Runlength dependent spacing

In this article we’ll look at how to code a DRC rule for run length dependent spacing. This is a spacing rule between two shapes which requires larger spacing for long, parallel edges.

In the following image we allow a spacing rule of 36nm if the edges are less than 56nm in their projecting length. Edges longer than this require a spacing of 50nm.

There are two spacing rules to implement this check: the first checks projecting edges longer that 56nm. The required spacing in this case is 50nm:

geomSpace(m1, 0.050, 0.056, greaterthan, ‘M1 space < 50nm for runlength > 56nm’)

The second checks projecting edges that are less than or equal to 56nm. The required spacing is 36nm:

geomSpace(m1, 0.036, 0.056, lessthan, ‘M1 space < 36nm for runlength < 56nm’)

We are using the flags to distinguish between the two cases and give the DRC error as shown in the image.

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