Non-diffusive heat transport in twin nanoheater lines on silicon

As the size of electric and optoelectronic devices is reduced to nanoscale, self-heating becomes a major reliability concern. Leveraging designs that could intrinsically remove or reduce the heat and in turn decrease temperature is desirable. In this work, twin nanoscale heater lines with four-probe electrical measurement combined with full-field thermal imaging are used to elucidate the departure from Fourier Law. Thermoreflectance thermal imaging is employed to obtain temperature distribution of twin nanoheater lines where one is a heat source and the second one is a thermometer. The temperature change, due to Joule heating, on the heater line as well as the temperature profile on the thermometer line 0.3-0.5gm away, is measured by thermoreflectance imaging. The average temperature change of the heater lines is also measured independently using temperature-dependent electrical resistivity. Experimental results suggest that the modified Fourier theory ceases to explain the thermal distribution of submicron size heat sources. As the width of heat sources decreases, the temperature of the heater lines exceeds predictions of Fourier equation while the temperature on the thermometer line is significantly lower than the Fourier prediction. This could potentially be beneficial in the design of compact multi-finger high power transistor structures.