Nanoscale Thermal and Thermoelectric Mapping of Semiconductor Devices and Interconnects

Three scanning probe microscopy techniques have been developed and applied for thermal and thermoelectric characterization of semiconductor devices and interconnects. These methods are Scanning Thermal Microscopy (SThM), Electrostatic Force Microscopy (EFM), and Scanning Thermoelectric Microscopy (SThEM). The SThM uses a temperature sensor microfabricated at the tip end of an Atomic Force Microscope (AFM) probe to map out temperature distribution on a surface with a spatial resolution approaching 50 nm. This nanoscale thermal imaging method has been applied to obtain surface temperature distribution of nanotransistors, interconnect structures, and molecular electronic devices. Combined with the nanoscale electric field distribution obtained using the EFM, the thermal imaging results can shed light on electron‐phonon transport mechanisms in nanoelectronics and can locate defects in the devices. The SThEM employs an ultra‐high‐vacuum (UHV) Scanning Tunneling Microscope (STM) tip to measure the Seebeck coefficient of nanostructures with a spatial resolution of about 6 nm. This method has been applied to obtain the Seebeck coefficient profile of a p‐n junction. An abrupt change of Seebeck coefficient across the junction is observed. This abrupt change allows for accurate junction delineation. The obtained Seebeck coefficient profile further reveals detailed bandstructure and carrier concentration profile.