Conformal, Wafer-Scale and Controlled Nanoscale Doping of Semiconductors Via the iCVD Process

Abstract

For the first time, a novel doping technique using an initiated CVD (iCVD) process was developed, facilitating the conformal, wafer-scale and controlled nanoscale doping of semiconductors at a high concentration. iCVD poly(boron allyloxide) (pBAO) and poly(triallyl phosphate) (pTAP) were used as a p-type and n-type dopant diffusion source, respectively. In detail, an optimized integration process was developed involving copolymer p(BAO-co-V3D3) passivation for pBAO and double-step deposition for pTAP. It was found that a dopant-containing polymer layer with a sub-10-nm thickness provided a high doping concentration at a shallow junction depth (10 nm) for both the p-type (10(20) cm(-3)) and the n-type (10(21) cm(-3)). Furthermore, the conformality and dopant distribution of the iCVD polymer layer were investigated using a high-aspect-ratio Si fin (5:1). The SOI nFET with iCVD doping at the source/drain regions exhibited better subthreshold swing and on-current values than a SOI nFET with conventional ion-implantation doping. Compared to other diffusion doping methods, the iCVD process could achieve lower sheet resistance.