Design and Fabrication of DRIE-Patterned Complex

This paper reports the design and fabrication of high-aspect-ratio needlelike silicon structures that can have com- plex geometry. The structures are hundreds of micrometers tall with submicrometer-sharp protrusions, and they are fabricated using a series of passivated and unpassivated deep reactive-ion etching (DRIE) steps. A simple model is presented to predict the geometry of the structure based on the etch mask and the etch se- quence. Model predictions are in good qualitative agreement with fabrication results, making it a useful design tool. The model is compared with literature reports on tapered DRIE. (2009-0118) Index Terms—Deep reactive-ion etching (DRIE), microneedle, 3-D microfabrication.