Fabrication Process for Integrating Nanoparticles With Released Structures Using Photoresist Replacement of Sublimated p-Dichlorobenzene for Temporary Support

This letter introduces a fabrication technique that enables deposition of a wide variety of materials on released microelectromechanical systems devices by providing a temporary support layer of photoresist (PR). The technique is particularly useful for materials that cannot survive aggressive wet etchants or high-temperature processes. The novel step of the process involves continuous replacement of solid p-dichlorobenzene (p-DCB) by liquid PR as the p-DCB sublimates from a released structure, without ever allowing the structure to dry. The PR serves as both a temporary support for the device and a mold for targeted deposition of the material. As a demonstration of the process, fully released silicon microresonators were coupled with nanoparticles that would not survive common sacrificial oxide etch processes. The process is shown to produce nanoparticle-functionalized resonators that operate as functional resonant gas sensors.