US Patent 7468138 Flexural plate wave sensor

A method for manufacturing a flexural plate wave sensor, the method including the steps of depositing an etch-stop layer over a substrate, depositing a membrane layer over said etch stop layer, depositing a piezoelectric layer over said membrane layer, forming a comb pattern with drive teeth which span across an entire length of the piezoelectric layer on said piezoelectric layer, etching a cavity through the substrate, the cavity having substantially parallel interior walls, and removing a portion of the etch stop layer between the cavity and the membrane layer to expose a portion of the membrane layer.