Atomistic modeling and physical comprehension of the effects of implant dose rate on boron activation in pMOSFET S/D

Abstract

This study is aimed to understand the mechanisms leading to different device behaviors while switching from one type of implanter, which scans a batch of wafers with a spot ion beam, to another one, which scans a single wafer with a ribbon ion beam. Thanks to atomistic simulations, we bring to the fore that the implant dose rate is responsible for the observed mismatch. Increasing the dose rate reduces the amount of interstitials present beyond the amorphous layer. During subsequent annealing, these interstitials first accelerate boron clusters dissolution at projected range, then agglomerate themselves into stable dislocation loops. The latter will in turn deactivate the boron in source and drain region, modifying the electrical characteristics of the device.