A mechanism of increase in the on-current and offcurrent due to a slightly smaller spacer in state-of- the-art p-channel MOS transistors during manufacturing

Abstract

Our observation is that both the oncurrent and off-current of state-of- the-art pchannel MOS transistors tend to become larger when the spacer becomes smaller. In this paper, we propose 2 mechanisms involved in this on-current and offcurrent increase due to a slightly smaller spacer. Mechanism A is a decrease in the effective channel length. Because of a TED/BED (transient enhanced diffusion/boron enhanced diffusion) mechanism, the deep p-type D/S implant closer to the channel region makes the p-type D/S extension implant to diffuse farther into the channel region, resulting in a smaller effective channel length Leff. Mechanism B is a decrease in the series resistance. The deep ptype D/S implant moving closer into the channel region also causes a reduction in the D/S series resistance Rseries*The smaller Leffand Rseriestogether can produce a higher on-current. The smaller Leff also causes a significant increase in off-current.