Release-control structures for cantilever-based sensors
|Title||Release-control structures for cantilever-based sensors|
|Publication Type||Journal Article|
|Year of Publication||1998|
|Authors||Nikpour, B., Naseh S., Landsberger L. M., Kahrizi M., Paranjape M., Antaki R., and Currie J. F.|
|Journal||Sensors and Materials|
This paper concerns a cost-effective method of obtaining intact, released poly-in-oxide cantilever beams using bulk micromachining, within the constraints of simple postprocessing of a standard CMOS fabrication sequence. An extension to the basic cantilever is used to prevent the main oxide/poly beam from bending upwards until the main cantilever is completely released from the underlying Si. This prevents a likely device failure mechanism. The cantilever and extension are designed based on etch anisotropy. The connection tethers joining the main cantilever with the extension can be set at an angle with respect to the underlying crystal structure such that the underetch rate of the etchant is high. The devices are fabricated using a standard commercially available CMOS process, and the beam-extension combination is released by postprocess anisotropic etching of silicon using TMAH. The devices are tested by applying known forces to the beam tips and determining the response of the piezoresistive poly element.