Spatially and temporally resolved thermal imaging of cyclically heated interconnects by use of scanning thermal microscopy

A scanning thermal microscope with a Wollaston probe was used to investigate the spatial distribution and temporal variation of temperature in interconnect Structures subjected to thermal cycling. The probe, utilized in passive temperature sensing mode, was calibrated From 20 degrees C to 200 degrees C using a single-layer aluminum microdevice. Spatial measurements were performed on nonpassivated aluminum interconnects sinusoidally heated by a 6 MA/cm(2) current at 200 Hz. The interconnects were determined to have temperatures that decreased with position from a maximum located at the center of both the interconnect length and width. Time-resolved temperature measurements were performed on the same structures sinusoidally heated by a 6 MA/cm(2) Current at 2 Hz. Both the peak-cycle temperature and average-cycle temperature were found to decrease with increasing distance from the center of the width of the interconnects.