The effect of surface electric and magnetic fields on negative charge-up during high-current ion implantation

The breakdown characteristics of a thin gate oxide during high-current ion implantation with an electron shower have been investigated by controlling the energy distribution of the electrons. Deterioration of the oxide has also been discussed with regard to the total charge during ion implantation in comparison with that of the TDDB (time dependent dielectric breakdown). Experimental results show that the high-energy and high-density electrons which concentrated in the circumference of the ion beam due to the space charge effect cause the degradation of the thin oxide. It is confirmed that eliminating the high-energy electrons by applying magnetic and electric fields lowers the electron energy at the water surface, thereby effectively suppressing the negative charge-up.