抄録
During extreme ultraviolet lithography, the surfaces of the imaging optics and mask become contaminated with organic compounds. As more and more contaminants are deposited on a Mo/Si multilayer, the reflectivity and exposure intensity become lower, and the resolution of the imaging optics is degraded. A novel in-situ method of removing contaminants without heating has been developed. In an O2 atmosphere at a pressure of 5.0 × 10-2 Pa and at an electron beam current of the synchrotron storage ring of 150 mA, it removes a 0.1-μm-thick layer of contamination in 7 hours. The removal of the contamination restores the reflectivity of a Mo/Si multilayer without causing any surface damage.
