Binary pseudo random array standard for EUV lithography tool characterization

Extreme ultraviolet (EUV) imaging tools play a crucial role in EUV lithography. Achieving high accuracy in EUV metrology is essential for advanced semiconductor manufacturing, requiring thorough characterization of the instrumentation in use. Binary Pseudo Random Arrays (BPRA) are an established standard for calibrating and characterizing optical instruments in the frequency domain. This work expands the BPRA standard to applications in EUV imaging. To extend the technology to the EUV spectral range, a high-resolution BPRA target with a smallest feature size of 40nm is developed. The EUV BPRA target establishes an in-situ and portable calibration and alignment standard for EUV imaging. The target is patterned by means of electron-beam lithography, using a nickel absorber with a thickness of 39nm. The substrate is a 4” silicon wafer with a molybdenum/silicon multilayer coating. To demonstrate the efficacy of the target and develop the instrument calibration protocol, the target is imaged on the SHARP EUV mask microscope. Power Spectral Density (PSD) data is presented. The characteristics of the imaging system are imprinted on the PSD. The Modulation Transfer Function (MTF) is extracted from the PSD data. A partially coherent imaging model is used as a reference for the experimental results.