Radiation induced interface traps in MOS capacitors made by industrial 2 /spl mu/m CMOS process

A couple of industrially produced MOS capacitors on p-type silicon have been irradiated by a /spl gamma/-irradiation source to total doses up to 500 krad without applied bias. A low frequency impedance analyser was used to obtain admittance data at frequencies ranging from 100 Hz to 10 MHz and at bias conditions in depletion and weak inversion. Interface trap properties were determined by fitting the capacitance in depletion to a model including band bending fluctuations. The generation of a continuum of interface traps in the lower half of the bandgap was observed. The hole capture cross-sections of the radiation induced traps seem to be larger than those of the pre-irradiation traps.