Fabrication of 3-D Silicon Microneedles Using a Single-Step DRIE Process
Fabrication of 3-D microstructures is one of the most challenging aspects of silicon micromachining. In this paper, we present a novel microfabrication method using one single-step deep reactive ion etching process with gray-scale e-beam lithography mask that offers deeply etched (>350-µm deep) dual-angle 3-D microneedles with control over the height and shape of the structures. Moreover, we found that the shape of the e-beam lithography patterns can determine the general configuration and features of the final etched microneedles, and that the etching process parameters have the most impact on the microneedles' shape, such as size and vertical base angle. Large arrays of 20 x 20 microneedles with height uniformity of better than 3% are fabricated.
© 2015 IEEE. Manuscript received July 14, 2014; revised January 30, 2015; accepted February 11, 2015. Date of publication March 5, 2015; date of current version September 29, 2015. This work was supported in part by the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA, under a contract with the National Aeronautics and Space Administration under Grant 105571, and in part by the U.S. Government Sponsorship. Subject Editor R. Maboudian. The authors would also like to thank Dr. Frank Greer for insightful discussions before publication.