Effect of germanium preamorphization implant on performance and gate-induced drain leakage in SiGe channel pFET

Abstract

Silicon-germanium (SiGe) channel pMOSFET is considered as a replacement for silicon channel device for 32-nm node and beyond, because of its lower threshold voltage and higher channel mobility. Lower SiGe bandgap makes gate-induced drain leakage (GIDL) important for low leakage, high threshold voltage device designs. In this letter, the effect of prehalo/LDD Ge preamorphization implant (PAI) on GIDL and performance is investigated using experimental data and simulations. Results suggest that GIDL reduction of 40 % is achieved without Ge PAI and the total off-state leakage (I<inf>OFF</inf>) is reduced by ∼ 50 % with a slight reduction in drive current (I<inf>ON</inf>) and similar short-channel effects as compared with the case with PAI for same process conditions, which is not reported yet. The reduction in GIDL, and hence the improvement in I<inf>ON</inf>/I<inf>OFF</inf> ratio is because of elimination of end-of-range defects at the source/drain sidewall junction regions. It is also shown that a slight reduction in I<inf>ON</inf> in the absence of Ge PAI is because of a small increase in the extrinsic series resistance.