Suspended Silicon Nitride Platforms for Thermal Sensing Applications in the Limit of Minimized Membrane Thickness

Silicon nitride has long been employed in the microfabrication of thermal sensors due to its favorable material properties and the ease with which it facilitates surface micromachining. While a variety of studies have utilized thin silicon nitride membranes for high sensitivity thermal measurements, limited reports exist on the physical characteristics of membranes and platforms in a thickness limit much less than 100 nm. Herein, we report on the development of low-stress, suspended silicon nitride platform devices that enable thermal characterization of membranes ranging from 120 nm to less than 10 nm in thickness, providing thermal conductivities as low as 1.1 W m-1 K-1 near room temperature. Applications of these platforms may enable appreciable enhancement in the performance of devices reliant upon environmental thermal isolation including bolometers, calorimeters, and gas sensors, among others. [2024-0003].