ignoring  'honorImplantSpacing' option.

Attched is the related LEFrule :

LAYER VTH_P
    TYPE IMPLANT ;
    WIDTH 0.18 ;
    SPACING 0.18 ;
END VTH_P

LAYER VTH_N
    TYPE IMPLANT ;
    WIDTH 0.18 ;
    SPACING 0.18 ;
END VTH_N

Can you please advice if SOC can prevent this violation ?

Thanks,

David

 

  • Kari

     Hi David,

    It looks like you need another line in each implant layer's definition in the LEF. Something like:

    LAYER VTH_P
        TYPE IMPLANT ;
        WIDTH 0.18 ;
        SPACING 0.18 ;
        SPACING 0.18 LAYER VTH_N ;
    END VTH_P

    The warning is telling you that a spacing rule between the two implant layers is what's missing.

    Hope that helps,

    - Kari

  • DavidBD

     Hi Kari,

    You are right this remove the warning but do solve the problem and looks like I did not explain the issue correctly so lets try agian :

    TSMC 40nm proccess defines VTH_N/VTH_P/VTL_N/VT_LP implant spacing as described before.

    The rule defines spacing between the same VT layers and not as you mentioned and this is not the issue here and it looks that this placement switch related to implant rule between differant VT layers ( LVT Vs HVT ).

    Looking into the Encounter violations it looks like the Encounter keep this rule on the same row and not on two rows. The verifyGeometry define this rule as "implant check" and report it as "NSMetal" violation.

    Preventing this violation on the same row can be implemented by insering HVT fillers cells between two HVT std cells or cell location swaping.

    The question is how to tell Encounter to keep this rule between two row ?

     David

     

     

  • Kari

    Hi David,

    Here's what the current recommendation is:

    After you have run verifyGeometry to flag these violations, rerun your addFiller command (with all the same settings you had before), but this time add the -fixDRC switch. This will attempt to fix any filler-related DRC problems by replacing the current fill cells with others.

    It's possible that addFiller will not be able to find a drc-clean solution in every spot and you will have a few gaps that need fixing by hand.

    Let us know how this works for you!

    - Kari

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