Temperature mapping of metal interconnects using scanning thermoreflectance microscope

High spatial and temporal resolution thermometry techniques are needed to investigate the impact of temperature rise, distribution and gradients on the electrostatic discharge (ESD) and electromigration (EM) phenomena in microelectronic devices and interconnects. This paper presents a laser scanning thermoreflectance microscope capable of mapping the transient surface temperature rise of microdevices subjected to the brief electrical heating pulse. The calibration of the thermoreflectance coefficient is performed using a differential scheme and by performing electrical resistance thermometry in the same structure. The temperature profile along the suspended metal bridge subjected to electrical stress was obtained to demonstrate the feasibility of this approach to study the impacts of absolute temperature rise, as well as its gradient on the failure due to electromigration in interconnects.