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A Process for Topographically-Selective Deposition on 3D Nanostructures by Ion Implantation Woo-Hee Kim, Fatemeh Sadat Minaye Hashemi, Adriaan J.M. Mackus, Joseph Singh, Yeongin Kim, Dara Bobb-Semple, Yin Fan, Tobin Kaufman-Osborn, Ludovic Godet, and Stacey F. Bent ACS Nano, Just Accepted Manuscript • DOI: 10.1021/acsnano.6b00094 • Publication Date (Web): 07 Mar 2016 Downloaded from http://pubs.acs.org on March 10, 2016

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A Process for Topographically-Selective Deposition on 3D Nanostructures by Ion Implantation Woo-Hee Kim,† Fatemeh Sadat Minaye Hashemi,‡ Adriaan J. M. Mackus, † Joseph Singh,§ Yeongin Kim,† Dara Bobb-Semple, † Yin Fan,ǁ Tobin Kaufman-Osborn,ǁ Ludovic Godet,ǁ and Stacey F. Bent†,* †

§

Department of Chemical Engineering, ‡Department of Materials Science and Engineering, and

Department of Chemistry, Stanford University, 443 Via Ortega, Stanford, California 94305,

United States. ǁ

Applied Materials, 974 E. Arques Avenue, M/S 81280, Sunnyvale, California 94085, United

States. KEYWORDS: Area-selective deposition, atomic layer deposition, ion implantation, 3D nanostructure, geometric selectivity

ABSTRACT: Area-selective atomic layer deposition (AS-ALD) is attracting increasing interest because of its ability to enable both continued dimensional scaling and accurate pattern placement for next-generation nanoelectronics. Here we report a strategy for depositing material onto three-dimensional (3D) nanostructures with topographic selectivity using an ALD process with the aid of an ultrathin hydrophobic surface layer. Using ion implantation of fluorocarbons (CFx), a hydrophobic interfacial layer is formed, which in turn causes significant retardation of

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nucleation during ALD. We demonstrate the process for Pt ALD on both blanket and 2D patterned substrates. We extend the process to 3D structures, demonstrating that this method can achieve selective anisotropic deposition, selectively inhibiting Pt deposition on deactivated horizontal regions while ensuring that only vertical surfaces are decorated during ALD. The efficacy of the approach for metal oxide ALD also shows promise, though further optimization of the implantation conditions is required. The present work advances practical applications that require area-selective coating of surfaces in a variety of 3D nanostructures according to their topographical orientation.

TABLE OF CONTENTS GRAPHIC:


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Recently, as the Si-based technology node nears ~10 nm and approaches its physical limit, alternative methodologies are required for further extension of Moore’s law, with current strategies focusing on the implementation of integration-feasible structures such as 3D FinFETs and nanowires (NWs) in place of the conventional planar MOSFET.1-3 In accordance with these structural challenges, extremely small feature patterning is required to satisfy the increasing process complexity of modern electronic devices beyond the sub-10 nm technology regime. In conventional device fabrication, patterning has been achieved by a top-down process based largely on photolithography and subsequent etching, but these critical processing steps are facing fundamental limits for device downscaling.4, 5 Of several paths being explored for novel nanopatterning, area-selective atomic layer deposition (AS-ALD)—a method suitable for patterning with nanoscale dimensions that enables selective growth of thin films in conjunction with surface modification—has received intensive attention as an alternative bottom-up approach.5-9 ALD itself is a powerful thin film deposition technique with excellent conformality, atomic scale thickness controllability, and large-area uniformity thanks to its growth mechanism based on self-limiting surface reactions.10-14 Regarding the surface chemistry, it has been found that the nucleation of ALD is facile on hydrophilic OH-terminated substrates, whereas it is difficult on hydrophobic H-terminated surfaces.4, 5, 15 For AS-ALD, therefore, this inherent surface reactivity can be exploited with the aid of surface modification methods, because the deposition characteristics of ALD strongly depend on the surface properties of the employed substrates.16 For most studies of AS-ALD, the surface chemical property of the desired substrates has been modified by attaching self-assembled monolayers (SAMs).4, 5 Typically, these SAMs are monolayer organic films composed of alkyl chains as a backbone and reactive groups at one or


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both ends of the molecules; the head group is spontaneously adsorbed onto the solid surface and the tail group is directly exposed for ALD reaction, allowing either hydrophobic or hydrophilic termination, depending on the tail.4 In other words, the SAMs can either enhance or prevent initial nucleation and growth during the ALD process depending on their terminal functional groups. To date, the majority of work on AS-ALD reported in the literature has deactivated the surface by attaching SAMs with hydrophobic tail groups.17-22 Nevertheless, SAMs introduce several constraints for their stable utilization in future integration processes. First, for formation of SAMs, the head groups must be directly bonded onto the surface of the substrates through chemisorption, limiting the selection of molecules to those for which such bonding will occur. Second, it is known that deactivation against ALD is critically associated with the quality of the SAM packing.4, 23, 24 Consequently, tail groups such as long chain hydrocarbons are desired to enhance the packing quality because such tail groups impose less steric hindrance and experience strong van der Waals attraction. Further, to achieve effective blocking during the ALD process, a sufficiently long coating time (e.g. dipping time longer than 12 h) is usually required to form densely packed hydrophobic SAMs without microscopic pinholes, leading to issues with low throughput.9, 25 All these restrictions may cause compatibility issues for suitable SAM adoption, especially for large scale nanopatterning processes on 3D nanostructures. To overcome these drawbacks and facilitate practical application of the AS-ALD process, alternative approaches with higher stability and lower process complexity should be investigated. Based on previous work showing that nucleation in ALD is inhibited with the aid of a hydrophobic surface,17-22 it is evident that


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the artificial manipulation of surface hydrophobicity—albeit with a more simplified process— will be a valuable tool for attaining a highly efficient AS-ALD process. In the present study, therefore, we investigate a new strategy for achieving area selective ALD of metal thin films in combination with surface deactivation by ion implantation. This method eliminates the need for SAMs and therefore has the potential to shorten the overall processing time and to expand the type of surface materials for which blocking can be achieved. Moreover, this approach allows for not just spatial selectivity, but also topographical selectivity, in which deposition can be achieved on surfaces of 3D patterned substrates based on their geometric orientation. Although an early study in the 1990s looked at selective growth of diamond films on ion-implanted Si by chemical vapor deposition (CVD),26, 27 the mechanism in that work was one of implantation-induced defects that relied upon damage of the underlying substrate.27 Other more recent work has examined selective etching induced by ionimplantation.28 However, the use of ion implantation to modify surface properties such as hydrophobicity in order to control deposition has not been previously explored. In this work we investigate the ion implantation of an ultrathin CFx layer on a Si substrate as a model hydrophobic surface to inhibit nucleation.29-31 The surface hydrophobicity is characterized by static water contact angle (WCA) measurement, and X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS) analyses further confirm the surface properties of the implanted CFx layer. The ALD Pt process is employed to evaluate the blocking ability and durability against ALD. By applying a selective CFx deactivation process, we demonstrate successful area-selective deposition of ALD Pt films on both planar and 3D samples. The efficacy of the process toward ZnO and Al2O3 ALD on planar samples is also compared. The experimental strategy that we used to verify 3D AS-ALD of Pt thin films is


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schematically illustrated in Figure 1. Si fin array nanostructures are prepared by a self-aligned double patterning process (Figure 1a), followed by anisotropic CFx ion implantation (Figure 1b). This allows the deactivation of only horizontal surfaces, such that no Pt growth occurs on horizontal regions, providing vertical decoration along the sidewalls of the Si fin arrays (Figure 3c). We expect that this advanced new approach for AS-ALD that allows for topographicallyselective growth control may provide an opportunity for functional coating of various emerging nanostructures.

Figure 1. Schematic illustration of 3D AS-ALD of Pt thin films on vertical sidewalls of Si fin array nanostructures. (a) Formation of Si fin arrays with self-aligned double patterning. (b) Anisotropic CFx implantation: deactivation of top and bottom surfaces against ALD. (c) Formation of selective Pt thin films along the vertical sidewall of Si fin arrays during Pt ALD. RESULTS AND DISCUSSION The chemical composition and bonding structure of the CFx-implanted Si surface were first evaluated by XPS. The spectrum of the XPS survey scan in Figure 2a reveals that the asimplanted CFx surface is composed mainly of F and C, with a small amount of O and Si caused by the contribution from the underlying Si substrate; the XPS data indicates a fluorine-to-carbon (F/C) ratio of 2.3. The high resolution F 1s spectrum shows a single symmetric peak centered at


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688.9 eV in Figure 2b, which is indicative of a C-F covalent bond.32 To further elucidate the fluorocarbon bonding features, a high resolution spectrum of the lower C 1s peak is deconvoluted into five distinct peaks, which are assigned to CF3 (292.5 eV), CF2 (290.5 eV), CF (288.3), C-CF (286.5 eV) and C-C (284.5 eV) components, respectively, as shown in Figure 2c. These peaks are in good agreement with reference values in the literature for CFx films.33-35 Further information on the Si 2p spectrum is available in Figure S1. In Figure S1, only a peak associated with either Si-Si or Si-C bonds is seen; there is no observable signal from Si-F bonds, expected at around 107-110 eV36, 37 Hence, the combination of the F 1s and Si 2p spectra suggest that the fluorocarbon layer formed by ion implantation bonds to the Si through Si-C bonds. In addition, LEIS analysis provides further insight into the surface coverage and thickness of the outer CFx layer. Figure 2d shows 3 keV 4He+ LEIS spectra of the CFx-implanted Si and several reference samples. Here, reference samples of Teflon and two different Si samples (nontreated and in-situ cleaned with O atoms for 10 min to remove adsorbed hydrocarbons, respectively) were also measured to help in the analysis. The LEIS spectrum of the CFx-coated sample shows a clear F peak and a shoulder on the higher energy side of the F peak. The shoulder is attributed to Si below the outmost atomic layer of containing a fluorine and therein contains no direct peak for Si, which suggests that the outmost atomic layer contains negligible Si content. However, the absence of a Si peak may be partially due to the presence of hydrocarbon contamination on the sample, as seen on the non-treated Si reference sample which also shows no Si peak. Therefore, to determine if a complete fluorocarbon layer is present, the F peak of the CFx-implanted sample is further compared with that of the Teflon reference. The F peak area of the CFx implanted sample is found to be ~92 % that of the Teflon sample, suggesting that the layer is almost closed, with ~8 % of the surface contaminated by probable


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hydrocarbons on either the CFx-covered layer or Si. Additionally, the thickness of the CFx layer is determined by LEIS to be ~1.5 ± 0.2 nm. Therefore, based on the XPS and LEIS analyses, we conclude that the surface is coated by a well-packed CFx layer.

Figure 2. Surface analyses of as-implanted CFx layer on Si substrate. (a) XPS survey scan. (b) F 1s high resolution XPS scan. (c) C 1s high resolution XPS scan. (d) 3 keV 4He+ LEIS spectra, in which reference Teflon and two kinds of Si samples (non-treated and in-situ cleaned with O


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atoms for 10 min to remove adsorbed hydrocarbons, respectively) were employed for comparison. The ability of the CFx-implanted layer to block deposition against ALD was evaluated next. For comparison, a piranha-cleaned Si substrate with a high concentration of OH termination groups was employed for a reference sample because it is well-known to be efficient in growing high quality Pt films without a significant nucleation delay.15, 38 Pt ALD was carried out on both of the substrates, and the corresponding survey XPS spectra are shown in Figures 3a. Following 400 cycles of Pt ALD, no noticeable Pt peaks are observed on the CFx-implanted surface in contrast to the clearly-evident Pt peaks on piranha-cleaned Si. The only peaks observed on the former spectrum are identical to those of the as-implanted CFx surface, indicating the effective inhibition of Pt nucleation. To confirm its blocking capability, we carried out plan-view SEM (Figure S2) and AFM (Figures 3b-3c) measurements. On the basis of both the morphological analyses, an almost continuous Pt thin film was grown on the piranha-cleaned Si substrate after 400 ALD cycles,38 whereas no Pt growth was observed on the CFx-implanted surface. Additionally, Figures 3c and 3d show corresponding AFM line scan data for both samples, from which the measured RMS roughness was estimated to be 1.05 nm and 0.30 nm for the clean and CFx-implanted samples, respectively. The RMS value after Pt ALD on the CFx-treated sample is almost identical to that of the as-implanted CFx layer, indicating its good blocking capability against Pt ALD (Figure S3). In the same manner, the hydrophobicity of the CFx-implanted sample is still maintained after ALD, with only a slight decrease in WCA value from 104.8˚ to 97.1˚ after 400 cycles of Pt ALD (Figure S4).


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Figure 3. XPS and AFM analyses after 400 cycles of Pt ALD. (a) XPS survey scan. (b-c) Oblique-view AFM image (1 x 1 µm2) on piranha-cleaned Si surface and CFx implanted surface, respectively. (d-e) AFM line scan profile along the dashed black line on the piranha-cleaned Si surface and CFx implanted surface, respectively. Because there was modest degradation in hydrophobicity after the ALD process, the robustness of the CFx blocking layer as a function of ALD cycle number was further examined. Figure 4a shows the water contact angle plotted versus the number of ALD cycles. The contact angle gradually decreases from 100.5˚ to 73.6˚ following 300-1000 cycles of Pt ALD, suggesting degradation of the CFx film. It would be expected that as the CFx overlayer degrades, Pt nucleation and growth may begin to occur. To probe for the degradation of the CFx layer and the presence of Pt, XPS survey scans were performed, as shown in Figure 4b, and the quantitative results of atomic compositions are summarized in Table S1. Consistent with WCA results, not only is there a noticeable decrease in the F 1s peak assigned to a C-F covalent bond but a gradual loss of the C 1s peak assigned to C-F bonds (magnified C 1s spectra shown in Figure S5) is also observed with increasing number of ALD cycles. Significantly, although no Pt signal was observed for up to 500 cycles, a small Pt signal appeared by 700 cycles of Pt ALD, and a


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significant amount of Pt was detected after 1000 ALD cycles. The results indicate that the onset of Pt nucleation is related to the degradation of C-F bonds. The blocking ability under other implantation conditions was also examined. The results (shown in Table S2 and Figure S6) indicate that blocking of Pt ALD can be achieved under a range of implantation parameters. To further elucidate the Pt nucleation process on CFx-implanted substrates, morphological measurements were taken by plan-view SEM and AFM. Figure 4c-f shows plan view SEM images for these samples after increasing ALD cycles. No nuclei are seen at 300 cycles, and only very few Pt nuclei begin to form on the CFx-treated surface following 500 cycles. Although no Pt was detected by XPS after 500 cycles, it is likely that this small Pt content is below the XPS detection limit. With further increase in the number of ALD cycles up to 1000 cycles, more Pt nuclei are seen and the size distribution of the individual Pt nuclei becomes broader. These SEM results are consistent with those from AFM measurements (Figure S7). The images reveal hemispherical nuclei, which are different in shape from Pt nuclei formed on the typical SiO2 surface.15, 38 The shape is likely related to the poor wetting properties of Pt on the CFx-coated surface. We hypothesize that Pt nucleation occurs on microscopic pinholes caused by gradual degradation of CFx layer; future studies will be carried out to test this hypothesis. The areal coverage of Pt on the CFx-implanted substrates extracted from the plan-view SEM data, together with the film thickness determined from the spectroscopic ellipsometry and crosssectional SEM data, are plotted versus the number of ALD cycles in Figure 4g; those on the piranha-cleaned Si substrate are also included as reference. In contrast to the reference data, which shows nearly 100% Pt coverage after 300 cycles, the areal coverage for Pt grown on the CFx layer remains very low for more than 500 cycles, and then slowly approaches 70% by 1000 ALD cycles. The data hence indicate that nucleation and coalescence toward a closed Pt film is


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still occurring on the CFx-implanted substrate even after 1000 cycles of Pt ALD. Nevertheless, once nucleation is initiated on the CFx surface at ~500 cycles of Pt ALD, the growth rate becomes nearly constant, with an average growth rate per cycle of ~0.5 Å/cycle, comparable to that on a piranha-cleaned Si substrate (~0.45 Å/cycle).

Figure 4. (a) Water contact angle plotted versus the number of Pt ALD cycles on CFx-implanted surface (inset: pictures of water droplets during contact angle measurement), (b) XPS survey scan spectra collected after 300, 500, 700, and 1000 cycles of Pt ALD on a CFx-implanted surface. (c-f) Plan-view SEM images observed after 300, 500, 700, and 1000 cycles of Pt ALD


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on CFx-implanted surface, respectively. (g) Film thickness (filled markers and solid lines) and areal coverage (open markers and dashed lines) plotted versus the number of Pt ALD cycles on CFx-implanted surface and on piranha-cleaned Si. To test the generality of the ion implantation process toward other ALD systems, preliminary studies were also carried out in which ZnO and Al2O3 ALD was performed on the CFx-implanted Si samples. The results are shown in Figures S9 and S10. The CFx-implanted surface exhibits significant nucleation retardation against ZnO ALD, although the blocking ability is somewhat weaker than that for Pt ALD. On the other hand, although some retardation against Al2O3 ALD is observed, the CFx surfaces under the implantation conditions that we investigated do not effectively block initial nucleation of Al2O3 ALD. However, we believe that blocking of these metal oxide ALD processes can be achieved through optimization of the implantation conditions or species, and such studies are currently under way in our laboratory. In addition to these experiments, we are currently undertaking density-functional calculations to further explore the detailed surface nucleation mechanism and degradation of the CFx film, the results of which will be presented in a separate publication. Having established the ability of CFx-implantation to block Pt ALD, the feasibility of using this approach for AS-ALD was evaluated on a 2D checkerboard pattern composed of alternating CFx-implanted and unimplanted regions at the surface, a structure prepared by a photolithography-assisted process (Figure S11). Figure 5a shows a plan-view SEM image after 500 cycles of Pt ALD on the 2D checkerboard patterns (5 x 5 µm2); in this image, the darker squares are those where CFx implantation took place, and the bright squares are the unimplanted regions. Figures 5b and 5c show the Pt signal from scanning AES and the AES line scan, respectively, taken from the same region. In these images, a brighter color indicates a higher


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intensity of the Pt element (Figure 5b), which corresponds with the Pt line scan profile (Figure 5c). In contrast, the darker regions occur where no Pt signal is observed, and these areas are coincident with those of the CFx-implanted squares, indicating excellent selectivity of the current AS-ALD process. Further information on the 2D AS-ALD studies of Pt thin films is available (Figures S12-S14).

Figure 5. Spatial analysis after 500 cycles of Pt ALD on the 2D checkerboard patterns (5 x 5 µm2) with alternating CFx-implanted surfaces. (a) Plan-view SEM image (bright colored region corresponds to Pt thin film on the unimplanted region; darkly colored region to the CFximplanted surface), (b) AES areal mapping of Pt, and (c) AES line scan profile of Pt. Given the success of the ion implantation-assisted AS-ALD process on 2D patterns, we investigated the application of AS-ALD of Pt thin films on 3D structured Si fin arrays with selectively CFx-covered surfaces, as shown in the schematic illustrations of Figure 1. Figure 6a shows a cross-sectional TEM image of the as-constructed Si fin arrays with the CFx implantation. The Si fin arrays are structured with a bottom width and depth of 65 nm and 200 nm, respectively, and a fin spacing of 65 nm. After CFx implantation, 500 cycles of Pt ALD were carried out on the 3D fin arrays. The cross-sectional TEM image taken after ALD (Figure 6b) clearly shows that Pt growth occurs selectively on the vertical sidewalls but not on the CFx-


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implanted horizontal regions. The magnified image in Figure 6c further confirms that continuous Pt thin films are well-decorated only along the vertical sidewalls. The current results thus show that this AS-ALD scheme provides an excellent method for achieving highly selective thin films on desired areas via a facile control of implant directionality. We foresee that this method will be useful for simplified area-selective growth applicable to next-generation 3D nanostructures, in which selective coating of surfaces can be controlled according to their topographical orientation.

Figure 6. Cross-sectional TEM images of Si fin array structures (bottom width and depth of 65 nm and 200 nm, respectively, with a spacing of 65 nm) with horizontal surfaces treated by CFx implantation (a) before and (b) after 500 cycles of Pt ALD, respectively. (c) The magnified TEM image of the region in the dashed red box of part (b). CONCLUSIONS In conclusion, we successfully demonstrate topographically-selective growth of Pt thin films by the combination of ALD and directional surface treatment by ion implantation. A CFx layer formed by ion implantation acts as a hydrophobic model surface to inhibit ALD nucleation. The as-implanted CFx layer is mostly composed of various C-F related bonding species (C-C-CF, CF,


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CF2, and CF3) with an F/C ratio of ~2.2 and found to be an ultrathin closed film (surface coverage: ≥ 92 %, and thickness: ~1.5 nm), imparting high hydrophobicity (WCA: ~104.8°). The blocking capability and stability of the hydrophobic CFx layer as a nucleation deactivator against the ALD process was evaluated, and we found that it could be sustained over nearly 500 cycles of Pt ALD at 250 ˚C. Additional ALD cycles eventually lead to nucleation and growth of Pt. By exploiting this robust blocking property, we achieve excellent area-selectivity of Pt thin films on both 2D and 3D patterned substrates, completely inhibiting Pt growth on horizontally deactivated CFx regions of a substrate. The current method we presented here is expected to offer a new route toward practical selective deposition, applicable to various emerging nanostructures. EXPERIMENTAL METHODS ALD Processes. For this study, a custom-made ALD reactor controlled by LabVIEW software was used for Pt ALD, while a commercial ALD reactor (GEMStar-6 reactor, Arradiance Inc.) was utilized for ZnO and Al2O3 ALD. Both ALD setups are designed to transport the precursors and carrier gas efficiently from the manifold to the substrate, and then to the exhaust. ALD of Pt films was carried out using MeCpPtMe3 and dry air as the Pt precursor and counter reactant, respectively, at 250 °C. ALD of ZnO and Al2O3 films was performed using diethylzinc (DEZ) and trimethylaluminum (TMA), respectively, with H2O as a count oxidant at 150 °C. The Pt precursor contained in a glass bubbler was heated to 50 °C to obtain a sufficient vapor pressure, whereas DEZ and TMA containing bubblers were maintained at room temperature. All the delivery lines were heated to a temperature 10-15 °C higher than those of the bubblers to prevent precursor condensation. The precursor vapor was carried into the reaction chamber with N2 carrier gas controlled by mass flow controller (MFC). N2 gas at the same flow rate was also used for purging excess gas molecules and byproducts between each precursor and


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counter reactant exposure step. Further information on the Pt, ZnO, and Al2O3 ALD processes can also be found in our earlier publications.9,15,22,38 Substrate Preparation Methods. As a model hydrophobic surface for the new AS-ALD process, fluorocarbon-coated substrates were prepared by ion implantation. The CFx+ implantation was performed on Si(001) blanket wafers at 1kV with an implant dose of 1 x 1016 ions/cm2, leading to the formation of an ultrathin CFx-containing hydrophobic layer. Contact angle images of water droplets clearly show the difference in hydrophobicity before and after the formation of the CFx layer (Figure S15). The estimated WCA values were 38.5° and 104.8°, respectively. For reference controls for a routine Pt ALD process, the Si(001) wafer was immersed in piranha solution (volume ratio, 3:1 of H2SO4:H2O2 mixture), leading to high surface hydrophilicity due to chemical oxide formation with an increased number of surface hydroxyl groups.15, 39, 40 Analytical Methods. The atomic composition of the outer CFx layer was estimated by LEIS using 3 keV 4He+ ion scattering. The elemental composition and chemical bonding structure of the films were further analyzed by XPS (a detection limit: ~100 ppm) using an Al Kα monochromatic source of 1486.6 eV. The surface hydrophobicity was estimated at three different spots by static WCA measurements, and the average value was taken to represent the hydrophobicity of each film. The film thickness was measured by spectroscopic ellipsometry with a spectral range of 380−900 nm at three different angles of incidence (65°, 70°, and 75°) and with the polarizer set to 45°. The surface morphology of the films was analyzed by planview observation of field emission scanning electron microscopy (FE-SEM) and by atomic force microscopy (AFM), and the surface coverage was calculated computationally using ImageJ software from the planar SEM images. The microstructure of the films was analyzed by grazing


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incidence x-ray diffraction (GIXRD) performed at beam line 11-3 of the Stanford Synchrotron Radiation Lightsource (SSRL). The GIXRD data were collected by a MAR345 2D imaging detector using a 12.7 KeV x-ray source with an incident angle of 0.5˚. The detector was 150 mm away from the sample and the position calibrated using a LaB6 reference and the WxDiff software package. The 2D elemental mapping of selectively patterned films was carried out by Auger electron spectroscopy (AES). The cross-sectional view of 3D patterned films was explored by transmission electron microscopy (TEM).

ASSOCIATED CONTENT Supporting Information. This material is available free of charge via the Internet at http://pubs.acs.org. Experimental details, additional characterization data, supporting table and figures (Tables S1-S2 and Figures S1-S15)

AUTHOR INFORMATION Corresponding Author * E-mail: [email protected]. Notes The authors declare no competing ﬁnancial interest. ACKNOWLEDGMENT


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This work was by the Department of Energy under Award Number DE-SC0004782 (WHK and SFB). F.S.M.H was supported by the Kodak Graduate Fellowship. A.J.M.M. was supported by the Netherlands Organization for Scientific Research (NWO-Rubicon 680-50-1309). J.S. was supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-114747. Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource, a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Stanford University. REFERENCES 1. Lauhon, L. J.; Gudiksen, M. S.; Wang, D.; Lieber, C. M., Epitaxial Core-Shell and CoreMultishell Nanowire Heterostructures. Nature 2002, 420 , 57-61. 2. Goldberger, J.; Hochbaum, A. I.; Fan, R.; Yang, P., Silicon Vertically Integrated Nanowire Field Effect Transistors. Nano Lett. 2006, 6 , 973-977. 3. Zhang, P.; Mayer, T. S.; Jackson, T. N., 2007 IEEE Device Research Conference: Tour de Force Multigate and Nanowire Metal Oxide Semiconductor Field-Effect Transistors and Their Application. ACS Nano 2007, 1 , 6-9. 4. Lee, H. B. R.; Bent, S. F., Nanopatterning by Area-Selective Atomic Layer Deposition. In Atomic Layer Deposition of Nanostructured Materials, First Edition ed.; Pinna, N.; Knez, M., Eds. Wiley-VCH Verlag GmbH & Co. KGaA: Weinheim, 2011; pp 193-225. 5. Mackus, A.; Bol, A.; Kessels, W., The Use of Atomic Layer Deposition in Advanced Nanopatterning. Nanoscale 2014, 6 , 10941-10960. 6. Chen, R.; Bent, S. F., Chemistry for Positive Pattern Transfer Using Area-Selective Atomic Layer Deposition. Adv. Mater. 2006, 18 , 1086-1090. 7. Knez, M.; Nielsch, K.; Niinistö, L., Synthesis and Surface Engineering of Complex Nanostructures by Atomic Layer Deposition. Adv. Mater. 2007, 19 , 3425-3438. 8. Kim, W.-H.; Heo, K.; Lee, Y. K.; Chung, T.-M.; Kim, C. G.; Hong, S.; Heo, J.; Kim, H., Atomic Layer Deposition of Ni Thin Films and Application to Area-Selective Deposition. J. Electrochem. Soc. 2011, 158 , D1-D5. 9. Hashemi, F. S. M.; Prasittichai, C.; Bent, S. F., A New Resist for Area Selective Atomic and Molecular Layer Deposition on Metal–Dielectric Patterns. J. Phys. Chem. C 2014, 118 , 10957-10962. 10. Lim, B. S.; Rahtu, A.; Gordon, R. G., Atomic Layer Deposition of Transition Metals. Nat. Mater. 2003, 2 , 749-754. 11. Shin, H.; Jeong, D. K.; Lee, J.; Sung, M. M.; Kim, J., Formation of TiO2 and ZrO2 Nanotubes Using Atomic Layer Deposition With Ultraprecise Control of The Wall Thickness. Adv. Mater. 2004, 16 , 1197-1200. 12. Kim, W.-H.; Park, S.-J.; Son, J.-Y.; Kim, H., Ru Nanostructure Fabrication Using an


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