Backexposure Effect in Chemically Amplified Resist Process upon Exposure to Extreme Ultraviolet Radiation

With the progress in the resist development toward the realization of 22nm high volume production using extreme ultraviolet (EUV) lithography, practical issues such as defects, filtering, and etching durability have recently attracted much attention. The side wall profile of resist patterns is among such issues. Although EUV radiation is hardly reflected at the resist-underlayer boundary, secondary electrons generated in the underlayer sensitize acid generators in the resist. In this study, the backexposure effect on the side wall profile of line-and-space patterns was theoretically investigated. The potential difference between the resist and the underlayer and the absorption coefficient of the underlayer significantly affected the sidewall profile. The image quality at the bottom of the resist layer was also improved by increasing the absorption coefficient of the underlayer. (C) 2011 The Japan Society of Applied Physics