Design tradeoff guidelines for n-channel delta-doped Si/SiGe heterojunction MOSFETs

A design trade-off study for n-channel delta-dolped Si/SiGe heterojunction MOSFETs has been performed using a combination of numerical simulation and analysis. A few design guidelines resulted from our study. We have shown th at the cap and channel layer must always be made as thin as possible to red uce the separation of the mobile charge centroid from the surface, in which case better short-channel immunity, better leakage and driving ability wil l result. A deep potential well does not improve driving ability by much an d leads to high leakage, although the short-channel immunity is better. A t hick setback layer results in better leakage and driving ability but leads to poor short-channel immunity. A high delta-doping dose provides excellent short-channel immunity but leakage is high and driving ability is low. We summarize our study by constructing viable design regions enclosed by surfa ces corresponding to performance constraints. (C) 2000 Elsevier Science Ltd . All rights reserved.