High-throughput parasitic-independent probe thermal resistance calibration for robust thermal mapping with scanning thermal microscopy

Abstract

Nanostructured materials, critical for thermal management in semiconductor devices, exhibit a strong size dependence in thermal transport. Studying thermal resistance variation across grain boundaries is critical for designing effective thermal interface materials. Frequency-domain thermoreflectance (FDTR)-based techniques can provide thermal resistance mapping at the micrometer (μm) scale. Scanning Thermal Microscopy (SThM) enables quantification of local thermal transport with significantly higher spatial resolution (<100 nm). However, challenges in quantifying the raw signal to thermal conductivity and surface sensitivity limit its widespread adoption for understanding nanoscale heat transport and defect-mediated thermal properties in nanostructured films. Here, we introduce a circuit-based probe thermal resistance (Rp) calibration technique independent of parasitic heat pathways, enabling accurate determination of probe heat dissipation and tip temperature rise, thereby allowing extraction of local thermal resistance. SThM achieved sub-100 nm spatial resolution in mapping thermal resistance across a 15 nm-thick Al film deposited via e-beam evaporation on a SiO2 substrate. The thermal resistance maps are converted to thermal conductivity using robust analytical and finite element models that account for tip–sample geometry, lateral heat spreading, and buried interface effects. Gaussian distribution fitting of pixel-level thermal resistance values yields kAl=45.1−3.6+4.7 W/(mK) for the ultra-thin Al film (13–15 nm), representing a 5.3-fold reduction from bulk aluminum [237 W/(mK)]. These results agree with published experimental data and theoretical frameworks explaining thickness-dependent heat transport in ultra-thin metallic films.