Directed fabrication of ceramic nanostructures on fragile substrates using soft-electron beam lithography (soft-eBL)

We demonstrate the use of a facile nanopatterning scheme known as soft electron beam lithography (soft-eBL) to fabricate and site specifically position a variety of functional ceramic nanostructures onto two fragile substrates: a 75-nm-thick electron-transparent silicon nitride membrane and suspended microhotplates with embedded heaters. The patterned nanostructures on nitride membranes can be readily probed with a variety of characterization tools without any postfabrication sample preparation, allowing observation of the nanostructures in near-pristine condition. We demonstrate this by characterizing the structural, chemical, and optical properties of several ceramic nanostructures patterned on membranes using electron microscopy and surface scanning probe tools such as atomic force microscopy and near-field scanning optical microscopy. We further demonstrate that such nanostructures, upon integration with microelectromechanical systems (MEMS) microhotplate platforms, can function as gas-sensing elements; we evaluate their sensing performance at micromoles per mole target analyte concentration levels.