SU-8 process for biomedical inspection μ-carriers

The present study provides a novel carrier fabrication method for biomedical application. The SU-8 thick photoresist fabrication process is used to produce the μ-carrier of 200 μm×200 μm with various thicknesses. These μ-carriers will be used for the purpose of biomedical inspection after proper surface modification by chemicals. To quantify and qualify the immersed μ-carriers in the inspected solution, specific marker is designed and fabricated on every μ-carrier as identification according to the application. Hence, a precise control on the marker feature dimension will be crucial for the application. In addition, the thick resist layer uniformity is very important in defining the marker pattern on the surface of carrier. Besides, the sidewall profile is also crucial especially for the fabrication of 10 μm through-hole markers on the carriers of 50 μm to 100 μm thick. The orthogonal array experimental design method is employed to optimize the process parameters, including the soft bake, exposure, postexposure bake, and development parameters. Moreover, the effect of development with ultrasonic agitation is also investigated.