Defining Glass or Chrome Areas
One of the most common errors when designing mask layout is deciding if the drawn features on your layout data (closed/filled shapes) should be clear (glass) or dark (chrome) on the mask.
This is often referred to as “polarity” or “field tone”. We use a positive photoresist, so exposed areas of the resist are developed and the underlying chrome is etched away, creating a clear (glass) transparent area. Unexposed areas remain chrome, so they are opaque at the given exposure wavelength.
For each mask layer, you must define if the drawn areas (often referred to as “digitized data”), should appear as glass (exposed, developed, and etched in the drawn areas) or chrome, (exposing the space between the drawn areas) on the final mask.
If you are unsure what areas should be glass or chrome, please contact us. There is also help and guidance when you are using our online mask order form or, requesting a quote from our customer portal.