A troublesome phenomenon usually encountered during this realization of free-standing microstructures, for example beams, diaphragms and accelerometers, is that released structures stick to the substrate. This effect occurs during wafer drying once the sacrificial etching process has been completed. Besides, the etching of the sacrificial layer is usually the last step of the fabrication of the devices, so some kind of protection of the CMOS circuits in the same chip is necessary. In this paper we propose to etch the sacrificial layer in the first processing steps, right after the deposition of the structural layer. The last processing step is then the dry patterning of the already released structural layer, so that neither does sticking take place nor is special protection of CMOS circuits necessary.
|Journal||Journal of Micromechanics and Microengineering|
|Publication status||Published - 1 Mar 1996|