Potential of large diameter MgF 2 single crystal grown by Czochralski method

Abstract

Magnesium fluoride (MgF 2 ) single crystal is expected as the alternative of Quartz for polarizing materials in high power lithography system. MgF 2 is anisotropic crystal and its physical properties are different along each crystal axes. Therefore it is difficult to make large diameter single crystal by using Bridgman method which is mainly used for growth of fluoride crystals. We have been studying on making large diameter and high quality single crystal by using Czochralski (CZ) method [1,2]. Previously we reported the stable growth of it with 150mm diameter. This time we succeeded to grow the crystal with over 200mm diameter. Additionally, by improving the purification process and growth process, we succeeded to reduce 75 percent of the amount of color center induced by irradiation of ArF laser.