J.-H. Boo

Deposition of aluminum-doped zinc oxide films by RF magnetron sputtering and study of their structural, electrical and optical properties

Highly oriented undoped and aluminum-doped ZnO (AZO) films in the (002) direction were prepared by RF magnetron sputtering on glass substrates with specifically designed ZnO targets containing different amounts of Al(OH)3 powder as doping source. A systematic study of the influence of deposition parameters such as Al(OH)3 content in the target, the target–substrate distance (Dts), deposition time and substrate temperature on the structural, electrical and optical properties of the as-grown AZO films was carried out. XRD shows that AZO (002) crystal grew parallel to the substrate. With increasing Dts the growth rate increased, while the substrate temperature did not affect the growth rate. The as-grown AZO films not only have an average transmittance of >85% in the visible region, but also have an optical bandgap between 3.2 and 3.64 eV, depending on the sputtering parameters. The resistivity of the film deposited at Dts=45 mm from a 4 wt.% Al(OH)3-doped ZnO target was approximately 9.8×10−2 Ω cm, showing semiconductor properties.

Deposition of aluminum-doped zinc oxide films by RF magnetron sputtering and study of their surface characteristics

Transparent conductive, undoped and aluminum-doped ZnO (AZO) thin films were prepared on the glass substrates at deposition temperature in the range of room temperature (R.T.) ;300 8C by RF magnetron sputtering. Highly oriented AZO films in the w002x direction were obtained with specifically designed ZnO targets. A systematic study on the dependence of deposition parameters on the structural, optical and electrical properties of the as-grown AZO films was mainly investigated in this work. The AZO film prepared at R.T. with 4 wt.% Al(OH) doped a ZnO target under a target-to-substrate distance (D ) of 3 ts

Plasma-Polymerized Toluene Films for Corrosion Inhibition in Microelectronic Devices

In view of decreasing dimensions in microelectronic devices, the question of how to protect effectively the multilevel interconnections from corrosion becomes more and more important. Generally, the corrosion failure of electronic devices is mainly related to interconnect metals such as copper forming porous oxide layers on the surface and the increased use of new developed polymers as interlayer dielectrics in microelectronic devices. In this paper plasma-polymerized toluene films were considered as a possible candidate for a interlayer dielectric for multilevel metallization of ultra large scale integrated (ULSI) semiconductor devices. The protective abilities of plasma-polymerized toluene films as a function of RF power and deposition temperature in a 3.5 wt.% NaCl solution were examined by electrochemical methods and FT-IR analyses. The protective efficiency of the film increased with increasing RF power and deposition temperature, which induced the higher degree of cross-linking in the film.

High-rate deposition of plasma polymerized thin films using PECVD method and characterization of their optical properties

Abstract Plasma polymerized organic thin films were deposited at temperature in the range of room temperature to 693 K by plasma enhanced chemical vapor deposition method using the thiophene (C4H4S) precursor. Radio frequency (RF) with 13.56 MHz was applied and the RF power was changed in the range from 30 to 100 W with a gas ratio of Ar:H2=1:1. The as-grown organic thin films were basically characterized with ellipsometry, UV–Vis spectroscopy, and photoluminescence (PL) measurements. In order to compare the difference of optical properties of the plasma polymerized organic thin films, the effects of the RF power and deposition temperature on their structural properties were mainly studied in this work. UV–Vis spectra showed an energy band gap shift from 3.78 to 4.02 eV with increasing RF power and quite high optical transmittance up to 95%. During CVD, moreover, the plasma diagnostics were in situ carried out by using optical emission spectroscopy that showed a strong dependency of intensity on RF powers. To check a possibility of optical device application, PL measurements were also carried out. From the PL data, we could obtain the maximum PL emission intensity at approximately 550 nm wavelength from a plasma polymerized organic thin film grown at room temperature and RF power of 70 W with gas ratio of Ar:H2=1:1. The maximum growth rate is obtained to be 115 nm/min.

Hydrogenated amorphous and crystalline SiC thin films grown by RF-PECVD and thermal MOCVD; comparative study of structural and optical properties

Thin films of hydrogenated amorphous silicon carbide (a-SiC:H) and crystalline silicon carbide (c-SiC) with different compositions were deposited on Si( 100 ) substrates by both RF plasma enhanced chemical vapor deposition and thermal metal organic chemical vapor deposition methods using a SiH qCH gas mixture and a single molecular precursor of diethylmethylsilane, 44 respectively. In this experiment, we mainly investigated the dependence of structural and optical properties of a-SiC:H and c-SiC thin films on the deposition parameters such as deposition temperature, pressure, RF power and annealing temperature. From this comparative study on structural and compositional differences of the a-SiC:H and c-SiC thin films, we realized that there are much different hydrogen contents and crystallinity in the films depending on the deposition temperature and annealing temperature. With increasing these parameters, moreover, the hydrogen contents and crystallinity are drastically changed to be less hydrogen and better crystalline films starting from amorphous, polycrystalline and single crystalline, sequentially. In addition, their optical properties are also strongly changed, for example, the refractive index and optical band gap are increased with increasing deposition temperature, pressure, RF power and annealing temperature. And the structural and optical properties of c-SiC thin film were analyzed with X-ray diffraction, scanning electron microscope, and infrared absorption techniques. 2003 Elsevier Science B.V. All rights reserved.

Physical and optical properties of plasma polymerized thin films deposited by PECVD method

Polymer-like organic thin films were deposited at room temperature and different radio-frequency (r.f.) powers by PECVD method using ethylcyclohexane as precursor. To compare the optical properties as well as the electrochemical properties of the organic films, the effects of the r.f. plasma power were mainly investigated in this study. The optical properties of as-grown plasma polymerized thin films were analyzed by ellipsometry and UV–visible spectroscopy. The corrosion protective abilities were also examined by potentiodynamic curves measurements in 3.5 wt.% NaCl solution. The experimental results show an increased of corrosion protective abilities for ethylcyclohexane were provided an increased corrosion performance with increasing r.f. power. The AFM and SEM data showed that the polymer films with smooth surface and sharp interface could be grown under different r.f. powers. 2003 Elsevier Science B.V. All rights reserved.

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.

Deposition of silicon carbide films using a high vacuum metalorganic chemical vapor deposition method with a single source precursor: Study of their structural properties

Silicon carbide (SiC) thin films were prepared on Si(100) substrates by high vacuum metalorganic chemical vapor deposition using a single-source precursor at various growth temperatures in the range of 700–1000 °C. The precursor is diethylmethylsilane, and is used without carrier gas. The effects of substrate temperature as well as deposition time on the crystal growth were investigated. The optimum temperature for the formation of high quality polycrystalline SiC thin films was found to be 900 °C on the basis of x-ray diffraction and transmission electron diffraction results. X-ray photoemission spectroscopy shows that SiC films grown at 900 °C have slightly carbon-rich compositions (Si:C=1:1.2) in the surface region, but stoichiometric composition in the bulk. Scanning and transmission electron microscope images show the influence of substrate temperature on the grain size and crystallinity of the films. Large grain sizes and high quality crystallinity can be obtained below 900 °C.

Fabrication of subwavelength-size aperture for a near-field optical probe using various microfabrication procedures

We successfully fabricated subwavelength-size silicon oxide apertures on a cantilever array as a near-field optical probe. Various semiconductor processes were utilized for subwavelength-size aperture fabrication. The anisotropic etching of the Si substrate by alkaline solutions followed by anisotropic crystal orientation dependent oxidation, anisotropic plasma etching, and isotropic oxide etching was carried out. 2, 3, and 4 μm size dot arrays were initially photolithographically patterned on a Si(100) wafer. After fabrication of a V-groove shape by anisotropic etching, oxide growth at 1000 °C was performed to have an oxide etch mask. The oxide layer on the Si(111) plane has been utilized as an etch mask for plasma dry etching and water-diluted HF wet etching for subwavelength-size aperture fabrication. A Au thin layer was deposited on the fabricated oxide aperture on the cantilever array. After this procedure, the initial opening, 300 nm of the oxide aperture was reduced down to ∼95 nm.

Synthesis of a material for semiconductor applications: Boron oxynitride prepared by low frequency rf plasma-assisted metalorganic chemical vapor deposition

We have synthesized a material, boron oxynitride (BON), deposited as films on Si(100) substrates by low frequency rf-derived plasma-assisted metalorganic chemical vapor deposition (MOCVD), and have studied the electrical and optical properties of these films. The effects of growth conditions such as the flux of the feed gas and growth time on these properties are investigated. Our data show that the electrical resistance decreases with an increase in nitrogen flux and growth time. Amorphous BON thin films grown at relatively low temperatures have higher resistance than microcrystal-containing films deposited at high temperature. Thus by controlling the nitrogen content of the film we can make BON thin films that are either semiconducting or insulating. We also monitored optical emission spectra (OES) during MOMCVD to analyze reaction of the gas phase in the plasma. Based on the OES result we confirm that BON thin films can be prepared under a nitrogen plasma.