The characterization of thin film parameters derives from the measurement difference between the coated and bare substrate. This method of comparison is based on the stationarity of the substrate: the characteristics of the substrate do not depend on the presence of the film. However, the thermoelastic loss of a coated substrate depends on the thermo-mechanical parameters of the film as well, which are generally unknown. When thermoelastic loss is dominant, the coating loss measurements are completely altered. In this paper, we propose a model that helps to understand the role of each material property in the thermoelasticity of layered plates, and with this we identified three possible cases in which any coating-substrate combination could be classified. In particular, we analyzed the IBS silica film deposited on silicon. Using the model, we were able to explain the experimental results and also selected a thinner substrate for future coating loss measurements. With this choice, cryogenic loss measurements on bare substrate confirm that thermoelastic loss becomes irrelevant for temperatures below 130 K–180 K, depending on the mode.

中文翻译：

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解决使用热弹性为主的基材的涂层损耗测量


薄膜参数的表征来自涂层和裸基板之间的测量差异。这种比较方法基于基材的平稳性：基材的特性不取决于薄膜的存在。然而，涂层基材的热弹性损失也取决于薄膜的热机械参数，这些参数通常是未知的。当热弹性损失占主导地位时，涂层损失测量值会完全改变。在本文中，我们提出了一个模型，有助于理解每种材料特性在多层板的热弹性伸缩中的作用，并以此我们确定了三种可能的情况，其中任何涂层-基材组合都可以进行分类。特别是，我们分析了沉积在硅上的 IBS 二氧化硅薄膜。使用该模型，我们能够解释实验结果，并为未来的涂层损耗测量选择更薄的基材。通过这种选择，裸基板上的低温损耗测量证实，热弹性损耗与低于 130 K–180 K 的温度无关，具体取决于模式。