Measuring and tailoring CTE within ULE glass
Measuring and tailoring CTE within ULE glass
复制标题
测量和定制 ULE 玻璃内的 CTE
DOI：
10.1117/12.484925
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
W. D. Navan
中科院分区：
文献类型：
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作者：
K. Hrdina;Bradford G. Ackerman;Andrew W. Fanning;Christine E Heckle;David C. Jenne;W. D. Navan
康宁公司正在改进材料和计量，以满足EUVL光学和光掩模衬底应用的要求。EUV光学要求对透镜设计者提出了独特的挑战。根据元件的几何形状和每个元件位置处的光束强度，系统中每个光学元件的温度可以经历不同的热分布。这就要求光学材料的热膨胀系数(CTE)均匀度变化小，并能够达到目标最佳的零CTE交叉温度。本文介绍了康宁公司以特定的CTE值为目标的能力，并讨论了一种新的测量玻璃内CTE变化的计量工具。过去的数据表明，材料内的折射率变化与CTE变化有关。这种相关性被用这里给出的结果进行了研究。这项初步工作提出了一种新的计量工具，能够在微米范围内对厚或薄样品进行非破坏性测量，在可能的空间频率下测量峰谷(P-V)CTE变化，精确到每度开尔文(ppt/K)70ppt/K。这项技术对于认证光掩模至关重要，并将成为将光掩模和光学器件的CTE变化降低到低于1 ppb/K的目标值以满足未来EUVL需求所需的基础。
Corning Incorporated is improving material and metrology in order to meet the requirements for both EUVL optics and photomask substrate applications. The EUV optics requirements present a unique challenge to the lens designer. The temperature of each optic in the system can experience a different thermal profile based upon the geometry of the element and the intensity of the beam at each element location. This places a need on the optical material for small variation in the coefficient of thermal expansion (CTE) uniformity and the ability to achieve targeted optimum zero CTE cross-over temperatures. This paper addresses Corning’s ability to target specified CTE values as well as discusses a new metrology tool for measuring CTE variations within the glass. Past data suggested that index variation within the material were related to CTE variations. This correlation was investigated with the results presented here. This preliminary work suggests a new metrology tool with the capability of non-destructively measuring peak to valley (P-V) CTE variations to within 70 parts per trillion per degree Kelvin (ppt/K) at possible spatial frequencies in the micron range on thick or thin samples. This technique is vital for certifying photomasks and will be the foundation needed to reduce CTE variations in photomasks and optics to targeted values of less than 1 ppb/K for future EUVL needs.