Application of PECVD SiC in glass micromachining

In this paper, we present an application of SiC for Pyrex glass micromachining in the MEMS fabrication process. SiC has very high etch resistance in most acid and alkaline solutions due to its chemical inertness. The PECVD (plasma-enhanced chemical vapor deposition) process allows deposition of SiC at a low temperature (200–400 ◦ C), which makes SiC have better compatibility with IC fabrication. The PECVD SiC film was characterized and the process was optimized accordingly. An annealing process was developed to reduce the residual stress and modify the interface adhesion, and therefore the mask defects as well as the undercut of glass were reduced. In our experiment, an etch angle of 41 ◦ was achieved with an annealed SiC mask. Finally, microchannels on the glass substrate utilizing PECVD SiC mask were demonstrated, and SiC microstructures, such as membranes and clamed-clamed beams, were successfully fabricated by this micromachining technology.