Fabrication of optical structures using SU-8 photoresist and chemically assisted ion beam etching

Lin Pang Wataru Nakagawa Yeshaiahu Fainman University of California, San Diego Department of Electrical and Computer Engineering 9500 Gilman Drive La Jolla, California 92093-0407 E-mail: [email protected] Abstract. We develop a method for the fabrication of optical structures in GaAs substrates using UV holographic lithography in SU-8 resist, processed to fabricate a mask, followed by chemically assisted ion-beam etching (CAIBE). The technique is based on simple processing steps without procedures of mask transfer, enabling easy fabrication of optical structures. A predevelopment relief behavior is investigated to optimize the processing parameter to form an etching mask in SU-8. By adjusting both exposure dose and time in the postexposure bake (PEB), an SU-8 mask with a flexible duty cycle and high profile quality can be easily produced. Furthermore, an optical structure with a rectangular shaped profile and a 1-mm period in a GaAs substrate is produced by optimizing the processing parameters during the CAIBE process. © 2003 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.1604399]