A non-destructive channel stress characterization for gate-all-around nanosheet transistors by confocal Raman methodology

Non-destructive stress characterization is essential for gate-all-around (GAA) nanosheet (NS) transistors technology, while it is a big challenge to be realized on nanometer-sized GAA devices by using traditional Micro-Raman spectroscopy due to its light spot far exceeding the device. In this work, a non-destructive stress characterization methodology of confocal Raman spectroscopy was proposed and performed for GAANS device fabrication. Channel stress evolution along the fabrication process was successfully characterized by designing high-density NS array and analyzing the linear scanned spectra in different structures. The related mechanism of stress evolution was systematically studied by Sentaurus process simulation. Additionally, applying this methodology on detecting the bending of suspended NS after channel release process was demonstrated. Therefore, this work might provide a promising solution to realize in-line characterization of channel stress in GAA NS transistors and process monitor of NS channel integrity.