Gregory Jursich

ALD and Characterization of Aluminum Oxide Deposited on Si ( 100 ) using Tris(diethylamino) Aluminum and Water Vapor

© The Electrochemical Society, Inc. 2006. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Katamreddy, R., R. Inman, G. Jursich, A. Soulet, and C. Takoudis, 2006, ALD and characterization of aluminum oxide deposited on Si (100) using tris(diethylamino) aluminum and water vapor: Journal of the Electrochemical Society, v. 153, no. 10, p. C701-C706.

Highly Liquid-Repellent, Large-Area, Nanostructured Poly(vinylidene fluoride)/Poly(ethyl 2-cyanoacrylate) Composite Coatings: Particle Filler Effects

Super-repellent nanostructured composite coatings applied over large areas by spray and subsequent thermal treatment are reported. Solution blending of poly(vinylidene fluoride) and poly(ethyl 2-cyanoacrylate) is implemented to formulate filler particle dispersions used to apply these coatings. The wettability of these coatings is manipulated using hydrophobic poly(tetrafluoroethylene) and hydrophilic zinc oxide particle fillers or their combination. The resulting coatings feature contact angles up to 164 degrees for water and 154 degrees for a water and isopropyl alcohol mixture (9:1 weight ratio; surface tension approximately 40 mN/m). A self-cleaning ability is revealed by droplet roll-off angles below 10 degrees . The results show that the fillers affect the coating surface energy and surface roughness, in turn influencing the wettability of the coatings.

Superhydrophobic–superhydrophilic binary micropatterns by localized thermal treatment of polyhedral oligomeric silsesquioxane (POSS)–silica films

Surfaces patterned with alternating (binary) superhydrophobic-superhydrophilic regions can be found naturally, offering a bio-inspired template for efficient fluid collection and management technologies. We describe a simple wet-processing, thermal treatment method to produce such patterns, starting with inherently superhydrophobic polysilsesquioxane-silica composite coatings prepared by spray casting nanoparticle dispersions. Such coatings become superhydrophilic after localized thermal treatment by means of laser irradiation or open-air flame exposure. When laser processed, the films are patternable down to ∼100 μm scales. The dispersions consist of hydrophobic fumed silica (HFS) and methylsilsesquioxane resin, which are dispersed in isopropanol and deposited onto various substrates (glass, quartz, aluminum, copper, and stainless steel). The coatings are characterized by advancing, receding, and sessile contact angle measurements before and after thermal treatment to delineate the effects of HFS filler concentration and thermal treatment on coating wettability. SEM, XPS and TGA measurements reveal the effects of thermal treatment on surface chemistry and texture. The thermally induced wettability shift from superhydrophobic to superhydrophilic is interpreted with the Cassie-Baxter wetting theory. Several micropatterned wettability surfaces demonstrate potential in pool boiling heat transfer enhancement, capillarity-driven liquid transport in open surface-tension-confined channels (e.g., lab-on-a-chip), and select surface coating applications relying on wettability gradients. Advantages of the present approach include the inherent stability and inertness of the organosilane-based coatings, which can be applied on many types of surfaces (glass, metals, etc.) with ease. The present method is also scalable to large areas, thus being attractive for industrial coating applications.

Annealing behavior of atomic layer deposited hafnium oxide on silicon : Changes at the interface

Thin films of hafnium oxide are deposited on Si(100) substrates by means of atomic layer deposition using tetrakis(diethylamino)hafnium and water on Si(100) at 300°C. Detailed studies of temperature induced annealing effects on the HfO2∕Si interface are done using angle resolved x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and time of flight secondary ion mass spectroscopy (ToF-SIMS). As-deposited films show mostly native silicon oxide at the interface. Crystallization of HfO2 film initiates at about 600°C. As the annealing temperature is increased, the hafnium silicate content in the film is found to increase and the mostly silicon oxide interlayer is found to grow thicker under Ar atmosphere. Also, the formation of hafnium silicide is found to take place at temperatures ⩾800°C. The XPS data shows decomposition of the interfacial hafnium silicate layer into hafnium oxide and silicon oxide at 1000°C along with increasing formation of hafnium silicide. The ToF-SIMS data ...

Fabrication of Anti-Aging TiO2 Nanotubes on Biomedical Ti Alloys

The primary objective of this study was to fabricate a TiO2 nanotubular surface, which could maintain hydrophilicity over time (resist aging). In order to achieve non-aging hydrophilic surfaces, anodization and annealing conditions were optimized. This is the first study to show that anodization and annealing condition affect the stability of surface hydrophilicity. Our results indicate that maintenance of hydrophilicity of the obtained TiO2 nanotubes was affected by anodization voltage and annealing temperature. Annealing sharply decreased the water contact angle (WCA) of the as-synthesized TiO2 nanotubular surface, which was correlated to improved hydrophilicity. TiO2 nanotubular surfaces are transformed to hydrophilic surfaces after annealing, regardless of annealing and anodization conditions; however, WCA measurements during aging demonstrate that surface hydrophilicity of non-anodized and 20 V anodized samples decreased after only 11 days of aging, while the 60 V anodized samples maintained their hydrophilicity over the same time period. The nanotubes obtained by 60 V anodization followed by 600 °C annealing maintained their hydrophilicity significantly longer than nanotubes which were obtained by 60 V anodization followed by 300 °C annealing.

Atomic layer deposition and characterization of hafnium oxide grown on silicon from tetrakis(diethylamino)hafnium and water vapor

In this work thin films of hafnium oxide are deposited on Si(100) substrates by means of atomic layer deposition (ALD) using tetrakis(diethylamino)hafnium and water vapor at substrate temperatures of 250–350oC. Our system capabilities include fast transient delivery of reactive fluids, real-time vapor phase detection (in situ tunable diode laser hygrometer), precursor thermochemical capabilities, and ppt level elemental analysis by inductive coupling plasma mass spectrometry. The composition, purity, and other properties of the films and resulting interfaces are determined using x-ray and Fourier transform infrared spectroscopies, Z-contrast imaging and electron energy loss spectroscopy in a scanning transmission electron microscope with A scale resolution, and spectroscopic ellipsometry. The observed ALD rate is ∼1.4A per cycle. The nonuniformity across the film is less than 4%. Negligible carbon contamination is found in the resulting stoichiometric films under all conditions studied. The pulse sequence...

Atomic Layer Deposition of Y2O3 Films on Silicon Using Tris(ethylcyclopentadienyl) Yttrium Precursor and Water Vapor

Yttrium oxide films are deposited on silicon using a new precursor, tris(ethylcyclopentadienyl) yttrium with water vapor as the oxidizer, by means of atomic layer deposition (ALD). Film growth kinetics has been examined under different reactor conditions, and growth saturation is evident from precursor dosage dependence. The film thickness increases linearly with the number of deposition cycles, yielding a growth rate of 1.7 ± 0.1 A/cycle at optimal ALD conditions. Increasing the reactor temperature from 200 to 400°C shows gradual increase in growth rate, with a narrow temperature plateau in the range of 250-285°C. X-ray photoelectron spectral analysis of Y 2 O 3 films indicates the film to be stoichiometric with no evidence of carbon contamination, whereas glancing incidence X-ray diffraction data of as-deposited Y 2 O 3 suggests the film structure to be polycrystalline.

Structural phase transformation of Y2O3 doped HfO2 films grown on Si using atomic layer deposition

HfO2 and Y2O3 films, along with Y2O3-doped HfO2 composite films, have been deposited on Si by means of atomic layer deposition (ALD) using tetrakis(diethylamino)hafnium and tris(ethylcyclopentadienyl)yttrium with water vapor as the oxidizer. The growth rate and structural properties of these films have been investigated by spectral ellipsometry, grazing incidence x-ray diffraction, and x-ray photoelectron spectroscopy (XPS). The film growth temperature dependence of both HfO2 and Y2O3 films indicate overlapping ALD windows in the 250–285°C region, which is critical for ALD of Y2O3-doped HfO2 films. The composition of such films is controlled by altering precursor cycle ratios, and XPS analyses of the resulting films indicate strong correlation between the precursor cycle ratio and the film composition. From structural analyses, the as-deposited HfO2 was found to be amorphous but after annealing at 600°C or higher, it became monoclinic. In contrast, all Y2O3 films whether annealed or not had evidence of cu...

Selective atomic layer deposition of HfO2 on copper patterned silicon substrates

Selective atomic layer deposition (ALD) was performed on copper patterned silicon substrates to selectively deposit HfO2 film on silicon. The selectivity is based on differences of surface physics/chemistry rather than use of any molecular masking such as self-assembled monolayers. On silicon, the growth rate of HfO2 is 0.11 nm /cycle with no initial inhibition of film growth, while on copper no HfO2 deposition was observed up to at least 25 ALD cycles. The selective growth on silicon over copper at 25 ALD cycles provides a patterned film deposition at thicknesses of 2.8 nm HfO2 which is relevant to semiconductor nanofabrication.

Controlling interfacial reactions between HfO2 and Si using ultrathin Al2O3 diffusion barrier layer

The authors investigated the effectiveness of atomic layer deposited (ALD) aluminum oxide barrier layer in controlling the interfacial reaction between ALD HfO2 film and Si substrate. The HfO2 was observed to form silicate and silicide at its interface with Si during 5min postdeposition annealing in Ar at 800 and 1000°C. A 0.5-nm-thick Al2O3 barrier layer was found to control interfacial reactions between HfO2 and Si during annealing at 800°C, but not at 1000°C, whereas a 1.5-nm-thick barrier of Al2O3 was needed to prevent interfacial reaction up to an annealing temperature of 1000°C.