Universal concept for fabricating micron to millimeter sized 3-D parylene structures on rigid and flexible substrates

This paper describes a novel fabrication concept of using wax as a molding/sacrificial material and conformal parylene deposition to produce large and thin 3D parylene structures on a rigid or flexible substrate such as silicon, metal sheet, paper, fabric, etc. The idea is to form a wax mold for a desired shape, followed by conformal deposition of parylene film over the wax mold, and then to remove the wax in toluene at room temperature to release parylene structures of micron to millimeter size. With this technique, we have fabricated a large area membrane (6 mm in diameter, 2 μm thick) over a curved surface or on a flexible substrate such as a sheet of paper. Also, we have fabricated the following useful devices: (1) parylene bellow tubings on a silicon wafer with microfluidic channels so that the fluidic channels at different levels of the silicon wafer may be connected through the flexible bellow tubings without any leak, and (2) dome-shaped-diaphragm transducers (DSDT) built on a parylene support diaphragm with a piezoelectric film and electrode films.