ABSTRACT
This chapter presents three micron-scale additive manufacturing techniques based on specialized microelectromechanical systems fabrication processes: bulk micromachining, surface micromachining, and micromolding. Bulk micromachining deals with subtractive processes in which the substrate itself is selectively etched through a variety of processes into the desired structure. Surface micromachining includes processes where thin films are deposited, patterned, and etched on top of a substrate to produce planar structures with features on the micron scale. Surface micromachined structures have limited aspect ratios due to the relatively thin layers that are used during fabrication. In microforming, however, devices are built on top of the substrate like surface micromachining but with much larger aspect ratios. In silicon-on-insulator micromaching, photolithography is used to pattern the device layer followed by silicon etching to form the devices. Multilevel micromaching is a hybrid microfabrication process where subsequent material layers are patterned and deposited in a similar fashion to surface micromachining or microforming.
