Via DRC Violation Issue

[StanleyAlwaysLoveYou]

Expected Behavior

The V1.1 violation will pop up when a via size is less than 0.26*0.26

Actual Behavior

I accidentally used 0.22*0.22 vias all over my layout and this V1.1 didn't show up when running the drc. Those four violations are the density violations.

Steps to Reproduce the Problem

1. Create a small block consisting of M1, M2, and via1 in my layout. Then copy to a new layout called testvia.txt and run the DRC. No V1.1 violation shows.

2. To figure out what happens. I create a new, identical layout called testvia2.txt manually(this time not copy from my previous layout). V1.1 violation shows

3. Now I compare testvia.txt with testvia2.txt, The only difference are time stamp and the name of layout.

4. These steps shows a weird issue of this via violation.

@msaligane @proppy @andylithia

Specifications

• Version: v0.0-1450-g140b622
• Platform: klayout

[atorkmabrains]

@StanleyAlwaysLoveYou Could you please use: https://github.com/efabless/globalfoundries-pdk-libs-gf180mcu_fd_pv/tree/main/klayout/drc instead of the DRC here?

[proppy]

@atorkmabrains isn't the content at https://github.com/efabless/globalfoundries-pdk-libs-gf180mcu_fd_pr (what's currently packaged in open_pdks) equivalent to what's in the _pv repo?

[atorkmabrains]

It's no longer the case @proppy. What in the PR repo is not up to date as PV. We have cleaned the DRC significantly due to the review we are doing with you. We improved the performance and fixed a handful of DRC bugs. And @RTimothyEdwards has just migrated the source of DRC for open_pdks from PR to PV:

https://github.com/RTimothyEdwards/open_pdks/commit/7ddd413a3495a9055f03ae60b4320b14d0d6dc55

I'm going to remove DRC from this PR repo as we have originally planned.

[proppy]

@RTimothyEdwards has just migrated the source of DRC for open_pdks from PR to PV:

Awesome!

I'm going to remove DRC from this PR repo as we have originally planned.

Perfect, maybe also add a line to the README to inform people of the new location.

Do we still plan to merge most of the content in https://github.com/google/globalfoundries-pdk-libs-gf180mcu_fd_pv? /cc @mithro

[atorkmabrains]

Yes, that has been always the plan to move to Google. But I think we are stuck with the issue of meeting the complex linting requirements for ruby at that point.

[proppy]

But I think we are stuck with the issue of meeting the complex linting requirements for ruby at that point.

Let's discuss this in https://github.com/google/globalfoundries-pdk-libs-gf180mcu_fd_pv/issues/40 I didn't realize it was a blocker.

[atorkmabrains]

Thanks @proppy

[atorkmabrains]

@StanleyAlwaysLoveYou I'll keep this ticket open until, I hear back from you about the results using pv version.

[StanleyAlwaysLoveYou]

I used the drc in pv version and still shows the different result: testvia.gds doesn't have the V1.1 rule violation while testvia2.gds has.

I guess there is some difference in these two .gds while they look identical in klayout, even the .txt files translated from the corresponding .gds file look the same. However I can't run the drc on the .txt file so it is hard to figure out what happens between these two "identical" layouts.

[atorkmabrains]

@StanleyAlwaysLoveYou Could you please upload the files this way we could test?

[StanleyAlwaysLoveYou]

I am not sure how to directly upload the files. I'll put them in a zip folder: testvia.zip

[StanleyAlwaysLoveYou]

Found another way, in case the file will change during compression. The below is the link of the two gds files https://drive.google.com/drive/folders/1bJGJSbtJjhNF4FMp3EHazQeSTnmY0TDa?usp=sharing Thanks a lot!

[atorkmabrains]

@FaragElsayed2 Could you please take a look at this?

[FaragElsayed2]

@atorkmabrains

The difference between them is database unit

This cause an issue in extended command as we have used 0.001 db value not um.

I have opened an issue to make DRC rules independent of DB unit. https://github.com/efabless/globalfoundries-pdk-libs-gf180mcu_fd_pv/issues/86

[atorkmabrains]

Thanks @FaragElsayed2

[atorkmabrains]

@StanleyAlwaysLoveYou Will be fixed soon.

[StanleyAlwaysLoveYou]

Thanks @FaragElsayed2 @atorkmabrains So the problem is I used the different database unit in these two layouts? May I ask what exactly the database unit is?

[atorkmabrains]

@StanleyAlwaysLoveYou Precision is a number that is stored in the layout file GDS/OASIS to tell it what each integer number represent in the layout. For example, if the precision is 1000, then each database unit is 0.001 um. If precision is 10000, then each database unit is 0.0001um. So on so forth.

[StanleyAlwaysLoveYou]

Oh I see. I saved testvia.gds as a new file with 0.001um database unit, then the V1.1 violation did work.

[atorkmabrains]

@StanleyAlwaysLoveYou and @proppy Fixed in https://github.com/efabless/globalfoundries-pdk-libs-gf180mcu_fd_pv/pull/88