Atomic Layer Deposition Growth Rate Research Articles

Compatibility between polymethacrylate-based extreme ultraviolet resists and TiO2 area-selective deposition

BackgroundExtreme ultraviolet (EUV) lithography is crucial to achieving smaller device sizes for next-generation technology, although organic resists face substantial challenges, such as low etch resistance, which limit the resolution of smaller features.AimEvaluate the potential for area-selective deposition (ASD) to improve EUV pattern resolution (e.g., by increasing etch resistance).ApproachWe evaluate thermal compatibility, atomic layer deposition growth rate, and selectivity for TiO2 ASD on various organic EUV resist materials using water contact angle, Rutherford backscattering spectrometry, and X-ray photoelectron spectroscopy. The effects of photo-acid generator (PAG) and EUV exposure on polymer properties and selectivity are considered.ResultsThe organic resist materials studied demonstrate thermal compatibility with TiO2 ALD (125°C for 60 min). The TiO2 ALD process from TiCl4 and H2O proceeds readily on poly(tert-butyl methacrylate), poly(p-hydroxystyrene), and poly(p-hydroxystyrene-random-methacrylic acid) polymers, with and without PAG incorporation, in either the as-formed or EUV exposed state. However, TiO2 is inhibited on poly(cyclohexyl methacrylate).ConclusionsWe demonstrate that as-formed EUV resists can serve as either the growth or nongrowth surface during TiO2 ASD, thereby enabling resist hardening and tone inversion applications, respectively. These results serve as a basis for further ASD studies on EUV resist materials to improve pattern resolution in next-generation devices.

Oxygen relocation during HfO2 ALD on InAs.

Atomic layer deposition (ALD) is one of the backbones for today's electronic device fabrication. A critical property of ALD is the layer-by-layer growth, which gives rise to the atomic-scale accuracy. However, the growth rate - or growth per cycle - can differ significantly depending on the type of system, molecules used, and several other experimental parameters. Typically, ALD growth rates are constant in subsequent ALD cycles, making ALD an outstanding deposition technique. However, contrary to this steady-state - when the ALD process can be entirely decoupled from the substrate on which the material is grown - the deposition's early stage does not appear to follow the same kinetics, chemistry, and growth rate. Instead, it is to a large extent determined by the surface composition of the substrate. Here, we present evidence of oxygen relocation from the substrate-based oxide, either the thermal or native oxide of InAs, to the overlayer of HfO2 in the initial ALD phase. This phenomenon enables control of the thickness of the initial ALD layer by controlling the surface conditions of the substrate prior to ALD. On the other hand, we observe a complete removal of the native oxide from InAs already during the first ALD half-cycle, even if the thickness of the oxide layer exceeds one monolayer, together with a self-limiting thickness of the ALD layer of a maximum of one monolayer of HfO2. These observations not only highlight several limitations of the widely used ligand exchange model, but they also give promise for a better control of the industrially important self-cleaning effect of III-V semiconductors, which is crucial for future generation high-speed MOS.

In Situ and Ex Situ diagnostics of ALD-Ultrathin Lithium-Ion Films

All solid-state ion layers has an ever-growing interest in order to accomplish on-chip energy storage devices. As such, lithium-ion synaptic transistor to build artificial neural networks, integrated area-enhanced capacitors and lithium-ion microbatteries for energy supply are suitable candidates fulfilling energy-efficient devices. Atomic layer deposition (ALD) is one of the most promising techniques for manufacturing ultrathin layers for lithium-ion devices with exceptional capabilities to enable conformal growth at atomic scale. In this area, in situ diagnostics has become of vital importance for the growth process understanding especially on view of the air-sensitivity character of lithium ultra-thin layers.The purpose of this work is to present an in situ spectroscopic ellipsometry (SE) study of ALD thin films used on the fabrication of lithium-ion devices. We will consider several aspects of ALD ultrathin films growth, such as film thickness, saturation curves and initial films nucleation. We shall compare in situ SE results with those of ex situ diagnostics such as XRR (x-ray reflectometry) and XPS (x-ray photoelectron spectroscopy).We focus on the characterization of 10-100 nm thin lithium phosphate electrolyte with and without nitrogen doping deposited at ALD temperature range 300-350°C using LiHMDS-TMPO and LiHMDS-DEPA precursors, respectively. On the other hand, the realization of silicon integrated lithium ionic devices requires the implementation of essential barrier films to prevent Li-ion into the Si substrate. We will explore here the ability of titanium nitride depositions to act as lithium-ion diffusion barriers. TiN deposition (10-20 nm thin) by ALD process (350°C-400°C) uses TiCl4 and NH3 precursors.First, we investigate the growth process of LiPO, LiPON and TiN intrinsic layers deposited using thermal ALD. Secondly, we apply in situ and ex situ diagnostics on exemplary LiPO/LiPON deposited on top of the 10 nm ALD TiN film (Figure 1: Monitoring of LiPON thickness vs deposition time using in-situ Ellipsometry). The film thickness deduced from in situ SE measurements was corroborated by thickness measurements with XRR technique (Figure 2: Evolution of LiPON thickness vs ALD cycles using Ellipsometry and SE characterization techniques). Ex situ SE was used most often for WiW uniformity evaluating (Figure 3: 8” Wafer thickness mapping of ALD LiPON layers (a: 10nm TiN film; b: 17nm LiPON film). The preliminary results underline the fact that ALD growth rate and nucleation of lithium electrolyte and titanium nitride obviously depends on the ALD process parameters (temperature, pulse and purge times, number of cycles) but on the substrate nature (silicon, thermal oxide, and metallic). In situ and ex situ diagnostics highlight that initial film growth of lithium electrolytes and TiN layers strongly depends on the precursors kind used in the ALD process and the substrate material employed. Figure 1

Optimal design of novel precursor materials for the atomic layer deposition using computer-aided molecular design

Nanomaterials and nanostructures with multi-functional properties found widespread applications such as electronics, optics, and coatings that can be fabricated using Atomic Layer Deposition (ALD). ALD is a vapor phase deposition technique to generate thin films of metals and metal oxides on a substrate. In this process, a precursor, which often comprises of organic functional groups that surround the depositing metal, chemisorbs on the substrate or reacts with the surface sites and with each other. Precursor chemisorption on the substrate leads ALD to be a self-limiting process. Thus, the precursor(s) should be chosen in a way to enhance deposition based on the ALD conditions. For a given application, it is practically impossible to carry out a large number of experiments using numerous precursors with varied deposition conditions to find the one that maximizes the growth rate in ALD. In addition, only existing precursors can be tested experimentally. The overall objective of this work is to develop a computational tool for the in-silico design of precursor materials using adsorbate solid solution theory (ASST). In the first part of this paper, we apply the ASST to derive properties of the functional groups present in the precursor using a new Group Contribution Method (GCM). The GCM is successfully derived and compared with the experimental data from ALD. The method shows good agreement and is useful for the design of novel materials. In the second part of this paper, using the thermodynamic properties as obtained from GCM, we develop a computer-aided molecular design (CAMD) framework for the optimal design of novel precursor materials with enhanced deposition properties for the ALD of metal oxides and metals. The metaheuristic efficient ant colony optimization algorithm (EACO) developed in-house is used for both parts. CAMD is a combinatorial optimization methodology, where molecules with optimal desired properties are generated from functional groups. The precursor selection optimization problem is posed as a mixed integer nonlinear programming problem, which is solved using EACO. The ALD growth kinetics is used as an objective of optimization and a solution is validated with thermodynamic constraints. Along with the number of groups, the temperature is also included in the optimization framework as decision variables. Forty-one novel titanium precursor molecular structures for ALD are generated with growth rates ranging from 1.23 Å/cycle to as high as 1.65 Å/cycle. Thus, these precursors have shown growth rates higher than the known titanium precursors. ALD growth rate is found to be a function of the combination of the precursor functional groups as well as temperature with a complex correlation among them.

Modulation of the adsorption chemistry of a precursor in atomic layer deposition to enhance the growth per cycle of a TiO2 thin film.

Atomic layer deposition (ALD) has scarcely been utilized in large-scale manufacturing and industrial processes due to its low productivity, even though it possesses several advantages for improving the device performance. The major cause of its low productivity is the slow growth rate, which is determined by the amount of chemisorbed precursor. The slow growth rate of ALD has become even more critical due to the introduction of heteroleptic-based precursors for achieving a higher thermal stability. In this study, we investigated the theoretical and experimental chemisorption characteristics of the Ti(CpMe5)(OMe)3 precursor during the ALD of TiO2. By density functional theory calculations, the relationship between the steric hindrance effect and the chemistry of a chemisorbed precursor was revealed. Based on the calculation result, a way for improving the growth per cycle by 50% was proposed and demonstrated, successfully.

Reduction in Absorption Edge of the Digital-Alloyed ZnMnO Thin Films Grown Using Atomic Layer Deposition

Transition metal doping has been used as a common approach for tuning the bandgap energy of zinc oxide (ZnO) based materials. In this work, manganese-doped ZnO (ZnMnO) thin films were grown using the atomic layer deposition (ALD) and used to study the effect of manganese incorporation in ZnO films. The effect of digital alloying on reducing the absorption edge of the ZnMnO thin films is studied by changing the ZnO to MnO cycle ratio during each ALD super-cycle. Room-temperature optical spectroscopic characterization showed a significant reduction in bandgap energy from 3.30 eV for pure ZnO to around 2.25 eV for the ZnMnO thin films with the ZnO:MnO cycle ratio of 5:3. This is likely due to the effect of band bending, which can be related to the formation of Mn-related impurity energy levels in the band structure of the ZnMnO. A notable change in the deduced optical bandgap energy was observed by further increasing the growth sequence of ZnO and MnO layers in each super-cycle. This was attributed to less Mn incorporation in these films caused by a highly suppressed ALD growth rate of MnO on ZnO. The observed changes in the optical bandgap of ZnMnO thin films demonstrates the potential for using them as the active light-absorbing or the window layer in high-efficiency multi-junction solar cells or photodiodes.

Surface modification of SOFC cathodes by Co, Ni, and Pd oxides

The effect of adding transition-metal catalysts to the surfaces of Solid-Oxide-Fuel-Cell (SOFC) cathodes was examined. Monolayer amounts of Pd, Ni, and Co were deposited by atomic layer deposition (ALD) to cathodes prepared by impregnation of La0.8Sr0.2FeO3 (LSF), La0.8Sr0.2CoO3 (LSCo), and La0.6Sr0.4 Co0.2Fe0.8O3 (LSCF) into YSZ scaffolds. Incorporating the catalysts by ALD allowed modification of the surface composition without changing the cathode surface area or structure. X-ray Photoelectron Spectroscopy and High Sensitivity-Low Energy Ion Scattering were used to confirm ALD growth rates that were measured gravimetrically. Electrochemical impedance spectroscopy indicated that the addition of Pd had a small negative effect on all of the cathodes. Ni and Co exhibited only a small effect on LSCo and LSCF cathodes but both decreased the cathode impedance for LSF. It is suggested that an essential feature in cathode promotion by Co and Ni is that these cations are incorporated into the perovskite surface and thereby increase the concentration of oxygen vacancies, while Pd only blocked adsorption sites.

Estimating the Interrelation between the Rate of Atomic Layer Deposition of Thin Platinum-Group Metal Films and the Molecular Mass of Reactant Precursors

The published data on the atomic layer deposition of thin platinum-group metal (Ru, Rh, Pd, Os, Ir, and Pt) films with the use of different reactant precursors and second reactants (O2, O3, H2, etc.) are generalized in the context of microelectronic technologies. A procedure for analyzing the data on the atomic layer deposition kinetics is discussed. The rate of atomic layer deposition of metallic ruthenium is not higher than 0.15 nm/cycle. An inverse dependence of the limiting atomic layer deposition growth rate on the precursor molecular mass is established. The rates of atomic layer deposition of thin films of all the remaining metals in the group range between 0.03–0.07 nm/cycle, which is lower than the values for a monolayer of these metals by several times. The methodology and ways of enhancing the reliability of the kinetic data on the atomic layer deposition are discussed, including the need for taking into account the sample surface types and effects of nucleation delays at the initial growth stages of the thin platinum-group metal film. The possible occurrence of chemical deposition reactions with intermediate products involved at the pulsed injection of the reactants is considered.

Violet Emission of ALD‐Grown ZnO Nanostructures on Confined Polymer Films: Defect Origins and Emission Control via Interface Engineering Based on Confinement of the Bottom Polymer Template

AbstractZnO thin films on polymer templates (polystyrene, PST) show strong influence of the interface via degree of confinement of the bottom polymer template in introducing the controlled defect levels in the ZnO nanostructures and consequently yield significant variation at room temperature photoluminescence (PL). The thickness of the polymer thin film in terms of its radius of gyration (R g) defines the degree of confinement of PST. Simultaneous growth of ZnO thin films by atomic layer deposition (ALD) with 150 cycles at 35 °C on spin‐coated polystyrene (PS) films of different thicknesses forms sets of ZnO/PST hybrid systems. The ZnO thin film exhibits a distinct/unusual violet emission (2.95 eV) along with the common near‐band‐edge and green emissions, when it grows on 6.5R g PST. Such defect‐induced emissions disappear with increasing degree of confinement of the bottom PST from 6.5R g to 1.5R g, and sharper UV peak dominates the PL spectra along with a prominent redshift in near‐band‐edge. Furthermore, with increasing film thickness of the bottom PST template from 1.5R g to 6.5R g, the ALD growth rate of ZnO increases by 25%. The study offers new insights into the research on opto‐electronic applications of ZnO thin films in the emerging field of organic electronics.

Aluminum Interdiffusion into LiCoO2 Using Atomic Layer Deposition for High Rate Lithium Ion Batteries

Here, as with previous work, atomic layer deposition (ALD) has been used to deposit Al2O3 on positive electrode active materials, LiCoO2, to create a protective barrier layer, suppress the high potential phase transition, and thus reduce the subsequent Co dissolution. However, in this study it was found that it also resulted in the reduction of the charge transfer resistance at the positive electrode–electrolyte interface, thus enhancing the performance of the battery. Energy-dispersive X-ray spectroscopy, in conjunction with transmission electron microscopy, shows that a discrete Al2O3 shell was not formed under the selected growth conditions and that the Al diffused into the bulk LiCoO2. The resulting active oxide material, which was significantly thicker than the nominally ALD growth rate would predict, is proposed to be of the form LiCoO2:Al with amorphous and crystalline regions depending on the Al content. The cells consisting of the modified electrodes were found to have good cycling stability and ...

Atomic layer deposition of tin oxide thin films from bis[bis(trimethylsilyl)amino]tin(II) with ozone and water

Tin oxide thin films were grown by atomic layer deposition (ALD) from bis[bis(trimethylsilyl)amino]tin(II) with ozone and water. The ALD growth rate of tin oxide films was examined with respect to substrate temperature, precursor doses, and number of ALD cycles. With ozone two ALD windows were observed, between 80 and 100 °C and between 125 and 200 °C. The films grown on soda lime glass and silicon substrates were uniform across the substrates. With the water process the growth rate at 100–250 °C was 0.05–0.18 Å/cycle, and with the ozone process, the growth rate at 80–200 °C was 0.05–0.11 Å/cycle. The films were further studied for composition and morphology. The films deposited with water showed crystallinity with the tetragonal SnO phase, and annealing in air increased the conductivity of the films while the SnO2 phase appeared. All the films deposited with ozone contained silicon as an impurity and were amorphous and nonconductive both as-deposited and after annealing. The films were further deposited in TiO2 nanotubes aiming to create a pn-junction which was studied by I-V measurements. The TiO2 nanostructure functioned also as a test structure for conformality of the processes.

Classification of processes for the atomic layer deposition of metals based on mechanistic information from density functional theory calculations

Reaction cycles for the atomic layer deposition (ALD) of metals are presented, based on the incomplete data that exist about their chemical mechanisms, particularly from density functional theory (DFT) calculations. ALD requires self-limiting adsorption of each precursor, which results from exhaustion of adsorbates from previous ALD pulses and possibly from inactivation of the substrate through adsorption itself. Where the latter reaction does not take place, an "abbreviated cycle" still gives self-limiting ALD, but at a much reduced rate of deposition. Here, for example, ALD growth rates are estimated for abbreviated cycles in H2-based ALD of metals. A wide variety of other processes for the ALD of metals are also outlined and then classified according to which a reagent supplies electrons for reduction of the metal. Detailed results on computing the mechanism of copper ALD by transmetallation are summarized and shown to be consistent with experimental growth rates. Potential routes to the ALD of other transition metals by using complexes of non-innocent diazadienyl ligands as metal sources are also evaluated using DFT.

Comparison of the Atomic Layer Deposition of Tantalum Oxide Thin Films Using Ta(NtBu)(NEt2)3, Ta(NtBu)(NEt2)2Cp, and H2O.

The growth characteristics of Ta2O5 thin films by atomic layer deposition (ALD) were examined using Ta(NtBu)(NEt2)3 (TBTDET) and Ta(NtBu)(NEt2)2Cp (TBDETCp) as Ta-precursors, where tBu, Et, and Cp represent tert-butyl, ethyl, and cyclopentadienyl groups, respectively, along with water vapor as oxygen source. The grown Ta2O5 films were amorphous with very smooth surface morphology for both the Ta-precursors. The saturated ALD growth rates of Ta2O5 films were 0.77 Å cycle-1 at 250 °C and 0.67 Å cycle-1 at 300 °C using TBTDET and TBDETCp precursors, respectively. The thermal decomposition of the amido ligand (NEt2) limited the ALD process temperature below 275 °C for TBTDET precursor. However, the ALD temperature window could be extended up to 325 °C due to a strong Ta-Cp bond for the TBDETCp precursor. Because of the improved thermal stability of TBDETCp precursor, excellent nonuniformity of ∼2% in 200 mm wafer could be achieved with a step coverage of ∼90% in a deep hole structure (aspect ratio 5:1) which is promising for 3-dimensional architecture to form high density memories. Nonetheless, a rather high concentration (∼7 at. %) of carbon impurities was incorporated into the Ta2O5 film using TBDETCp, which was possibly due to readsorption of dissociated ligands as small organic molecules in the growth of Ta2O5 film by ALD. Despite the presence of high carbon concentration which might be an origin of large leakage current under electric fields, the Ta2O5 film using TBDETCp showed a promising resistive switching performance with an endurance cycle as high as ∼17 500 for resistance switching random access memory application. The optical refractive index of the deposited Ta2O5 films was 2.1-2.2 at 632.8 nm using both the Ta-precursors, and indirect optical band gap was estimated to be ∼4.1 eV for both the cases.

Experimental and numerical investigations into the transient multi-wafer batch atomic layer deposition process with vertical and horizontal wafer arrangements

This paper investigates two types of wafer arrangements, vertical and horizontal, in a multi-wafer atomic layer deposition (ALD) reactor. The growth rate of ALD deposited alumina thin film is characterized and compared experimentally and numerically. It’s found that the wafer layout influences the deposition process significantly. Vertical multi-wafer arrangement is shown superior to the horizontal arrangement in terms of film deposition rate because of the enhanced collisions between precursor molecules and wafer surfaces in vertical arrangement. Studies using three-dimensional transient numerical model of fluid dynamics and surface reaction kinetics in multi-wafer batch ALD reveal the self-limiting details on the physical and chemical nature of ALD process. First, the deposition process is shown highly “self-limited”: surface reactions in ALD are completely terminated once surface species conversion comes to the end. Second, deposition process is found under a joint influence of precursor concentration and surface site saturation status. Before deposition rate reaches its peak, the precursor concentration is dominant in determining the deposition rate, but it is largely confined by the available surface reactive sites after the peak. Position dependence of deposition rate as shown by both experiments and simulations is weak and negligible.

Atomic Layer Deposition of AlF3 Using Trimethylaluminum and Hydrogen Fluoride

The atomic layer deposition (ALD) of AlF3 was demonstrated using trimethylaluminum (TMA) and hydrogen fluoride (HF). The HF source was HF-pyridine. In situ quartz crystal microbalance (QCM), quadrupole mass spectrometer (QMS), and Fourier transform infrared (FTIR) spectroscopy measurements were used to study AlF3 ALD. The AlF3 ALD film growth was examined at temperatures from 75 to 300 °C. Both the TMA and HF reactions displayed self-limiting behavior. The maximum mass gain per cycle (MGPC) of 44 ng/(cm2 cycle) for AlF3 ALD occurred at 100 °C. The MGPC values decreased at higher temperatures. The MGPC values were negative at T > 250 °C when TMA and HF were able to etch the AlF3 films. Film thicknesses were also determined using ex situ X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) measurements. The AlF3 ALD growth rate determined by the ex situ analysis was 1.43 A/cycle at 100 °C. These ex situ measurements were in excellent agreement with the in situ QCM measurements. FTIR analysis monitor...

Isotope analysis of diamond-surface passivation effect of high-temperature H2O-grown atomic layer deposition-Al2O3 films

The Al2O3 film formed using an atomic layer deposition (ALD) method with trimethylaluminum as Al precursor and H2O as oxidant at a high temperature (450 °C) effectively passivates the p-type surface conduction (SC) layer specific to a hydrogen-terminated diamond surface, leading to a successful operation of diamond SC field-effect transistors at 400 °C. In order to investigate this excellent passivation effect, we carried out an isotope analysis using D2O instead of H2O in the ALD and found that the Al2O3 film formed at a conventional temperature (100 °C) incorporates 50 times more CH3 groups than the high-temperature film. This CH3 is supposed to dissociate from the film when heated afterwards at a higher temperature (550 °C) and causes peeling patterns on the H-terminated surface. The high-temperature film is free from this problem and has the largest mass density and dielectric constant among those investigated in this study. The isotope analysis also unveiled a relatively active H-exchange reaction between the diamond H-termination and H2O oxidant during the high-temperature ALD, the SC still being kept intact. This dynamic and yet steady H termination is realized by the suppressed oxidation due to the endothermic reaction with H2O. Additionally, we not only observed the kinetic isotope effect in the form of reduced growth rate of D2O-oxidant ALD but found that the mass density and dielectric constant of D2O-grown Al2O3 films are smaller than those of H2O-grown films. This is a new type of isotope effect, which is not caused by the presence of isotopes in the films unlike the traditional isotope effects that originate from the presence of isotopes itself. Hence, the high-temperature ALD is very effective in forming Al2O3 films as a passivation and/or gate-insulation layer of high-temperature-operation diamond SC devices, and the knowledge of the aforementioned new isotope effect will be a basis for further enhancing ALD technologies in general.

ALD of Ultrathin Ternary Oxide Electrocatalysts for Water Splitting

Semiconducting oxides, particularly mixtures of different transition-metal oxides, are promising materials for oxygen evolution reaction (OER) catalysts. Assessment of these materials is often complicated by inadequate dispersion of the materials, charge transport limitations, and lack of surface area characterization. Thin films deposited by atomic layer deposition (ALD) present an excellent way to overcome these issues. Here, we present the first work using ALD to investigate ternary oxide electrocatalysts, specifically with the Ti–Mn ternary oxide system. Thin-film mixtures of between 1.4 and 2.8 nm in thickness are successfully synthesized by ALD and show a high degree of mixing. At compositions between ∼10 and 70% Mn:(Mn+Ti), there is a reduction in ALD growth rate relative to the growth rates of the binary constituents. Moreover, we observe a shift in the chemical binding energies of both Mn and Ti over this composition range. An elevation in the activity of Mn active sites for OER is observed with increasing MnOx content in TiO2, increasing the turnover frequency (TOF) by approximately an order of magnitude. These results are consistent with previous DFT calculations. We also explore the effect of film thickness of the ternary metal oxide on catalytic activity, highlighting how ALD allows for charge transport limitations to be minimized.

Spatial atomic layer deposition on flexible substrates using a modular rotating cylinder reactor

Spatial atomic layer deposition (ALD) is a new version of ALD based on the separation of reactant gases in space instead of time. In this paper, the authors present results for spatial ALD on flexible substrates using a modular rotating cylinder reactor. The design for this reactor is based on two concentric cylinders. The outer cylinder remains fixed and contains a series of slits. These slits can accept a wide range of modules that attach from the outside. The modules can easily move between the various slit positions and perform precursor dosing, purging, or pumping. The inner cylinder rotates with the flexible substrate and passes underneath the various spatially separated slits in the outer cylinder. Trimethyl aluminum and ozone were used to grow Al2O3 ALD films at 40 °C on metallized polyethylene terephthalate (PET) substrates to characterize this spatial ALD reactor. Spectroscopic ellipsometry measurements revealed a constant Al2O3 ALD growth rate of 1.03 Å/cycle with rotation speeds from 40 to 100 RPM with the outer cylinder configured for one Al2O3 ALD cycle per rotation. The Al2O3 ALD growth rate then decreased at higher rotation rates for reactant residence times < 5 ms. The Al2O3 ALD films were also uniform to within <1% across the central portion of metallized PET substrate. Fixed deposition time experiments revealed that Al2O3 ALD films could be deposited at 2.08 Å/s at higher rotation speeds of 175 RPM. Even faster deposition rates are possible by adding more modules for additional Al2O3 ALD cycles for every one rotation of the inner cylinder.

Real-time observation of atomic layer deposition inhibition: metal oxide growth on self-assembled alkanethiols.

Through in situ quartz crystal microbalance (QCM) monitoring, we resolve the growth of a self-assembled monolayer (SAM) and subsequent metal oxide deposition with high resolution. We introduce the fitting of mass deposited during each atomic layer deposition (ALD) cycle to an analytical island-growth model that enables quantification of growth inhibition, nucleation density, and the uninhibited ALD growth rate. A long-chain alkanethiol was self-assembled as a monolayer on gold-coated quartz crystals in order to investigate its effectiveness as a barrier to ALD. Compared to solution-loading, vapor-loading is observed to produce a SAM with equal or greater inhibition ability in minutes vs days. The metal oxide growth temperature and the choice of precursor also significantly affect the nucleation density, which ranges from 0.001 to 1 sites/nm(2). Finally, we observe a minimum 100 cycle inhibition of an oxide ALD process, ZnO, under moderately optimized conditions.

Effect of O3 on Growth of Pt by Atomic Layer Deposition

The growth characteristics of Pt deposited by atomic layer deposition (ALD) with methylcyclopentadienyltrimethylplatinum (MeCpPtMe3) and O3 are studied both experimentally and by modeling. The growth rate of Pt ALD using O3 is higher than that using either air or O2 counter reactants. In addition, a low deposition temperature of 150 °C for the deposition of metallic Pt using O3 is obtained. To investigate the role of O3 during initial growth, Pt is deposited on O3-pretreated SiO2 using air as the counter reactant. Pt deposited in this way on O3-pretreated SiO2 shows a rapid increase of surface coverage, which is similar to Pt ALD using O3 and different from Pt ALD using air on untreated SiO2. From the modeling study, it is found that pretreating the surface with O3 increases the steady state nucleation rate and decreases the nucleation incubation time on the SiO2 surface, the same phenomena which are believed to occur during the initial growth of ALD Pt using O3 counter reactant.