title: Optical performance of extreme ultraviolet lithography mask with an indium tin oxide absorber.
abstract: In this study, we propose a new extreme ultraviolet (EUV) binary mask with an indium tin oxide (ITO) absorber. The optical constant of ITO film at 13.5 nm wavelength in the EUV regime was determined by means of X-ray reflectivity measurements and the chemical composition was determined using Rutherford backscattering spectrometry. The reflectance of a binary mask with an ITO absorber layer at various thicknesses was also measured to investigate the optical performance in the EUV regime. It was found that the extinction coefficient of ITO film is higher than that of a typical absorber layer, TaN, and that the reflectance of the ITO absorber in the binary mask at a wavelength of 13.5 nm is reduced to 0.62% at a thickness of 45 nm. Therefore, it is expected that the ITO film can be employed as a thin absorber of a binary mask to reduce the geometrical shadow effect in extreme ultraviolet lithography.
authors: Department of Physics, Inha University, Incheon 402-751, Korea.
authors: Hee Young
authors: HY
authors: Kang
authors: Sungjin
authors: S
authors: Park
authors: Chang Kwon
authors: CK
authors: Hwangbo
authors: Hwan-Seok
authors: HS
authors: Seo
authors: Seong-Su
authors: SS
authors: Kim
authors: Han-Ku
authors: HK
authors: Cho