Three-dimensional microfabrication for a multi-degree-of-freedom capacitive force sensor using fibre-chip coupling

The design and fabrication of a novel multi-degree-of-freedom force sensor is described. The three-dimensional structure of the sensor is a result of combining several microfabrication techniques: wet bulk micromachining, fus ion bonding, chemical mechanical polishing, deep RIE, LPCVD, PECVD and ther mally evaporated thin films. The sensor is designed to operate in the 0-500 muN force range and the 0-10 mu Nm torque range. The flexibility of the pr ocess to create overhanging structures with arbitrary lengths and heights i s illustrated by the integration of micro-tweezers directly onto the force sensor. Among other advantages of the developed process is a dicing-free se lf-release of wafer structures. This allows very fragile structures, such a s micromirrors and other optical components, to be individually packaged.