Characterization of the temperature dependence of the thermoreflectance coefficient for conductive thin films

Abstract

We describe a novel approach for calibration of the thermoreflectance coefficient, ideally suited for measurements in a vacuum thermostat, and present the high temperature thermoreflectance coefficients for several metals commonly encountered in electronic devices: gold, platinum, and aluminum. The effect of passivation on these metals is also examined, and we demonstrate the signal to noise ratio of a thermoreflectance measurement can be improved with informed selection of the dielectric layer thickness. Furthermore, the thermo-optic coefficients of the metals are extracted over a wide temperature range. The results presented here can be utilized in the optimization of experimental configurations for high temperature thermoreflectance imaging.

Transient Thermoreflectance for Gate Temperature Assessment in Pulse Operated GaN-Based HEMTs

“…However, this procedure has some disadvantages. For instance, the stage can move during the heating process introducing some error in the reflectivity measurement for a small gate metal, requiring larger test structures therefore; considering that the typical values of K are small, e.g., -2.36·10 -4 °C -1 for bare gold at 530 nm [17], and even smaller for other metals used for gate contacts, these measurements have a large error bar in themselves.…”

Simultaneous imaging of magnetic field and temperature distributions by magneto optical indicator microscopy

“…The reflectance of the MOIs and gold thin film decreased linearly along with an increase of applied power with different slopes depending on the bismuth concentration and wavelength of the probing light. From the temperature measured by a thermocouple, the calculated thermo-reflectance coefficient of the gold thin film was −3.63 × 10 −4  K −1 , which was slightly larger than the known value (−2.36 × 10 −4  K −1 )23. This overestimation could be the result of the temperature being measured by the thermocouple being slightly smaller than the real temperature of the PCB circuit.…”

“…In addition, we conducted the same experiments by using a gold thin film (thickness: 100 nm) coated on a glass substrate as the indicator to compare the temperature sensitivity. The gold thin film is useful to estimate the temperature sensitivity of the MOIs because it has a high thermoreflectance coefficient at the green wavelength light23. Figure 3c shows the change of a local reflectance of MOIs and the gold thin film as a function of applied electrical power to the PCB circuit.…”

Stable thermoreflectance thermal imaging microscopy with piezoelectric position control

“…The reflected light will be captured by a CCD camera and from the change in reflectivity when the electrical bias is turned on and off, the temperature is evaluated. ∆ = 1 ∆ links the reflectivity and the temperature of the sample surface, where CTR is the coefficient of thermoreflectance, which depends on the sample surface material, optics used in the experimental apparatus, and illumination wavelength, among other factors [2], [3]. In order to perform an accurate measurement, one requires sufficient knowledge about the CTR of materials in the sample under study; therefore, calibration plays a crucial role.…”