Local temperature measurement of nano/micro-structures using optical thermometry

Abstract

Measurement of temperature and thermophysical properties of the materials is important in order to understand phenomena around miniaturized materials, components and systems (i.e., graphene, nanotubes, transistors, semiconductor devices, light-emitting-diodes, etc.) that are widely used in science and applications and to analyze the failure mechanisms of electronic devices such as memory and display devices due to heat. Therefore, in this thesis, we have accurately measured temperature of various materials and micro/nano structures by combining thermoreflectance and temperature sensitive paints (TSP) with an optical microscope and an atomic force microscope (AFM). Especially, we have proposed a novel thermometry through the combination of thermoreflectance and AFM, and local temperature measurement of micro/nano structures becomes possible. Thermoreflectance method is a thermometry based on the fact that optical reflection from a solid surface varies with temperature due to changes of the dielectric function. Thermoreflectance technique allows temperature measurements in a variety of materials and structures. By measuring the reflectance of an sample using a laser, temperature of the sample can be extracted. In this study, by taking into account the size of the focused laser beam and the width of the sample, it is possible to determine the absolute temperature of a local region of the heater from the measured reflectance during the scanning, even though the width of the heater line is only 39% of the size of the laser beam. Furthermore, we present a novel technique, which enables simultaneous measurement of temperature and topography of nano-structures without using a complicated probe. We exploit a conventional AFM commonly used for topography measurement without any modifications on the probe nor extra accessories for data acquisition and measure local temperature of micro/nano structures with less than 50 nm spatial resolution. Also, in this thesis, temperature sensitive paints are deposited unformly on micro/nano structures and the 2-D temperature distribution of micro/nano structures can be quantitatively measured through an optical microscope as a non-contact thermometry.