Electrical characteristics of highly reliable ultrathin hafnium oxide gate dielectric

The work function (WF) of several phases of Pt-Al alloys is investigated. A first-principles study is performed to determine the dependence of the vacuum WF (VWF) on the phase, crystallographic orientation, and atomic termination. In parallel, the effective WF (EWF) of these alloys is experimentally measured using metal-oxide semiconductor devices. A detailed microstructural characterization based on x-ray diffraction and transmission electron microscopy allows the comparison between experiment and calculations. It is found that despite the formation of a complex microstructure, the calculated VWF values are in good agreement with the experimental EWF values. The possible VWF range for each phase has a relatively small (∼0.5 eV) span for different orientations and atomic terminations, and it is found that Pt atoms in the terminating plane are more dominant than Al atoms. The results demonstrate that first-principles calculations of the WF of alloys can be used to successfully predict the experimental WF and that knowledge of the microstructure is important for the accuracy of these calculations.

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“…Moreover, similar EWF were estimated 9 for Pt/HfO 2 (5.23 eV, based on Ref. 64) and for Pt/ZrO 2 (5.05 eV, based on Ref. 65).…”

Section: Electrical Resultssupporting

confidence: 70%

Composition and crystallography dependence of the work function: Experiment and calculations of Pt-Al alloys

et al. 2012

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“…An alternative is to replace the common dielectric material with higher dielectric (κ) materials, such as ZrO 2 , HfO 2 , Ta 2 O 5 , Y 2 O 3 and TiO 2 [2,3]. It has been shown that HfO 2 , when grown on Si, has excellent properties which include a high dielectric constant (κ > 20), low leakage current, good thermal and chemical stability with negligible dispersion and excellent reliability [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…There are several HfO 2 thin film growth techniques, such as electron-beam evaporation [9], Hf reactive sputtering in O 2 atmosphere [4], laser oxidation [10,11] and scanning probe lithography (SPL) [12]. Among them, SPL allows nanoscale manipulations with high spatial resolution thus creating a controlled oxide pattern based on the electrochemical process between a conductive tip and the metallic surface under a bias voltage [13].…”

Section: Introductionmentioning

confidence: 99%

Local oxidation nanolithography on Hf thin films using atomic force microscopy (AFM)

Büyükköse¹,

Okur²,

Aygün³

2009

J. Phys. D: Appl. Phys.

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Well controlled Hf oxide patterns have been grown on a flat Hf thin film surface produced by the dc magnetron sputtering method on Si and SiO x substrates. These patterns have been created by using the technique of semi-contact scanning probe lithography (SC-SPL). The thickness and width of the oxide patterns have been measured as a function of applied voltage, duration and relative humidity. There is a threshold voltage even at 87% humidity, due to insufficient energy required to start the oxide growth process for a measurable oxide protrusion. Electrical characterization was also performed via the I -V curves of Hf and HfO x structures, and the resistivity of HfO x was found to be 4.284 × 10 9 cm. In addition to the I -V curves, electric force microscopy and spreading surface resistance images of Hf and HfO x were obtained.

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“…As a promising high-k dielectric, HfO 2 ͑k ϳ 25͒ has demonstrated improved gate leakage properties in Si-based MOS capacitor. 5 Also, HfO 2 is also used as the blocking oxide 6,7 and tunneling oxide 7,8 in floating-gate nonvolatile semiconductor memory to achieve lower program/erase voltage and longer retention time respectively. However, Ge MOS device with HfO 2 as gate dielectric exhibits large gate leakage current ͑J g ͒ due to Ge diffusion into the HfO 2 layer.…”

mentioning

confidence: 99%

Improved interface properties of Ge metal-oxide-semiconductor capacitor with TaTiO gate dielectric by using in situ TaON passivation interlayer

Jiang

Liu

et al. 2011

Applied Physics Letters

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TaON is in situ formed as a passivating interlayer in Ge metal-oxide-semiconductor (MOS) capacitors with high-k TaTiO gate dielectric fabricated simply by alternate sputtering of Ta and Ti. Also, postdeposition annealing is performed in wet N2 to suppress the growth of unstable GeOx at the Ge surface. As a result, excellent electrical properties of the Ge MOS devices are demonstrated, such as high equivalent dielectric constant (22.1), low interface-state density (7.3×1011 cm−2 eV), small gate leakage current (8.6×10−4 A cm−2 at Vg−Vfb=1 V), and high device reliability. Transmission electron microscopy and x-ray photoelectron spectroscopy support that all these should be attributed to the fact that the nitrogen barrier in the TaON interlayer can effectively block the interdiffusions of Ge and Ta, and the wet-N2 anneal can significantly suppress the growth of unstable low-k GeOx.

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Electrical characteristics of highly reliable ultrathin hafnium oxide gate dielectric

Cited by 221 publications

References 7 publications

Composition and crystallography dependence of the work function: Experiment and calculations of Pt-Al alloys

Composition and crystallography dependence of the work function: Experiment and calculations of Pt-Al alloys

Local oxidation nanolithography on Hf thin films using atomic force microscopy (AFM)

Improved interface properties of Ge metal-oxide-semiconductor capacitor with TaTiO gate dielectric by using in situ TaON passivation interlayer

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