SURFACE/INTERFACE CHARGE IMAGING BY TIME-RESOLVED SURFACE PHOTOVOLTAGE

To date, surface charge monitoring has been done with capacitance-voltage measurements on MIS test capacitors. New surface photovoltage (SPV) methods offer fast, non-destructive, no preparation measurements. We describe SPV surface charge monitoring designed for wafer-scale imaging. The changes of the surface barrier caused by high intensity laser pulses of variable frequency are analyzed in real time with a computerized system. A time resolved method based on frequency dispersion enables distinguishing between lifetime effects, fast interface charge and oxide charge.