Need grid = 0.0005um for advanced node

[selldream2]

Dear Patrick,

I'm really respect to develop this kind of big project and usefulness.
I'm try to use this as much as I can.

However, I'm developing the advanced CMOS technology. they need 0.0005nm grid.

Not supporting it, I can not use your OPC anymore.

Would you mind considering to support this function as your priority?

Sincerely

billy

[patrickschulz]

Hello Billy,

thanks for your interest and usage in/of opc. I have (sort of) good news: opc supports sub-nano-meter resolution, at least to some extent. The documentation in celldesign.pdf states that the base unit of openPCells is a nanometer, but that is only half of the truth. The documentation used to be phrased a bit differently, but I changed that for clarity. To be honest, I did not expect sub-nano-meter resolution to show up :D
Anyway, the geometric sizes in opc are unit-less. What a point.create(1, 1) is depends on the interpretation. Yes, without any additional settings the GDS and SKILL exports will produce files that interprete a '1' as '1 nanometer'. But theoretically, both exports did already support to change the base unit, it was just never used and tested. I just tested it and consequently pushed a commit fixing minor issues (commit 433d977). Please try the following:

opc --export SKILL --technology GF22FDSOI --cell __test/subnanometer  -X '--base-unit 10000'
opc --export gds --technology GF22FDSOI --cell __test/subnanometer  -X '--database-unit 1e-10 --user-unit 10000'

These calls should produce two files (openPCells.il and openPCells.gds) with the following content:

openPCells.il:
let(
    (cv)
    cv = geGetEditCellView()
    dbCreateRect(cv list("M1" "drawing") list(0.0000:0.0000 0.0001:0.0001))
) ; let

and

openPCells.gds (as seen by `opc --show-gds-data`):
HEADER (6) -> data: 600 
BGNLIB (28) -> data: 2022 3 15 13 59 53 2022 3 15 13 59 53 
    LIBNAME (10) -> data: "opclib"
    UNITS (20) -> data: 0.0001 1e-10 
    BGNSTR (28) -> data: 2022 3 15 13 59 53 2022 3 15 13 59 53 
        STRNAME (16) -> data: "opctoplevel"
        BOUNDARY (4)
            LAYER (6) -> data: 15 
            DATATYPE (6) -> data: 0 
            XY (44) -> data: 0 0 1 0 1 1 0 1 0 0 
        ENDEL (4)
    ENDSTR (4)
ENDLIB (4)

Please note the formatting of the coordinates in the SKILL code (0.0001, 100 picometer) and the UNITS record in the GDS file, which shows that the base unit is now 100 picometer.

This probably can solve your problem practically. However, the manufacturing grid is, sub-nano-meter or not, inherently a tricky topic and shows subtle and tricky issues in many corners. I am currently planning a major design overhaul, which will remove support for floating point numbers and division in the lua interpreter. This will force cell writers and users to explicitly deal with "grid-destroying" mathematical operations. This change however will be not happening in the near future, as solutions for grid issues already exist, just have to be used.

Closing remarks: I am excited you are using opc for cutting-edge nodes. I'm happy to provide support for these. I'd be interested in your use case and your work-flow, as well as data representation. Sub-nanometer resolution breaks with many things that are standard in data handling. Sure, GDS and virtuoso do support other grids in theory, but I have never seen that in real life and I'd not be surprised if there would be bugs in the handling code.

[selldream2]

Thanks for suggetion. So I need to give input for 15 for 1.5nm with '--database-unit 1e-10'. is it right my understand?

As example, I'd like to put 20nm size contact at the center of 51nm area. Left position would be 10.5nm and right position would be 30.5 nm. I can not treat this case smartly.

[patrickschulz]

Yes, your understanding is correct.

Try this cellscript:

local cell = object.create("cell")

geometry.rectanglebltr(cell, generics.metal(1),
    point.create(0, 0),
    point.create(510, 510)
)
geometry.rectanglebltr(cell, generics.metal(2),
    point.create(0, 0),
    point.create(510, 510)
)
geometry.rectanglebltr(cell, generics.viacut(1, 2),
    point.create(155, 155),
    point.create(355,355)
)

return cell

(This is just a proof-of-concept with random layers.)
Export this like I've shown in my previous post, then you'll get (in SKILL):

let(
    (cv)
    cv = geGetEditCellView()
    dbCreateRect(cv list("M1" "drawing") list(0.0000:0.0000 0.0510:0.0510))
    dbCreateRect(cv list("M2" "drawing") list(0.0000:0.0000 0.0510:0.0510))
    dbCreateRect(cv list("V1" "drawing") list(0.0155:0.0155 0.0355:0.0355))
) ; let