Atomic Layer Deposition of Gadolinium Aluminate using Gd(iPrCp)3, TMA, and O3 or H2O

Adelmann, Christoph; Pierreux, Dieter; Swerts, Johan; Dewulf, Daan; Hardy, An; Tielens, Hilde; Franquet, Alexis; Brijs, Bert; Moussa, Alain; Conard, Thierry; Bael, Marlies K. Van; Maes, Jan Willem; Jurczak, M.; Kittl, J. A.; Elshocht, Sven Van

doi:10.1002/cvde.200906833

Cited by 27 publications

(40 citation statements)

References 46 publications

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“…Instead, we suggest that H 2 O is sorbed by the hygroscopic layer and results in additional precursor reactions during subsequent Gd-and Al-pulses (often referred to as "a CVD component"). The moisture sensitivity is composition dependent: uniform layers can be deposited to ∼75% Gd using H 2 O (see Figure 1(d)), but for layers with a higher Gdcontent and in the limit pure Gd 2 O 3 the non-uniformity strongly increased (27 From this point of view, the use of O 3 seems a viable alternative for the deposition of Gd 2 O 3 and Gd-rich GdAlO x layers. However, the O 3 process results in a significantly higher carbon level than the H 2 O-based process (see Figure 2(a)), resulting in a higher leakage current density (Figure 2(b)).…”

Section: Resultsmentioning

confidence: 94%

(Invited) Rare Earth Materials for Semiconductor Applications

Elshocht¹,

Adelmann²,

Popovici³

et al. 2010

ECS Trans.

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Rare earth based oxides are researched for logic and memory semiconductor applications. Their hygroscopic nature and tendency to form silicates make them a challenging class of materials in respect of processing and stability. Using LaAlO 3 , LuAlO 3 , and GdAlO 3 we have explored the impact of the oxidant, H 2 O or O 3 , during deposition, their stability when exposed to air, and their stability towards silicate formation. We show that the rare earth content of the material has a significant impact on the uniformity of the process using water-based atomic layer deposition as well as on the material stability during air exposure. We also describe silicate formation for these materials and demonstrate that an oxidation process can be used to make silicate layers with well-controlled composition.

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Section: Resultsmentioning

confidence: 94%

(Invited) Rare Earth Materials for Semiconductor Applications

Elshocht¹,

Adelmann²,

Popovici³

et al. 2010

ECS Trans.

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“…[24] For Gd-doped HfO 2 , no variation of the dopant content throughout the film thickness is visible, whereas for Aldoped HfO 2 , the Al dopants diffused to the interfacial region. [24] It is worth noting that different precursors and oxygen sources were used for the ALD depositions, so that different impurity levels [25,26] or microstructures [27] cannot be excluded, which may affect the distribution of the dopant atoms. [24] It is worth noting that different precursors and oxygen sources were used for the ALD depositions, so that different impurity levels [25,26] or microstructures [27] cannot be excluded, which may affect the distribution of the dopant atoms.…”

Section: Chemical Compositionmentioning

confidence: 99%

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

Richter

Schenk

Park

et al. 2017

Adv Elect Materials

151

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a wealth of different elements from the periodic table [7][8][9] have since exhibited ferroelectric properties. In their original publication, Böscke et al. [10] used ≈10 nm thick films of Si:HfO 2 and found the electrical behavior to evolve from paraelectric (PE) to ferroelectric (FE) and antiferroelectriclike to paraelectric again with a continuous increase in the Si dopant concentration. A similar electric evolution has also been shown for aluminum doping [11] and for (Hf,Zr)O 2 . [6,12] For the latter, an advanced understanding of the phase stabilization could be established, assisted in part by the very wide concentration window over which the changes occur. Ab initio calculations [13] interrogated the impact of surface energy in this system, revealing a phase transition from monoclinic pure HfO 2 to orthorhombic Hf 0.5 Zr 0.5 O 2 to tetragonal pure ZrO 2 for 10 nm film thickness, which aligns well the experimental observations. Moreover, inclusion of an electric field effect explained the antiferroelectriclike polarization hysteresis of pure ZrO 2 as the result of a fieldinduced phase transition from a nonpolar tetragonal to a polar orthorhombic phase. [6,13,14] Thus, instead of the term antiferroelectricity, field-induced ferroelectricity (FFE) is becoming a more precise and commonly used way to describe this behavior. While Si:HfO 2 and Al:HfO 2 have quickly been used in applications such as ferroelectric field effect transistors in 28 nm technology [15,16] and 3D capacitors, [17] basic material studies of doped ferroelectric HfO 2 have lagged those of the (Hf,Zr) O 2 system. By exploring a wide Si concentration range in fine steps, this work aims to gain insight into the phase transformations that occur in a doped HfO 2 system. Results and Discussion Impact of Annealing ConditionsAs a first step, planar capacitor stacks (Figure 1) with ≈36 nm thick HfO 2 films are deposited using a 22:1 HfO 2 :SiO 2 cycle ratio. As shown later, this results in a Si content that is slightly higher than the one that has produced the highest remanent polarization P r values in this study (Figure 7). As visible in Figure 2, the P r (measured under an electric field of 4 MV cm −1 and 10 kHz) increases for anneals at higher temperatures.Silicon doped hafnium oxide was the material used in the original report of ferroelectricity in hafnia in 2011. Since then, it has been subject of many further publications including the demonstration of the world's first ferroelectric field-effect transistor in the state-of-the-art 28 nm technology. Though many studies are conducted with a strong focus on application in memory devices, a comprehensive study on structural stability in these films remains to be seen. In this work, a film thickness of about 36 nm, instead of the 10 nm used in most previous studies, is utilized to carefully probe how the concentration range impacts the evolution of phases, the dopant distribution, the field cycling effects, and their interplay in the macroscopic ferroelectric response of the films. Si:HfO 2 appear...

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“…The observation that the C concentration is not highest in the ALD film deposited at 140 8C is at odds with the GATR-FTIR data, which showed additional C-related vibrational modes. This discrepancy can be resolved if the vibrational modes did not stem from the formation of oxycarbonates during deposition, [53] but from reactive surface (or near surface) adsorption of CO 2 or carboxyl groups from the atmosphere, as the low-temperature-grown ALD films show low density. [54] This interpretation is further upheld by the post-deposition anneal behavior of the low-temperaturegrown ALD films at 400 8C in an inert N 2 atmosphere.…”

mentioning

confidence: 97%

NiO Thin Films Synthesized by Atomic Layer Deposition using Ni(dmamb)₂ and Ozone as Precursors

Premkumar

Toeller

Adelmann

et al. 2012

Chemical Vapor Deposition

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NiO thin films are deposited by atomic layer deposition (ALD) from the Ni(dmamb) 2 (dmamb ¼ 1-dimethylamino-2-methyl-2-butanolate) precursor using O 3 as the oxidizer. The films are analyzed for wafer uniformity, structure, composition, morphology, microstructure, and homogeneity. The Ni(dmamb) 2 half-cycle shows an initial rapid partial saturation followed by slower further adsorption. By contrast, the O 3 half-cycle shows good saturation behavior. In the studied deposition temperature range for ALD, the films are polycrystalline with negligible amounts of carbon in the films. Furthermore, the films are homogeneous in thickness and composition, demonstrating that high-quality NiO films can be deposited by ALD from Ni(dmamb) 2 .

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Atomic Layer Deposition of Gadolinium Aluminate using Gd(ⁱPrCp)₃, TMA, and O₃ or H₂O

Cited by 27 publications

References 46 publications

(Invited) Rare Earth Materials for Semiconductor Applications

(Invited) Rare Earth Materials for Semiconductor Applications

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

NiO Thin Films Synthesized by Atomic Layer Deposition using Ni(dmamb)₂ and Ozone as Precursors

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Atomic Layer Deposition of Gadolinium Aluminate using Gd(iPrCp)3, TMA, and O3 or H2O

Cited by 27 publications

References 46 publications

(Invited) Rare Earth Materials for Semiconductor Applications

(Invited) Rare Earth Materials for Semiconductor Applications

Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

NiO Thin Films Synthesized by Atomic Layer Deposition using Ni(dmamb)2 and Ozone as Precursors

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Atomic Layer Deposition of Gadolinium Aluminate using Gd(ⁱPrCp)₃, TMA, and O₃ or H₂O

NiO Thin Films Synthesized by Atomic Layer Deposition using Ni(dmamb)₂ and Ozone as Precursors