Bulk Si Micromachining for Integrated Microsystems and MEMS Processing

Abstract

The ability to etch deep, high-aspect ratio, anisotropic, Si features has opened up new areas of application for microelectromechanical systems (MEMS) devices, as well as revolutionized the conception and implementation of “mixed technology” integration and packaging. For MEMS devices, deep, high-aspect ratio Si etching enables increases in capacitance, “Z” dimension stiffness, mass, and actuation force for a wide range of components such as accelerometers, gyros, and electrostatic drives. Thus, device functionality and sensitivity can be improved. For example, current surface micromachined devices can be used as sensors for airbag applications; however, with the improved performance and sensitivity offered by deep silicon trench etching these designs may become useful for micro-navigation applications. Perhaps even more importantly, this new capability may enable the utilization of MEMS-type processing to the development of entirely new markets and applications. In addition to its use as a process module in MEMS processing, deep Si trench etching also has notable applications to packaging and systems integration. The development of integrated microsystems and advanced packaging capabilities in an integrated circuit (IC) batch manufacturing technology will lower cost, reduce size and weight, and improve performance and reliability [1]. A complete integrated microsystem could include sensors, actuators, electronics, fluidics, and optics in a variety of material systems on a single chip or in a single package. For example, deep anisotropic features could be etched into a Si wafer to accurately locate discrete components while maintaining system planarity. In this chapter we will discuss potential applications of this emerging technology.