  Scanning Thermal Microscopy (SThM) uses micromachined thermal sensors
integrated in a force sensing cantilever with a nanoscale tip can be highly
useful for exploration of thermal management of nanoscale semiconductor
devices. As well as mapping of surface properties of related materials. Whereas
SThM is capable to image externally generated heat with nanoscale resolution,
its ability to map and measure thermal conductivity of materials has been
mainly limited to polymers or similar materials possessing low thermal
conductivity in the range from 0.1 to 1 W/mK, with lateral resolution on the
order of 1 \mum. In this paper we use linked experimental and theoretical
approaches to analyse thermal performance and sensitivity of the micromachined
SThM probes in order to expand their applicability to a broader range of
nanostructures from polymers to semiconductors and metals. We develop physical
models of interlinked thermal and electrical phenomena in these probes and then
validate these models using experimental measurements of the real probes, which
provided the basis for analysing SThM performance in exploration of
nanostructures. Our study then highlights critical features of these probes,
namely, the geometrical location of the thermal sensor with respect to the
probe apex, thermal conductance of the probe to the support base, heat
conduction to the surrounding gas, and the thermal conductivity of tip material
adjacent to the apex. It is furthermore allows us to propose a novel design of
the SThM probe that incorporates a carbon nanotube (CNT) or similar high
thermal conductivity graphene sheet material positioned near the probe apex.
The new sensor is predicted to provide spatial resolution to the thermal
properties of nanostructures on the order of few tens of nm, as well as to
expand the sensitivity of the SThM probe to materials with heat conductivity
values up to 100-1000 W/mK.
