Fabrication of fine pitch gratings by holography, electron beam lithography and nano-imprint lithography

Fine pitch gratings (200 mn - 240 nm) are required for a variety of devices such as optical filters, semiconductor lasers and sensors for bio-medical applications. Various lithographic techniques are commercially available for fabricating gratings, with the choice depending on the type of grating required, cost and volume of manufacture. It is possible to use state of the art high-resolution projection steppers, common to silicon device manufacturing, for half pitch gratings down to 65 mn, but for much smaller volume manufacturing of photonic devices these tools have a prohibitive cost of ownership. Thus, remaining techniques for sub 120 mn half pitch gratings are holography, electron beam lithography, and nano-imprint lithography. In this paper we compare, characterize, and discuss the practical application of these three methods. Examples of gratings fabricated at the Canadian Photonics Fabrication Centre (CPFC) are shown as well as some application examples.