High-yield wafer chuck for single-sided wet etching of MEMS structures

We describe a new O-ring setup for wet etching processes. The low-cost approach using siloxane-based sealing rings has been successful for the single-sided etching of silicon and silicon dioxide using a reduced volume of KOH and BHF, respectively. With this approach, the previously fabricated device elements on the reverse wafer side are not damaged. The etchant was heated by an infrared lamp. The achieved etch control allowed the fabrication of membranes only 5 μm thick with good accuracy using an etch stop layer