Mask structures for photoetching procedures

Abstract

A mask structure is described which is extremely useful for use in various photoetching processes where etching rate depends on radiation intensity on the etched surface. Such processes are extremely useful for producing various geometrical patterns on surfaces. The mask is made up of alternate areas of opaque and transparent areas which when introduced into an optical imaging system ordinary aberrations produce a pattern on the surface to be etched with the desired continuous spatial variation of radiation intensity. A particular advantage of the mask structure is that it can easily be made using an Electron Beam Exposure System. The mask is particularly useful for electrochemical photoetching processes carried out on compound semiconductors. The mask structure is usefully used to photoetch integral lenses on light emitting diodes. This photoetching process produces a variety of lens structures on LED devices with great accuracy. Also, a large array of lens structures are produced simultaneously which is highly advantageous economically.

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