EUV reflectometry and scatterometry for thin layer and periodic structure characterization

Abstract

Non-destructive nano-metrology is a fundamental tool for semiconductor device manufacturing. Practically, a combination of several metrology techniques is needed throughout the fabrication process of semiconductor chips, from EUV photomask inspection to patterned wafer metrology. EUV light not only facilitates the production of smaller features in lithography but also emerges as a powerful approach for the metrology required to characterize and analyze these intricate features in future technology nodes, thanks to its short wavelength, relevant penetration depth, and high reflectivity with relatively high grazing angles compared to that of X-rays. The reflective grazing incidence nanoscope for EUV (REGINE) at the Swiss Light Source is a prototype platform for reflectometry, scatterometry, and coherent diffraction imaging. It operates in the soft X-ray and EUV region (80 to 200 eV photon energy), and covers a grazing incidence angle range of 0 • to 28.6 • . REGINE provides the possibility to perform grazing incidence reflectometry and scatterometry for semiconductor metrology. In this study, we present the results of optical constants (n and k) determination and layer thickness characterization with reflectometry procedure for an EUV attenuated phase shifting mask blank, and the analysis of scatterometry results of line-space grating profile reconstruction and overlay measurement.