Detection of dynamic temperature modulation using a thermal scanning probe lithography (t-SPL) system

Nanoscale measurements of thermophysical properties, based on detecting temperature responses to periodic heat stimulation, can be achieved using a localized heating point instead of a localized sensing point. However, the concept of determining localized thermophysical properties via nano-heating as an alternative to nano-sensing has not yet been validated. In this study, we demonstrate the measurement of thermal diffusivity within a nanoscale-confined volume using a thermal scanning probe lithography (t-SPL) system. The sharp tip of the t-SPL probe is employed to locally and periodically heat the sample, which is placed on a pre-fabricated micro-thermocouple. Using the temperature wave analysis method, the thermal diffusivity of the sample is inferred from the frequency-dependent phase shift in the temperature response of a thermocouple. This technique was applied to the microscale structure of a chemically amplified negative-tone photoresist (mr-DWL). We show that confining the heat source to a nanoscale point contact can achieve spatial resolution at the nanoscale (10-100 nm), offering an alternative approach to miniaturizing the detector sensor.