Radical Enhanced Atomic Layer Deposition of Titanium Dioxide

Niskanen, Antti; Arstila, Kai; Leskelä, Markku; Ritala, Mikko

doi:10.1002/cvde.200606546

Cited by 47 publications

(47 citation statements)

References 56 publications

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“…Consequently, this can lead to higher growth per cycle values. 31,32,40,58,60,134,154,187,207,208,229,233,254,259,261,274,294 Moreover, the plasma can be switched on and off very rapidly, which enables fast pulsing of the plasma reactant species 255,273,274,293,295 and reduced purge times (depending on the gas residence time in the reactor). 46,60 The latter is especially important for the ALD of metal oxides at low temperatures (room temperature up to 150 C), where purging of H 2 O, in the case of thermal ALD, requires excessively long purge times and, therefore, long cycle times.…”

Section: E Increased Growth Ratementioning

confidence: 99%

Plasma-Assisted Atomic Layer Deposition: Basics, Opportunities, and Challenges

Profijt

Potts

Sanden

et al. 2011

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

729

537

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Plasma-assisted atomic layer deposition (ALD) is an energy-enhanced method for the synthesis of ultra-thin films with Å-level resolution in which a plasma is employed during one step of the cyclic deposition process. The use of plasma species as reactants allows for more freedom in processing conditions and for a wider range of material properties compared with the conventional thermally-driven ALD method. Due to the continuous miniaturization in the microelectronics industry and the increasing relevance of ultra-thin films in many other applications, the deposition method has rapidly gained popularity in recent years, as is apparent from the increased number of articles published on the topic and plasma-assisted ALD reactors installed. To address the main differences between plasma-assisted ALD and thermal ALD, some basic aspects related to processing plasmas are presented in this review article. The plasma species and their role in the surface chemistry are addressed and different equipment configurations, including radical-enhanced ALD, direct plasma ALD, and remote plasma ALD, are described. The benefits and challenges provided by the use of a plasma step are presented and it is shown that the use of a plasma leads to a wider choice in material properties, substrate temperature, choice of precursors, and processing conditions, but that the processing can also be compromised by reduced film conformality and plasma damage. Finally, several reported emerging applications of plasma-assisted ALD are reviewed. It is expected that the merits offered by plasma-assisted ALD will further increase the interest of equipment manufacturers for developing industrial-scale deposition configurations such that the method will find its use in several manufacturing applications.

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Section: E Increased Growth Ratementioning

confidence: 99%

Plasma-Assisted Atomic Layer Deposition: Basics, Opportunities, and Challenges

Profijt

Potts

Sanden

et al. 2011

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

729

537

View full text Add to dashboard Cite

show abstract

“…A model was proposed for the ALD precursors' adsorption on surface and diffusion into the subsurface of polymers without active groups [19], and it was found that the process temperature significantly affected the interface between the deposition layer and the substrate [26,27]. There are some reports on the deposition of metal oxides by ALD on PP substrates but most studies are focused on the deposition of metal oxides, mainly Al 2 O 3 , on nonporous PP films [19,[27][28][29][30]. One work was reported on the ALD deposition of Al 2 O 3 on porous PP membranes with the purpose to improve the wettability of electrolyte solutions and the thermal stability of the PP membrane in the use of lithium ion batteries [31].…”

Section: Introductionmentioning

confidence: 98%

Hydrophilization of porous polypropylene membranes by atomic layer deposition of TiO2 for simultaneously improved permeability and selectivity

Xü

Yang

Dai

et al. 2013

Journal of Membrane Science

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“…8,9 A variety of synthesis techniques have been used, including chemical vapor deposition ͑CVD͒, 8,10 sputtering, 1,2 plasma-enhanced CVD ͑PECVD͒, 11,12 and atomic layer deposition ͑ALD͒. 4,5,[13][14][15][16][17][18] Emerging applications demand improved quality and control. ALD imparts digital control over film thickness and composition, as well as exceptional film quality.…”

mentioning

confidence: 99%

Self-Limiting Deposition of Anatase TiO[sub 2] at Low Temperature by Pulsed PECVD

Kubala

Rowlette

Wolden

2009

Electrochem. Solid-State Lett.

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The self-limiting deposition of anatase TiO 2 was accomplished by pulsed plasma-enhanced chemical vapor deposition ͑PECVD͒ using a simultaneous delivery of TiCl 4 and O 2 . The amorphous to anatase phase transition was examined as a function of temperature, plasma power, and film thickness. Films deposited at T = 120°C, with the plasma power set at 100 W were amorphous, containing residual amounts of chlorine. At 200 W, the films displayed an anatase structure, and no chlorine was detected by X-ray photoelectron spectroscopy. Spectroscopic ellipsometry, Fourier transform infrared, and X-ray diffraction measurements concur that a minimum film thickness of ϳ25 nm is required for the formation of the anatase phase.Titanium dioxide ͑TiO 2 ͒ thin films are of major technological interest due to their versatile physical and chemical attributes. Titania's high refractive index makes it a common component in optical filters and coatings. 1,2 TiO 2 is a leading photocatalyst 3-5 and serves as a critical component in emerging photovoltaic technology. 6,7 With its extraordinarily high dielectric constant, TiO 2 thin films are a leading candidate for both memory and thin-film transistor applications. 8,9 A variety of synthesis techniques have been used, including chemical vapor deposition ͑CVD͒, 8,10 sputtering, 1,2 plasma-enhanced CVD ͑PECVD͒, 11,12 and atomic layer deposition ͑ALD͒. 4,5,13-18 Emerging applications demand improved quality and control. ALD imparts digital control over film thickness and composition, as well as exceptional film quality. The main drawback of ALD is its low rate, which precludes its use for the commercial synthesis of mesoscale structures ͑100-1000 nm͒ for single-wafer processing such as optical components. ALD typically requires temperatures Ͼ200°C to produce the anatase phase, which is desired for photocatalyst applications. In this article, we describe the selflimiting production of anatase films by pulsed PECVD at temperatures well below 200°C.Our group has established pulsed PECVD as an alternative to ALD for the self-limiting growth of metal oxide thin films, including Ta 2 O 5 , 19,20 Al 2 O 3 , 21,22 and ZnO. 23 The process has been described in detail previously 24,25 and is briefly reviewed here. In pulsed PECVD, O 2 and the metal precursor are mixed and delivered simultaneously. To be self-limiting, the precursor must be unreactive with O 2 so that no deposition occurs with the plasma off. TiCl 4 is unreactive with O 2 below 400°C, 10 but other precursors such as TiI 4 that are reactive with O 2 26 would not produce self-limiting growth by this technique. Purge steps are eliminated, and growth occurs discretely by modulating the plasma power at low frequency ͑ap-proximately in hertz͒. The nature of the self-limiting growth is fundamentally different from ALD. Instead of relying on surface chemistry, growth terminates during each plasma step due to the consumption of the precursor. The process is self-limiting in the sense that no deposition occurs with the plasma off or with the plas...

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Radical Enhanced Atomic Layer Deposition of Titanium Dioxide

Cited by 47 publications

References 56 publications

Plasma-Assisted Atomic Layer Deposition: Basics, Opportunities, and Challenges

Plasma-Assisted Atomic Layer Deposition: Basics, Opportunities, and Challenges

Hydrophilization of porous polypropylene membranes by atomic layer deposition of TiO2 for simultaneously improved permeability and selectivity

Self-Limiting Deposition of Anatase TiO[sub 2] at Low Temperature by Pulsed PECVD

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