Showing papers by "Anabela Veloso published in 2004"

Demonstration of fully Ni-silicided metal gates on HfO/sub 2/ based high-k gate dielectrics as a candidate for low power applications

Abstract: We have fabricated fully Ni-silicided metal gate (FUSI) CMOS devices with HfO2-based gate dielectrics for the first time. We demonstrate that full silicidation eliminates the Fermi level pinning at the polySi-HfO2 dielectric interface in pFETs. For nMOS devices, a 5 orders of magnitude reduction in short channel sub-threshold leakage is obtained with similar drive current compared to the poly gate devices. In addition, the FUSI process does not degrade the hysterisis nor the dielectric breakdown. This result makes FUSI on high-K a strong candidate for scaled low power technologies.

Diffusion-less junctions and super halo profiles for PMOS transistors formed by SPER and FUSI gate in 45 nm physical gate length devices

Abstract: This paper reports on the successful integration of truly diffusion-less (less-than-650/spl deg/C) junction formation by SPER in pMOSFETs in combination with Ni-FUSI gates for the first time. The obtained drive currents are 355 /spl mu/A//spl mu/m for an off-state of 10 /spl mu/A//spl mu/m at Vdd= -1.2V and 1.4nm EOT SiON. We demonstrate that the gate de-activation problem associated with SPER is effectively solved by the use of the FUSI gate electrode. Super halo profiles are obtained with SPER, which opens up the halo design space for accurate SCE control. The junction leakage is greatly reduced by engineering the damage region away from the junction depletion region.

Work function engineering by FUSI and its impact on the performance and reliability of oxynitride and Hf-silicate based MOSFETs

Abstract: In this work, we report an extensive characterisation of fully silicided gate (FUSI) devices with oxynitride (SiON) and Hf-silicate gate dielectrics. Enhanced drive current is obtained, in comparison with poly gate devices, together with an increase in electron/hole mobility and reduction in CET values. We show that the work function (WF) can be engineered by doping of the poly gates prior to FUSI for SiON devices but not for Hf-silicate devices. With reference to the poly gate, Hf-silicate/FUSI devices exhibit improved TDDB reliability behavior, having higher acceleration factor (/spl gamma/) values. NBTI gives a maximum operating voltage above 1.2 V for /spl Delta/V/sub T/ = 10% or 30 mV, as extrapolated for a 10 years-lifetime.

Further optimization of plasma nitridation of ultra-thin oxides for 65nm node MOSFETs

Abstract: Optimization of MOSFET gate dielectric nitridation is performed via N 2 plasma characterization. The energy scales of the electrons and ions are measured in inductively coupled pulsed radio frequency nitrogen plasmas. Controlling both the instantaneous and time-averaged energy scales of the electrons and ions is found to be possible through modifications to the pulsed-RF plasma apparatus. These modifications result in up to a 15% and 7% improvement in nMOS and pMOS low-field mobility, respectively, at fixed gate leakage current when compared to results with the standard apparatus. The results indicate a means to extend silicon oxynitride as a useful gate dielectric for the 65 nm node.

Study of pulsed RF DPN process parameters for 65 nm node MOSFET gate dielectrics

Abstract: In order to understand how N2 plasma conditions impact on the incorporation of nitrogen species into a thin SiO2 (14 nm), tuning of some pulsed RF (pRF) Decoupled Plasma Nitridation (DPN) process parameters was performed: duty cycle (DC) or on-time per period, frequency (f), process time (t) and some cross-combinations (DC*f, DC*t, DC*f*t) The N2 plasma and the SiOx Ny film were characterized using Langmuir probe analysis (LP) and Delay to Reoxidation (D2R) techniques, respectively Correlations are established between ion density and electron temperature and the resultant nitrogen concentration and parasitic physical thickness increase The LP results indicate that while DC impacts the ion density and energy, the frequency has no impact to first order This is consistent with the physical characteristics of the film From the combination of DC*f*t, the importance of the off-time portion of the pulse was revealed With the help of a modified pulsed RF DPN generator, allowing a decrease of the frequency down to 2 kHz, a 5% improvement of the drive current for pMOS transistors was obtained