Separation of Horizontal and Vertical Dependencies in a Surface/Volume Integral Equation Approach to Model Quasi 3-D Structures in Multilayered Media

A new and efficient integral equation approach is presented to model heterogeneous dielectric volumes in a multilayered environment. The dielectric volumes can be vertically large, they can cross dielectric interfaces and they should be "quasi 3-D," which means that the contour faces should be placed either horizontally or vertically in the multilayered environment. In this way, a perpendicular prismatic mesh can be fitted on the volumes and the 3-D displacement currents can be expanded in generalized rooftop functions with separated horizontal x, y- and vertical z-dependencies. This makes it possible to evaluate all z, z' reaction integrals fully analytically in the spectral domain and ensures an efficient implementation. The formulation of the source-field relations is adapted to the quasi 3-D geometries as a hybrid dyadic-mixed potential form. Additionally, the electromagnetic coupling between dielectric volumes and metal sheets is included using a coupled volume/surface formulation. This turns the implementation into a complete full wave solver for planar antennas containing both finite and infinite dielectric regions. In order to illustrate and validate the presented approach, two patch antennas with a local volumetric inhomogeneity under the patch are numerically analyzed in a multilayered environment. Eventually, a matrix fill time comparison is used to demonstrate the improvement in computation efficiency     

Modeling Effects of Random Rough Interface on Power Absorption Between Dielectric and Conductive Medium in 3-D Problem

We study the effects of a random rough surface on the power absorption between a dielectric and conductive medium in a 3-D configuration where the surface height varies in both horizontal directions. The analytic small perturbation method of second order and numerical T-matrix method are used. The absorption depends on the root mean square height, correlation length, and correlation function of the random rough surface. A closed-form expression of power absorption enhancement factor is obtained from small perturbation method of second order. Results show that the T-matrix method agrees with the small perturbation method for rough surfaces with a small slope. We further compare the 3-D results to the previous 2-D results and show significant difference. The power absorption enhancement factor exhibits saturation for the Gaussian correlation function, but not for the exponential correlation function     

Three-dimensional surface reconstruction using optical flow formedical imaging

The recovery of a three-dimensional (3-D) model from a sequence of two-dimensional (2-D) images is very useful in medical image analysis. Image sequences obtained from the relative motion between the object and the camera or the scanner contain more 3-D information than a single image. Methods to visualize the computed tomograms can be divided into two approaches: the surface rendering approach and the volume rendering approach. In this paper, a new surface rendering method using optical flow is proposed. Optical flow is the apparent motion in the image plane produced by the projection of real 3-D motion onto the 2-D image. The 3-D motion of an object can be recovered from the optical-flow field using additional constraints. By extracting the surface information from 3-D motion, it is possible to obtain an accurate 3-D model of the object. Both synthetic and real image sequences have been used to illustrate the feasibility of the proposed method. The experimental results suggest that the proposed method is suitable for the reconstruction of 3-D models from ultrasound medical images as well as other computed tomograms     

YMnO_3薄膜的铁电性能及其应用

对金属 -铁电体 -半导体场效应晶体管器件而言 ,具有六方晶系结构的稀土锰酸盐 ( Re Mn O3)是性能优良的薄膜材料 ,它们的介电常数低 ,仅仅只有单一的极化轴 ,没有挥发性的元素 Pb、Bi等。本文作者对 Re Mn O3材料的结构特征、制备方法及其铁电性能等进行了介绍 ,并指出存在的困难及其发展方向。     

内置金属/电介质同心圆柱的金属孔阵列结构强透射特性

采用有限时域差分(FDTD)法研究了内置金属/电介质同心圆柱结构的材料属性、半径及其相对高度对金属孔阵列强透射特性的影响.发现该结构与内置单一金属、单一电介质和电介质/金属三种不同的同心圆柱结构相比较,光的透射性能得到显著的增强;这种内置金属/电介质同心圆柱结构具有进一步增强表面等离激元与局域表面等离激元共振耦合作用.结果表明,金属、电介质的材料属性对强透射特性影响明显,当金属圆柱为Au、电介质圆柱折射率较小时,其透射性能较好;圆柱半径是影响透射率与共振峰位置的主要因素,半径越大,共振峰红移越明显,但其透射率先增大而后持续减小.同时,金属/电介质圆柱的相对高度也影响透射率大小,当金属圆柱高度为60 nm时,其透射性能较好.     

Capacitance computations in a multilayered dielectric medium usingclosed-form spatial Green's functions

An efficient method to compute the 2-D and 3-D capacitance matrices of multiconductor interconnects in a multilayered dielectric medium is presented. The method is based on an integral equation approach and assumes the quasi-static condition. It is applicable to conductors of arbitrary polygonal shape embedded in a multilayered dielectric medium with possible ground planes on the top or bottom of the dielectric layers. The computation time required to evaluate the space-domain Green's function for the multilayered medium, which involves an infinite summation, has been greatly reduced by obtaining a closed-form expression, which is derived by approximating the Green's function using a finite number of images in the spectral domain. Then the corresponding space-domain Green's functions are obtained using the proper closed-form integrations. In both 2-D and 3-D cases, the unknown surface charge density is represented by pulse basis functions, and the delta testing function (point matching) is used to solve the integral equation. The elements of the resulting matrix are computed using the closed-form formulation, avoiding any numerical integration. The presented method is compared with other published results and showed good agreement. Finally, the equivalent microstrip crossover capacitance is computed to illustrate the use of a combination of 2-D and 3-D Green's functions     

Application of a point-matching MoM reduced scheme to scatteringfrom finite cylinders

One of the most common methods for the solution of three-dimensional (3-D) scattering problems is the electric-field volume integral equation numerically solved by the application of the method of moments (MoM)-usually the point-matching version. Although simple to formulate, it shows inherent difficulty and complexity because of the 3-D integrals appearing in the interaction matrix elements and of the singularity of the dyadic Green's function (DGF) present in the computation of the self-cell elements. In this paper, a transformation method is presented, which in the case of the point-matching MoM, both reduces the 3-D integrals to two-dimensional (2-D) ones, and also eliminates the need of separate treatment of the singularity while maintaining the same degree of approximation. Comparison to published results is made for the case of scattering by a finite dielectric cylinder. Further examples are presented for scattering by layered dielectric cylinders and lossy cylindrical shells excited by uniform plane waves     

Integration of High Aspect Ratio Tapered Silicon Via for Silicon Carrier Fabrication

This paper provides a detailed overview of silicon carrier-based packaging for 3-D system in packaging application. In this work the various critical process modules that play a vital role in the integration and fabrication of silicon carrier with high aspect ratio tapered through-silicon interconnections have been explained and discussed with experimental data. A method of fabricating tapered deep silicon via in a three-step approach has been developed and characterized which controls via depth, sidewall profile, and surface roughness effectively. A low-temperature dielectric deposition process is also developed that has minimum residual stress and good dielectric coverage on the via sidewall. The above processes were then integrated with back-end processes like seed metallization, copper electroplating, chemical mechanical polishing, and wafer thinning to realize a fully integrated silicon carrier fabrication technology. The silicon carriers were finally assembled and tested for through silicon interconnection.      

Electromagnetic modeling of waveguides involving finite-sizedielectric regions

A moment method for handling arbitrarily shaped 2-D and 3-D waveguides that involve either conductors, finite-size dielectric regions, or both is presented. A procedure for modeling the dielectric allows 2-D rooftop functions to represent both the 3-D polarization current in the dielectric and the surface current on the conductors, and precludes the presence of fictitious charge within the dielectric. Examples include coaxial, microstrip, and dielectric waveguides. Numerical convergence, consistency with physical principles, and agreement with the literature are demonstrated     

Omnidirectional reflective contacts for light-emitting diodes

An electrically conductive omnidirectional reflector (ODR) is demonstrated in an AlGaInP light-emitting diode (LED). The ODR serves as p-type contact and comprises the semiconductor, a metal layer and an intermediate low-refractive index dielectric layer. The dielectric layer is perforated by an array of AuZn microcontacts thus enabling electrical conductivity. It is shown that the ODR significantly increases light extraction from an AlGaInP LED as compared to a reference LED employing a distributed Bragg reflector (DBR). External quantum efficiencies of 18% and 11% are obtained for the ODR- and the DBR-LED, respectively.     

Dielectric deposition process for Cu/SiO2 integration in a dual damascene interconnection architecture

A challenge to integrate Cu in device interconnections is to avoid Cu diffusion into silicon active zone that could seriously damage device performance, and into interlevel dielectric that could induce shorts or degrade dielectric performance. This paper relates the integration of Cu-CVD with SiO₂. Structures studied are SiO₂ deposited on Cu-CVD, and SiO₂/SiN/Cu structure: a thin SiN layer is deposited on Cu before SiO₂ to act as diffusion barrier and as an etch stop during the interconnect structure patterning. Both SiO₂ and SiN dielectric processes are made in plasma-enhanced chemical vapor deposition processes, from SiH₄ precursor with addition of, respectively, N₂O or NH₃. Cu contamination is shown to occur during the dielectric deposition onto Cu, and is enhanced by the fluorine presence in the deposition chamber. Deposition processes were evaluated in order to lower Cu contamination in the dielectric bulk. On an other hand, a noticeable degradation in Cu layer resistance was evidenced after dielectric deposition due to copper contamination during the dielectric deposition process. This issue can be addressed by the optimization of the dielectric deposition process.     

E-P-AMCBFM分析介质与PEC混合体的电磁散射

使用基于表面积分方程的矩量法来分析介质与理想导体混合体的电磁散射是计算电磁学的一大热点。对理想导体目标体表面建立电场积分方程,在介质目标体表面建立PMCHW方程组,与基于矩阵分块技术的自适应修正特征基函数法结合,对介质涂敷理想导体目标体的电磁散射进行分析,将其称之为EFIE-PMCHW-AMCBFM(E-P-AMCBFM)。并讨论不同参数如基函数阶数,矩阵块间重叠区域等对计算效率的影响,数值结果表明E-P-AMCBFM对于处理介质-理想导体混合体的电磁散射问题具有较高的精度和效率。     

A new approximate solution for scattering by thin dielectric disks of arbitrary size and shape

In this paper, an approximate solution for electromagnetic scattering by a very thin planar homogeneous dielectric object is presented. This solution is obtained from a volumetric integral equation using Fourier transform and is shown to be uniformly valid from low to high frequencies at all incidence angles including edge-on incidence. Validity of the solution is demonstrated through a comparison with canonical objects such as an infinite dielectric slab, and a number of two-dimensional (2-D) and three-dimensional (3-D) dielectric scatterers. For 2-D, and 3-D scatterers, the approximate solution is compared with a method of moments solution. In all cases examined the approximate formulation provides very accurate results except for situations where the dielectric constant is very high.     

三维介质频率选择表面结构的多模网络分析

该文采用多模网络与严格模匹配相结合的方法分析了介质周期结构在电磁波斜入射情况下的散射特性。定量地分析了这种三维频率选择表面结构的频率选择特性随入射波的频率、入射角度、周期层和均匀层的厚度与介电常数等结构参数的变化关系,从而为三维介质频率选择表面的设计和应用提供了依据。     

Effective work function of NiSi/HfO2 gate stacks measured with X-ray photoelectron spectroscopy

A method to measure an effective work function, WF_eff, of a metal electrode in contact with particular dielectric in a metal–oxide–semiconductor stack is proposed by in situ monitoring core level binding energy shifts of dielectric constituents upon deposition of an ultrathin metallic layer on top. The proposed method is utilized to measure relative changes in WF_eff between Ni and NiSi electrodes in contact with HfO₂, as well as to investigate the role of Sb and Ti δ-layers at NiSi/HfO₂ interface.     

A new 3-D display method for 12-lead ECG

A new three-dimensional (3-D) 12-lead electrocardiogram (ECG) display method is presented which employs a 3-D rectangular coordinate system to display the 12-lead cardiac electric signals in two 3-D graphs. The 3-D graph consists of a temporal axis representing the time domain of the cardiac signals, a spatial axis representing the lead positions, and an amplitude axis representing the voltages of the cardiac signals. The six horizontal plane leads and the other six frontal plane leads were displayed in two 3-D graphs, respectively. The voltages of the cardiac signals were represented in rainbow-like colors. Cubic interpolation was employed to insert interconnecting points between neighboring leads on each plane and to smooth the surface of the 3-D ECG graphs. The 3-D ECG graphs of a normal subject, a patient with myocardial infarction, and a patient with left bundle branch block were presented in this paper. This new display method could not only be used as a complementary display method to the 12-lead ECG, but also provide physicians with an overall integral view about the spatial distribution of the cardiac signals.     

Charge-Programmable Photopolymers for 3D Electronics via Additive Manufacturing

Charge-programmed 3D printing enables the fabrication of 3D electronics with lightweight and high precision via selective patterning of metals. This selective metal deposition is catalyzed by Pd nanoparticles that are specifically immobilized onto the charged surface and promises to fabricate a myriad of complex electronic devices with self-sensing, actuation, and structural elements assembled in a designed 3D layout. However, the achievable property space and the material-performance correlation of the charge-programmed printing remain unexplored. Herein, a series of photo-curable resins are designed for unveiling how the charge and crosslink densities synergistically impact the nanocatalyst-guided selective deposition in catalytic efficiency and properties of the 3D printed charge-programmed architectures, leading to high-quality 3D patterning of solid and liquid metals. The findings offer a wide tunability of the structural properties of the printed electronics, ranging from stiff to extreme flexibility. Capitalizing on these results, the printing and successful application of an ultralight-weight and deployable 3D multi-layer antenna system operating at an ultrahigh-frequency of 19 GHz are demonstrated.     

Multiple layers of CMOS integrated circuits using recrystallizedsilicon film

This letter presents a method to fabricate high performance three-dimensional (3-D) integrated circuits based on the conventional CMOS SOI technology. The first layer of transistors is fabricated on SOI and the second layer is fabricated on large-grain polysilicon-on-insulator (LPSOI), using oxide as the interlayer dielectric. The LPSOI film is formed by the recrystallization of amorphous silicon through metal induced lateral crystallization (MILC). The grain size obtained by the LPSOI process is much larger than the transistors and the transistor performance is similar to those fabricated on the SOI layer. Three-dimensional (3-D) CMOS inverters have been demonstrated with p-channel devices stacking over the n-channel ones     

Effects of the sputtering deposition process of metal gate electrode on the gate dielectric characteristics

Effects of the N₂-introduced reactive sputtering deposition of metal gate electrodes on the gate leakage current and the dielectric reliability of the W/WN_x and W/TiN metal gate MOS capacitors are investigated. The gate dielectric characteristics of W gate MOS capacitor are degraded during the sputtering deposition of the gate electrode. However, the sputtering process-induced degradation of the dielectric characteristics is improved by increasing N₂ flow ratio during the deposition of WN_x gate electrode. This improvement is considered to be due to the termination of the dangling bonds in the surface-damaged layer in the gate dielectric by the surface nitridation. The nitridation of 1.5 at.% is found to effectively improve both gate leakage characteristics and dielectric reliability of the W/WN_x gate MOS capacitor to a level comparable to those of the poly-Si gate. The characteristics of W/WN_x gate MOS transistors are also improved by the surface nitridation through the decrease of the gate leakage current. However, the surface nitridation enhances the electron trapping probability under substrate injection, which results in the lower activation energy of CVS–Q_bd of metal gate MOS capacitors.