The yield of a large-area ultra-thin display panel depends on the realization of designed thickness of multilayer films of all pixels. Measuring the thicknesses of multilayer films of a single pixel is crucial to the accurate manufacture. However, the thinnest layer is reaching the sub-20nm level, and different layers feature remarkable divergence in thickness with similar optical constants. This turns to a key obstruction to the thickness characterization by optical spectroscopy. Based on the tiny differences in absorptivity, a fast method for measuring the film thickness in a single pixel is proposed which combines the layer number reducing model and micro-area differential reflectance spectroscopy. The lower layers can be considered as semi-infinite in the corresponding spectral range whose thickness is infinite in the fitting algorithm. Hence, the thickness of the upper layer is fitted in a simplified layer structure. For demonstration, a multilayer silicon microstructure in a single pixel, p-Si/a-Si/n-Si (10nm/950nm/50nm) on complex substrate, is measured. The light spot diameter is about 60 microns with measuring-time in 2 seconds. The measurement deviation is 3% compared by a commercial ellipsometer. To conclude, the proposed method realizes the layer number reduction for fitting multilayer thickness with large thickness difference and similar optical constants, which provides a powerful approach for multilayer microstructure characterizations.

中文翻译：

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使用差分反射光谱法测量多层硅基微结构

大面积超薄显示面板的产量取决于所有像素的多层膜设计厚度的实现。测量单个像素的多层膜的厚度对于精确制造至关重要。但是，最薄的层达到了20nm以下的水平，并且不同的层在厚度上具有明显的差异，并且具有相似的光学常数。这变成了通过光谱学对厚度表征的主要障碍。基于吸收率的微小差异，提出了一种结合层数减少模型和微区差分反射光谱法的快速测量单个像素膜厚的方法。在拟合算法中，下层可以被视为在对应的光谱范围内其厚度是无限的半无限。因此，上层的厚度适合简化的层结构。为了说明，测量了在复杂基板上的单个像素p-Si / a-Si / n-Si（10nm / 950nm / 50nm）中的多层硅微结构。光斑直径约为60微米，测量时间为2秒。与商用椭偏仪相比，测量偏差为3％。综上所述，该方法实现了以较大的厚度差和相似的光学常数来拟合多层厚度的层数减少，为多层微结构表征提供了有力的方法。光斑直径约为60微米，测量时间为2秒。与商用椭偏仪相比，测量偏差为3％。综上所述，该方法实现了以较大的厚度差和相似的光学常数来拟合多层厚度的层数减少，为多层微结构表征提供了有力的方法。光斑直径约为60微米，测量时间为2秒。与商用椭偏仪相比，测量偏差为3％。综上所述，该方法实现了以较大的厚度差和相似的光学常数来拟合多层厚度的层数减少，为多层微结构表征提供了有力的方法。