A Novel Approach to Reduce Damages in Gate Oxides Induced by Bias Sputtered Sio2 Deposition

Vth shifts of MOS transistors, on which the conventinal bias sputtered SiO2 films were deposited, became negligibly small after annealing at 450°C. But, ¿Vth´s by bias stress test were larger than those of reference samples, since damages consisted of neutral traps were induced in gate oxides of MOS transistors in the bias sputtered SiO2 deposition which result from the effect of secondary X-ray, generated by electrons which come from the target, on gate oxides. The grid electrode was used for decrease of electrons from the target to the substrate. This novel approach reduced damage introduction to the degree acceptable in practical use.