Ultrahigh-accuracy measurement of the coefficient of thermal expansion for ultralow-expansion materials
Ultrahigh-accuracy measurement of the coefficient of thermal expansion for ultralow-expansion materials
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超低膨胀材料热膨胀系数的超高精度测量
DOI：
10.1117/12.472323
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
M. Linder
中科院分区：
文献类型：
--
作者：
V. Badami;M. Linder
微光刻系统依赖于精确的对准和高水平的尺寸稳定性来实现所需的性能。在关键应用中，通过在诸如反射光学器件和机器结构之类的部件中使用诸如ULE之类的低线性热膨胀系数（下文称为CTE并且由a）材料来实现对热致尺寸变化的免疫。ULE具有通常在0 + 30 ppb K-1范围内的CTE，并且其可以被工程化以实现特定值。热膨胀系数的高精度测定对于过程控制和为误差预算目的的这种系统的设计提供必要的输入都是必不可少的。目前，需要在273-373 K温度范围内以扩展不确定度U（a）（k=2）< 1 ppb K-1测定CTE。本文沿着介绍了热膨胀系数高精度绝对测量的最新进展，并讨论了每种技术的主要误差来源。计量技术，样品设计和仪器描述沿着与代表性的仪器的不确定性估计。介绍了满足上述要求的新型仪器的设计思想和前景。
Microlithographic systems rely on precision alignment and a high-level of dimensional stability to achieve required performance. In critical applications, immunity to thermally induced dimensional changes is achieved by the use of low linear coefficient of thermal expansion (hereafter referred to as CTE and denoted by a) materials such as ULE in components such as reflective optics and machine structures. ULE has a CTE that is typically in the 0 + 30 ppb K-1 range and it may be engineered to achieve a specific value. A high-accuracy determination of the CTE is essential for both process control and for providing an essential input to the design of such systems for error budgeting purposes. Currently, there is a need for CTE determination with an expanded uncertainty U(a)(k=2) < 1 ppb K-1 in the 273-373 K temperature range. A survey of the state-of-the-art of high-accuracy absolute measurement of CTE is presented along with a discussion of the significant error sources in each of the current techniques. The metrology techniques, sample design and instrumentation are described along with uncertainty estimates for representative instruments. The design philosophy and prospects for a new instrument that satisfies the above mentioned need are described.