Using L-Edit's DRC to make sure no VCs on waveguides

Adding VCs is tedious and it's easy to make a mistake. Here's how to use L-edit's built-in design rule check (DRC) function to make sure there aren't any VC's on top of the waveguides. The DRC is fairly easy to set up, and could be used for enforcing any design rule.

Setting up DRC

• On the top menu bar, go to Tools>DRC Setup...
• Check the box next to DRC standard rule set
• On the right hand side of the box, click Edit...

The standard rule set doesn't actually have any rules defined until you add them.

• In the dialog box that pops up, click Add. Name your rule.
• In the "rule type" box, click "spacing"
• Under "rule distance", enter a spacing. This will end up being the minimum distance between the WG trench and a VC that is outside the waveguide - since the WGs are usually smaller than vertical channels, any distance will cause a misplaced VC to show up as an error.
• Enter the appropriate rule layers.
• Click the "Geometry Flags..." button
• Click "unmark all" - otherwise, all your waveguide bends, most text, stepper global AMs, etc. will get tagged as errors.
• Click OK until you get back to the regular layout window

Running DRC

Click the DRC button, or go to Tools>DRC. The check will take ~1 minute. Then a list of errors pops up, and you can go through them by clicking on them.

Tips

It's nice to have a second VC layer for structures that are allowed near waveguides (e.g. verniers, dicing lines) so that these don't generate errors.