Anisotropic dielectrics and ferromagnetic materials are widely used in dispersion-engineered metamaterials. For example, nonreciprocal magnetic photonic crystals (MPhCs) are periodic structures whose unit cell is composed of two misaligned anisotropic dielectric layers and one ferromagnetic layer and they have extraordinary characteristics such as wave slowdown and field amplitude increase. We develop an unconditionally stable complex-envelop alternating-direction-implicit finite-difference time-domain method (CE-ADI-FDTD) suitable for the transient analysis of anisotropic dielectrics and ferromagnetic materials. In the proposed algorithm, the perfectly-matched-layer (PML) is straightforwardly incorporated in Maxwell's curl equations. Numerical examples show that the proposed PML-CE-ADI-FDTD method can reduce the CPU time significantly for the transient analysis of anisotropic dielectrics and ferromagnetic materials while maintaining computational accuracy.

A miniaturized and bandwidth-enhanced implantable antenna is designed for wireless biotelemetry in the medical implantable communications service (MICS) frequency band of 402-405MHz. To reduce the antenna size and enhance the available bandwidth with regard to the reflection coefficients, a meandered planar inverted-F antenna (PIFA) structure is adopted on a dielectric/ferrite substrate which is an artificial magneto-dielectric material. The potential of the proposed antenna for the intended applications is verified through prototype fabrication and measurement with a 2/3 human muscle phantom. Good agreement is observed between the simulation and measurement in terms of resonant characteristics and gain radiation patterns; the bandwidth is enhanced in comparison with that of the ferrite-removed antenna, and antenna gain of -27.7dB is obtained in the measurement. Allowances are made for probable fabrication inaccuracies and practical operating environments. An analysis of 1-g SAR distribution is conducted to confirm compliance with the specific absorption rate limitation (1.6W/kg) of the American National Standards Institute (ANSI).

On-chip transmission lines are widely used in ultrahigh-frequency integrated circuits. One of the issues in modeling such transmission lines is that no reference impedance can be established on a chip. Conventionally, the parallel admittance Yp has been adopted as a reference parameter for on-chip transmission lines instead of a reference characteristic impedance of 50Ω. In the case of CMOS processes, however, Yp can have complicated characteristics in the short-millimeter-wave band owing to the frequency characteristics of the electric permittivity of low-k materials, which cannot be expressed using a simple circuit. To solve this problem, we propose the use of the series impedance Zs as a reference parameter for transmission-line modeling since it basically can be determined from the geometrical dimensions and the frequency-stable permeability and resistivity. The parameters of transmission lines obtained by the proposed method were compared with those obtained by conventional methods using a 40nm CMOS process. By using the equivalent circuit model of Yp along with RLC resonators, it is shown that the peaks of the frequency characteristics of Yp can be used to explain the absorption spectrum of the dielectric. This suggests that the proposed method is suitable for CMOS short-millimeter-wave transmission lines.

As means to control interface reactions between HfO2 and Ge(100), chemical vapor deposition (CVD) of ultrathin Ta-rich oxide using Tri (tert-butoxy) (tert-butylimido) tantalum (Ta-TTT) on chemically-cleaned Ge(100) has been conducted prior to atomic-layer controlled CVD of HfO2 using tetrakis (ethylmethylamino) hafnium (TEMA-Hf) and O3. The XPS analysis of chemical bonding features of the samples after the post deposition N2 annealing at 300 confirms the formation of TaGexOy and the suppression of the interfacial GeO2 layer growth. The energy band structure of HfO2/TaGexOy/Ge was determined by the combination of the energy bandgaps of HfO2 and TaGexOy measured from energy loss signals of O 1s photoelectrons and from optical absorption spectra and the valence band offsets at each interface measured from valence band spectra. From the capacitance-voltage (C-V) curves of Pt-gate MIS capacitors with different HfO2 thicknesses, the thickness reduction of TaGexOy with a relative dielectric constant of 9 is a key to obtain an equivalent SiO2 thickness (EOT) below 0.7 nm.

A stacked structure consisting of ∼ 1 nm-thick MgO and ∼ 4 nm-thick HfO2 was formed on thermally grown SiO2/Si(100) by MOCVD using dipivaloymethanato (DPM) precursors, and the influences of N2 anneal on interfacial reaction and defect state density in this stacked structure were examined. The chemical bonding features of Mg atom were evaluated by using an Auger parameter independently of positive charge-up during XPS measurements. With Mg incorporation into HfO2, a slight decrease in the oxidation number of Mg was detectable. The result suggests that Mg atoms are incorporated preferentially near oxygen vacancies in the HfO2, which can be responsible for a reduction of the flat band voltage shifts observed from C-V characteristics.

We investigated the use of AlOx:N/SiNy stacked gate dielectric as an alternate gate dielectric, which were prepared by alternately repeating sub-nanometer deposition of Al2O3 from an alkylamine-stabilized AlH3 + N2O gas mixture and rapid thermal nitridation in NH3. The negative fix charges, being characteristics of almina, were as many as 3.91012 cm-2 in the effective net charge density. The effective dielectric constant and the breakdown field were 8.9 and 8 MV/cm, respectively, being almost the same as pure Al2O3. And we have demonstrated that the leakage current through the AlOx:N/SiNy stacked gate dielectric with a capacitance equivalent thickness (CET) of 1.9 nm is about two orders of magnitude less than that of thermally-grown SiO2. Also, we have confirmed the dielectric degradation similar to the stress-induced leakage current (SILC) mode and subsequent soft breakdown (SBD) reported in ultrathin SiO2 under constant current stress and a good dielectric reliability comparable to thermally-grown ultrahin SiO2. From the analysis of n+poly-Si gate metal-insulator-semiconductor field effect transistor (MISFET) performance, remote coulomb scattering due to changes in the gate dielectric plays an important role on the mobility degradation of MISFET with AlON/SiON gate stack.

A miniaturized rectangular resonator made of a novel anisotropic artificial dielectric material is investigated which has advantages of small size and big separation of the higher-modes. To obtain a property of anisotropic permittivity, artificial dielectric material is fabricated by lamination of rectangular metal strips etched on a printed circuit board. Artificial dielectric rectangular resonators are designed to excite TE10δ mode selectively, aligning the rectangular metal patterns along the direction of the mode electric field line. The resonant frequencies and coupling coefficient of artificial dielectric rectangular resonators encapsulated in a metal waveguide are analyzed theoretically, and compared with the experimental result. As a microwave application, a high selectivity TE10δ mode bandpass filter (BPF) using two artificial dielectric rectangular resonators is demonstrated. A two-stage BPF with the center frequency of 1.718 GHz, bandwidth of 78 MHz, and insertion loss of 1.3 dB is successfully realized in a rectangular waveguide.

We prepared HfO2 films by atomic layer deposition (ALD) on three kinds of silicon substrate surfaces (chemical oxide, HF-last surface and thermal oxide), and characterized their morphologies, structures, compositions, and crystallinities by physical analysis. The results revealed that the as-deposited HfO2 films consisted of nano-crystalline particles with a different crystalline system from that of the annealed films. The size of the nano-crystalline particles on the film on the chemical oxide was smaller than those on the other surfaces. The reason is thought to be the difference in OH concentration on the substrate surface. The predominant crystalline phases of all HfO2 films were monoclinic after annealing. Moreover, the film prepared on the chemical oxide had the smoothest surface after annealing. However, island structures with grain boundaries developed in the films on the other surfaces.

We compare the numerical results for electron direct tunneling currents for single gate oxides, ON- and ONO-structures. We demonstrate that stacked dielectrics can keep the tunneling currents a few orders of magnitude lower than electrostatically equivalent single oxides. We also discuss the impact of gate material and of the modeling of electron transport in silicon.

For the expansion of using the integral equation methods on wave-field analysis, a new method called "Source and Radiation Field Solution" is suggested. This solution uses a couple of integral equations. One of them is the traditional integral expression giving the scattered field from the wave source, another is newly proposed one which expresses the wave source from both of the source and the scattered field, by using the conjugate Green function expression. Therefore this method can derive both of the source and the scattered field at the same time by coupled two equations. For showing the effect of this method, we analyze scattering problems for dielectrics in this paper.

Thickness dependence of breakdown properties in control and N2O-Oxynitrided oxides was investigated. Nitrogen atoms piled up at the Si/SiO2 interface increase charge-to-breakdown (QBD) under substrate injection conditions for oxide thickness below 10 nm, while no meaningful improvement is observed above 10 nm. This thickness dependence is explained by the fact that N2O-oxynitridation reduces oxide defects near the Si/SiO2 interface. N2O-oxynitridation of the oxides reduces the number of neutral electron traps due to the chemical reaction of oxide defect with nitrogen atoms. Electron trapping of N2O-oxynitrided oxides is significantly suppressed; the reduction of electron trapping events into neutral electron traps increases QBD under substrate injection. On the other hand, under gate injection, N2O-oxynitrided oxides show low rate of hole trapping during the initial stress period. However, in heavily injected condition, electron trapping is not suppressed, resulting in little improvement of QBD. In addition, the control and N2O-oxynitrided oxides show quite similar dependence of QBD on stress current density, which is related primarily to the carrier transport phenomena (tunneling, traveling, impact ionization and hole injection).

For an application to the optical signal processing devices, we propose the optical X coupler which consists of two bending waveguides and a nonlinear dielectric region. To analyze this structure accurately we utilized the iterative finite difference beam propagation method (iterative FD-BPM). In this paper the formulation of the iterative FD-BPM for one wave and two waves cases are presented, respectively. We investigate following two cases. First, we consider the case that the light is launched into one of the input ports. We calculate the evolutions of the field amplitude and the transmission characteristics for the input power. Second, we consider the case that the signal light with the constant power is launched into one of the input ports and that the control light with the wavelength different from that of the signal light is launched into another input port. We calculate the evolutions of the field amplitude and the transmission characteristics of the signal light for the power of control light. As a result of the analysis, we show that all-optical switching operation is possible in the proposed structure.

Material research on capacitor dielectrics for DRAM applications is reviewed. The state of the art technologies to prepare Si3N4,Ta2O5, and SrTiO3 thin films for capacitors are described. The down-scaling limits for Si3N4 and Ta2O5 capacitors seem to be 3.5 and 1.5 nm SiO2 equivalent thickness, respectively. Combined with a rugged polysilicon electrode surface,Si3N4 and Ta2O5 based-capacitors are available for 256 Mbit and 1 Gbit DRAMs. At the present time, the minimum SiO2 equivalent thickness for high permittivity materials is around 1 nm with the leakage current density of 10-7 A/cm2. Among the great variety of ferroelectrics, two families of materials,i.e., Pb (Zr, Ti) O3 and (Ba, Sr) TiO3 have emerged as the most promising candidates for 1 Gbit DRAMs and beyond. If the chemical vapor deposition technology can be established for these materials, capacitor dielectrics should not be a limiting issue for Gbit DRAMs.

Two kinds of nitrided ultrathin (510 nm) SiO2 films were formed on the silicon (100) face using rapid thermal NH3-nitridation (RTN) and rapid thermal N2O-oxynitridation (RTON) technologies. The MOS capacitors with RTN SiO2 film showed that by Fowler-Nordheim (F-N) electron injection, both electron trap density and low-field leakage increase by the NH3-nitridation. In addition, the charge-to-breakdown (QBD) value decreases owing to NH3-nitridation. By contrast, RTON SiO2 films exhibited extremely low electron trap density, almost no increase of the leakage current, and large QBD value above 200C/cm2. The oxide film composition was evaluated by secondary ion mass spectroscopy (SIMS). The chemical bonding states were also examined by Fourier transform-infrared reflection attenuated total reflectance (FT-IR ATR) and X-ray photoelectron spectroscopy (XPS) measurements. These results indicate that although a large number of nitrogen (N) atoms are incorporated by the RTN and RTON, only the RTN process generates the hydrogen-related species such as NH and SiH bounds in the film, whereas the RTON film indicates only SiN bonds in bulk SiO2. From the dielectric and physical properties of the oxide films, it is considered that the oxide wearout by high-field stress is the result of the electron trapping process, in which anomalous leakage due to trap-assisted tunneling near the injected interface rapidly increases, leading to irreversible oxide failure.