B.-C. Kang

Growth of TiO2 thin films on Si(100) substrates using single molecular precursors by metal organic chemical vapor deposition

Abstract Growth of titanium dioxide (TiO2) thin films on Si(100) substrates was carried out using a single molecular precursor at deposition temperature in the range of 300–700°C by the metal organic chemical vapor deposition (MOCVD) method. Titanium(IV) isopropoxide, (Ti[OCH(CH3)2]4), was used as a precursor without any carrier gas. Crack-free, anatase type TiO2 polycrystalline thin films with a stoichiometric ratio of Ti and O were successfully deposited on Si(100) at temperature as low as 500°C. XRD and TED data showed the formation of the highly oriented anatase phase with the [211] direction for the TiO2 thin films grown on Si(100) at below 500°C, whereas with increasing the deposition temperature to 700°C, the main film growth direction was changed to be [200], suggesting a possibility of epitaxial thin film growth. Two distinct growth behaviors were observed from the Arrhenius plots. Below 500°C, the growth rate of TiO2 is apparently limited the substrate temperature. The activation energy for TiO2 film deposition calculated in this region is approximately 77.9 kJ/mol, while that for a film grown above 500°C shows a negative value, indicating a predominant diffusion controlled deposition process. Using Al/TiO2/p-Si metal-insulator semiconductor (MIS) diode structure, a dielectric constant was also obtained from a capacitance-voltage (C–V) curve to be 21.

Growth of β-SiC nanowires and thin films by metalorganic chemical vapor deposition using dichloromethylvinylsilane

We deposited β-SiC thin films and β-SiC nanowires by metalorganic chemical vapor deposition (MOCVD) on bare Si(100) and Ni-coated Si(100) substrates using dichloromethylvinylsilane [CH2CHSi(CH3)Cl2] as a single molecular precursor. Deposition pressures and temperatures were about 50 mTorr and 800–1200 °C, respectively, and deposition durations were 0.5–2 h. Nickel plays an important role as a catalyst in growing β-SiC nanowires. As-deposited zinc-blende SiC thin films and nanowires were grown separately. Initial growth rates are strongly dependent on deposition temperature. TEM analysis showed that the as-deposited β-SiC nanowires are wrapped with very thin amorphous carbon layers, have a [111] growth direction with well-crystallized structure, and modulated diameters. XPS and EDX analyses show that the Si:C compositions are about 1.0:1.2, suggesting possible applications to both field emitters and electronic devices.

Selective growth of TiO2 thin films on Si(100) surfaces by combination of metalorganic chemical vapor deposition and microcontact printing methods

We successfully patterned TiO2 thin films by metalorganic chemical vapor deposition (MOCVD) on Si(100) substrates where the surface was first modified by an organic thin film. The organic thin film [octadecyltrichlorosilane (OTS)] of self-assembled monolayers (SAMs) was deposited by microcontact printing. Selective deposition of a 130 nm thick TiO2 film was done on a 300–500 °C surface prepared by MOCVD without any carrier or bubbler gas. Auger electron spectroscopy and x-ray diffraction analyses showed that the deposited TiO2 material was stoichiometric, polycrystalline, and consisted of anatase phase. Alpha-step profile and optical-microscopic images also showed that the boundaries between the OTS SAMs and selectively deposited TiO2 thin film areas are definite and sharp. Capacitance–voltage measurement of a TiO2 thin film yielded a dielectric constant of 29, suggesting possible application to electronic materials.

Selective growth of iron oxide thin films using the combined method of metal-organic chemical vapor deposition and microcontact printing

The authors have carried out the selective deposition of magnetite iron oxide (Fe3O4) thin films with about 50nm thickness on Si(100) surfaces which were patterned by octadecyltrichlorosilane (OTS) using microcontact printing (μCP) method. The μCP method showed that hydrophobic patterns with microdimension were able to be formed on hydrophilic area such as silicon surface. Iron oxide thin films were deposited on the Si(100) substrates by thermal metal-organic chemical vapor deposition (MOCVD) method using single molecular organometallic precursor of iron pentacarbonly [Fe(CO)5] with high purity (99.999%) oxygen gas. The deposition was performed in the range of 250–350°C substrate temperature for 2–10min under 1×10−2Torr in a homemade MOCVD system. In order to check the selectivity of as-deposited thin films optical microscopy, scanning electron microscopy, and atomic force microscopy analyses were performed. To confirm the crystallinity of deposited thin films, x-ray diffraction patterns and micro-Raman w...

Selective Deposition of Hafnium Oxide Nanothin Films on OTS Patterned Si(100) Substrates by Metal–Organic Chemical Vapor Deposition

Soft lithography is a method for the manufacture of micro/nano size patterns and structures by using organic materials without the use of high energy. In particular, microcontact printing (muCP) is a very convenient and nonphotolithographic technique that can generate patterned features of self-assembled monolayers (SAMs). In this study, we carried out the selective deposition of HfO2 nano-thin films on Si(100) substrates by combination of muCP using octadecyltrichlorosilane (OTS) and metal-organic chemical vapor deposition (MOCVD). Single molecular precursor of Hf(OtBu) 4 was used for the growth of HfO2 nano-films, and the deposition was carried out between 150degC and 400degC at a pressure of 3times10-2 torr. The as-grown films were characterized by x-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), x-ray photoelectron spectroscopy (XPS), and capacitance-voltage (C-V) and current-voltage (I-V) measurement. It is expected that the combination of muCP of SAM and MOCVD is a better method for fabricating the HfO 2 thin films between micro and nano sizes

Micropatterning of TiO2 Thin Films by MOCVD and Study of Their Growth Tendency

In this work, we studied the growth tendency of TiO2 thin films deposited on a narrow-stripe area (<10 μm). TiO2 thin films were selectively deposited on OTS patterned Si(100) substrates by MOCVD. The experimental data showed that the film growth tendency was divided into two behaviors above and below a line patterning width of 4 μm. The relationship between the film thickness and the deposited area was obtained as a function of f(x) = a[1 − e(−bx)]c. To find the tendency of the deposition rate of the TiO2 thin films onto the various linewidth areas, the relationship between the thickness of the TiO2 thin film and deposited linewidth was also studied. The thickness of the deposited TiO2 films was measured from the alpha-step profile analyses and cross-sectional SEM images. At the same time, a computer simulation was carried out to reveal the relationship between the TiO2 film thickness and deposited line width. The theoretical results suggest that the mass (velocity) flux in flow direction is directly affected to the film thickness.

Iron Oxide Thin Film Deposition on Si(100) Substrate using MOCVD Method

We have deposited iron oxide thin films on Si(100) substrates using single molecular precursor in the range of 300–500°C by metal‐organic chemical vapor deposition (MOCVD) method. Iron pentacarbonyl [Fe(CO)5] and oxygen gas were used as the iron source and oxidizing agent, respectively. The Si(100) wafer was used a substrate and it was cleaned by sequential ultrasonic baths of acetone, ethanol, HF (10%) and rinsed by de‐ionized water. To deposit the iron oxide thin films on the substrate, O2 reactive gas was needed during the deposition. We have studied the changes of morphology, crystallinity and thickness of films deposited at various ratios of injected precursor to O2 volume as well as several deposition temperatures. The as‐grown thin film was first characterized by X‐ray diffraction (XRD) for the study of crystallinity. To confirm the morphologies and thickness, scanning electron microscopy (SEM) analysis was also performed. To identify the composition of the deposited thin films, energy dispersive X‐ray (EDX) and X‐ray photoelectron spectrometry (XPS) analyses were carried out.

Study of selective deposition of TaN thin films on OTS patterned Si(100) substrates

Cubic TaN thin films have been selectively deposited on Si(100) substrates in the temperature range of 400 - 500 °C by combination of micro-contact printing (μCP) and metalorganic chemical vapour deposition (MOCVD) methods. The patterned Si(100) substrates were initially fabricated with the self-assembled monolayers (SAMs) using an organic molecule of octadecyltrichlorosilane (OTS) by μCP method. Ta(N(MeEt))3(NtBu) and NH3 were used for the growth of TaN thin film. For a selective growth study, we characterized the as-grown films with optical microscopy (OM), micro-Raman spectrometer and atomic force microscopy (AFM). In the beginning of film deposition TaN thin film preferred to grow on silicon surface area rather than OTS printed area due to hydrophilicity of silicon surface, however, the selectivity of TaN thin film deposition was depended on the deposition time in the deposition temperature range.

Selective Deposition of Hafnium Oxide Nano-Thin Films on OTS Patterned Si

The patterning of thin films is of considerable scientific and technological interest. Various ways to obtain micro/nano patterns of thin films have been thoroughly investigated. Soft lithography is the method to make micro/nano size patterns and structures simply using organic materials without involving high energy. In particular, microcontact printing (μCP) is a very convenient, nonphotolithographic technique that can generate patterned features of self-assembled monolayers (SAMs) on both planar and nonplanar surfaces. Moreover, the μCP technique shows that hydrophobic patterns with micro/nano dimensions can be formed on hydrophilic surfaces. In this study, we carried out the selective deposition of HfO2nano-thin films on Si

Cubic SiC Nano-thin Films and Nano-wires: High Vacuum MOCVD, Surface Characterization, and Application Tests

Singlecrystalline, epitaxial cubic silicon carbide (β-SiC) nano-thin films have been deposited on Si