Study on nano-scale thermophysical properties measurement method with Scanning Thermal Microscope

本研究旨在开发扫描热显微镜上具有纳米尺度空间分辨率的局部热导率测量方法。通过制作多功能微悬臂探头，对其性能进行了实验检验。悬臂有2微米厚，600微米长的SiO2主体，上面有5个热装置。探头末端有用于检测接触温度的接触式热电偶电极，其次有用于校准热流传感器的铂薄膜加热器，用于检测沿悬臂梁的热流的热电堆传感器，用于测量悬臂梁体温的薄膜热电偶和用于控制靠近硅基板的体温的另一个加热器。对于高精度的局部热导率测量，要求同时高精度地测量接触热导率和接触温度。本研究开发的悬臂式探头可以根据已知的Pt加热器的发热情况对热流传感器进行标定，并利用加热器的温度依赖性来确定薄膜热电偶的热电动势。通过消除微加工传感器常见的模糊性和引入自校准功能，提高了测量精度。它可以引导热导率测量的改进。将基于原子力显微镜的悬臂探针附着在SThM上，并在低于10^<-4> Pa的真空条件下工作，得到了以下结果：主动测温，其中热反馈补偿悬臂和样品之间的温差，可以提供比以前的测温探头更高的灵敏度。通过不断加热尖端附近的Pt加热器，并使用热电堆传感器监测从探针到样品的热流，也可以获得高空间分辨率的热导成像。此外，通过将探针与涂有金薄膜的样品接触，利用尖端的接触热电偶测量接触温度。结果表明，热导率和接触温度的同时测量是可能的，并允许用SThM定量测量局部热导率。少

This research aims to develop the local thermal conductivity measurement method with nano-scale spatial resolution on the scanning thermal microscope. With fabricating the multi-functional micro cantilever probe, its performance has been experimentally examined. The cantilever has 2 micron thick and 600 micron long body of SiO2, and five thermal devices on it. There is electrode of contact thermocouple at the end of the probe for detecting the contact temperature, Pt thin film heater for calibrating heat flow sensor next, thermopile sensor for detecting heat flow along the cantilever, thin film thermocouple for measuring cantilever body temperature and another heater for controlling the body temperature near Si base plate. For the local thermal conductivity measurement with high-accuracy, it is required to measure the contact thermal conductance and the contact temperature simultaneously with high accuracy. The cantilever probe developed in the research enable to calibrate the thermopi … More le heat flow sensor with known heating of the Pt heater, and to identifying thermoelectricmotive force of the thin film thermocouple by using temperature dependency of the heaters. Improvement in accuracy was conducted by eliminating the common ambiguity of the micro-fabricated sensors and introducing the self-calibration functions. It can lead the improvement in thermal conductivity measurement.Following results were obtained by attaching the cantilever probe on the SThM based on the AFM and operating under vacuum condition of below 10^<-4> Pa. The active thermometry, where thermal feedback compensates temperature difference between the cantilever and sample, can be available with higher sensitivity than a previous thermometry probe. Thermal conductance imaging with high spatial resolution can be also available by constantly heating the Pt heater near the tip and monitoring the heat flow from the probe to the sample with the thermopile sensor. Furthermore, the contact temperature is measured with the contact thermocouple at the tip by contacting the probe with the sample coated with gold thin film. It shows that the simultaneous measurement of the thermal conductance and the contact temperature is possible and allows the quantitative local thermal conductivity measurement with the SThM. Less