Generalized formulations for aerial image based lens aberration metrology in lithographic tools with arbitrarily shaped illumination sources.
Generalized formulations for aerial image based lens aberration metrology in lithographic tools with arbitrarily shaped illumination sources.
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DOI：
10.1364/oe.18.020096
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发表时间：
2010-09
期刊：
影响因子：
3.8
通讯作者：
Wei Liu;Shiyuan Liu;T. Shi;Zirong Tang
中科院分区：
文献类型：
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作者：
Wei Liu;Shiyuan Liu;T. Shi;Zirong Tang
在目前用于半导体制造的光刻工艺中，由于需要严格的临界尺寸控制，不同形状的照明源已被广泛使用。本文提出了一种适用于任意形状照明光源的透镜像差的现场测量技术。利用一组Zernike阶数，这些像差灵敏度可以被视为一组解析核，这些解析核成功地构造了灵敏度函数空间。解析核函数考虑了波前像差与照明光源之间的相互作用，揭示了部分相干成像系统的物理本质，实现了待测Zernike系数与可测物理信号之间的线性解析关系。将具有空间可变强度分布的各种主流照明光源输入PROLITH进行模拟工作，这证明并确认了广义公式适用于测量不同类型光源分布下高达高阶Zernike系数的透镜像差。该技术是简单的实施，并将有潜在的应用在当前的光刻工具的成像质量的在线监测。
In the current optical lithography processes for semiconductor manufacturing, differently shaped illumination sources have been widely used for the need of stringent critical dimension control. This paper proposes a technique for in situ measurement of lens aberrations with generalized formulations of odd and even aberration sensitivities suitable for arbitrarily shaped illumination sources. With a set of Zernike orders, these aberration sensitivities can be treated as a set of analytical kernels which succeed in constructing a sensitivity function space. The analytical kernels reveal the physical essence of partially coherent imaging systems by taking into account the interaction between the wavefront aberration and the illumination source, and take the advantage of realizing a linear and analytical relationship between the Zernike coefficients to be measured and the measurable physical signals. A variety of mainstream illumination sources with spatially variable intensity distributions were input into the PROLITH for the simulation work, which demonstrates and confirms that the generalized formulations are suitable for measuring lens aberrations up to a high order Zernike coefficient under different types of source distributions. The technique is simple to implement and will have potential applications in the in-line monitoring of imaging quality of current lithographic tools.