Radical-Enhanced Atomic Layer Deposition of Metallic Copper Thin Films

Niskanen, Antti; Rahtu, Antti; Sajavaara, Timo; Arstila, Kai; Ritala, Mikko; Leskelä, Markku

doi:10.1149/1.1824046

Cited by 63 publications

(46 citation statements)

References 24 publications

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“…7(a). Examples of such plasma sources are microwave surfatron systems 100 and the radiofrequency-driven R*Evolution (MKS Instruments) 315 and Litmas RPS (Advanced Energy) 316 systems, which are also commonly used for plasma-based reactor cleaning. Due to technical constraints on existing ALD reactors, plasma generation typically takes place at a relatively far distance from ALD reaction zone.…”

Section: A Radical-enhanced Aldmentioning

confidence: 99%

“…A classic example is the ALD of metal oxides from b-diketonate precursors, such as those with acac (acetylacetonate), [97][98][99][100] hfac (1,1,1,5,5,5-hexafluoroacetylacetonate), 101,161,162 and thd (2,2,6,6,-tetramethyl-3,5-heptanedionato) 102,104,[275][276][277][278][279] ligands. Such precursors require more reactive co-reactants as they show no or low reactivity with H 2 O (in essence, they do not readily undergo hydrolysis reactions).…”

Section: Increased Choice Of Precursors and Materialsmentioning

confidence: 99%

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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: A Radical-enhanced Aldmentioning

confidence: 99%

Section: Increased Choice Of Precursors and Materialsmentioning

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

“…9 Of these deposition approaches, ALD shows the most promise in surmounting the island growth problem as well as meeting future demands of device scaling. [10][11][12] Many copper organometallic compounds are used with H 2 or H 2 plasma in copper ALD experiments [13][14][15][16][17][18] . However, these processes lead to impurities and discontinuous films either because of the higher temperature requirement or because of the strong reducing or oxidizing nature of the co-reagents.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Coverage Dependent Reaction Mechanisms of the Copper Atomic Layer Deposition from Copper Dimethylamino-2-propoxide and Diethylzinc

Maimaiti

Elliott

2016

Chem. Mater.

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Original citationMaimaiti, Yasheng; Elliott, Simon D. (2016) Just Accepted "Just Accepted" manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides "Just Accepted" as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. "Just Accepted" manuscripts appear in full in PDF format accompanied by an HTML abstract. "Just Accepted" manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). "Just Accepted" is an optional service offered to authors. Therefore, the "Just Accepted" Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the "Just Accepted" Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these "Just Accepted" manuscripts. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 mechanism. During both reaction mechanisms, ligand diffusion and reordering are generally endothermic processes, which may result in residual ligands blocking the surface sites at the end of the Et 2 Zn pulse, and in residual Zn being reduced and incorporated as an impurity. We also find that the nearby ligands play a cooperative role in lowering the activation energy for formation and desorption of by-products, which explains the advantage of using organometallic precursors and reducing agents in Cu ALD. The ALD growth rate estimated for the mechanism is consistent with the experimental value of 0.2 Å/cycle. The proposed reaction mechanisms provide insight into ALD processes for copper and other transition metals.

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“…Overall it is important to emphasize that the GPC values achieved under the aforementioned optimized conditions, i.e. ~2 Å/cycle are almost an order of magnitude higher than the values reported for the growth of copper films via radical-enhanced ALD using the same precursor 45 and via conventional ALD using copper(I) chloride as the copper source. 30 It is well known that the reaction of Cu(acac)2 with H2O primarily deposits Cu2O.…”

Section: Resultsmentioning

confidence: 69%

Efficient Process for Direct Atomic Layer Deposition of Metallic Cu Thin Films Based on an Organic Reductant

Tripathi

Karppinen

2017

Chem. Mater.

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We report a promising approach to use an organic reductant for in situ atomic layer deposition (ALD) of metallic copper films. The process is based on sequentially pulsed precursors copper acetyl acetonate (acac), water, and hydroquinone (HQ) and yields crystalline copper films at temperatures as low as <200 °C with an appreciably high deposition rate of ∼2 Å/cycle. Deposition parameters are explored for the process m × [n × (Cu(acac) 2 −H 2 O)−HQ] with several values of m and n, keeping m × n fixed to 500. The films are found crystalline with metallic copper as the main phase, but different trace amounts of Cu 2 O are observed when the HQ pulse frequency decreases below 1 / 5 . The as-deposited copper films are shiny and specularly reflecting and show metallic-type electrical conductivity. The absolute resistivity of the films estimated at room temperature is in the order of 2−5 μΩ cm, having a sizable contribution, with 0.5 μΩ cm from residual resistivity as a result of impurities and/or imperfections. We believe that the new process could yield benefits in interconnect applications.

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Radical-Enhanced Atomic Layer Deposition of Metallic Copper Thin Films

Cited by 63 publications

References 24 publications

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

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

Kinetics and Coverage Dependent Reaction Mechanisms of the Copper Atomic Layer Deposition from Copper Dimethylamino-2-propoxide and Diethylzinc

Efficient Process for Direct Atomic Layer Deposition of Metallic Cu Thin Films Based on an Organic Reductant

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