Yoshida Toshiya, Nishimoto Keiji, Sekine Keiichi, Etoh Kazuyuki
Central Research Laboratory, Japan Aviation Electronics, Ltd., 3-1-1 Musahino, Akishima-shi, Tokyo 196-8555.
Appl Opt. 2006 Mar 1;45(7):1375-9. doi: 10.1364/ao.45.001375.
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.
深紫外（DUV）光刻需要光学质量高的氟化物材料涂层。我们已应用离子束溅射（IBS）来获得表面光滑的氟化物薄膜。由于吸收损耗的降低，在193nm波长处的消光系数约为10^(-4)。MgF2/GdF3抗反射涂层在193nm波长处的透过率高达99.7%。IBS沉积薄膜的表面非常光滑，以至于AlF3/GdF3薄膜的表面粗糙度与CaF2衬底相当。MgF2/GdF3涂层满足了军事规范的温度和湿度要求。因此，IBS沉积的氟化物薄膜有望用于DUV光刻光学器件。
