The temperature sensitivity is one of the critical parameters for the thin film bulk acoustic resonator (FBAR) based temperature sensors. In this work, FBARs with Au/Fe_0.8Ga_0.2/Ti/AlN/Mo structure are developed. The size effect of the Ti insertion layer on the temperature sensitivity of the devices is systematically investigated. The devices were fabricated by MEMS process and characterized by a network analyzer under variable temperatures. It is found that the temperature sensitivity of the devices is strongly related to the thickness of the Ti insertion layer. A super-high temperature sensitivity up to 546 kHz C⁻¹ was obtained with 20 nm Ti inserted thin film; that feature can even reach 825 kHz C⁻¹ for some devices, showing great potential for ultra-sensitive temperature monitoring. Mason model is used to analyze the extraordinary characteristics of the device and finite element method (FEM) is used to analyze the strain distribution in the device. The supreme performance of the temperature sensor can be explained by the size effect of the temperature coefficient of Young’s modulus (TCE) of Ti film, which means that the TCE was enhanced when the thickness of the Ti film is around 20 nm. This work provides a new approach for the design of high sensitivity temperature sensor based on FBAR.

温度灵敏度是基于薄膜体声波谐振器 (FBAR) 的温度传感器的关键参数之一。在这项工作中，开发了具有 Au/Fe _0.8 Ga _0.2 /Ti/AlN/Mo 结构的FBAR 。系统地研究了 Ti 插入层对器件温度敏感性的尺寸效应。这些器件是通过 MEMS 工艺制造的，并在可变温度下通过网络分析仪进行表征。发现器件的温度敏感性与 Ti 插入层的厚度密切相关。使用 20 nm Ti 插入薄膜获得了高达 546 kHz C ^-1的超高温灵敏度；该特性甚至可以达到 825 kHz C ⁻¹对于某些设备，显示出超灵敏温度监测的巨大潜力。Mason 模型用于分析器件的非凡特性，并采用有限元法 (FEM) 分析器件中的应变分布。温度传感器的卓越性能可以通过 Ti 薄膜杨氏模量 (TCE) 温度系数的尺寸效应来解释，这意味着当 Ti 薄膜的厚度在 20 nm 左右时，TCE 得到增强。该工作为基于FBAR的高灵敏度温度传感器的设计提供了一种新方法。