A RIE process for submicron, silicon electromechanical structures

A reactive ion etching (RIE) process is used for the fabrication of submicron, movable single-crystal silicon (SCS) mechanical structures and capacitor actuators. The process is called SCREAM for single crystal reactive etching and metallization process. The RIE process gives excellent control of lateral dimensions (0.2 mu m approximately 2 mu m) while maintaining a large vertical depth (1 mu m approximately 4 mu m) for the formation of high aspect ratio, freely suspended SCS structures. The silicon etch processes are independent of crystal orientation and produce controllable vertical profiles. The process also incorporates process steps to form vertical, 4 mu m deep, aluminum, capacitor actuators. Using SCREAM, the authors have designed, fabricated and tested two-dimensional x-y microstages and circular SCS structures. For the x-y stage they measured a maximum displacement of +or-6 mu m in x and y with 40 V DC applied to either x or y, or both x and y actuators. The process technology offers the capability to use a structural stiffness as low as 10-2 N m-1.