Guidelines for Designing a Gridded Library for Innovus

Use the following general guidelines to simplify the internal data structures that Innovus uses during routing (assuming horizontal rows):

Make cell width a multiple of the vertical routing track pitch.
Cell widths should be a multiple of the vertical routing pitch if there is only one vertical routing layer.
Make cell heights a multiple of the horizontal routing layer pitch.
If there is more than one horizontal routing layer, use a multiple of the greatest common denominator of the horizontal track spacing.
Create pins that cover routing grid intersection points by half the minimum width.
The CPU time increase for on-grid versus off-grid routing varies from 20% to 30%, depending on how many off-grid pins are in the library. The quality of route is not significantly degraded with off-grid routing.
Make blockages cover grid intersection points.
Blockages and pins should cover grid intersection points even after the blockages are fractured.
The routers can use any grid intersection point not covered by a pin or blockage shape.