Fixed oxide charge, interface traps and border traps in MOS structures, grown on plasma hydrogenated (100)-psi

摘要

The subject of the present study is the interface region of MOS structures with oxides grown on (100)-pSi hydrogenated wafers. The hydrogenation was accomplished in an RF plasma, the Si substrates being either unheated or kept at 300 degrees C. The oxides were thermally grown in dry O-2 at 850 degrees C. Information was gained on the concentration of charged defects and their location in the Si/oxide interface region, from examination of the capacitance-voltage (C-V) frequency behaviour. A comparative analysis was performed on the electrically active defects for the structures, with different hydrogenation conditions. The concentrations of border traps were determined by analysis of the hysteresis of the C-V curves. The interface trap density profiles over the Si bandgap were investigated by a standard high frequency method from the 300 kHz C-V characteristics of the MOS structures. The intrinsic fixed oxide charges were determined from the transition frequencies of the interface trap response separating low from high frequencies for the different samples. The concentration and nature of the defects were found to depend on the substrate temperature during plasma exposure. In oxides on unheated Si, negatively charged oxide defects were found.