Nucleation of atomic-layer-deposited HfO2 films, and evolution of their microstructure, studied by grazing incidence small angle x-ray scattering using synchrotron radiation

Green, Martin L.; Allen, Andrew J.; Li, Xiang; Wang, Junling; Ilavský, Ján; Delabie, Annelies; Puurunen, Riikka L.; Brijs, Bert

doi:10.1063/1.2164417

Cited by 14 publications

(15 citation statements)

References 17 publications

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“…For the ALD of HfO 2 or ZrO 2 thin films, a Volmer-Weber type growth was observed in previous studies, [58][59][60] and the accordingly expected tensile stress was experimentally confirmed in ferroelectric doped HfO 2 and Hf 0.5 Zr 0.5 O 2 films. [27,61,62] During the heating phase of the in situ XRD experiment, the tensile strain should decrease since the TEC of the Si substrate is smaller than that of HfO 2 .…”

Section: Wwwadvelectronicmatdesupporting

confidence: 67%

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction

Park

Chung

Schenk

et al. 2018

Adv Elect Materials

100

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crystalline phase in doped HfO 2 thin film. [17,18] However, this phase cannot be observed in the phase diagram of bulk HfO 2 and ZrO 2 , [19,20] even when doped with elements that are used in the thin film counterparts. [21] Therefore, multiple factors were suggested as origin of the stabilization of the ferroelectric phase. Materlik et al. suggested that the o-phase can be stabilized due to surface energy effects, [22] and Park et al. comprehensively examined the surface energy model and their experimental observations. [23] In the latter study, it was confirmed that the o-phase can be stabilized within the nuclei formed during the atomic layer deposition (ALD) process, but the interface/grain boundary effect is not sufficient to stabilize the o-phase within the final grain size after annealing. [23] Therefore, it was suggested that the crystalline phase of the initial nuclei can remain even after crystallization, implying that the phase transformation to the monoclinic phase (m-phase, space group: P2 1 /c) can be kinetically suppressed. [23,24] Stress in thin films was also suggested as a possible origin, [1,25,26] and Shiraishi et al. experimentally proved that the polymorphism of Hf 0.5 Zr 0.5 O 2 thin films is strongly affected by the thermal expansion coefficient (TEC) of the used substrate. [27] However, the detailed mechanism of the formation of the unexpected o-phase is not yet resolved.It is generally known that the structure and electrical properties of perovskite ferroelectrics are strongly coupled. [28][29][30] The ferroelectric properties of doped HfO 2 thin films are also believed to be determined by their crystalline structure. ParkThe ferroelectricity in fluorite oxides has gained increasing interest due to its promising properties for multiple applications in semiconductor as well as energy devices. The structural origin of the unexpected ferroelectricity is now believed to be the formation of a non-centrosymmetric orthorhombic phase with the space group of Pca2 1 . However, the factors driving the formation of the ferroelectric phase are still under debate. In this study, to understand the effect of annealing temperature, the crystallization process of doped HfO 2 thin films is analyzed using in situ, high-temperature X-ray diffraction. The change in phase fractions in a multiphase system accompanied with the unit cell volume increase during annealing could be directly observed from X-ray diffraction analyses, and the observations give an information toward understanding the effect of annealing temperature on the structure and electrical properties. A strong coupling between the structure and the electrical properties is reconfirmed from this result.

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Section: Wwwadvelectronicmatdesupporting

confidence: 67%

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction

Park

Chung

Schenk

et al. 2018

Adv Elect Materials

100

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“…Recently, several researchers have reported XRR analysis on initial growth in ALD. [19,20] Initial growth in the ALD of HfO 2 on two different surfaces, chemical SiO x and H-terminated Si, has been investigated using synchrotron radiation X-ray scattering and reflectivity, together with RBS. [20] Recently, we reported the PE-ALD of Co using CoCp 2 and NH 3 plasma as a precursor and a reactant, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…[19,20] Initial growth in the ALD of HfO 2 on two different surfaces, chemical SiO x and H-terminated Si, has been investigated using synchrotron radiation X-ray scattering and reflectivity, together with RBS. [20] Recently, we reported the PE-ALD of Co using CoCp 2 and NH 3 plasma as a precursor and a reactant, respectively. [4] Highly pure Co films were obtained with very low 3 , however we observed good film quality of Co only from PE-ALD using NH 3 plasma reactant.…”

Section: Introductionmentioning

confidence: 99%

“…So far, analysis techniques such as Rutherford backscattering (RBS), ellipsometry, and X-ray photoelectron spectroscopy (XPS) have been used for the study of initial growth during ALD. [17][18][19][20] Because any single analysis tool for the study of initial growth has limitations, such as thickness resolution and complicated model dependency, complementary techniques would be needed. XRR enables the simultaneous acquirement of various physical properties such as thickness, density, and roughness.…”

Section: Introductionmentioning

confidence: 99%

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Initial Stage Growth during Plasma‐Enhanced Atomic Layer Deposition of Cobalt

Lee

Park

Baik

2012

Chemical Vapor Deposition

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The initial growth of Co thin films during plasma-enhanced atomic layer deposition (PE-ALD) is investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), and synchrotron radiation X-ray reflectivity (SR-XRR). For the PE-ALD of Co, CoCp 2 and NH 3 plasma were used as precursor and reactant, respectively. From XRR simulation, the growth rate at the initial stage of growth did not linearly increase with growth cycles, showing deviation from ideal ALD growth. The low density of PE-ALD-produced Co film up to 100 cycles is observed from XRR and confirmed by AFM and SEM results. The growth behavior of Co is explained by island growth under substrate-inhibited growth mode.

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“…This deposition selectivity was attributed to the incubation time of HfO 2 deposition on the Cu surface [91]. In fact, surface-dependent growth has been reported several times in ALD [92][93][94][95]. Moreover, the dependence of ALD incubation time on the substrate has been reported many times [96][97][98][99].…”

Section: Inherent Surface Reactivitymentioning

confidence: 92%

Nanopatterning by Area‐Selective Atomic Layer Deposition

Lee

Bent

2011

Atomic Layer Deposition of Nanostructured Materials

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In conventional device fabrication, patterning is a top-down process based largely on photolithography and etching and is a main bottleneck for device downscaling. Atomic layer deposition (ALD) can provide an alternative bottom-up method for patterning when used in conjunction with self-assembled materials and selective chemistries. As presented in previous chapters, ALD is a powerful technique for depositing thin films for nanoscale device fabrication thanks to its excellent conformality, atomic scale thickness controllability, and large-area uniformity. Film growth controlled by surface reactions is one of the inherent properties of ALD. Because in an ideal ALD process, all of the precursors used for ALD react with each other only at the surface, highly conformal films can be deposited even inside complex 3D structures. By taking advantage of this inherent surface reaction property, ALD can be utilized for patterning based on a bottom-up process. In the following chapter, selective deposition methods will be presented. The contents include the surface modification techniques that are employed to exploit the surface reaction properties of ALD and related patterning processes with reported results. Concept of Area-Selective Atomic Layer DepositionFilm growth by ALD begins with formation of nuclei through a reaction of precursor molecules and surface species. Once nuclei are formed on a surface, the growth of the film may proceed by growth and coalescence of the nuclei, whereas if no nucleation occurs no film will be deposited. Therefore, the deposition characteristics of ALD strongly depend on the surface properties of the substrate. For example, in many cases, the nucleation of ALD is easy on hydrophilic OH-terminated substrates (e.g., SiO 2 ), while it is difficult on hydrophobic H-terminated surfaces (e.g., Si) [1][2][3][4]. Similarly, a nucleation delay in ALD, typically called the incubation time, is due to difficulty of nucleation at the surface. The nucleation delay and the variability of the growth characteristics depending on the surface can be problematic in typical thin

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Nucleation of atomic-layer-deposited HfO2 films, and evolution of their microstructure, studied by grazing incidence small angle x-ray scattering using synchrotron radiation

Abstract: Articles you may be interested inA general model for estimating the ordering of mesoporous film by grazing incidence small angle X-ray scattering

Cited by 14 publications

References 17 publications

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction

Initial Stage Growth during Plasma‐Enhanced Atomic Layer Deposition of Cobalt

Nanopatterning by Area‐Selective Atomic Layer Deposition

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Nucleation of atomic-layer-deposited HfO2 films, and evolution of their microstructure, studied by grazing incidence small angle x-ray scattering using synchrotron radiation

Abstract: Articles you may be interested inA general model for estimating the ordering of mesoporous film by grazing incidence small angle X-ray scattering

Cited by 14 publications

References 17 publications

Effect of Annealing Ferroelectric HfO2 Thin Films: In Situ, High Temperature X‐Ray Diffraction

Effect of Annealing Ferroelectric HfO2 Thin Films: In Situ, High Temperature X‐Ray Diffraction

Initial Stage Growth during Plasma‐Enhanced Atomic Layer Deposition of Cobalt

Nanopatterning by Area‐Selective Atomic Layer Deposition

Contact Info

Product

Resources

About

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction