Jin Yong Kim

Infrared spectroscopy study of low-dielectric-constant fluorine-incorporated and carbon-incorporated silicon oxide films

Bonding characteristics of low-dielectric-constant (low-k) fluorine-incorporated silicon oxide (SiOF) and carbon-incorporated silicon oxide (SiOC) films prepared by plasma enhanced chemical vapor deposition were investigated by Fourier transform infrared spectroscopy (FTIR). The frequency of Si–O stretching vibration mode in SiOF film shifted to higher wave number (blueshift) with the increase of fluorine incorporation, while that in SiOC film shifted to lower wave number (redshift) as the carbon content increased. In N2-annealed SiOC film, the Si–O stretching frequency slightly shifted to lower wave number. To elucidate these phenomena, we have developed the “bonding structure model” based on the electronegativity of an atom. The frequency shifts observed in the FTIR spectra of SiOF and SiOC films were well explained by this model.

Origin of low dielectric constant of carbon-incorporated silicon oxide film deposited by plasma enhanced chemical vapor deposition

Dielectric properties of carbon-incorporated silicon oxide (SiOC) films deposited by plasma enhanced chemical vapor deposition (PECVD), using a bis-trimethylsilylmethane precursor, were compared with the dielectric properties of silicon oxide thermally grown in a furnace (thermal oxide) and also with oxide deposited by PECVD using a tetraethoxysilane (TEOS) precursor (PE-TEOS oxide). The electronic contribution to the dielectric constant of the three oxide films was calculated from their refractive indices measured at 632.8 nm by ellipsometry. Ionic contributions were computed from their IR reflection spectra, measured at 650–4000 cm−1, by using the Kramers–Kronig relation. The dipolar contribution was qualitatively analyzed from temperature dependence of the polarizability, on a per unit volume basis. The dielectric constant of the SiOC films, which was measured at 1 MHz, decreased from 4.2 to 2.3 as the carbon content increased from 0 to 19.6 at. %. Although there was a significant reduction of the diel...

Deposition of MgO thin films by modified electrostatic spray pyrolysis method

Abstract MgO thin films were deposited on SiO 2 /Si(100) substrates by a modified electrostatic spray pyrolysis (ESP) method using Mg(tmhd) 2 as a precursor source. In this modified ESP system, a guide, guide heaters, and an extraction electrode were added to the conventional ESP system, which has been widely used to synthesize sub-micrometer and nano-sized particles of oxidic materials. The growth rates of the films were changed from 34 to 87 A/min depending on the substrate and the guide temperature. The MgO films deposited at temperatures as low as 400–500°C exhibited a (100)-preferred orientation even without a post-annealing treatment. No impurities were incorporated in the films within the detection limit of X-ray photoelectron spectroscopy analysis.

Experimental and theoretical characterization of the surface acoustic wave propagation properties of GaN epitaxial layers on c-plane sapphire

Surface acoustic wave (SAW) propagation properties of gallium nitride (GaN) epitaxial layers on sapphire were theoretically and experimentally characterized. GaN thin films were grown on a c-plane sapphire substrate using a metalorganic chemical vapor deposition system. The experimental characterization of SAW propagation properties was performed with a linear array of interdigital transducer structures, while SAW velocities were calculated by matrix methods. Experimentally, we found pseudo-SAW and high-velocity pseudo-SAW modes in the GaN/sapphire structure, which had a good agreement with calculated velocities.

Passivation layer effects on power durability of SAW duplexer

The power durability of the ladder-type SAW filter was investigated with various electrode materials and passivation layers. Among the aluminum alloys, the Al-2%Cu electrode showed the longest lifetime. In addition, the Al-2%Cu/Ti structure electrode showed about 27 times longer lifetime than that of Al-0.5%Cu IDT at an input power level of 31 dBm. The passivation layer effects on the power durability were examined by using SiO2, Si3N4, and AlN thin film layer. The 300 nm thick SiO2 layer suppressed the migration of aluminum and prevented from shorting out IDT electrodes effectively. The lifetime of SiO2-coated Al-2%Cu IDT could be about 30,000 hr at an input power level of 31 dBm.

SAW characteristics of diamond-like carbon thin films on various piezoelectric substrates

We studied SAW characteristics of DLC thin films sputter deposited on various substrates, such as Si, quartz, and LiTaO/sub 3/. The film properties as well as SAW characteristics showed quite a large dependence on the kind of substrates on which the film was deposited. To examine their SAW properties, 1-port SAW resonators and 2IDT-type SAW filters were fabricated. The ZnO/IDT/DLC/Si(100) multilayer structure showed the 1st mode SAW velocity at kH/sub DLC/=0.262 and kH/sub ZnO/=0.837 was 5614 m/sec. On the contrary, DLC films on quartz and LiTaO/sub 3/ were observed to decrease SAW velocity. This contradictory result might be due to different properties of the DLC film according to the substrate on which it was deposited.

Surface acoustic wave propagation properties of nitrogenated diamond-like carbon films

Nitrogenated diamond-like carbon (a-C:N) thin films on Si(100) were deposited by radio frequency magnetron reactive sputtering. Using ZnO piezoelectric thin films, the surface acoustic wave (SAW) propagation properties of a-C:N thin films on Si(100) have been experimentally investigated using bidirectional interdigital transducers between ZnO and a-C:N/Si(100). A generalized SAW mode with velocities between 5000 and 7000 m/s were observed. A high velocity pseudo-SAW mode was also observed and identified with simulated data, of which the velocity was 13 850 m/s. We calculated the film elastic constants from the phase velocities in the layered structure. The calculated constants for a-C:N thin films on Si were c11=392.1 and c44=185.7 GPa.

Effect of dielectric layer in ZnO/dielectric/Si layered structure on GSAW and HVPSAW propagation properties

The propagation characteristics of the GSAW and HVPSAW modes in ZnO/dielectric/Si layered structures were examined theoretically and experimentally. The dielectric layer effects on SAW propagation properties were examined by using SiO/sub 2/, Si/sub 3/N/sub 4/, and TiO/sub 2/ thin film layer. In case of ZnO/SiO/sub 2//Si structure, both GSAW and HVPSAW modes were observed experimentally. The HVPSAW mode velocity at kH/sub ZnO/=1.1 and kH(SiO/sub 2/)=0.02 was found at the value of 9,180 m/s. On the contrary, in ZnO/Si/sub 3/N/sub 4//Si and ZnO/TiO/sub 2//Si structures only GSAW modes were found.

Surface acoustic wave propagation properties of the relaxor ferroelectric PMN-PT single crystal

The characteristics of acoustic waves propagation in the single crystal lead magnesium niobate-lead titanate(PMN-PT) are theoretically and experimentally investigated. This single crystal has ultrahigh piezoelectric coefficient (d33>2000 pC/N) and electromechanical coupling coefficient( k33>90%). High coupling single crystal can be used as the wide band filter devices. PMN-PT is a solid solution of PMN and PT. Hence, by PT compositon control material properties can be changed for the better device performance. Using Bridgman method we prepared PMN-PT single crystals with 33% PT content respectively. We investigated SAW velocities of these crystals experimentally. The results agreed with the calculations based on reported material constants.

Surface acoustic wave properties of ZnO/DLC/Si(100) multilayer structure

We investigated SAW properties of ZnO/DLC/Si (100) multilayer structure. Surface smoothness and intensity ratio of sp/sup 3//sp/sup 2/ of DLC films were enhanced with increasing a substrate d.c. bias voltage. At condition of KH(ZnO)=0.837 and KH(DLC)=0.262, the velocity of 1st mode wave was about 5,614 m/sec which was higher than cut-off velocity of ZnO/Si(100) structure.