P000033
CD-SEM Characterization of Smoothly Varying Wave Structures with a Monte Carlo Simulation
*Muhammad Saadat Shakoor Khan (Department of Physics and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China)
Deng Xiao (Institute of Precision Optics, Department of Physics, Science and Engineering, Tongji University, Shanghai, 200092, P.R. China)
Mao shifeng (Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei, Anhui 230026. P.R. China)
Zou Yanbo (School of Physics & Electronic Engineering, Xinjiang Normal University, Urumqi, Xinjiang 830054, P.R. China)
Li Yonggan (Key Laboratory of Materials Physics, Institute of Solid-State Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R. China)
Li Huimin (Super Computation Center, University of Science and Technology of China, Hefei, Anhui 230026, P.R China)
Ding Zejun (Department of Physics and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China)
Scanning electron microscopy (SEM) characterization of smoothly varying nanograting structure (Pt-coated Cr grid on Si substrate) in sinusoidal waveform has been carried out by a Monte Carlo (MC) simulation technique. Previous studies on critical dimension (CD) by CD-SEM have been mostly concerned about the line structures having sharp edges so that there is an obvious edge bloom in the linescan profile of secondary electrons. In contrast, the present grating structures prepared by a laser-focused atomic deposition technique have smoothly varying waveforms in cross-sectional profile, which presents a larger difficulty for quantitative structural characterization by SEM. The grating structure, having a fixed pitch of λ/2 as a period of the standing-wave laser light field, where λ is the wavelength of the corresponding laser light, can be used as an ideal nanoscale metrological length tool; therefore, it is important to characterize the structural features over a large deposited area by SEM imaging for quality control towards mass reproduction. The present work extends the CD characterization of the MC simulation methods to more complex structures. Taking into account different experimental factors, i.e., primary electron beam parameters, geometrical parameters, and material properties, the unknown geometrical parameters (i.e., base height, peak height, linewidth shrinkage, and peak tilt angle) of the grating lines have been successfully extracted from the experimental linescan profiles of SEM images.