Lateral spread of ion-implanted impurities in silicon

Abstract

A technique for measuring the overlaps of the gate electrodes of field‐effect structures is described. Ion‐implanted self‐aligned gate FET structures were used to evaluate the lateral spread of low‐energy (RP <0.1 μm) high‐dosage (5×1015/cm2) phosphorus and boronimplantations and was found to be less than 10−5 cm. Sheet resistance of the implanted region can also be evaluated by this technique. Some series resistance effects associated with inadequate annealing as well as two‐dimensional field aspects on the threshold voltage associated with short channel devices in this experiment were observed.