Novikova Tatiana, De Martino Antonello, Ben Hatit Sami, Drévillon Bernard
Laboratoire de Physique des Interfaces et des Couches Minces, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7647, Ecole Polytechnique, Palaiseau, France.
Appl Opt. 2006 Jun 1;45(16):3688-97. doi: 10.1364/ao.45.003688.
Fast and efficient metrology tools are required in microelectronics for control of ever-decreasing feature sizes. Optical techniques such as spectroscopic ellipsometry (SE) and normal incidence reflectometry are widely used for this task. In this work we investigate the potential of spectral Mueller polarimetry in conical diffraction for the characterization of 1D gratings, with particular emphasis on small critical dimensions (CDs). Mueller matrix spectra were taken in the visible (450-700 nm) wavelength range on a photoresist grating on a Si substrate with 70/240 nm CD/period nominal values, set at nine different azimuthal angles. These spectra were fitted with a rigorous coupled-wave analysis (RCWA) algorithm by using different models for the grating profile (rectangular and trapezoidal, with or without rounded corners). A detailed study of the stability and consistency of the optimal CD values, together with the variation of the merit function (the mean square deviation D2) around these values, clearly showed that for a given wavelength range, this technique can decouple some critical parameters (e.g., top and bottom CDs, left and right sidewall projections) much more efficiently than the usual SE.
微电子领域需要快速高效的计量工具来控制不断缩小的特征尺寸。诸如光谱椭偏仪（SE）和正入射反射仪等光学技术被广泛用于这项任务。在这项工作中，我们研究了锥形衍射中的光谱穆勒偏振测量法用于一维光栅表征的潜力，特别关注小临界尺寸（CD）。在具有70/240 nm标称CD/周期值的硅衬底上的光刻胶光栅上，在可见光（450 - 700 nm）波长范围内，以九个不同的方位角获取了穆勒矩阵光谱。通过使用不同的光栅轮廓模型（矩形和梯形，有或没有圆角），用严格耦合波分析（RCWA）算法对这些光谱进行了拟合。对最佳CD值的稳定性和一致性以及这些值周围的品质因数（均方差D2）变化的详细研究清楚地表明，对于给定的波长范围，该技术能够比通常的SE更有效地解耦一些关键参数（例如，顶部和底部CD、左侧和右侧壁投影）。
