The Al <sub> 2 </ Sub> O <sub> 3 </ Sub> And Laf <sub> 3 </ Sub> Thin Films In The Characteristics Of The 193nm Band

In recent years, rapid development of excimer lasers has promoted the study of thin film in DUV/VUV. Currently, the research of 193nm UV film has focused on some fluoride and a handful of oxides. Fluoride and oxides present great difference in short-wave absorption, microstructure, crystalline state, optical stability, stress etc. The single layer of major high refractive index materials fluoride LaF₃ and oxides Al₂O₃ were fabricated and studied in the dissertation. The effects of deposition rate and substrate temperature on the optical properties and microstructure of the film was discussed. In order to calculate the reflectivity of mirror, The multilayer dielectric film was designed and the optical properties was discussed.The absorption of LaF₃ single layer is less than the Al₂O₃ single layer in 193nm.The extinction coefficient of LaF₃ is approximately 8.1 × 10^-4 in 205nm,compared with 2.5 × 10^-3 of Al₂O₃. Al₂O₃ presents excellent optical stability, the transmission rate tested six months later accords with the data tested after deposition. The transmission rate of LaF₃ declines two days later and wavelength drift is discovered.When the deposition rate is 0.2nm/s, the Al₂O₃ film shows the best optical properties. With the increase of the deposition rate , the transmission rate of the single layer drops. Optical loss studies shows that absorption caused by loss of oxygen is the major reason. In order to obtain excellent optical properties, it is necessary to make sure that the deposition rate is 0.5nm/s below. Tests show the deposition rate has little effect on LaF₃, even in the condition of deposition rate of 5nm/s, the optical properties of LaF₃ films is perfect.Under the same deposition condition, the surface roughness of Al₂O₃ single layer is large. According to the scalar scattering theory, the TIS of Al₂O₃ is more than that of LaF₃. With the raise of substrate temperature, the surface roughness of LaF₃ single layer increased.The single layer of Al₂O₃ and SiO₂ obtained by electron beam evaporation areamorphous, LaF₃ film contains amorphous structure, but in some areas crystal is found.The theoretical calculations show that the reflection rate of LaF₃/MgF₂ mirror is 99% in 193nm.