Characterization of Hf0.3Al0.7OxFabricated by Atomic-Layer-Deposition Technique Using Monoenergetic Positron Beams

Uedono, Akira; Goto, Masakazu; Higuchi, Kohei; Shiraishi, Kenji; Yamabe, Kikuo; Kitajima, Hiroshi; Mitsuhashi, Riichiro; Horiuchi, Atsushi; Torii, Kazuyoshi; Arikado, T.; Suzuki, Ryoichi; Ohdaira, Toshiyuki; Yamada, Keiichi

doi:10.1143/jjap.43.7848

Cited by 8 publications

(9 citation statements)

References 5 publications

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“…For all samples, the diffusion length of positrons in the HfSiO x film was below 1 nm, suggesting that almost all positrons annihilated from the trapped state in the HfSiO x film. 18,19,23 The derived S for the HfSiO x film from the fitting was almost the same as S obtained at E Х 1 keV. Thus, we concluded that the change in the S value at E Х 1 keV was due to the change in the momentum distribution of electrons in HfSiO x , before and after PDA.…”

Section: Resultssupporting

confidence: 67%

“…[14][15][16][17][18] For thin high-k films, the size of the open volumes detected by positron annihilation has been found to be strongly correlated with MOS electrical properties. 19 In the present study, we used monoenergetic positron beams to study the effects of annealing on the open volumes in thin HfSiO x and HfAlO x films fabricated on Si substrates.…”

Section: Introductionmentioning

confidence: 99%

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Annealing properties of open volumes in HfSiOx and HfAlOx gate dielectrics studied using monoenergetic positron beams

Uedono

Ikeuchi

Yamabe

et al. 2005

Journal of Applied Physics

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Thin Hf0.6Si0.4Ox and Hf0.3Al0.7Ox films fabricated by metal-organic chemical-vapor deposition and atomic-layer-deposition techniques were characterized using monoenergetic positron beams. Measurements of the Doppler broadening spectra of annihilation radiation and the lifetime spectra of positions indicated that positrons annihilated from the trapped state by open volumes that exist intrinsically in amorphous structures of the films. For HfSiOx, the mean size of the open volumes and their size distribution decreased with increasing postdeposition annealing (PDA) temperature. For HfAlOx, although the overall behavior of the open volumes in response to annealing was similar to that for HfSiOx, PDA caused a separation of the mean size of the open volumes. When this separation occurred, the value of the line-shape parameter S increased, suggesting an oxygen deficiency in the amorphous matrix. This fragmentation of the amorphous matrix can be suppressed by decreasing the annealing time.

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Section: Resultssupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Annealing properties of open volumes in HfSiOx and HfAlOx gate dielectrics studied using monoenergetic positron beams

Uedono

Ikeuchi

Yamabe

et al. 2005

Journal of Applied Physics

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“…It has been shown by positron annihilation experiments that actual a-Hf x Al 1−x O y and a-Hf x Si 1−x O y films have large open spaces in their amorphous structures. 50,51 Such large pore with a radius larger than 5 Å does not exist in our a-HfO 2 models, and this could be the reason for the difference between theoretical and experimental densities of a-HfO 2 . Ikeda et al reported that a-HfO 2 and a-Hf x Si 1−x O y models with a large pore have been generated and investigated by the melt-and-quench first-principles MD simulations using the fixed unit cell during the MD simulations.…”

Section: B Amorphous Hfomentioning

confidence: 81%

Dielectric constants of amorphous hafnium aluminates: First-principles study

et al. 2007

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Amorphous model structures of hafnium aluminate having a Hf content of 0.2 ͑a-Hf 0.2 Al 0.8 O 1.6 ͒, alumina ͑a-Al 2 O 3 ͒, and hafnia ͑a-HfO 2 ͒ are theoretically generated, and dielectric responses of the amorphous model structures are studied by the first-principles method. The models have corner, edge, and face shared AlO n ͑n =4-6͒ and HfO n ͑n =5-8͒ polyhedra, and the a-Hf 0.2 Al 0.8 O 1.6 model structures are phase separated at the atomistic level, having Al 2 O 3 and HfO 2 domains. Calculated dielectric constants of the models increase with increasing Hf content, and the dielectric constant increase is dominated by the lattice polarization contribution to the dielectric constant. We found that low-frequency phonon modes having a frequency less than 200 cm −1 largely contribute to the high lattice dielectric constant and that inter-HfO 2 domain vibrations and vibration of atoms in distorted metal-oxygen polyhedra are dominant in the modes.

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“…We used a monoenergetic positron beam to measure the Doppler broadening spectra of annihilation radiation for the samples as a function of incident positron energy E [13][14][15][16]. For each E, a spectrum with 1×10…”

Section: Methodsmentioning

confidence: 99%

“…Point defects in transition-metal oxides have been investigated by using positron annihilation [5][6][7][8][9][10][11][12], and the results show that positrons are a useful probe for studying vacancy-type defects in such materials. Thin high-k dielectrics deposited on Si substrates were characterized also using monoenergetic positron beams [13][14][15][16]. In the present study, we used this technique to probe open volumes in thin HfAlO x and HfSiO x films.…”

mentioning

confidence: 99%

Study of high‐k gate dielectrics by means of positron annihilation

Uedono

Naito

Otsuka

et al. 2007

Phys. Status Solidi (c)

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PACS 77.55.+f, 78.70.Bj High-dielectric constant (high-k) gate materials, such as HfSiO x and HfAlO x , fabricated by atomic-layerdeposition techniques were characterized using monoenergetic positron beams. Measurements of the Doppler broadening spectra of annihilation radiation and the lifetime spectra of positrons indicated that positrons annihilated from the trapped state by open volumes that exist intrinsically in amorphous structures of the films. The size distributions of the open volumes and the local atomic configurations around such volumes can be discussed using positron annihilation parameters, and they were found to correlate with the electrical properties of the films. We confirmed that the positron annihilation is useful technique to characterize the matrix structure of amorphous high-k materials, and can be used to determine process parameters for the fabrication of high-k gate dielectrics. 1 Introduction According to the international technology roadmap for semiconductors [1], the technology node for mass production of LSI devices will reach the 45-nm level in 2010; as a result, the need to replace SiO 2 with high-dielectric (high-k) materials will be indispensable for fabrication of metal-oxidesemiconductor field effect transistors (MOSFETs). Among many candidates for high-k materials, hafnium (Hf) based oxides (such as HfAlO x and HfSiO x ) have advantages such as a moderately high dielectric constant and high thermal stability in contact with Si [2,3]. Although the electric properties of MOS using metal oxides have been intensively studied, behaviour of the metal oxides during device processing is not fully understood. This might be due to a lack of techniques to characterize very thin films (≤5 nm). Positron annihilation is one established technique for investigating defects in materials [4]. Point defects in transition-metal oxides have been investigated by using positron annihilation [5][6][7][8][9][10][11][12], and the results show that positrons are a useful probe for studying vacancy-type defects in such materials. Thin high-k dielectrics deposited on Si substrates were characterized also using monoenergetic positron beams [13][14][15][16]. In the present study, we used this technique to probe open volumes in thin HfAlO x and HfSiO x films.

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Characterization of Hf_0.3Al_0.7O_xFabricated by Atomic-Layer-Deposition Technique Using Monoenergetic Positron Beams

Cited by 8 publications

References 5 publications

Annealing properties of open volumes in HfSiOx and HfAlOx gate dielectrics studied using monoenergetic positron beams

Annealing properties of open volumes in HfSiOx and HfAlOx gate dielectrics studied using monoenergetic positron beams

Dielectric constants of amorphous hafnium aluminates: First-principles study

Study of high‐k gate dielectrics by means of positron annihilation

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