ABSTRACT
In-line Raman spectroscopy is an increasingly important metrology technique for nanosheet gate-all-around devices because it provides direct access to intrinsic material properties such as strain and SiGe composition through phonon mode
analysis. While Raman peak positions primarily reflect these intrinsic properties, peak amplitudes are jointly governed by material properties and the three-dimensional (3D) device geometry. This amplitude-geometry relationship becomes critical in fully integrated 3D device structures, where multiple materials, deep canyons, and strong near-field localization can drive measurement sensitivity and signal crosstalk. Here, we demonstrate the value of model-based Raman (MBR) simulations to (i) attribute measured Raman contributions to specific regions of complex 3D structures, (ii) optimize
wavelength and polarization configurations for targeted sensitivity (e.g., nanosheet channel versus substrate/fin), and (iii) mitigate interference between signals from different materials in the structure. Proof-of-concept results on Si1-xGex line/space gratings and TiN-containing stacks, as well as case studies on integrated targets after high‑k deposition and after pFET source/drain epitaxy, illustrate how MBR-guided configuration selection enhances sensitivity and supports robust in-line monitoring of strain and composition in nanosheet transistor technology.
Keywords: Raman spectroscopy, model-based simulation, nanosheet transistor, gate-all-around, strain metrology, inline
metrology
*Corresponding author: [email protected]