| 摘要 |
<P>PROBLEM TO BE SOLVED: To evaluate, with a simpler operation and high accuracy, a zinc impurity concentration in a calcium fluoride singe crystal to be used for a lens, a prism, a window material or the like which is used for an optical system in a lithography device for semiconductor and to be used by transmitting a vacuum ultraviolet light. <P>SOLUTION: A transmission spectrum of calcium fluoride singe crystal is measured, an absorption wavelength that is a reference transmittance for evaluating a zinc impurity concentration in the transmission spectrum is determined from within an absorption wavelength range of 120 to 200 nm in the transmission spectrum, and the zinc impurity concentration in the calcium fluoride singe crystal is determined using a change in the absorption wavelength. This method enables the zinc impurity concentration to be evaluated in a non-destructive manner in a shorter period of time with a simpler operation, as compared with a precision chemical analysis such as ICP-MS (Inductively Coupled Plasma-Mass Spectroscopy) requiring an advanced analysis technology. <P>COPYRIGHT: (C)2012,JPO&INPIT |
