ANALYSIS OF THE SIO2 DEFECTS ORIGINATED BY PHOSPHORUS IMPLANTATION INMOS STRUCTURES

Medium-dose ion implantation is widely used in CMOS technology, howeve r unwanted effects may occur when the doping ions are implanted throug h the thermally grown SiO2 layer. We study the effect of the P+ implan tation in the dose range 10(11)-10(13 cm-2 and annealing treatment met hods on the carrier trapping centres concentration in bulk SiO2 and th e interface-state density at the SiO2-Si interface. Trapping kinetics analysis has been performed using photoinjection as a charging tool. W e have found a dominant electron trapping centre with a capture cross Section of (1-2) x 10(-17) cm2 and a second electron trapping centre w ith (1-3) x 10(-16) cm2. The density of the dominant trap has been fou nd to be dependent on annealing treatment. These results are explained taking into account the damage introduced by the implantation process , which leads to the generation of carrier traps into the oxide. The i nitial interface state density rises with increasing dose and is also dependent upon the thermal treatment method. We also observe interface state generation after charge injection with a generation rate value higher than that usually found in nonimplanted structures, independent ly of implantation parameters.