【摘要】 对用于ArF准分子激光器的CaF2衬底进行了表征实验研究。采用分光光度计测量了CaF2衬底的透射光谱和反射光谱,利用激光量热法测量了CaF2衬底吸收,分别利用原子力显微镜(AFM)和白光干涉仪(WLI)测量了CaF2衬底的表面粗糙度,并计算了功率谱密度(PSD)和表面散射,最后分别测量了CaF2衬底的荧光光谱、红外光谱和拉曼光谱。激光量热法测量5 mm厚准分子级CaF2衬底的吸收结果为922×10-6。AFM和WLI测得的CaF2衬底表面粗糙度均方根值分别为0.22和1.24 nm,计算表面散射损耗分别为0.005%和0.25%。荧光光谱在紫外(UV)级CaF2衬底中检测到Ce3+等杂质离子。红外光谱和拉曼光谱在CaF2衬底表面没有检测到水气和有机污染物。实验结果表明,激光量热法可以精确地测量和评价准分子级CaF2衬底的吸收,表面粗糙度的测量结果需要与散射的实测结果综合起来进行评价,荧光和红外等光谱技术是检测CaF2衬底内部痕量杂质及表面污染的有效手段。更多还原

【Abstract】 Experimental characterizations of the CaF2 substrates for applications of ArF excimer lasers are performed.The measured absorption for an excimer-grade CaF2 substrate with 5 mm thickness is equal to 922×10-6.The root-mean-square(RMS) surface ronghness measured by atomic force microscope(AFM) and white light interferometer(WLI) are 0.22 and 1.24 nm,respectively,and the corresponding calculated surface scattering losses are 0.005% and 0.25%,respectively.The emission of impurity of Ce3+ and Eu3+ ions in the ultraviolet(UV)-grade CaF2 substrates is detected and ascertained by fluorescence.No water molecular or other contamination on the surface of CaF2 is detected in Fourier transform infrared(FTIR) and Raman spectroscopy.The experimental results prove that laser calorimeters are suited to precisely measure the weak absorption of excimer-grade CaF2 substrates;the power spectral densities(PSDs) obtained by different measuring methods should be compared with each other and combined with the practical scattering losses to appropriately evaluate the surface roughness of CaF2 substrates;spectroscopy methods,such as fluorescence,FTIR and Raman spectroscopy,can effectively detect the trace impurities or defects in the CaF2 crystal and the contaminations on the surface of the polished CaF2 substrates.更多还原