A process for forming grooves of different depths using a single masking step is presented. In the preferred embodiment of the present invention a photoresist material is used as a single masking layer. The grooves of different types are defined in the masking layer such that the image for a first type...http://www.google.de/patents/US4495025?utm_source=gb-gplus-sharePatent US4495025 - Process for forming grooves having different depths using a single masking step
