HfO
                  2
           gate dielectric with 0.5 nm equivalent oxide thickness

Harris, H. R.; Choi, Kyusun; Mehta, Narendra; Chandolu, A.; Biswas, N.; Kipshidze, G.; Nikishin, S.; Gangopadhyay, Shubhra; Temkin, H.

doi:10.1063/1.1495882

Cited by 82 publications

(47 citation statements)

References 22 publications

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“…Leakage of both samples is roughly 10 −4 A/cm 2 in accumulation ͑V fb − 0.5 V = −0.70 V with Ag and −1.25 V without Ag͒, whereas the leakage of virtually identically processed 5 nm HfO 2 is 10 −2 A/cm 2 . 6 This indicates that the addition of silver does not make the dielectric notably leakier and is in line with similarly fabricated high-thin films.…”

supporting

confidence: 58%

“…5 The deposition of semiconductor device grade films of Al 2 O 3 and HfO 2 on Si is well established. 6,7 However, prior work on using noble metal nanoparticles to increase dielectric constants has focused primarily on polymer and glass dielectrics and processes that are not readily compatible with current integrated circuit fabrication. [8][9][10] Conversely, studies utilizing techniques similar to that used here have not focused explicitly on permittivity enhancement or dielectric properties.…”

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confidence: 99%

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Permittivity enhancement of aluminum oxide thin films with the addition of silver nanoparticles

Ravindran

Gangopadhyay

et al. 2006

Applied Physics Letters

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Multilayer reactive electron-beam evaporation of thin aluminum oxide layers with embedded silver nanoparticles ͑Ag-nps͒ has been used to create a dielectric thin film with an enhanced permittivity. The results show a frequency dependent increase of the dielectric constant . Overall stack of the control sample was found to be 7.7-7.4 in the 1 kHz-1 MHz range. This is in comparison with = 16.7-13.0 over the same frequency range in the sample with Ag-nps. ideally suited for use with n-and p-type Si over a range of doping levels. The drawback is that the intermediate dielectric constant of Al 2 O 3 limits the capacitance density compared with other high-dielectrics. It is worth noting at this point that the permittivity of metal nanoparticles has been theorized to be superior to that predicted by the classical electrostatic model. 4 This is explained considering the dipole behavior of nonspherical nanoparticles dispersed in a medium. Each nanoparticle dipole is recognized as behaving like a basic harmonic oscillator or dipole with a relaxation frequency. 5 The deposition of semiconductor device grade films of Al 2 O 3 and HfO 2 on Si is well established. 6,7 However, prior work on using noble metal nanoparticles to increase dielectric constants has focused primarily on polymer and glass dielectrics and processes that are not readily compatible with current integrated circuit fabrication. [8][9][10] Conversely, studies utilizing techniques similar to that used here have not focused explicitly on permittivity enhancement or dielectric properties. 11 The primary differences between the work presented here and earlier works on permittivity enhancement with nanoparticles are the manner in which the silver nanoparticles ͑Ag-nps͒ are deposited, the dielectric medium into which they dispersed, and the deposition and characterization of the film on Si substrates.A control set without Ag-nps and an experimental set with Ag-nps were fabricated. In each set, samples were prepared on both p-and p + -Si ͑100͒ with resistivities of 1-10 and 0.0030-0.00 70 ⍀ cm, respectively. The Si substrates were first cleaned with a modified Shiraki process to remove the native oxide and provide a clean, hydrogen passivated surface. 12,13 After drying under nitrogen, they were immediately transferred to a Kurt J. Lesker AXXIS e-beam evaporation system. From a base pressure of 5 ϫ 10 −7 torr, the substrates were heated to 50°C and oxygen was introduced at 5 SCCM ͑SCCM denotes cubic centimeter per minute at STP͒ and 5 ϫ 10 −5 torr. For control samples without silver, 8.73± 0.08 nm of Al 2 O 3 was then evaporated at 0.5 Å / s. For samples with incorporated Ag-nps, Al 2 O 3 , approximately 3 nm in thickness, was deposited and the chamber was again pumped down to 5 ϫ 10 −7 torr. An ultrathin layer of Ag-nps, about half a nanometer in nominal thickness, was deposited under high vacuum. Oxygen was reintroduced, and approximately 3 nm of Al 2 O 3 was again evaporated. This process was repeated until the film consisted of three layers of Al 2 O 3 with tw...

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confidence: 58%

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confidence: 99%

Permittivity enhancement of aluminum oxide thin films with the addition of silver nanoparticles

Ravindran

Gangopadhyay

et al. 2006

Applied Physics Letters

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“…10͒ is approximately two orders of magnitude lower that the simulated JVs based on direct tunneling 1 . While thinner EOT HfO 2 films have been demonstrated using e-beam technique, 7 such a low leakage current is unusual. This behavior could be explained similarly to the evolution of the CV characteristics of Fig.…”

Section: -6mentioning

confidence: 99%

“…6 However, for dielectric materials which evaporate stoichiometrically, the electron beam ͑e-beam͒ evaporation technique is a very costeffective way of investigating the basic chemical and electrical properties of high-k films, as well as providing a route for screening a wide range of potential high-k materials as suitable candidates for gate dielectric applications. 7 This technique could also help in discriminating between intrinsic properties of the dielectric material and extrinsic material issues such as impurity contamination.…”

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confidence: 99%

Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation

Cherkaoui

Monaghan

Negara

et al. 2008

Journal of Applied Physics

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High dielectric constant hafnium oxide films were formed by electron beam ͑e-beam͒ evaporation on HF last terminated silicon ͑100͒ wafers. We report on the influence of low energy argon plasma ͑ϳ70 eV͒ and oxygen flow rate on the electrical, chemical, and structural properties of metal-insulator-silicon structures incorporating these e-beam deposited HfO 2 films. The use of the film-densifying low energy argon plasma during the deposition results in an increase in the equivalent oxide thickness ͑EOT͒ values. We employ high resolution transmission electron microscopy ͑HRTEM͒, x-ray photoelectron spectroscopy ͑XPS͒, and medium energy ion scattering experiments to investigate and understand the mechanisms leading to the EOT increase. We demonstrate very good agreement between the interfacial silicon oxide thicknesses derived independently from XPS and HRTEM measurements. We find that the e-beam evaporation technique enabled us to control the SiO x interfacial layer thickness down to ϳ6 Å. Very low leakage current density ͑Ͻ10 −4 A / cm 2 ͒ is measured at flatband voltage +1 V into accumulation for an estimated EOT of 10.9Ϯ 0.1 Å. Based on a combined HRTEM and capacitance-voltage ͑CV͒ analysis, employing a quantum-mechanical CV fitting procedure, we determine the dielectric constant ͑k͒ of HfO 2 films, and associated interfacial SiO x layers, formed under various processing conditions. The k values are found to be 21.2 for HfO 2 and 6.3 for the thinnest ͑ϳ6 Å͒ SiO x interfacial layer. The cross-wafer variations in the physical and electrical properties of the HfO 2 films are presented.

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“…However, Hafnium Dioxide (HfO 2 ) is attractive due to its high dielectric constant (22-25), relatively large band gap (5.8 eV) and thermodynamic stability in direct contact with silicon [1,2]. HfO 2 films prepared by sputtering, atomic layer deposition, pulse laser deposition, and electron beam evaporation had been widely studied [3][4][5][6]. However, the formation of interfacial layer, due to the oxidation of Si substrate during film fabrication and subsequent annealing, and the crystallization of HfO 2 films are still serious issues [7][8][9].…”

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Growth and characterization of UHV sputtering HfO2 film by plasma oxidation and low temperature annealing

Wang

et al. 2006

J Electroceram

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Ultra-thin (∼4.0 nm) HfO 2 films were fabricated by plasma oxidation of sputtered metallic Hf films with post low temperature annealing. Advantage of this fabrication process is that the pre-deposition of Hf metal can suppress the formation of interfacial layer between HfO 2 film and Si substrate. The as-deposited HfO 2 films were subsequently treated by rapid thermal annealing at different temperatures in N 2 to investigate the effects of thermal annealing on the physical and electrical properties of HfO 2 film. A SiO 2 -rich interface layer was observed after higher temperature rapid thermal annealing and the phase change of HfO 2 film from amorphous into crystalline occurred at about 700 • C. As a result of higher temperature annealing, effective dielectric constant and leakage current were significantly influenced by the formation of interface layer and the crystallization of HfO 2 film.complementary metal-oxide-semiconductor (CMOS) device. Several metal oxides with higher dielectric constant (k) in the range of 10-25, such as Al 2 O 3 (∼10) and La 2 O 3 (∼20), have been proposed as potential candidates for SiO 2 gate replacement. However, Hafnium Dioxide (HfO 2 ) is attractive due to its high dielectric constant (22-25), relatively large band gap (5.8 eV) and thermodynamic stability in direct contact with silicon [1, 2]. HfO 2 films prepared by sputtering, atomic layer deposition, pulse laser deposition, and electron beam evaporation had been widely studied [3-6]. However, the formation of interfacial layer, due to the oxidation of Si substrate during film fabrication and subsequent annealing, and the crystallization of HfO 2 films are still serious issues [7][8][9]. Recently, remote plasma oxidation has been performed to form the stoichiometric HfO 2 film, in which the oxygen radicals oxidize the Hf metal selectively other than Si substrate [10]. In comparison to rapid thermal annealing (RTA), plasma oxidation technique has advantages of suppressing the interfacial diffusion at the interface between HfO 2 film and Si substrate [11]. Plasma oxidation, using oxygen radicals to oxidize Hf metal at low temperatures, can maintain HfO 2 film in an amorphous phase with silicate interface, but it leads to both reduction of equivalent oxide thickness (EOT) and leakage current density (J g ) [12]. Rapid thermal annealing at elevated temperature can be used to densify the deposited oxide film and improve the properties of the films. However, uncontrolled formation of an interfacial oxide layer during annealing is undesirable and will increase the EOT.In this paper, we investigated the effects of post-deposition annealing of HfO 2 film (∼4 nm) on their interfacial, microstructural and electrical characteristics. As a result of higher temperature annealing, a SiO 2 -rich interface layer was observed. The phase transition of HfO 2 film from amorphous into crystalline occurred at about 700 • C. The formation of Springer

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HfO 2 gate dielectric with 0.5 nm equivalent oxide thickness

Cited by 82 publications

References 22 publications

Permittivity enhancement of aluminum oxide thin films with the addition of silver nanoparticles

Permittivity enhancement of aluminum oxide thin films with the addition of silver nanoparticles

Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation

Growth and characterization of UHV sputtering HfO2 film by plasma oxidation and low temperature annealing

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