Characterization of line edge roughness and line width roughness of nano-scale typical structures

Two kinds of nano-scale typical structures were fabricated for characterizing line edge roughness (LER) and line width roughness (LWR). With Cr and Si₃N₄ thin films alternately deposited on a silicon substrate and electronic beam lithography employed on a positive resist ZEP520 layer, a nano-scale multiple linewidth standard and a nano-scale grating structure were processed respectively. In regard to the nano-scale multiple linewidth standards, an offline image analysis algorithm of scanning electron microscopy (SEM) image and a random error analysis method were employed to characterize its LER and LWR, including standard deviations 3 sigma_LER and 3 sigma_LWR. With respect to the nano-scale grating structure, sampling and evaluation length, amplitude standard deviation, skewness, kurtosis, auto-correlation function as well as power spectral density function of the nano-scale grating structure were analyzed based on stochastic process analysis to show LER characteristics. Similarly Motif parameters-based analysis also was introduced to get LER characteristics of the nano-scale grating structure.