Tailoring anchor shape during release of MEMS microbeams using microfluidic flow

Laminar flow assisted wet etching has been employed to control the sacrificial layer etch progression during the release of silicon nitride (SiN_x) microbeams, on a porous silicon (PS) sacrificial layer. A removable 3-inlet polydi-methylsiloxane (PDMS) microfluidic cassette allowed different fluids to be passed over the sample surface to generate a fluid mask. In contrast to solid masking, microfluidic devices can provide non-homogeneous etching conditions which can be controlled in real-time. In this work device input flow rates were altered during the etch, allowing specific surfaces to be exposed to etchant, resulting in beams with asymmetric anchor configurations.