The photomask self interference (PSI) method utilises theinterference field generated by the first and transmitted orders of ahigh precision grating. The authors describe a low cost replicationprocess for PSI mask manufacture, and development to date, on anentirely new approach involving embossing directly into a thin film onthe fragile semiconductor substrate. In both the techniques the aim isto produce high quality, uniform, profiles in a holographic recordingmaterial on the surface of the semiconductor substrate. These gratingsare then used as a mask in the etching of the substrate that transferthe profiles into the waveguide layer. This novel approach aims tocapitalise on the accuracy of the electron beam systems coupled with thehigh throughput and relatively low cost of a conventional contact maskregime
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