A study of changes in oxide properties on metal-oxide-semiconductor (MOS) structure after electrical overstress

In this research, the impact of electrical overstress on the oxide properties of MOS structure is studied. Prior to electrical overstress, normal C-V characteristic is observed and current conduction through the oxide layer is almost negligible. Once the device is subjected to electrical overstress, capacitance no longer depends on voltage, while leakage current increases drastically and is able to be detected by a photon emission microscope. Physical defects such as oxide damage and pinholes could be observed under a variable pressure field emission scanning electron microscope. These defects are highly likely induced during fabrication process and detrimental to the oxide strength.