Change manufacturing grid for streamout in IC613

Hi Tarek

Actually this function has been removed in all IC6.1.x releases. As of the latest IC614.485, it is not possible to change dbuPerUU during streamout. There are some plans to put back this function but it would take some time, perhaps in IC615 or an even later release. It seems debatable as to whether a layout should be scaled during streamout because it might introduce some errors/loss of precision in the gds. That's why the function was removed. But some customer flows really does require this function (i.e. they don't want to use the standard value of 2000 dbuPerUU). Hence there is a possibility that this function might make a return.

A possible workaround is as follows:
a. Change the dbuPerUU value in the techfile
b. Use XScale to magnify/shrink the design
c. Stream out the design

Please refer to $CDSHOME/doc/wincfg/wincfg.pdf for more details on XScale.

Best regards
Quek

Hi Quek,

Thanks for the info. Our process uses different grid sizes when streaming out for tapeout submission and streaming out for Calibre DRC, so this function is important for us. I checked the grid size from the tech file via:

techid=techGetTechFile(ddGetObj("myprocess"))
minGRID=techGetMfgGridResolution( techid ) 

Does the resulting value indicate the grid size for streamout?

Thanks,

Tarek

Hi Tarek

The cmd to use is not techGetMfgGridResolution. Manufacturing grid determines the precision of the coordinates of layout objects. E.g. if it is 0.05u, then all layout objects should have coordinates that are multiples of 0.05u. Otherwise, it becomes offgrid (e.g. 123.06u is bad, should be 123.05u or 123u or 123.1u ,etc).

The cmd should be techGetDBUPerUU. E.g.

techGetDBUPerUU(techid "maskLayout")

The above cmd retrieves the DBUPerUU value for "maskLayout" from "viewTypeUnits" section of the techfile. If you convert the gds to ascii format, you can see the following line in the output file:

size of data base units : 0.0005

I have 0.0005 because my maskLayout DBUPerUU is 2000 (1/2000=0.0005). Here is what you need to do:

a. Dump out the techfile
b. Edit the DBUPerUU value for maskLayout in viewTypeUnits section
c. Re-compile the techfile as a new library
d. Use XScale to change the dimensions of the layout
e. Stream out using the new tech lib

It is better to modify the value in a backup tech lib to avoid messing up your setup.

Best regards
Quek

Hi Quek,

Thanks for clearing that up. Our foundry advised that we should streamout from IC613, then streamin to IC5141 and streamout again from IC5141 using the correct DBUperUU. I figured as much, but wanted to hear from them before doing it.

Thanks,

Tarek

It shouldn't really matter what DBUperUU you have in a GDS file, as long is it has sufficient resolution. 

There is a record in stream format called "UNITS" which has two numbers:

1. The number of user units in a database unit
2. The size of a database unit in meters

Strictly speaking the user unit doesn't really matter that much either, since the numbers in the stream file are integers in database units, and database units are a well defined absolute size (based on the second number in the UNITS record).

So anything reading the stream file should be able to convert the database units in the stream file into whatever database units that application is using. The cases which I've heard of which have had problems have been to do with Mentor's Calibre, but I don't actually know whether the problem was with Calibre itself (which I'd be surprised) or whether it was just the appropriate option in the rule deck for Calibre was not used.

So I would strongly ask the foundry why they need to database unit in the stream file to be a specific size - it really shouldn't matter.

Regards,

Andrew.