Carbon junction implant: Effect on leakage currents and defect distribution

Abstract

In this paper we present a detailed investigation on the influence of carbon co-implantation in the source/drain extension on leakage current and defect density in PFET transistors. Carbon is used to reduce the transient enhanced boron diffusion, to decrease short channel effects and to control the overlap length of the transistor. Leakage currents are measured and separated in order to analyze the influence of the carbon on the different MOSFET regions. An increase in carbon dose by a factor of 1.15 leads to an enhanced source/drain extension leakage which is caused by carbon induced defects. No effect of the carbon implantation on source/drain junction leakage was found as the co-implant is located above the source/drain depletion region. In addition an increase of gate induced drain leakage with carbon dose was observed. This increase is further analyzed by charge pumping technique. ©2010 IEEE

Microscopic origins of dry-etching damages in silicon large-scaled integrated circuits revealed by electrically detected magnetic resonance

“…However, the signal intensity of G11 was much smaller than that of "Ci" (G12-type), despite the fact that our devices went through the high-temperature thermal processes (over-1000 C activation anneal for seconds as well as over-400 C anneal for hours). We suggest that a large amount of excess Si i in MOSFETs 1,2 causes the dominant formation of the G12-type centers [C þ Si] i rather than the G11 centers (C i þ C s ). Also strongly strained Si lattice by the surrounding structures 12 may affect the thermal stability of the defects.…”

“…They are intentionally introduced by co-implantation in order to form an abrupt junction profile of Si metal-oxide-semiconductor field effect transistors (MOSFETs). 1,2 In the implanted regions, carbon and fluorine atoms can trap excess interstitial Si atoms and strongly suppress the transient enhanced diffusion of boron and phosphorous dopants. 1,2 They are also unintentionally introduced by dry etching.…”

“…1,2 In the implanted regions, carbon and fluorine atoms can trap excess interstitial Si atoms and strongly suppress the transient enhanced diffusion of boron and phosphorous dopants. 1,2 They are also unintentionally introduced by dry etching. 3,4 Fluorocarbon containing fluorine and carbon is one of the most popular gases for reactive ion etching (RIE) of SiO 2 and SiN films.…”

“…Both carbon and fluorine atoms can create lattice defects 5,6 and may become the source of the leakage currents of p-n junctions. 2,7 However, microscopic entities of such defects are still unclear. Since Si MOSFETs are fabricated via a number of LSI processes, the formation and survival of defects inside MOSFETs are very complicated issues.…”