Silicon microfilter device fabrication and characterization for diverse microfluidics applications

In this paper we report on a silicon fabrication process used for the development of microfilters as components of microfluidics systems. Silicon micro-fabrication allows very accurate control of size and uniformity of micropillar filter structures. We report on the process flow for the development of complete microfluidics sytem. The paper describes an oxide capping technique that allows bridging the interpillar space with a PECVD oxide layer, resulting in a planar surface. This helps to overcome challenges in lithography with high topography and in protecting micro-pillars during subsequent processing. The subsequent processing includes etching of supply channels, anodic bonding the Si wafer to Pyrex and backside processing to connect to the supply channels. The system was then used to characterize the quality of the Si micropillar filter by separating two component coumarin dyes.