Model-Based Raman Simulations for Optimized Metrology in Nanosheet Transistor Devices

Strain, composition, and doping in nanosheet transistors critically impact device performance, yet precise metrology at nanoscale dimensions remains challenging. In-line Raman spectroscopy can probe these parameters, but signal overlap from S/D regions, nanosheet channels, and gate materials as well as dopant effects complicate analysis in integrated devices. We present Model-Based Raman (MBR) simulations that compute local field distributions and scattering efficiency based on device geometry and Raman tensors. Combined with Optical Critical Dimension (OCD) measurements, MBR enables optimized setups that enhance sensitivity and isolate structural contributions. This approach improves characterization of SiGe epitaxial layers and supports accurate strain analysis in nanosheets. Experimental validation across several device geometries confirms the effectiveness of MBR-guided metrology.