Robustness of ultrathin aluminum oxide dielectrics on Si(001)

Copel, M.; Cartier, E.; Gusev, Evgeni; Guha, Supratik; Bojarczuk, N. A.; Poppeller, M.

doi:10.1063/1.1367902

Cited by 122 publications

(87 citation statements)

References 16 publications

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“…It is suggested that the amorphous Al 2 O 3 phase becomes metastable with respect to a crystalline alumina polymorph, due the nanometer size scale of the film/substrate combination. Since some of the uses for ALD Al 2 O 3 films include gate oxide for electronics, 3,4 protective barriers, 5 as well as potential coatings in energy materials, [6][7][8][9][10] it is critical to characterize these coatings on the nanoscale. For example, in the case of energy materials, there are recent reports of enhanced stability and extended cycling of Li-ion battery nanomaterials coated with ALD Al 2 O 3 thin films, [6][7][8][9][10] 9 This work assumes that the Al 2 O 3 coating is amorphous, as would be expected.…”

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confidence: 99%

Growth of crystalline Al2O3 via thermal atomic layer deposition: Nanomaterial phase stabilization

2014

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We report the growth of crystalline Al2O3 thin films deposited by thermal Atomic Layer Deposition (ALD) at 200 °C, which up to now has always resulted in the amorphous phase. The 5 nm thick films were deposited on Ga2O3, ZnO, and Si nanowire substrates 100 nm or less in diameter. The crystalline nature of the Al2O3 thin film coating was confirmed using Transmission Electron Microscopy (TEM), including high-resolution TEM lattice imaging, selected area diffraction, and energy filtered TEM. Al2O3 coatings on nanowires with diameters of 10 nm or less formed a fully crystalline phase, while those with diameters in the 20–25 nm range resulted in a partially crystalline coating, and those with diameters in excess of 50 nm were fully amorphous. We suggest that the amorphous Al2O3 phase becomes metastable with respect to a crystalline alumina polymorph, due to the nanometer size scale of the film/substrate combination. Since ALD Al2O3 films are widely used as protective barriers, dielectric layers, as well as potential coatings in energy materials, these findings may have important implications.

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Growth of crystalline Al2O3 via thermal atomic layer deposition: Nanomaterial phase stabilization

2014

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“…Al 2 O 3 is a well-known good oxygen diffusion barrier that may protect the Si surface from oxidation, 10,11 and Al 2 O 3 is thermodynamically stable in contact with Si. Similar to SiO 2 , Al 2 O 3 is also a good glass former; thus, if alloyed with ZrO 2 and HfO 2 , their amorphous structure can be stabilized during high temperature annealing.…”

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confidence: 99%

Growth and characterization of Hf–aluminate high-k gate dielectric ultrathin films with equivalent oxide thickness less than 10 Å

Lee

Wong

Chan

et al. 2003

Journal of Applied Physics

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Ultrathin amorphous Hf-aluminate ͑Hf-Al-O͒ films have been deposited on p-type ͑100͒ Si substrates by pulsed-laser deposition using a composite target containing HfO 2 and Al 2 O 3 plates. Transmission electron microscopy observation of Hf-Al-O films showed that the amorphous structure of Hf-Al-O films was stable under rapid thermal annealing at temperatures up to at least 1000°C. Capacitance-voltage measurement of a 38 Å Hf-Al-O film revealed that the relative permittivity of the film was about 16. Such a film showed very low leakage current density of 4.6ϫ10 Ϫ3 A/cm 2 at 1 V gate bias. The Hf-Al-O film under optimized condition did not show any significant interfacial layer at the interface and an equivalent oxide thickness of less than 10 Å has been achieved. The formation of Hf-O and Al-O bonds in the film was revealed by x-ray photoelectron spectroscopy. © 2003 American Institute of Physics. ͓DOI: 10.1063/1.1554764͔A gate dielectric with a relative permittivity higher than that of SiO 2 is required to meet the next generation complementary metal-oxide-semiconductor ͑MOS͒ technology requirement. [1][2][3] Recent publications show that HfO 2 and ZrO 2 as well as their silicates are becoming leading candidates for high-k gate dielectric application due to their thermodynamic stability in contact with Si. 4 -9 However, due to the weakness as an oxygen diffusion barrier of HfO 2 and ZrO 2 , formation of interfacial SiO 2 rich layer in contact with Si substrate or polysilicon gate material is still a problem affecting the application. Formation of silicide at the interface without oxygen is another serious problem.Al 2 O 3 is a well-known good oxygen diffusion barrier that may protect the Si surface from oxidation, 10,11 and Al 2 O 3 is thermodynamically stable in contact with Si. Similar to SiO 2 , Al 2 O 3 is also a good glass former; thus, if alloyed with ZrO 2 and HfO 2 , their amorphous structure can be stabilized during high temperature annealing. 12,13 In addition, Al 2 O 3 has a large band gap ͑8.8 eV͒ and large band offset with Si. To take advantage of both HfO 2 and Al 2 O 3 , it is desirable to make multicomponent MAl x O y ͑MϭHf, Zr͒ films with high dielectric constant that are thermodynamically stable in contact with Si. Recent results on aluminates of Zr ͑Zr-Al-O͒ indicate that such material system exhibits encouraging gate dielectric properties. 12,13 Van Dover and co-workers have reported Zr 0.62 Al 0.38 O 1.8 thin film in which the crystallinity starts to appear at 850°C. 14 Accommodation of Al 2 O 3 layer with HfO 2 films in order to increase the interfacial stability with Si has been reported recently, 8,9 and some thermal stability studies on Hf-Al-O films have also been reported recently. 15 Electrical properties such as electron trapping and band alignment in amorphous Hf-Al-O have also been reported. 16,17 However, the understanding of thermodynamic stability and interfacial structure of the Hf-Al-O thin film is still limited. In this article we report the synthesis and characterization of ...

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“…Many experimental studies of high-k materials such as aluminum oxide (Al 2 O 3 ), hafnium oxide (HfO 2 ), and zirconium oxide (ZrO 2 ) grown by atomic layer deposition (ALD) have been reported. [4][5][6][7][8][9][10][11][12][13][14] The ALD technique can control the uniformity and thickness of films on substrate surfaces at an atomic scale. 15,16 The important thing for the ALD process is the initial reaction between the molecule and surface, because it determines the high-k/surface interface structure.…”

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confidence: 99%

Reaction of Tri-methylaluminum on Si (001) Surface for Initial Aluminum Oxide Thin-Film Growth

Kim¹,

Kim²,

Jeong³

et al. 2010

Bulletin of the Korean Chemical Society

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We studied the reaction of tri-methylaluminum (TMA) on hydroxyl (OH)-terminated Si (001) surfaces for the initial growth of aluminum oxide thin-films using density functional theory. TMA was adsorbed on the oxygen atom of OH due to the oxygen atom's lone pair electrons. The adsorbed TMA reacted with the hydrogen atom of OH to produce a di-methylaluminum group (DMA) and methane with an energy barrier of 0.50 eV. Low energy barriers in the range of 0 -0.11 eV were required for DMA migration to the inter-dimer, intra-dimer, and inter-row sites on the surface. A unimethylaluminum group (UMA) was generated at each site with low energy barriers in the range of 0.21 -0.25 eV. Among the three sites, the inter-dimer site was the most probable for UMA formation.

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Robustness of ultrathin aluminum oxide dielectrics on Si(001)

Abstract: Articles you may be interested inThermal annealing effects on the structure and electrical properties of Al 2 O 3 gate dielectrics on fully depleted SiGe on insulator

Cited by 122 publications

References 16 publications

Growth of crystalline Al2O3 via thermal atomic layer deposition: Nanomaterial phase stabilization

Growth of crystalline Al2O3 via thermal atomic layer deposition: Nanomaterial phase stabilization

Growth and characterization of Hf–aluminate high-k gate dielectric ultrathin films with equivalent oxide thickness less than 10 Å

Reaction of Tri-methylaluminum on Si (001) Surface for Initial Aluminum Oxide Thin-Film Growth

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