Mechanism for the Atomic Layer Deposition of Copper Using Diethylzinc as the Reducing Agent: A Density Functional Theory Study Using Gas-Phase Molecules as a Model

Dey, Gangotri; Elliott, Simon D.

doi:10.1021/jp304460z

Cited by 35 publications

(49 citation statements)

References 35 publications

(65 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…11 The growth mechanism of this process has been investigated using density functional theory (DFT) in a gas-phase model and it is predicted that the surface is probably covered with a Cu(I) intermediates. 12 Later, a thin film of very pure Cu has been deposited using a three-step ALD process which entails the sequential reactions of Cu(dmap) 2 , formic acid and hydrazine (N 2 H 4 ) at 120 °C. 6 Recently, low temperature Cu ALD has also been demonstrated using a two-step process of Cu(dmap) 2 and borane dimethylamine [BH 3 (NHMe 2 )]…”

Section: Introductionmentioning

confidence: 99%

Precursor Adsorption on Copper Surfaces as the First Step during the Deposition of Copper: A Density Functional Study with van der Waals Correction

Maimaiti

Elliott

2015

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

Copper dimethylamino-2-propoxide [Cu(dmap) 2 ] is used as a precursor for low-temperature atomic layer deposition (ALD) of copper thin films. Chemisorption of the precursor is the necessary first step of ALD, but it is not known in this case whether there is selectivity for adsorption sites, defects, or islands on the substrate. Therefore, we study the adsorption of the Cu(dmap) 2 molecule on the different sites on flat and rough Cu surfaces using PBE, PBE-D3, optB88-vdW, and vdW-DF2 methods. We found the relative order of adsorption energies for Cu(dmap) 2 on Cu surfaces is E ads (PBE-D3) > E ads (optB88-vdW) > E ads (vdW-DF2) > E ads (PBE). The PBE and vdW-DF2 methods predict one chemisorption structure, while optB88-vdW predicts three chemisorption structures for Cu(dmap) 2 adsorption among four possible adsorption configurations, whereas PBE-D3 predicts a chemisorbed structure for all the adsorption sites on Cu(111). All the methods with and without van der Waals corrections yield a chemisorbed molecule on the Cu( 332) step and Cu(643) kink because of less steric hindrance on the vicinal surfaces. Strong distortion of the molecule and significant elongation of Cu−N bonds are predicted in the chemisorbed structures, indicating that the ligand−Cu bonds break during the ALD of Cu from Cu(dmap) 2 . The molecule loses its initial square-planar structure and gains linear O−Cu−O bonding as these atoms attach to the surface. As a result, the ligands become unstable and the precursor becomes more reactive to the coreagent. Charge redistribution mainly occurs between the adsorbate O−Cu−O bond and the surface. Bader charge analysis shows that electrons are donated from the surface to the molecule in the chemisorbed structures, so that the Cu center in the molecule is partially reduced.

show abstract

Section: Introductionmentioning

confidence: 99%

Precursor Adsorption on Copper Surfaces as the First Step during the Deposition of Copper: A Density Functional Study with van der Waals Correction

Maimaiti

Elliott

2015

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

show abstract

“…Careful thermal decomposition studies showed metal formation by the oxidation of a ligand through β-hydrogen abstraction, coupled with reductive elimination to produce one equivalent of the parent ligand ( Figure 6). It should be noted that the mechanism given in Figure 6 incorporates the chemisorption modeled at the Tyndall Institute, 12 and so is our reinterpretation of the (similar) original mechanism. In this model, the simple chemisorption of a variety of copper(II) precursors (CuX 2 ) was shown to undergo a ligand shift of one ligand to a growing copper surface while the chemisorbed species maintained its second ligand:…”

Section: Aminoalkoxidesmentioning

confidence: 80%

“…In both cases where diethyl zinc was used, reductive elimination of butane from diethyl zinc is the likely contributor to the metallic impurity, as discussed at length in a computational model from Tyndall. 12 It should be noted that the computational study modeled all species as gas phase molecules, while this review uses surface species notation (for consistency with subsequent chemical equations and schemes). In general, the elimination of ZnX 2 where X is an anionic ligand, is more likely when ZnX 2 is a more volatile species, and this was modeled in two steps in this paper ( Figure 3).…”

Section: Diethyl Zincmentioning

confidence: 99%

“…Cu 2+ prefers a square planar arrangement due to its favorable electronic configuration, but distortion from this geometry by steric effects is not uncommon. 12 This generally means that CuX 2 species undergo cleavage upon chemisorption to a surface. In general, one can consider the growing film to consist of copper metal atoms, and so one ligand can adsorb to the surface, while the copper center in the precursor becomes a ligand-supported surface adatom.…”

Section: Comparison Of Cvd and Ald Of Coppermentioning

confidence: 99%

See 1 more Smart Citation

Trends in Copper Precursor Development for CVD and ALD Applications

Gordon

Kurek

Barry

2014

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

The continued dominance of copper in microelectronic manufacturing is due in part to the techniques that have kept pace with the relentless trend towards smaller feature sizes. Pure and defect-free copper features can be created at these and smaller scales using gas phase deposition methods such as chemical vapor deposition (CVD) and atomic layer deposition (ALD). Here we review the deposition processes and in particular surface chemistry for depositing copper metal by CVD and ALD. A summary of known processes is given, and new trends in copper film deposition research are discussed. As well, process parameters and properties of copper films deposited from precursors using key ligand systems such as aminoalkoxides, amidinates, guanidinates, betadiketonates and betaketoiminates are presented. Surface chemistry is examined from the point of view of the similarities of CVD and ALD, considering precursors that can be used in both types of processes. This serves to highlight trends in decomposition mechanisms and illuminates some interesting similarities in process temperature and other parameters.

show abstract

“…The state of the art to 2012 is summarized in ref 62. Since then, our most recent atomic-scale simulations have revealed new details of the mechanism of oxide ALD [43], have accounted for the stoichiometry of ternary oxides [63], have assessed precursor ligands for alkaline earth metal oxides [64] and for copper metal [65] and have developed kinetic Monte Carlo models of film growth [66].…”

Section: Ald Development and Understandingmentioning

confidence: 99%

Studying chemical vapor deposition processes with theoretical chemistry

Pedersen

Elliott

2014

Theor Chem Acc

Self Cite

View full text Add to dashboard Cite

In a chemical vapor deposition (CVD) process, a thin film of some material is deposited onto a surface via the chemical reactions of gaseous molecules that contain the atoms needed for the film material.These chemical reactions take place on the surface and in many cases also in the gas phase. To fully understand the chemistry in the process and thereby also have the best starting point for optimizing the process, theoretical chemical modeling is an invaluable tool for providing atomic-scale detail on surface and gas phase chemistry. This overview briefly introduces to the non-expert the main concepts, history and application of CVD, including the pulsed CVD variant known as atomic layer deposition (ALD), and put into perspective the use of theoretical chemistry in modeling these processes. KeywordsChemical Vapor Deposition, Atomic Layer Deposition, Thin Films, Surface Chemistry, Gas Phase Chemistry, Theoretical Chemistry 3 An introduction to vapor-phase deposition techniquesThin films are layers of materials with thicknesses ranging from less than one nanometer (a few atomic layers) to hundreds of micrometers (for reference, a human hair is about 75 µm thick) [1]. The importance of thin films in today's society is enormous and thin films can be found everywhere; from low friction coatings in a car engine to the anti-reflecting coating on the lenses of spectacles, as well as the decorative coating on their frames. Most metal objects around us have been machined by cutting tools that are coated with a hard, wear-resistant thin film. Replacement parts for the human body, such as hip-joints, are often coated with a thin film to make them more bio-compatible.Furthermore, today's nanoelectronic devices are built up very precisely from stacks of thin films of various materials with different electrical properties, with some of the films as thin as one atomic layer. Technologically important thin films can be amorphous, polycrystalline or epitaxially-grown single crystals and the properties of the materials can often be tuned with great precision to suit various applications.To coat an object (the "substrate") with a thin film, it is often preferred to start from atoms or molecules in a vapor phase and place the object(s) to be coated in that vapor, letting atoms and/or molecules from the vapor build up a thin film on the surface of the object. These vapor-based thin film synthesis methods are classified as either physical vapor deposition (PVD) or chemical vapor deposition (CVD), depending on whether the film deposition process is driven by physical impacts or by chemical reactions, respectively. Generating the vapor in the reactor is of course straightforward when the desired element is available in gaseous form, e.g. O 2 , but this is not the case for most elements. Therefore, in PVD, a solid sample containing the target elements is subjected to substantial energy, often in the form of a plasma or an electric discharge, thereby ejecting atoms and producing a vapor, which can then condense onto the substrate ...

show abstract

Mechanism for the Atomic Layer Deposition of Copper Using Diethylzinc as the Reducing Agent: A Density Functional Theory Study Using Gas-Phase Molecules as a Model

Abstract: Access to the full text of the published version may require a subscription. intermediate, as otherwise it will lead to a stable copper molecule rather than copper metal. Volatile ZnL 2 will favor the ALD reaction as it will carry the reaction forward. Rights

Cited by 35 publications

References 35 publications

Precursor Adsorption on Copper Surfaces as the First Step during the Deposition of Copper: A Density Functional Study with van der Waals Correction

Precursor Adsorption on Copper Surfaces as the First Step during the Deposition of Copper: A Density Functional Study with van der Waals Correction

Trends in Copper Precursor Development for CVD and ALD Applications

Studying chemical vapor deposition processes with theoretical chemistry

Contact Info

Product

Resources

About