Effect of nitrogen incorporation on the thermal stability of sputter deposited lanthanum aluminate dielectrics on Si (100)

Sivasubramani, P.; Kim, J.; Kim, M. J.; Gnade, Bruce E.; Wallace, Robert M.

doi:10.1063/1.2361170

Cited by 11 publications

(3 citation statements)

References 24 publications

(18 reference statements)

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“…[14][15][16][17][18] Out-diffusion of La in amorphous and polycrystalline La-based high-k dielectrics have been studied by Sivasubramani and co-workers. No Hf or Ta was detected in the Si substrate after deprocessing (data not shown).…”

Section: Resultsmentioning

confidence: 99%

Thermal stability, microstructure, and electrical properties of atomic layer deposited Hf₆Ta₂O₁₇ gate dielectrics

Triyoso¹,

Yu²,

Gregory³

et al. 2007

J. Mater. Res.

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The intent of this work is to investigate thermal stability, microstructure, and electrical properties of thin Hf 6 Ta 2 O 17 high-k gate dielectrics. X-ray diffraction and transmission electron microscopy analysis reveal that an as-deposited Hf 6 Ta 2 O 17 film is amorphous with a ∼1-nm interfacial layer. After a 1000°C anneal, the film is a mixture of orthorhombic-Hf 6 Ta 2 O 17 and monoclinic HfO 2 with a thicker interfacial layer. Uniform Hf and Ta Auger depth profiles are observed for as deposited and annealed films. Secondary ion mass spectrometry (SIMS) analysis shows Hf and Ta profiles are unchanged following the 1000°C anneal, indicating good thermal stability. There is, however, a clear indication of Si up-diffusion into Hf 6 Ta 2 O 17 , particularly after annealing at 1000°C. No Hf or Ta is found in the Si substrate. Well-behaved capacitance-voltage curves and low leakage current characteristics were obtained for Mo/ Hf 6 Ta 2 O 17 capacitors for as-deposited and 1000°C annealed films. A flatband voltage (V fb ) shift towards negative voltage is observed for the annealed film when compared to the as-deposited film, indicating the presence of more positive charge, or less negative charge. Furthermore, capacitance-voltage stress measurements were performed to study charge trapping behaviors. A smaller V fb shift is observed for as deposited (<10 mV) versus the 1000°C annealed (30-40 mV) Hf 6 Ta 2 O 17 , indicating more charge trapping after the high temperature anneal.

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Section: Resultsmentioning

confidence: 99%

Thermal stability, microstructure, and electrical properties of atomic layer deposited Hf₆Ta₂O₁₇ gate dielectrics

Triyoso¹,

Yu²,

Gregory³

et al. 2007

J. Mater. Res.

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“…It has been shown for amorphous LaAlO 3 films on Si that at a temperature of ~950 °C, the dielectric crystallizes, and significant amounts of La and Al diffuse into the Si. Only with significant nitridation (LaAlO x N y ) can the amorphous phase stability be improved, and La diffusion effectively be eliminated (23). We have demonstrated that for lanthanum silicate a nitridation anneal is unnecessary, as the amorphous phase is maintained after a 1000 °C, 10 sec N 2 RTA of ~1 nm EOT devices (13,24), as shown in the HRTEM image of Fig.…”

Section: Materials Properties Of Lanthanum Oxide and Silicate Thin Filmsmentioning

confidence: 93%

Overview of Materials Processing and Properties of Lanthanum-Based High-k Dielectrics

2007

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Lanthanum-based high-Κ dielectrics remain attractive for gate dielectric applications, in the forms of either lanthanum oxide, lanthanum silicate, or as a lanthanum addition to other dielectrics. Lanthanum oxide and silicate MIS devices have been reported to have EOT values as low as 0.5 nm under low temperature processing. After 1000 °C, 10 sec anneals consistent with dopant activation, lanthanum silicate is shown by cross-sectional TEM to remain in the amorphous phase, with no La diffusion into the Si substrate as measured by back side SIMS. Lanthanum addition to hafnium-based dielectrics is presently of interest for the purposes of increasing the dielectric constant, and for providing threshold voltage (V T ) control for obtaining band-edge nMOSFET device operation. A 400-500 mV reduction in V T is obtained using a lanthana cap layer on HfSiON, achieving band edge nMOSFETs with minimal mobility degradation.

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“…On an off-axis substrate, bombardment by all these species is decreased. [6][7][8][9] Oxide dielectric films can also be deposited by on-axis sputtering from a ceramic oxide target, [10][11][12] though anomalously high dielectric constants for well known materials such as Ta 2 O 5 have been attributed to quenched-in vacancies at high sputtering pressures. 3 Sputtering of dielectrics is an important research laboratory technique for the investigation of new candidate dielectric materials.…”

Section: Dielectric Response Of Tantalum Oxide Subject To Induced Ionmentioning

confidence: 99%

Dielectric response of tantalum oxide subject to induced ion bombardment during oblique sputter deposition

Barron

Noginov

Werder

et al. 2009

Journal of Applied Physics

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We describe the deposition of insulating tantalum oxide thin films under conditions of controlled ion bombardment, which can be achieved using reactive sputtering on 90° off-axis substrates with an applied substrate bias. Capacitive measurements of Ta2O5 deposited on unbiased off-axis substrates indicate low frequency dielectric constants as high as εr∼300. Low frequency loss tangents are high, tan δ>0.5, and have a pronounced frequency dependence. Deposition of the film off-axis with sufficient applied rf bias to the substrate (negative bias >−70 V) recovers the on-axis properties typical of Ta2O5, e.g., εr∼22 and tan δ∼0.02. The recovery of normal dielectric behavior is attributed to the ion bombardment of the growing film under substrate bias, similar to on-axis depositions but absent from depositions on off-axis substrates with no applied substrate bias. We suggest that insufficiently bombarded films develop a Maxwell–Wagner type polarization along columnar voids. The void structure and the associated dielectric response vary with distance from the sputtering source due to variations in ion density and angle from the sputtering source. A similar dielectric response is observed in depositions on on-axis substrates as a function of angle from the central sputter gun axis. Our results suggest that ion bombardment is necessary for good quality sputtered dielectric films but that a controlled Ar+ flux is essentially equivalent to the uncontrolled O2−/O2− flux of on-axis reactive sputtering.

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Effect of nitrogen incorporation on the thermal stability of sputter deposited lanthanum aluminate dielectrics on Si (100)

Cited by 11 publications

References 24 publications

Thermal stability, microstructure, and electrical properties of atomic layer deposited Hf₆Ta₂O₁₇ gate dielectrics

Thermal stability, microstructure, and electrical properties of atomic layer deposited Hf₆Ta₂O₁₇ gate dielectrics

Overview of Materials Processing and Properties of Lanthanum-Based High-k Dielectrics

Dielectric response of tantalum oxide subject to induced ion bombardment during oblique sputter deposition

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Effect of nitrogen incorporation on the thermal stability of sputter deposited lanthanum aluminate dielectrics on Si (100)

Cited by 11 publications

References 24 publications

Thermal stability, microstructure, and electrical properties of atomic layer deposited Hf6Ta2O17 gate dielectrics

Thermal stability, microstructure, and electrical properties of atomic layer deposited Hf6Ta2O17 gate dielectrics

Overview of Materials Processing and Properties of Lanthanum-Based High-k Dielectrics

Dielectric response of tantalum oxide subject to induced ion bombardment during oblique sputter deposition

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Thermal stability, microstructure, and electrical properties of atomic layer deposited Hf₆Ta₂O₁₇ gate dielectrics

Thermal stability, microstructure, and electrical properties of atomic layer deposited Hf₆Ta₂O₁₇ gate dielectrics