The Short Channel Effect on PMOS Device for BF2 Implant and The Molecular Dissociation

摘要

The pre-accelerated BF2 ion after magnet analysis selection could be dissociated to B and F before or during post-acceleration to cause deeper implant. The deeper p~+ junction was formed from higher energy boron implant. The PMOS source/drain junction depletion region was extended to channel area to cause the short channel effect which caused the threshold voltage shift to lower value. The result was compared to the drift mode implant of BF2 ion with only preacceleration energy. In two stage of acceleration of BF2 implant, the process concern of energy contamination from molecular dissociation would cause the electrical degradation of device as shown in the experimental data. Instead of BF2 implant, the unique B atom is suggested for the critical junction depth implant.