EUV grazing-incidence lensless imaging wafer metrology

Abstract

Non-destructive metrology for photomasks and wafers has always been an important requirement for semiconductor lithography, and with the advent of EUVL, enabling further shrinkage of semiconductor devices, the challenges in this field have increased significantly. Coherent diffraction imaging (CDI) is a promising alternative to standard imaging for EUV photomask actinic inspection. EUV light can also be used for wafer inspection to benefit from the resolution improvement allowed by its short wavelength. In order to perform lensless imaging for patterned wafers, however, we need to probe the sample surface at grazing incidence to ensure a sufficiently high reflectance. The EUV reflective grazing incidence nanoscope (REGINE) at the Swiss Light Source was develped to perform grazing incidence lensless imaging for patterned wafers. REGINE is a tool that combines CDI, scatterometry and reflectometry in the photon energy range between 80 to 200 eV, and at the grazing incidence angle of 1 to 28 degrees. In this work, we will present the latest characterization of our system, and preliminary results.

EUV reflectometry and scatterometry for thin layer and periodic structure characterization

“…REGINE is a synchrotron-based instrument that is developed for thin film and grating characterization, along with coherent diffraction imaging (CDI) of patterned wafers. 9,10 Housed within a high vacuum chamber operating at the pressure of 10 −7 mbar, REGINE offers a comprehensive platform for advanced metrology tasks. Figure 1 provides an overview of the entire REGINE system.…”