학술논문
Reactive Ion-Beam-Sputtering of Fluoride Coatings for the UV/VUV Range
Document Type
stp-paper
Author
Source
Laser-Induced Damage in Optical Materials: 1990, Jan 1991, Vol. 1991, No. 1141, pp. 327-338.
Subject
Language
English
Abstract
Fluoride coatings produced by thermal evaporation suffer from high scatter losses, ageing and cracking due to high tensile stress. These problems impose severe limitations to the production of low loss multilayer coatings for the VUV range. A key position for improved performance is the microstructure of the layers.
The aim of our investigations is to improve the microstructure of AlF3- and LaF3-films by ion-beam-sputtering. Scatter measurements of single layers revealed lower values for IBS than for boat evaporation. Unfortunately, sputtered fluoride films have high absorption losses caused by decomposition of the coating material.
By sputtering in reactive atmospheres and annealing we were able to reduce the absorption losses significantly. Antireflective as well as high reflective coatings were produced. Reflection and transmission values were obtained with a VUV-spectrophotometer. Damage tests at the 193 nm ArF laser wavelength were performed at the Laser-Laboratorium Göttingen.
The aim of our investigations is to improve the microstructure of AlF3- and LaF3-films by ion-beam-sputtering. Scatter measurements of single layers revealed lower values for IBS than for boat evaporation. Unfortunately, sputtered fluoride films have high absorption losses caused by decomposition of the coating material.
By sputtering in reactive atmospheres and annealing we were able to reduce the absorption losses significantly. Antireflective as well as high reflective coatings were produced. Reflection and transmission values were obtained with a VUV-spectrophotometer. Damage tests at the 193 nm ArF laser wavelength were performed at the Laser-Laboratorium Göttingen.