Effects of Interfacial Organic Layers on Nucleation, Growth, and Morphological Evolution in Atomic Layer Thin Film Deposition

Dube, Abhishek; Sharma, Manish; Paul, Frédéric; Ercius, Peter; Muller, David A.; Engstrom, J. R.

doi:10.1021/jp072264e

Cited by 38 publications

(52 citation statements)

References 40 publications

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“…Reported AS-ALD processes using polymers are summarized in Table 9.2 [39,54,55,[76][77][78][79][80][81][82][83]. In early studies, researchers investigated the blocking ability of polymer layers against various ALD systems.…”

Section: Polymersmentioning

confidence: 99%

“…Many early researchers employed this solution-based deposition as summarized in Table 9.3 because it is very simple as well as easy to form high-quality SAMs; in those studies, the SAMs fully coated the entire surface without patterns, allowing the efficacy of deactivation to be investigated [39-42, 45, 51, 52, 54, 60, 61]. For polymer film fabrication, spin coating has typically been used [39,54,55,[76][77][78][79][80][81][82][83]. In spin coating, a polymer is dissolved in an appropriate solvent, and the solution is dropped onto a surface undergoing rotation.…”

Section: Surface Modification Without Patterningmentioning

confidence: 99%

“…An ab initio study based on density functional theory (DFT) Si [64] has also shown that the reaction of several Ti and Zr precursors including tetrakis (dimethylamido)titanium (TDMAT), tetrakis(diethylamido)titanium (TDEAT), titanium tetramide (Ti(NH 2 ) 4 ), tetrakis(dimethylamido)zirconium (TDMAZ), and zirconium tetramide (Zr(NH 2 ) 4 ) has reactivity in the order OH > SH > NH 2 [67]. Dube et al investigated the growth mode of TiN ALD experimentally using TDMAT and NH 3 on SAMs with several different tail groups such as OH, NH 2 , and CH 3 , and found that the CH 3 -terminated surface much more effectively attenuated TiN growth than OH-and NH 2 -terminated surface, which was strongly dependent on the structure and thickness of SAMs possessing a CH 3 tail group [55,63].…”

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confidence: 99%

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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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Section: Polymersmentioning

confidence: 99%

Section: Surface Modification Without Patterningmentioning

confidence: 99%

mentioning

confidence: 99%

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Nanopatterning by Area‐Selective Atomic Layer Deposition

Lee

Bent

2011

Atomic Layer Deposition of Nanostructured Materials

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“…The ALD process for SAMs has been applied to deposition of metals such as Ti, Ru, Hf, and Pt. The complex, tetrakis(dimethylamido)titanium has been used to deposit Ti on SAMs with ÀOH, ÀNH 2 , and ÀCH 3 terminal groups [94][95][96]. A two-step-ALD process of Cu deposition on ÀCH 3 and ÀCOOH SAMs on silicon substrates has been reported in which the second step was followed by H 2 exposure.…”

Section: Atomic Layer Depositionmentioning

confidence: 99%

Issues and Challenges in Vapor-Deposited Top Metal Contacts for Molecule-Based Electronic Devices

Maitani

2011

Unimolecular and Supramolecular Electronics I

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Metal vapor deposition to form ohmic contacts is commonly used in the fabrication of organic electronic devices because of significant manufacturability advantages. In the case of single molecular layer devices, however, the extremely small thickness, typically ~1-2nm, presents serious challenges in achieving good contacts and device integrity. This review focuses on recent scientific aspects of metal vapor deposition on monolayer thickness molecular films, particularly self-assembled monolayers, ranging across mechanisms of metal nucleation, metal-molecular group interactions and chemical reactions, diffusion of metal atoms within and through organic films, and the correlations of these and other factors with device function. Results for both non-reactive and reactive metal deposition are reviewed. Finally, novel strategies are considered which show promise for providing highly reliable and durable metal/organic top contacts for use in metal-molecule-metal junctions for device applications.

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“…For ALD, it can be argued that the density and spatial distribution of active adsorption sites after each half cycle is more relevant concerning the evolution of thin film morphology. 6,7 In any event, regardless of interpretation, LbL growth is clearly preferred in cases where one wishes to produce a conformal thin film possessing the smallest thickness and smoothest topology.…”

Section: Introductionmentioning

confidence: 99%