Refractive index modification of SU-8 polymer based waveguide via fabrication parameters

This paper presents refractive index modification of SU-8 polymer based waveguide via fabrication parameters. The current biosensor market needs easy manufacturing in large quantities, low cost, small in size, easy to be used and fast response time, thus, an appropriate optical waveguide material needed to be chosen. Hence, the optical properties of SU-8 must be well understood in order to design waveguide with single-mode and strong evanescent field to realize sensitive biosensor. It is known that process parameters such as spin speed, exposure dosage and curing temperature affect the polymerization which in turn affect the optical properties especially refractive index. Due to this reason, it is the aim of this paper to investigate the effects of spin speed, exposure dosage and curing temperature on the refractive index of SU-8. This project also aims to improve the process recipe of SU-8 for waveguide fabrication, which requires high resolution and steep sidewall with minimum defect.