Bi-Stable Lithography

Through previous research by Dr. Chen, he and his team have developed a process to create bi-stable structures that conform to a specified substrate and are self-supporting. This project was to further his efforts to produce bi-stable microstructures. The overarching idea is to develop a microfabrication process using photolithography. Due to advice from the UH Nanofabrication lab Faculty, Dr. Chang, the project scope shifted from producing 3D bi-stable microstructures to finalizing a process of photolithography where the film can be peeled off the silicon wafer without using buffed oxide etching (BOE). BOE is a typical process to lift a sample off a silicon wafer, but the HF chemical involved is hazardous and requires a lengthy training process. The new focus became testing a new quicker and less dangerous process where two polyimide films are set on top of each other and, after being patterned with bi-stable geometry, the top polyamide film is peeled off. The main concern was the thickness of the top film and having a thick enough photoresist to etch through the top film. The final sample was partially removed successfully, but more than half the film was damaged and thorned during the peeling process. While this process is functional, it is unreliable and the results were irreplicable due to varying thickness and etch rates despite following the same processes. This is likely due to human or machine errors. Overall more work will need to be done in order to reliable produce bi-stable microstructures without BOE.