Thermal Characterization of Ultra-Thin Suspended Silicon Nitride Platforms

Silicon nitride is widely used in the microfabrication of thermal sensors due to its favorable material properties. While numerous studies have leveraged thin silicon nitride membranes for highly sensitive thermal measurements, there have been limited reports concerning membranes and platforms with thicknesses well below 100 nm. Herein, we report on the development of low-stress, suspended platform devices designed to facilitate the thermal characterization of membranes spanning a thickness range from 120 nm down to less than 10 nm. Depending upon the membrane thickness, we observe a substantial reduction in the thermal conductivity from 2.4 W m⁻¹ K⁻¹ to 1.2 W m⁻¹ K⁻¹ near room temperature. These platforms in this low thickness regime can significantly enhance the performance of devices requiring thermal isolation, such as bolometers, calorimeters, and gas sensors.<br/><br/>*This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE, Office of Basic Energy Sciences, user facility. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.