Chemical Vapor Deposition Of Cu Research Articles

Investigation of the chemical vapor deposition of Cu from copper amidinate through data driven efficient CFD modelling

A chemical reaction model, consisting of two gas-phase and a surface reaction, for the deposition of copper from copper amidinate is investigated, by comparing results of an efficient, reduced order CFD model with experiments. The film deposition rate over a wide range of temperatures, 473K-623K, is accurately captured, focusing specifically on the reported drop of the deposition rate at higher temperatures, i.e above 553K that has not been widely explored in the literature. This investigation is facilitated by an efficient computational tool that merges equation-based analysis with data-driven reduced order modeling and artificial neural networks. The hybrid computer-aided approach is necessary in order to address, in a reasonable time-frame, the complex chemical and physical phenomena developed in a three-dimensional geometry that corresponds to the experimental set-up. It is through this comparison between the experiments and the derived simulation results, enabled by machine-learning algorithms that the prevalent theoretical hypothesis is tested and validated, illuminating the possible underlying dominant phenomena.

Low-pressure chemical vapor deposition of Cu on Ru using CuI as precursor

Low-pressure chemical vapor deposition (LPCVD) of Cu using copper(I)-iodide (CuI) as precursor was experimentally studied at low temperatures around 300 °C with understanding molecular structure of the precursor in the gas-phase. CuI was sublimated at temperatures around 300 °C in an evacuated reactor of LPCVD apparatus, while CuI was evaporated at high temperatures above 600 °C by atmospheric pressure CVD. Density functional theory (DFT) calculations supported CuI-trimer ((CuI)3) highly stabilized as an in-plane triangle is a major species in the gas phase and predicted the trimer is deformed by metal-atom such as Ru and Cu. Experimental results of the LPCVD, that preferentially oriented Cu(111) grains were deposited on Ru(001) at low temperatures around 300 °C but any deposits was not formed on SiOx/Si by the LPCVD, clearly indicating the activation energy of the precursor dissociation on the metal surfaces is lower than that on the dielectrics. Further, significantly low activation energy for the Cu-deposition rate dependent on the substrate temperature suggested the dissociation of the precursor is not driven by the thermal activation in the gas phase but by adsorption on the metal surfaces. Furthermore, the activation energy (85 kJ/mol) for the Cu-deposition rate dependent on the substrate temperature was found to be much lower than that for the dissociation of the CuI monomer (285 kJ/mol) or trimer (400 kJ/mol) in the gas phase. This finding indicates a catalytic dissociation of CuI on Ru and Cu metallic surfaces.

Metal-organic chemical vapor deposition of Cu(acac)2 for the synthesis of Cu/ZSM-5 catalysts for the oxidation of toluene

A heterogeneous catalyst (Cu/ZSM-5) was prepared by a metal-organic chemical vapor deposition (MOCVD) method under nitrogen atmosphere using Cu(acac)2 as the copper precursor, and further characterized by XRD, AAS, SEM, BET, H2-TPR and XPS as well as catalytic activity performance for the oxidation of toluene. N2 adsorption data revealed that the samples (CVD-4) prepared by MOCVD with calcination at 500 °C for 4 h possessed higher surface areas than that (CVD-BC) not calcined. The results of XPS demonstrated that CVD-4 exhibited higher redox property and more surface oxygen species compared with CVD-BC and IM (Cu/ZSM-5 catalyst prepared by impregnation). In particular, the CVD-4 catalysts prepared by MOCVD with calcinations showed the highest catalytic activity for toluene oxidation with 90% conversion of toluene at 293 °C with the feed concentration of 1000 ppm and GHSV of 15,000 h−1, which was lower than IM (310 °C). The results of a reaction durability test revealed that the Cu/ZSM-5 catalysts prepared by MOCVD possessed excellent durability for toluene oxidation for 63 h, while the conversion of toluene fell down from 90% to 60% after 48 h over IM catalyst.

Metallization of polymer composites by metalorganic chemical vapor deposition of Cu: Surface functionalization driven films characteristics

The present work is an evaluation of the most efficient pretreatments that are used in the field of metallization of poly-epoxies. In particular, we treat the case of MOCVD metallization with the constraints of limiting preparation steps and non-null, though limited thermal budget, and obtaining smooth, adherent, and highly conductive Cu coatings. Several results are presented after applying ex or in situ mechanical and chemical treatments. For the first time, transmission electron microscopy investigations illustrate the effect on the coating of H2O vapor addition during the first steps of the deposition process. In an original manner, we show that the enhancement of surface reactivity displaces the center of mass of the deposit towards the gas entry in the hot-wall reactor. Additionally, with the particularity of the hot-wall configuration, we show that differences in the deposition conditions along the reactor locally place the deposition in different regimes, i.e. diffusional or kinetic, with a strong effect on the coating microstructure and properties. Therefore, for both controlling the film properties and tuning the MOCVD reactor and the processing conditions, surface reactivity must be considered, in addition to the classical macroscopic processing parameters.

Experimental and computational investigation of chemical vapor deposition of Cu from Cu amidinate

Experiments and computations are performed for the Cu MOCVD from copper(I) N,N′-di-isopropylacetamidinate [Cu(iPr–Me–amd)]2 or [Cu(amd)]2 where amd=CH(CH3)2NC(CH3)NCH(CH3)2. The a priori choice of this precursor is dictated mainly by its oxygen and halogen–free ligands allowing co-deposition with oxophilic elements such as Al and by its ability to provide conformal Cu films in atomic layer deposition processes. The nucleation delay and the deposition rate as a function of deposition temperature and the evolution of the deposition rate along the radius of the substrate holder are experimentally determined with depositions performed at 1333Pa in a vertical, warm wall, MOCVD reactor. With the aim to propose a kinetic scenario for Cu deposition, based on recently published experimental results for the decomposition of [Cu(amd)]2, a predictive 3D model of the process is built, based on the mass, momentum, energy and species transport equations. In agreement with the previously mentioned experimental results, it is demonstrated that a single surface reaction is responsible for the deposition of Cu. Two surface kinetics expressions are implemented depending on the deposition regime; a simple Arrhenius type expression in the reaction limited regime and a Langmuir–Hinshelwood type expression prevailing in the transport limited regime which takes into account the inhibition effects. The two different kinetics designate a modification in the surface reaction mechanism. The results show good agreement between experiments and computations. Complementary computations are performed, in order to compare the deposition rates of the Cu films deposited via the [Cu(amd)]2 and the (hfac)Cu(VTMS) and Cu(hfac)2 so as to determine relative advantages and disadvantages of Cu MOCVD from [Cu(amd)]2.

Superconformal copper filling of a nano-scale trench by nucleation suppression at the trench entrance during metal organic chemical vapor deposition

Superconformal filling of copper (Cu) into the nano-scale SiO 2 trench was investigated by controlling the nucleation and growth conditions during the metal organic chemical vapor deposition of Cu. Inductively coupled H 2/Ar plasma pretreatment of the Ru-deposited trench pattern with a substrate biasing prior to deposition led to suppression of Cu nucleation on the top and entrance areas of the trench. In turn, Cu grows preferentially inside the trench. Controlled nucleation by plasma pretreatment enabled the achievement of superconformal Cu gap filling of sub-60 nm trenches without voids. Suppression of nucleation was attributed to deposition of sputtered silica (Si)-containing species on the top and entrance areas of the trench from the quartz window of the plasma reactor.

Fabrication of Micro- and Nano-electrodes by Selective Chemical Vapor Deposition of Cu on Si Substrates Patterned with AZ5214{trade mark, serif} and PMMA

Planar Cu electrodes with high length (starting from 1 mm down to 50 μm) and fine widths dimensions (starting from 20 μm and going down to 100 nm) were fabricated using selective chemical vapour deposition (SCVD) of the metal. For the fabrication, oxidized Si substrates were used on which a TiN layer was deposited and patterned either with AZ5214TM, for width dimensions of the order of microns, or by PMMA for lower dimensions. Then, Cu was deposited by SCVD on the exposed regions of the substrate only. Finally, the remaining polymers and the TiN were removed in acetone and by plasma etching, respectively. Due to the advanced CVD equipment used the above fabrication method proved to be robust, reproducible and with a high yield. The use of such equipment also assures a quite wide process window and inhibits the intrusion of other parameters which are known to destroy Cu SCVD.

Fabrication of Micro- and Nanoelectrodes by Selective Chemical Vapor Deposition of Cu on Si Substrates Patterned with AZ5214 and PMMA

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Iodine-catalyzed chemical vapor deposition of Cu on MPTMS monolayer surface in a low deposition temperature regime

Cu was deposited on a self-assembled monolayer of a 3-mercaptopropyltrimethoxysilane (MPTMS)-coated glass substrate by chemical vapor deposition (CVD) at temperatures ≤ 160 °C using (hfac)Cu(DMB) as a precursor. During deposition, there was an induction period for the Cu metal to nucleate on the MPTMS monolayer. This was attributed to the low mobility of Cu on the MPTMS surface in the low temperature regime as a result of an interfacial interaction between Cu and S. The addition of iodine significantly shortened the induction period, which was attributed to the iodine-aided surface diffusion of Cu. In addition, the iodine addition increased the growth rate, and improved the (111) texture. Moreover, the adsorbed iodine atoms had surfactant effects on promoting lateral growth.

Hot-wire assisted chemical vapor deposition of Cu by direct-liquid-injection of CupraSelect®

A novel chemical vapor deposition reactor for Cu films is presented in which the chemical reactions were assisted by a heated tungsten filament (hot-wire CVD, HWCVD). The vapors used were hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (CupraSelect®), which is liquid at room temperature and was injected into the reactor with the aid of a direct-liquid injection system using N 2 as carrier gas. The deposition rates of HWCVD Cu films obtained with this reactor were one and a half times higher than for typical thermally grown films at a filament temperature of 170 °C. Moreover, high quality Cu films were deposited on SiLK®, which cannot be done by thermal CVD. The resistivity of HWCVD Cu films is two to five times higher than those for thermally grown films due to the possible presence of impurities into the Cu films. The reaction of the CupraSelect® vapors with the W filament and the W-covered Si substrate, leads to the formation of Cu–W–O compounds in the Cu films. The presence of such compounds does not degrade catastrophically the conductivity of Cu HWCVD films.

Enhancement of the film growth rate by promoting iodine adsorption in the catalyst-enhanced chemical vapor deposition of Cu

The effect of H2 plasma pretreatment on the growth rate of films in the catalyst-enhanced chemical vapor deposition of Cu is presented. Cu(I) hexafluoroacetylacetonate-vinyltrimethylsilane [Cu(I)(hfac)(vtms)] and ethyl iodide (C2H5I) were used as a Cu precursor and a chemical source of iodine, respectively. Before adsorbing iodine onto the sputtered Cu seed layer, a pretreatment with H2 plasma promoted the adsorption of iodine. In addition, the Cu film growth rate was almost linearly enhanced with the surface concentration of the iodine adatom. The increment of the surface concentration of the iodine adatom was confirmed by secondary ion mass spectroscopy analysis. The iodine adatoms were not buried during the Cu deposition, but most of them continuously floated out to the film surface. Thus, the iodine on the surface of the Cu seed layer retained its catalytic effect until the film deposition finished. As a result, the H2 plasma pretreatment performed on the Cu seed layer prior to adsorbing iodine enhances the Cu film growth rate and improves the film qualities, such as electrical resistivity and surface smoothness, by promoting iodine adsorption.

Reactions of Cu(hfac)2 and Co2(CO)8 during Chemical Vapor Deposition of Copper−Cobalt Films

The reactions of Co2(CO)8 and submicron cobalt particles with Cu(hfac)2 (hfac = hexafluoroacetylacetonate) were studied in toluene. Reactions between these species in the gas phase were studied in a hot-wall, parallel-plate chemical vapor deposition (CVD) reactor. Similar results were obtained with both methods. The overall chemical reactions can be expressed by the following equations: 2Cu(hfac)2 + Co2(CO)6 → 2Cu + 2Co(hfac)2 + 8CO and Cu(hfac)2 + Co → Cu +Co(hfac)2. These results suggested that Co2(CO)8 is not a good source precursor for CVD of Cu−Co binary films when used in conjunction with copper(II) and some copper(I) hexafluoroacetylacetonate compounds and that chemical etching of cobalt metal by Cu(hfac)2 needs to be taken into account when depositing this binary film with copper(I) and copper(II) hexafluoroacetylacetonate compounds as copper source precursors.

Chemistry of cyclopentadiene on a Cu(100) surface: Detection of cyclopentadienyl (C5H5) species as reaction intermediates

The desorption and reaction of cyclopentadiene on Cu(100) were studied by temperature-programmed desorption and Auger electron spectroscopy. The dehydrogenation of cyclopentadiene is significant at low exposures (⩽0.8 L), producing cyclopentadienyl (C5H5) species as a reaction intermediate at ⩽335 K. The C5H5 groups are stable on the Cu(100) surface up to ∼600 K. At higher temperatures, cyclopentadienyl species undergo a self-hydrogenation reaction, with two-thirds of the C5H5 groups obtaining H from the others, and desorb from the surface as cyclopentadiene (C5H6) at ∼620 K. The remaining one-third of the C5H5 groups dehydrogenates to form hydrocarbon fragments that can be best described as C5H3 species, which further decompose to produce residue surface carbon and molecular H2 at ∼700 K. The implication of the current work to the previous observation of carbon contamination in the chemical vapor deposition of Cu is also discussed.

Chemical Vapor Deposition of Copper Films: Influence Of The Seeding Layers

AbstractThe low pressure chemical vapor deposition of Cu was investigated on TiN substrates that had been locally seeded with thin Cu layers. These Cu layers were 5Å, 40Å and 130Å thick and had been produced by PIB (Partially Ionized Beam) deposition. The growth rate and the XRD peak intensity ratio (I(111)/I(200)) of CVD-Cu increased somewhat in the case of Cu seeded TiN/Si substrates compared with as-received TiN/Si substrate. At the deposition temperature of 200°C, Cu film deposited on the 40Å seeded substrate had the lowest electrical resistivity value, 2.42 μ Ω cm that is as high as 1.5 times the bulk copper value. In adhesion test, as the seeding thickness increased from 0Å to 130Å, the adhesion strength increased from 21 N to 27 N.

Mechanistic Role of H2O and the Ligand in the Chemical Vapor Deposition of Cu, Cu2O, CuO, and Cu3N from Bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)copper(II)

The mechanism of chemical vapor deposition of Cu, Cu2O, CuO, and Cu3N from Cu(hfacac)(2)(H2O) was studied by XRD, MS, FTIR, XPS, SIMS, and NMR techniques. The molecular structure of the precursor was established by a single-crystal X-ray diffraction experiment. Crystallographic data (-165 degrees C): triclinic space group P1, a = 9.402(3) Angstrom, b = 11.068(3) Angstrom, c = 7.958(2) Angstrom, alpha = 105.71(2)degrees, beta = 100.99(2)degrees, gamma = 76.27(2)degrees, V = 767.31 Angstrom(3), Z = 2, R = 0.0303, R(w) = 0.0312. In the presence of excess water in the process gas stream, a facile release of free Hhfacac ligand from the copper complex is activated by a proton transfer from coordinated water. Ligand-mediated reduction of the metal from CU2+ to Cu+ and from Cu+ to Cu-0 oxidation states occurs in the absence of an external reducing agent at temperatures of 280 and 400 degrees C, respectively. Evidence for this ligand-mediated reduction is seen in the presence of the two major ligand-oxidation products (CF3COOH and CF3C(OH)(2)CH(OH)(2)) in the effluent from the deposition reaction. A labeling experiment using (H2O)-O-18 proved that oxygen in copper oxide films deposited from Cu(hfacac)(2) onto insulating substrates is derived from water and not the hfacac ligand. As an example of benefits that can be derived from this mechanistic knowledge, we have also shown that replacing H2O with NH3 leads to the formation of Cu3N.

Selective chemical vapor deposition of copper using (hfac) copper(I) vinyltrimethylsilane in the absence and presence of water

The selective chemical vapor deposition (CVD) of Cu was studied using (hfac)Cu(VTMS) (hfac  1,1,1,5,5,5-hexafluoro-acetylacetonate; VTMS [ vinyltrimethylsilane) in the absence and presence of water during CVD with SiO 2 surface passivation, derived from the silylating agent hexamethyldisilazane (HMDS), as a function of the nature of the carrier gas, HMDS and water vapor flow rates and chamber pressure. For CVD of Cu in the absence of water, pre-dosing with HMDS in the absence of water gave selective deposition. The deposition was feed rate limited and dense, smooth copper films were deposited selectively at rates of about 600 Å min −1. The selectivity for CVD of Cu in the presence of water depended on the pre-dosing conditions. Pre-dosing with both HMDS and water vapor gave selective deposition at rates of about 1200 Å min −1 in the presence of water, a factor of 2 higher compared with CVD in the absence of water vapor. Dense films with near-bulk resistivities were deposited selectively in the trenches on an underlying tungsten layer at the optimum water vapor flow rate and chamber pressure. Higher water vapor flow rates and chamber pressures resulted in porous, discontinuous films with significantly higher resistivities. An integration scheme utilizing selective CVD of Cu is proposed that allows formation of fully encapsulated copper lines without the need for a copper etch.

In situ mass spectral and IR studies of the role of auxiliary reagents in the enhancement of copper growth in the chemical vapor deposition of Cu(II) β-diketonate precursors

In spite of significant scientific and technical advances, the incorporation of chemical vapor deposition (CVD) of copper into emerging microelectronics manufacturing technologies remains inhibited by key processing and reliability issues. The most critical of these issues at present centers on the need to achieve industrially acceptable growth rates in the planarized and void-free copper CVD filling of aggressive vias and trenches (such as 0.25 μm structures with aspect ratio 4 and above). In this respect, recent studies have shown that the use of auxiliary reagents such as water and alcohols can lead to an enhancement of copper growth rates for both Cu(I) and Cu(II) β-diketonate precursors. However, the mechanisms that control this enhancement remain unclear. Accordingly, in situ quadrupole mass spectroscopy and Fourier transform IR studies were performed in the present investigation, under real CVD processing conditions, to examine the role of selected solvents (2-propanol, ethanol, methanol and 2-butanol) in enhancing the Cu growth rate in the plasma-assisted CVD of Cu from Cu II (hfac) 2. (hfac 1,1,1,5,5,5-hexafluoroacetylacetonate). The results of these studies showed that these solvents contribute atomic hydrogen which assists in the Cu II (hfac) 2 reduction process and lead to a higher probability of interaction-precursor reduction and therefore higher copper growth rates. In addition, the ability of these solvents to release atomic hydrogen was investigated through experimental measurements of the IR absorbances of the OH stretching bond in the parent solvent and the CO stretching bond in the ketone or aldehyde byproducts of the conversion reaction. By examining the ratios of absorbances for the CO and OH bands for the various solvents, the concentrations of ketone or aldehyde resulting from the conversion of the various alcohols were calculated and used to determine that 2-propanol can release hydrogen more efficiently than ethanol or 2-butanol. This ability was attributed to the hydrogen-primary carbon (CH) bond in these solvents, which is significantly weaker in 2-propanol than in ethanol or 2-butanol. This study thus confirms the present authors' earlier findings concerning the appropriateness of 2-propanol for use as a solvent in the delivery of the solid Cu IIhfac) 2 in liquid form, since not only can it readily decouple from the precursor in the gas phase but it can also help enhance copper growth rates.

FTIR Studies of the Adsorption/Desorption Behavior of Cu Chemical Vapor Deposition Precursors on Silica: IV . Interaction of (1,1,1,5,5,5‐hexafluoroacetylacetonato)(2‐butyne)copper(I), and (1,1,1,5,5,5,‐hexafluoroacetylacetonato)(vinyltrimethylsilane)copper(I), with Passivated Silica Surfaces and Comparison to Selective CVD of Cu

Selective chemical vapor deposition (CVD) on metals in the presence of can be achieved by passivating the surface using reagents which replace or shield isolated hydroxyl, hydrogen‐bonded hydroxyl, and four‐member rings with less reactive groups. This process was studied by FTIR of adsorption/desorption on unpassivated and passivated surfaces with varying surface concentrations of hydroxyl groups and four‐member rings. The passivating reagents included monofunctional trimethylchlorosilane (TMSCI), hexamethyldisilazane (HMDS), trimethyldimethylaminosilane (TMDMA), dimethyl‐t‐butyldimethylaminosilane (DMBDMA), and bi‐functional dimethylbis(dimethylamino)silane (DMDMA) species. Effective passivation was obtained by the rapid reaction of DMBDMA with hydroxylated surfaces even when exposed to water vapor. High‐temperature treatment of before passivation led to less effective passivation because a smaller fraction of the surface was protected by the passivating reagent. Bifunctional passivating reagents were less effective because the unreacted functional group on the reagent can react with species. Various other aspects of the interaction of species with surfaces and the implications of these results for selective CVD are discussed.

Surface analysis studies of copper chemical vapor deposition from 1,5-cyclooctadiene-copper(I)-hexafluoroacetylacetonate

The chemical vapor deposition of Cu from the 1,5-cyclooctadiene copper(I) hexafluoroacetylacetonate (COD-Cu-hfac) precursor has been studied using x-ray photoelectron spectroscopy, high-resolution electron energy-loss spectroscopy, and in situ reactor growth. Cu films are reproducibly grown on a Ag seed layer with resistivities of 2.0–2.4 μΩ cm with a deposition rate of 30–80 Å/min at 180 °C. After deposition, the surface of the Cu is covered by some adsorbed precursor fragments and residual hydrocarbon. Upon heating in vacuum, the precursor desorbs leaving behind about 3–5 Å carbon. Incorporation of carbon, oxygen, and fluorine into the bulk of the Cu films is limited to 1% or less. The reactive sticking coefficient of the COD-Cu-hfac molecule during deposition is estimated to be ∼ 1 × 10−3 at 180 °C. Cu grows somewhat selectively on metal relative to oxide surfaces at 180 °C. Room temperature adsorption of the precursor on Ag leads to dissociation of the molecule and loss of the COD ligand. The stoichiometry of the surface complex corresponds to Cu(I)-hfac. Heating the surface to ≳170 °C leads to desorption of the surface hfac ligand. This is consistent with a bimolecular disproportionation reaction in which 2 Cu(I)-hfac species react to form a volatile Cu(hfac)2 complex and a reduced Cu atom.

Laser Assisted Chemical Vapor Deposition of Cu from a New Cu Organometallic Complex

AbstractWe describe pyrolytic laser assisted chemical vapor deposition (LCVD) of copper onto silicon using a copper(I) hexafluoroacetylacetonate trimethylvinylsilane organometallic complex with 514.5 nm radiation from an Ar+ laser. Growth rates of 0.4-40 μm/min were obtained and at intermediate laser powers, the Cu lines had a resistivity comparable to that of bulk Cu. The line shape and morphology was strongly dependent upon laser power with volcano shapes appearing at higher powers. The growth was sensitive to the nature of the substrate suggesting that film nucleation was a critical element in the writing process.