"Edge not on Grid" Cadence DRC Error

Hi,

I have been using Cadence for quite soemtime now but have been stumped
by this error which says "Edge not on Grid". I am using technology data
provided by my foundry.

Please help me correct this error.

Thanking You,
Prashanth

 

I have been using Cadence for quite soemtime now but have been stumped

Each technology has a minimum grid all shapes have to be aligned on.

You can usually get this value by typing :
techGetMfgGridResolution( techGetTechFile( ddGetObj( "TECH_LIB" ) ) )
or
techGetMfgGridResolution( techGetTechFile( geGetEditCellView() ) )
if you have an open cellview.

Your layout has to comply with this. If you did a lot of layout without observing
this rule, you might be in trouble, as it can be a tedious job to correct all
offgrid errors.

to avoid having such errors, a simple security is to set the layout snap grid to
a multiple of the manufacturing (minimum) grid, so no point will end offgrid.

stéphane

 

I would like to add a note to stéphane's observation. Few DRC rule decks
get the manufacturing grid size from the DFII database. You should check
what the values are in the offGrid rules in the DRC rule deck as well.

 

And furthur note that a few Fabs specify a different grid for some
layers. ( Often requiring extra approval! )

-- Gerry

 

Hi Stephane,

Thanks for the quick reply.

I did my entire design in TSMC 0.18um technology and had no such
problems (edge not on grid). I am redoing the same in AMI 0.6.

techGetMfgGridResolution( techGetTechFile( geGetEditCellView() ) )
gives the minimum grid value as 0.15

I have set the X and Y snap in the Display Grid options to 0.15.
(although I had a doubt if this would help)
and I still ended up getting the same error. :-(

Please help me out :-( as I am running short of time.....Please give
the exact procedure as to what I have to do to correct it.....

Thanking You,
Prashanth

 

I have set the X and Y snap in the Display Grid options to 0.15.

Nice try, but this prevents from creating offgrid shapes. It does not fix existing
offgrid shapes.
If you want to see your manufacturing grid, in the display options set the minor
spacing to your grid and type to 'lines'. You will see a grid on the layout on which
your shapes should be aligned.

Also, in display options turn axis display on, and check that the origin of your cell
is on the grid. This is a stupid mistake - if you happen to move the origin offgrid then
all shapes become offgrid (you'd be lucky in that case).

Put your shapes on the grid, that's it. Lokk at this post maybe :

http://groups.google.ch/group/comp....omp.cad.cadence&rnum=1&hl=fr#c809293fd8f3c8b0

stéphane

 

Hi Stephane,


Thanks a lot .....it finally WORKED!!!!!!!!!.


Prashanth