Fabrication of glass suspended microchannel resonators

The goal of this project was to study if the fabrication of glass suspended microchannel resonators was possible. Through trial and error, the process parameters were determined, starting from the ideal dose in the dry etching process. The ideal size was determined by choosing a dose that guaranteed that all holes were properly opened, while keeping the critical dimensions (CD). This allowed us to keep holes small enough to be able to fill them later on in the process. The ideal was found to be 24 mJ/cm2. The next step of the project was to determine the right cleaning methods of the microchannels. After some unfruitful attempts, a cleaning process that worked was found. Its main steps are HF 1% during 3 minutes, followed by 1 minute in a KOH 9:1 IPA bath at room temperature. Finally, sputter deposition and LPCVD were tested to close the microchannels, with both presenting some advantages and disadvantages. During this final step, the stress buildup in the SiO2 film showed, creating cracks in the membrane. For this reason, this process flow is not viable to fabricate glass suspended microchannel resonators.