New article: A new method for high resolution curvature measurement applied to stress monitoring in thin films

09 février 2022
By combining the well-known grid reflection method with a digital image correlation algorithm and a geometrical optics model, a new method is proposed for measuring the change of curvature of a smooth reflecting substrate, a common reporter of stress state of deposited layers. This tool, called Pattern Reflection for Mapping of Curvature (PReMC), can be easily implemented for the analysis of the residual stress during deposition processes and is sufficiently accurate to follow the compressive-tensile-compressive stress transition during the sputtering growth of a Ag film on a Si substrate. Unprecedented resolution below 10−5 m−1 can be reached when measuring a homogeneous curvature. A comparison with the conventional laser-based tool is also provided in terms of dynamical range and resolution. In addition, the method is capable of mapping local variations in the case of a non-uniform curvature as illustrated by the case of a Mo film of non-uniform film thickness under high compressive stress. PReMC offers interesting perspectives for in situ accurate stress monitoring in the field of thin film growth.

Sergey Grachev 1, Quentin Hérault 1, Jun Wang 1, Matteo Balestrieri 1, Hervé Montigaud 1, Rémi Lazzari 2 and Iryna Gozhyk 1
A new method for high resolution curvature measurement applied to stress monitoring in thin films, 2022 Nanotechnology 33 185701
https://iopscience.iop.org/article/10.1088/1361-6528/ac4a2a

1 Surface du Verre et Interfaces, UMR 125 CNRS/Saint-Gobain Recherche, 39 quai Lucien Lefranc, 93303 Aubervilliers, France
2 CNRS UMR 7588, Sorbonne Université, Institut des NanoSciences de Paris, 4 place Jussieu, 75005 Paris, France

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