Date of Graduation
Statler College of Engineering and Mineral Resources
Lane Department of Computer Science and Electrical Engineering
Lawrence A. Hornak.
Sub-micron optical gratings are essential integrated elements to couple light into waveguides and for optical monitoring of microfluidic channels or MEMS devices. Since the required features in the sub-micron regime are difficult to achieve by mechanical ruling and photolithography, alternate fabrication techniques are investigated. Exposure by e-beam and laser are two direct write methods which are used. These methods preclude the need of a mask, require few processing steps, and can be used to write features of sizes desired for optical gratings. In this research, we explore and develop processes to create sub-micron gratings by both these methods. A resist bi-layer is patterned by e-beam exposure. After metal lift-off, the grating structure is transferred into silicon by reactive ion etching (RIE). Rectangular gratings with 200nm--500nm feature size and 50% pitch were successfully fabricated. Borofloat, silica and alumina have been etched using chrome as a mask with vertical sidewalls. Grating structures of any pitch can be created in these materials using e-beam writing in resist and RIE. A 255nm copper vapor laser was used to ablate lines in borosilicate glass.
Pisharoty, Divya, "Investigation of fabrication process development for integrated optical grating structures" (2005). Graduate Theses, Dissertations, and Problem Reports. 1614.