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Advanced high-κ dielectric stacks with polySi and metal gates: Recent progress and current challenges

QUALCOMM MEMS Technologies, 2581 Junction Avenue, San Jose, California 95134, USA
Ibm Journal of Research and Development (Impact Factor: 0.5). 08/2006; DOI: 10.1147/rd.504.0387
Source: IEEE Xplore

ABSTRACT The paper reviews our recent progress and current challenges in implementing advanced gate stacks composed of high-κ dielectric materials and metal gates in mainstream Si CMOS technology. In particular, we address stacks of doped polySi gate electrodes on ultrathin layers of high-κ dielectrics, dual-workfunction metal-gate technology, and fully silicided gates. Materials and device characterization, processing, and integration issues are discussed.

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    • "High-k material can be grown physically thicker than SiO 2 which has the same electrostatic effects that a thin SiO 2 of thickness equal to " Equivalent oxide thickness, EOT " has. The thick high-k dielectric offers required control over the channel with significant reduction in leakage current [10]. "
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    ABSTRACT: Ballistic performance of nanoscale In 0.3 Ga 0.7 Sb double gate n-MOSFET is studied for different gate oxides considering same Equivalent oxide thickness (EOT). Non equilibrium greens function method is utilized under the environment of well-known SILVACO's ATLAS device simulation package to carry out the simulation. Wave function penetration to the oxide is taken into account in the simulation. The results obtained from the simulation indicate that EOT is not solely control the device performance. Rather, a strong correlation is found between the I-V characteristics and the conduction band offset (E C) of the channel and dielectric materials. It is also found that the threshold voltage decreases and the subthreshold swing increases with the higher value of E C . It reveals that for nanoscale MOSFET design, another tunable variable is found to ensure best performance.
    8th International Conference on Electrical and Computer Engineering (ICECE 2014), Dhaka, Bangladesh; 12/2014
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    • "In that case the thickness of high-K material is equivalent to the thickness of SiO 2 , which is termed as " Equivalent oxide thickness " , or " EOT " . The thick high-k dielectric then offers required control over the channel with significant reduction in leakage current [11]. It has also been expected for different high-K material having different dielectric constant, if their EOT is the same, they would give same C ox and therefore provide same device performance. "
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    ABSTRACT: Different high-k dielectrics have been supposed to provide same device performance if their physical thickness are not equal but equivalent, called “Equivalent oxide thickness” (EOT). For ultra thin body (UTB) devices like XOI, despite of EOT, conduction band offset (ΔEC) at gate oxide-channel interface dominates the ballistic performance. In case of In0.3Ga0.7Sb XOI nFET using Al2O3 and HfO2 with 0.5 nm EOT, we show the threshold voltage decreases and the subthreshold slope (SS) increases with increase in ΔEC.
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    • "IGH-K (HK) materials and metal gate (MG) electrodes have been introduced into the CMOS technology for the 45-nm node and include, high gate leakage current at a small equivalent oxide thickness (EOT), poly-gate depletion, resistivity effects, boron penetration, and Fermi-level pinning [1]–[3], which arise from the use of SiO 2 and poly-Si as a dielectric and gate material. However, the implementation of low threshold voltage (V TH ) HK/MG pMOSFETs with a small EOT has been a crucial challenge in the gate-first CMOS flow because of the presence of various oxygen vacancies and defect sites in the HK gate dielectric [4]. "
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    ABSTRACT: The impact of aluminum ion implantation (Al I/I) on the 1/ (f) noise and random telegraph noise (RTN) characteristics of high- (k) /metal gate (HK/MG) pMOSFETs is investigated. The Al I/I technology was implemented to tune the effective work function (EWF) of pMOSFETs without increasing the equivalent oxide thickness and complicating the process. The RTN and 1/ (f) noise results showed that irrespective of the implanted dose, the HK/MG devices with Al I/I still exhibit lower slow oxide trap densities for the control device, because the Al filled the defect and formed a thin Al2O3 layer. In addition, for the HK/MG devices with different implanted doses, no significant differences in the trap properties are noted. However, the modulated EWF can be attributed to the Al I/I-induced dipoles at the HfO2/SiO2 interface.
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