Nanoscale resolution scanning thermal microscopy using carbon nanotube tipped thermal probes
We present an experimental proof of concept of scanning thermal nanoprobes that utilize the extreme thermal conductance of carbon nanotubes (CNTs) to channel heat between the probe and the sample. The integration of CNTs into scanning thermal microscopy (SThM) overcomes the main drawbacks of standard SThM probes, where the low thermal conductance of the apex SThM probe is the main limiting factor. The integration of CNTs (CNT-SThM) extends SThM sensitivity to thermal transport measurement in higher thermal conductivity materials such as metals, semiconductors and ceramics, while also improving the spatial resolution. Investigation of thermal transport in ultra large scale integration (ULSI) interconnects, using the CNT-SThM probe, showed fine details of heat transport in ceramic layers, vital for mitigating electromigration in ULSI metallic current leads. For a few layer graphene, the heat transport sensitivity and spatial resolution of the CNT-SThM probe demonstrated significantly superior thermal resolution compared to that of standard SThM probes achieving 20–30 nm topography and ∼30 nm thermal spatial resolution compared to 50–100 nm for standard SThM probes. The outstanding axial thermal conductivity, a high aspect ratio and robustness of CNTs can make CNT-SThM the perfect thermal probe for the measurement of nanoscale thermophysical properties and an excellent candidate for the next generation of thermal microscopes.