Controlled gradual and local thinning of free-standing nanometer thick Si3N4 films using reactive ion etch

Nanometer-scale devices are fabricated using numerous fabrication techniques since the last couple of decades. However, the advancement in nanotechnology gives new horizons to the researcher to develop nanometer-scale devices in a controlled manner while also providing high accuracy and precision with cost and time-effectiveness. This article focuses on the production of free-standing nano-scale thick Si3N4 films using Reactive Ion Etch technique. Although there are many reports in the literature on the required conditions to etch Si3N4, unfortunately, there are not many technical reports that illustrate the step-by-step fabrication and characterization together with the detailed optimization steps. Here in this study, the thinning of a membrane is achieved using CF4/Ar in controlled RF power conditions and a well-defined protocol is given with several preliminary optimization steps. By doing so, free-standing locally thinned Si3N4 membranes of about 20 nm thickness are successfully realized in a precise manner. Further assessments are given an offer to the readers of interest the ways to characterize the samples with the required cautions. The detailed procedure given here would potentially provide practical aspects for the researchers working in the field of nanofabrication.