Aerial image characteristics of a modified absorber model for extreme ultraviolet lithography (EUVL)

Abstract

The aerial image characteristics of the modified absorber model with various sidewall angles were quantitatively investigated by calculating the near field intensity on a mask and the aerial image intensity on a wafer. For the calculation of the near field intensity and the aerial image intensity of a 25-nm isolated patterned mask, SOLID-EUV, which is capable of a rigorous electromagnetic-field computation, was employed. The aerial image intensity of a patterned mask with positive and negative sidewall angles was calculated and compared with the value of the vertical sidewall model for various sidewall angle and illumination angle variations. Through the investigation of the aerial image characteristics of various absorber models, the absorber model with a positive sidewall angle can be suggested as the optimal absorber design to minimize the shadowing effect.