Combined electrical and optical heating in thermal wave microscopy of semiconductor devices

Insulating lines and channels implanted by focused ion beams on SIMOX wafer s have been investigated by thermal reflectance microscopy using optical an d electrical excitation In addition optical beam induced current (OBIC) has been measured from the same structures. A very poor contrast in thermo-ref lectance was observed with modulated optical pump only, whereas hot lines a nd hot spots can be visualized by modulated electrical heating. Insulating lines forming channels can only be imaged with simultaneous optical and ele ctrical excitation. Best contrast for the observation of the insulating lin es adjacent to a channel are achieved by recording the reflectance signal a t 4f where f is the modulation frequency of the optical and electrical pump , The results of the OBIC measurements point towards a thermal origin of th e double excited thermo-reflectance signal.