Fluoride antireflection coatings for deep ultraviolet optics deposited by ion-beam sputtering.
Optically high quality coatings of fluoride materials are required in deep ultraviolet (DUV) lithography. We have applied ion-beam sputtering (IBS) to obtain fluoride films with smooth surfaces. The extinction coefficients were of the order of 10(-4) at the wavelength of 193 nm due to the reduction of their absorption loss. The transmittance of the MgF2/GdF3 antireflection coating was as high as 99.7% at the wavelength of 193 nm. The surfaces of the IBS deposited films were so smooth that the surface roughness of the A1F3/GdF3 film was comparable with that of the CaF2 substrate. The MgF2/GdF3 coating fulfilled the temperature and humidity requirements of military specification. Thus, the IBS deposited fluoride films are promising candidate for use in the DUV lithography optics.
Yoshida
Toshiya
T
Central Research Laboratory, Japan Aviation Electronics, Ltd., 3-1-1 Musahino, Akishima-shi, Tokyo 196-8555. yoshidats@jae.co.jp
Nishimoto
Keiji
K
Sekine
Keiichi
K
Etoh
Kazuyuki
K