Study On Chemical Mechanical Polishing Of Calcium Fluoride Single Crystal

With the development of 157nm laser lithography, calcium fluoride (CaF₂) has become a very important material for excimer laser components. The optical performance of CaF₂ at 157nm is strongly related to its surface quality. The demands on the surface are high precision in figure and smoother surface roughness, The CMP has being finished various single crystals and optical glasses ultra-finely without deformed layer. We will try to use this technology to get DUV/VUV lithography-grade surface on CaF₂ single crystals. The SiO₂ colloid alkali slurry is used to polish CaF₂ wafer. The influence of the polishing pressure,wheel speed and slurry flow rate on removal rate is discussed in this paper. The finished surface geometry will be also measured in the range of macro to atomic scale. The results indicate that there is close relation between the material removal rate and polishing parameters. The surface and the removal rate can be best by using our polishing parameters. the precise on of the size and the precise on of the surface and figure are ensured . In practice, the article can be of assistance to the practitioners involving in processing CaF₂ components.