Simulation of Mass Transport for Deposition in Via Holes and Trenches

Wulu, H. C.; Saraswat, Krishna C.; McVittie, J.P.

doi:10.1149/1.2085881

Cited by 40 publications

(28 citation statements)

References 15 publications

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“…At the corresponding surface interval, one out of three processes can occur: ͑i͒ The particle can undergo surface recombination with a loss probability r; ͑ii͒ the particle can react and contribute to the ALD process with a reaction probability s; and ͑iii͒ the particle can be reflected, assuming that the particle is emitted with a new random direction according to a cosine distribution. 5 For the reflected particle, the algorithm starts over, beginning with the calculation of the new trajectory and intersection point. If the new intersection point is at the entrance of the trench, the particle is considered lost and a new particle is generated ͑unless the stop condition has been met͒.…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

“…Pores require longer precursor exposure for the same AR compared to trenches and, as a rule of thumb, can be considered equivalent to trenches of double AR. 5 When speculating on achievable ARs for coating 3D structures, the simulations suggest that for the plasma-assisted ALD processes with low recombination loss, ARs of 30 should be relatively straightforward. That is, compared to the dose required to saturate a planar surface, a relatively small increase in exposure is needed to saturate the 3D structure ͑factor of 4 for r = 0.01 and AR = 30͒.…”

Section: ͓1͔mentioning

confidence: 99%

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Conformality of Plasma-Assisted ALD: Physical Processes and Modeling

Knoops

Langereis

Sanden

et al. 2010

J. Electrochem. Soc.

173

116

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. For plasma-assisted atomic layer deposition ͑ALD͒, reaching conformal deposition in high aspect ratio structures is less straightforward than for thermal ALD due to surface recombination loss of plasma radicals. To obtain a detailed insight into the consequences of this additional radical loss, the physical processes in plasma-assisted ALD affecting conformality were identified and investigated through Monte Carlo simulations. The conformality was dictated by the recombination probability r, the reaction probability s, and the diffusion rate of particles. When recombination losses play a role, the saturation dose depended strongly on the value of r. For the deposition profiles, a minimum at the bottom of trench structures was observed ͑before reaching saturation͒, which was more pronounced with larger values of r. In turn, three deposition regimes could be identified, i.e., a reaction-limited regime, a diffusion-limited regime, and a new regime that is recombination-limited. For low values of r, conformal deposition in high aspect ratio structures can still be achieved, as observed for several metal oxides, even for aspect ratios as large as 30. For high surface recombination loss probabilities, as appears to be the case for many metals, achieving a reasonable conformality becomes challenging, especially for aspect ratios Ͼ10.

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Section: Monte Carlo Simulationsmentioning

confidence: 99%

Section: ͓1͔mentioning

confidence: 99%

Conformality of Plasma-Assisted ALD: Physical Processes and Modeling

Knoops

Langereis

Sanden

et al. 2010

J. Electrochem. Soc.

173

116

View full text Add to dashboard Cite

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“…14,27,28 As long as the cosine re-emission pattern and Maxwell-Boltzmann distribution are assumed, the unusual deposition behavior of the Ti component for the low precursor solution injection rate shown in Fig. 5 cannot be explained.…”

Section: C438mentioning

confidence: 99%

“…27 The cosine re-emission occurs due to the interaction between the impinging molecules and surfaces. The interaction is so strong that the incoming molecules completely lose their memory of the incoming trajectory.…”

Section: C438mentioning

confidence: 99%

Study on the Step Coverage of Metallorganic Chemical Vapor Deposited TiO[sub 2] and SrTiO[sub 3] Thin Films

Jeon

et al. 2005

J. Electrochem. Soc.

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The growth behavior and step coverage of TiO 2 thin films deposited by liquid-delivery metallorganic chemical vapor deposition ͑MOCVD͒ at temperatures ranging from 410 to 490°C were investigated. The film growth rates were controlled by the gas phase thermal decomposition reaction of the precursors, and the reaction shows an apparent activation energy of ϳ90 kJ/mol. The gas phase thermal decomposition produced several intermediate precursor molecules with different sticking coefficients. The intermediate precursors played a crucial role in the film growth and step coverage change. As the growth rate decreases, the step coverage degrades, which can be explained by Langmuir's isothermal adsorption model of the precursors with the assumption of the various intermediate molecular structures of the precursors. The bulkier intermediate molecular structure of the precursor increases the steric hindrance between the previously adsorbed molecules and the impinging molecules so that the step coverage improves. The unusual step coverage of an MOCVD SrTiO 3 film previously observed for a low precursor injection rate was successfully explained using the results derived from the TiO 2 MOCVD and nonsticking property of the Ti-precursor molecules on the SrO surface.The ceramic thin films ͑Ba,Sr͒TiO 3 ͑BST͒, 1-4 SrTiO 3 ͑STO͒, 5 and Pb͑Zr,Ti͒O 3 6-8 deposited by metallorganic chemical vapor deposition ͑MOCVD͒ have been investigated by many researchers as capacitor materials of dynamic random access memories or ferroelectric random access memories. Considering the shrinking cell area of memory devices, these materials should be deposited on three-dimensional ͑3D͒ structures as contact holes. 9,10 The MOCVD method can produce these films with satisfactory growth rate, electrical properties, and conformal deposition over the severe 3D structures applicable to mass production. However, a nonuniform cation composition of the deposited film over a 3D contact hole has been reported even with the MOCVD technique when the contact hole diameter is below 150 nm. 11 In some cases, the films grew predominantly at the bottom corner of the contact hole, which is unusual. 11 To improve the thickness and composition uniformity of the multication oxide films, an understanding of the deposition behavior of the films on contact holes is necessary. However, it is not easy to understand the details of MOCVD of multicomponent oxide thin films because the deposition is affected by many complex factors. The above-mentioned materials commonly have a Ti component. Therefore, the MOCVD behavior and step coverage of the TiO 2 films are investigated first in this study. From these experimental results, the experimental results on the compositionally nonconformal STO thin film deposition that were previously reported by the authors are analyzed again in this paper. Figure 1 shows the schematic diagram of the system for the deposition of TiO 2 thin films. It is composed of an inverted vertical MOCVD reactor, where the sample surface faces downward, and a liquid...

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“…The method can easily be extended to include complex chemistry, specular reflection of particles from the walls, surface diffusion [55], three-dimensional effects [56], etc. Application in the continuum regime, however, is prohibited by computational demands.…”

Section: Feature Scale Cvd Modelsmentioning

confidence: 99%