Recursive algorithm for calculating effective resistances in RCtree

Internal charges will affect the delay behaviour of a CMOS gate. To estimate each individual delay component due to charges stored in the different internal nodes, the effective resistance of each internal node is first computed. A recursive algorithm EER is proposed to solve this problem efficiently     

Secondary electron emission characteristics of dielectric materials in AC-operated plasma display panels

From the measurement of the ion-induced secondary electron emission yield γiit was shown that with increasing γiof the dielectric panel material the firing voltage of an ac gas discharge display panel decreased. The measurement of the energy distributflon of the secondary electrons showed that the dielectric material with higher γihas lower most-probable energy (MPE), and half-width (HW) values. The energy distribution introduced by Stolz in the ease of secondary electrons emitted from a metal was applied to the dielectric panel material and solved by using a computer. From this result, it was shown that the lower the electron affinity of the dielectric panel material, the higher is the γi. Under the condition when γibecame greater than unity, unstable self-sustained emission was observed even though the primary ion beam was cut off.     

Theoretical treatment of the conductivity of textured inhomogeneous materials

A theory is developed for the conductivity of textured inhomogeneous media. In the context of the effective medium approach, the conductivity’s tensor components for a polycrystalline medium are calculated as functions of the conductivity’s tensor components for the constituent crystallites, the degree of ordering of the crystallites in orientation, and the orientation of the sample in the laboratory system of coordinates. Some recommendations are given regarding the experimental determination of the basic characteristics of the sample, including the statistical spread of directions of the crystallite axes with respect to the texture axis.     

Determination of the degree of ordering of materials’ structure by calculating the information-correlation characteristics

A new method for the analysis of self-organization processes in solid-state materials by calculating the information-correlation characteristics of a surface (in particular, by calculating the average mutual information) is described. Criteria for determining the degree of ordering of a surface structure are suggested; these criteria have been tested for experimental semiconductor structures of single-, poly-crystalline, and amorphous silicon. The dependences of the information characteristics for films of disordered semiconductors on the technological conditions of their fabrication are established.     

一种用于电镀成本核算及资源优化的计算方法

以几种常见的电镀线生产设备为例,介绍了一种可以广泛应用于PCB生产过程中水平及类水平设备的生产时间计算方法,以此精确计算出产品在生产过程中所消耗的设备折旧成本,为销售人员报价提供参考。推导出同时适用于不同生产批量大小的产能计算公式,为生产管理提供理论依据,以达到资源优化,提高设备利用率,降低成本的目的。     

低温烧结介质基板材料研究进展

从陶瓷基介质材料和微晶玻璃基介质材料两个方面进行综述,介绍了几种低温烧结介质基板材料的国内外研究进展,研究了低温烧结介质基板材料与内电极的异相匹配共烧的重要性,探讨了低温烧结介质基板材料主要存在的问题和发展趋势。     

Periodic bandgap and effective dielectric materials in electromagnetics: characterization and applications in nanocavities and waveguides

The main objectives of this paper are to characterize and develop insight into the performance of photonic bandgap (PBG) periodic dielectric materials and to integrate the results into some novel applications. A powerful computational engine utilizing the finite-difference time-domain technique with periodic boundary conditions/perfectly matched layers integrated with Prony's method is applied to provide an in-depth look at the physics of PBG/periodic bandgap structures. Next, the results are incorporated into two classes of applications in the areas of nanocavity lasers and guidance of electromagnetic (EM) waves in sharp bends. A two-dimensional PBG structure with finite thickness is presented to strongly localize the EM waves in three directions and design a high-Q nanocavity laser. It is shown that the periodic PBG/total internal reflections remarkably trap the EM waves inside the defect region. The effect of the number of periodic cells and defect's dielectric constant on the Q of structure is investigated. It has been found that a seven-layer PBG with a dielectric impurity defect can be used in the design of a laser with a Q as high as 1050. Additionally, potential applications of the PBG structures for guiding the EM waves in sharp bends, namely, 90/spl deg/ and 60/spl deg/ channels are demonstrated. It is shown that shaping the bend by introducing small holes can noticeably improve the guidance of the waves at the bends and channel the EM waves with great efficiency. A comparative study between PBG and effective dielectric materials in controlling the EM waves is also provided and it is observed that the novel characteristics of the PBG cannot be modeled using the effective material for the frequencies within the bandgap.     

一种高效的计算Mie级数的新方法

介绍了一种在高频情况下高效计算Mie级数的新方法,利用这种方法,通过一系列变换将传统的Mie级数变换成一个新的留数序列并给出一个全新的推导过程.推导结论表明,这种方法同传统的Mie级数以及Sommerfeld-Waston变换的解相比物理概念更加清晰,同传统Mie级数解相比极大地减少计算所需的求和项的数目.仿真结果证实这种方法得到的结果同传统方法的结果一致吻合.     

Viscous dielectric materials for application in microwave microcircuits

Viscous dielectric materials made from mixtures of titania and Vaseline cover the relative-permittivity range from approximately 4 to 30. The main application is in experiments with microwave microcircuits. Measurements are reported using a resonance method with a cavity developed for this work. A previously quoted expression, giving mixture relative permittivity as a function of its component relative permittivities and their proportions, is shown to hold for this case.     

Methods for calculating point-to-point congestion in switched communication networks

This paper presents two simple algorithms for computing the point-to-point congestion probability in a switched communication network. Methods are straightforward and can easily be computerized. Examples illustrate the methods.     

USE OF FINITE-DIFFERENCE TIME-DOMAIN METHOD FOR CALCULATING EM ABSORPTION IN LOSSY DIELECTRIC SCATTERER

The problem for calculating EM energy absorption by lossy dielectric scatterer ir-radiated by plane wave are discussed.The factors affecting the accuracy of computation arediscussed.The calculated results of EM energy absorption and its distribution in homogeneousand layered homogenous lossy dielectric spheres are presented,and a comparison of these resultswith analytical solution is given.The calculation is carried out for dielectric cylinder on conduct-ing ground as well,and the results are compared with the image theory.All the computationsshew that the finite-difference time-domain method can give satisfactory results.     

一种微波介质材料介电常数的测量方法

介电常数和损耗是微波介质材料的重要参数。目前介电常数的测量方法比较多,但存在测试仪器昂贵、测量方法严格、样品制备苛刻等问题。在当今电磁商业软件十分强大的时代背景下,利用数值仿真详细研究了矩形波导中介质圆柱的谐振模态随自身介电常数和几何大小的变化规律,进而提出一种在矩形波导中直接放入待测样品,通过寻找样品的特征谐振峰得到介电常数的测量方法。研究结果表明,对于介电常数为2.5～100的介质材料,都可通过制备成直径为10 mm的圆柱样品放在BJ100波导中准确地测出其介电常数和损耗的大小。为证明方法的优越性,以氧化铝、滑石和其他陶瓷样品为例进行了实测,得到与第三方测试一致的结果。本文提出的方法简单、高效、便捷,能够对介质材料的广泛应用起到极大推动作用。     

A simple technique for calculating the propagation dispersion ofmulticonductor transmission lines in multilayer dielectric media

A multiconductor transmission line in a multilayer dielectric medium is complicated and therefore is frequently analyzed by the simple quasi-TEM (transverse electromagnetic) approach. Unlike the full wave eigenvalue approach, the quasi-TEM approach does not give the propagation dispersion characteristics of the line. This work overcomes this problem by first obtaining the solution of each multiconductor mode from the quasi-TEM approach. Then these solutions are used as both basis and testing functions in a variational formulation of the full wave eigenvalue analysis. The result is high accuracy in the dispersive propagation constants of the multiconductor modes. By solving only for high frequency eigenvalues, not for the high frequency eigenvectors, the method is simpler and faster than the conventional full wave dispersion analyses     

Evaluation of ultra-low-k dielectric materials for advanced interconnects

The International Technology Roadmap for Semiconductors predicts that continued scaling of devices will require ultra-low-k materials with k values less than 2.5 for the 100 nm technology node and beyond. Incorporation of porosity into dense dielectrics is an attractive way to obtain ultra-low-k materials. Electrical and physical properties of ultra-low-k materials have been characterized. Integration evaluations showed both feasibility and challenges of porous ultra-low-k materials. This paper discusses issues and recent progress made with porous ultra-low-k material properties, deposition processes, characterization metrologies, and process integration.     

Challenges for dielectric materials in future integrated circuit technologies

Dielectrics provide crucial functions in integrated circuits as gate dielectrics, transistor isolation structures, memory elements, interlevel dielectrics, and also provide charge storage in fast capacitors for power isolation. As the feature sizes of integrated circuits continues to decrease and speed increases, the performance requirements for these dielectrics increases significantly. Conventional materials such as thermal and CVD SiO₂ are being replaced with new materials such as high k gate dielectrics, and carbon doped SiO₂ for low k interlevel dielectrics. Even in package level power isolation capacitors, improvements in performance are becoming more difficult and new materials are needed. The challenges to dielectric materials will become even more severe as the industry approaches the l0 nm generation. In each of these applications, the requirements and integration issues are different, and this paper will highlight the long-term challenges for different applications of high k and low k materials. Nanotechnology has the potential to deliver new nano-structured materials to support these requirements, but significant challenges must be overcome before they can be useful.     

Methods of calculating atmospheric transmittance and radiance in the infrared

Radiation from remotely sensed objects in the earth's environment is attenuated in its passage through the atmosphere. In the infrared region of the spectrum, this is caused, for clear-sky conditions, mainly through absorption by atmospheric molecular species, i.e., the atmospheric gases. Molecular absorption is characterized by a highly variable, more-or-less random, frequency dependence which is difficult, if not impossible, to describe analytically in detail. On the other hand, most experimental work requiring an understanding of atmospheric attenuative phenomena is accomplished with instrumental spectral resolutions that are coarse enough to smooth out much of the spectral detail in molecular line structure. Therefore, methods are described for calculating atmospheric transmittance and radiance to correspond to spectral resolutions of those instruments used in remote sensing. These methods involve either numerical integration of the exact line structure over the desired spectral interval, or the use of band models derived from artificially created line structure. Limitations of these calculations are discussed in the light of factors such as the fidelity of model atmospheres used to simulate real ones and the utility of different routines regarding computer time and accuracy. A short section covers the effect of scattering.     

Polarization charge model for laser-induced ripple patterns in dielectric materials

An explanation of laser-induced ripples in dielectric surfaces is given. The model takes into account the polarization charge which is induced on the boundaries of defects by the applied laser field. It is shown that this charge results in a sinusoidally varying perturbation to the applied laser field in the vicinity of the defect, and that the perturbation field has a period oflambda/n, where λ is the laser wavelength andnis the index of the dielectric. It is further shown that this perturbation is greatest along the direction of laser polarization. At sufficiently high laser field intensities, the sum of the applied laser field and the maxima in the perturbation field will exceed the damage threshold, and a permanent ripple pattern in the surface will result. The predicted spacing and orientation of these ripples is in agreement with the experimentally observed data. Finally, it is shown how bootstrapping occurs to enhance the ripple pattern, once begun, and what roles propagation delays, defect size, and laser polarization state play in the process.     

Strip dielectric wave guide antenna-for the measurement of dielectric constant of low-loss materials

The value of dielectric constant are the most important parameters in material science technology. In micro-wave and millimeter wave circuits using dielectric materials the values of this parameters should be known accurately. It is observed that the number of methods are reported in litrature, however these methods impose difficulties in experimentation and are not very accurate. In this paper a novel approach to the measurement of the dielectric constant of low loss materials at micro-wave and millimeter wave frequencies has been discussed. In this method by using antenna theory, a metallic strip dielectric guide is taken in to constideration and band reject phenomenon of dielectric antenna is used. Frequency response of an antenna in band reject mode is a function of the dimensional parameters, such as the metallic strip period, the profile of the metallic strip and the dielectric constant of the material used. Hence if one measure the frequency responce of the antenna in band reject mode, the dielectric constant of the material is determined provided all other parameters are known. This method gives a direct measure of dielectric constant and is quite accurate as computer techniques are used for evaluating the dielectric constant. This method verified experimentally also.