Scaling planar silicon devices

The generation-over-generation scaling of critical CMOS technology parameters is ultimately bound by nonscalable limitations, such as the thermal voltage and the elementary electronic charge. Sustained improvement in performance and density has required the introduction of new device structures and materials. Partially depleted SOI, a most recent MOSFET innovation, has extended VLSI performance while introducing unique idiosyncrasies. Fully depleted SOI is one logical extension of this device design direction. Gate dielectric tunneling, device self-heating, and single-event upsets present developers of these next-generation devices with new challenges. Strained silicon and high-permittivity gate dielectric are examples of new materials that will enable CMOS developers to continue to deliver device performance enhancements in the sub-100 nm regime.     

混合信号芯片设计处理关键的转折阶段

通过简单地剪切和粘贴知识产权(IP)内核可以加快无工厂半导体公司的系统级芯片(SOC)设计。 过去十年中,涌现出大量的为系统制造商提供专用芯片(ASIC)的小型IC设计公司。这些被称为无工厂企业(因为他们将IC制造过程转交给商业芯片制造工厂),需要的启动资金较少,而且如果市场接受他们的产品的话,能够获得丰厚的回报。在大量设计工具的支持下,这些无工厂设计企业在历史悠久的大型芯片制造商,如IBM、Intel、Motorola和德州仪器公司所主导的市场中赢得了一席之地。     

A three-phase model for mixed columnar-equiaxed solidification

A three-phase model for mixed columnar-equiaxed solidification is presented in this article. The three phases are the parent melt as the primary phase, as well as the solidifying columnar dendrites and globular equiaxed grains as two different secondary phases. With an Eulerian approach, the three phases are considered as spatially coupled and interpenetrating continua. The conservation equations of mass, momentum, species, and enthalpy are solved for all three phases. An additional conservation equation for the number density of the equiaxed grains is defined and solved. Nucleation of the equiaxed grains, diffusion-controlled growth of both columnar and equiaxed phases, interphase exchanges, and interactions such as mass transfer during solidification, drag force, solute partitioning at the liquid/solid interface, and release of latent heat are taken into account. Binary steel ingots (Fe-0.34 wt pct C) with two-dimensional (2-D) axis symmetrical and three-dimensional (3-D) geometries as a benchmark were simulated. It is demonstrated that the model can be used to simulate the mixed columnar-equiaxed solidification, including melt convection and grain sedimentation, macrosegregation, columnar-to-equiaxed-transition (CET), and macrostructure distribution. The model was evaluated by comparing it to classical analytical models based on limited one-dimensional (1-D) cases. Satisfactory results were obtained. It is also shown that in order to apply this model for industrial castings, further improvements are still necessary concerning some details.     

Dynamics of Interacting OH– and OD– Ions in KCl

OH^– and OD^– defects are known to form rotational tunneling systems in KCl host crystals. We have studied the complex dielectric susceptibility of KCl doped with different concentrations of OH^– and OD^– in a wide range of frequencies and temperatures. Our main result is that there is a transition from coherent single ion tunneling at low defect concentration to an incoherent tunneling motion at high defect concentrations. In addition, we have studied the thermally activated motion of pairwise coupled hydroxide ions in an attempt to obtain information on the microscopic configurations of the different pairs contributing to the dielectric loss. PACS numbers: 61.72.Ji, 77.22-d, 78.30.Ly     

Low-power digital filtering using approximate processing

We present an algorithmic approach to the design of low-power frequency-selective digital filters based on the concepts of adaptive filtering and approximate processing. The proposed approach uses a feedback mechanism in conjunction with well-known implementation structures for finite impulse response (FIR) and infinite impulse response (IIR) digital filters. Our algorithm is designed to reduce the total switched capacitance by dynamically varying the filter order based on signal statistics. A factor of 10 reduction in power consumption over fixed-order filters is demonstrated for the filtering of speech signals     

The determination of protein hydrophobicity. 1. Determination of the hydrophobicity of selected cereal and milk proteins using their sodium dodecyl sulfate binding capacities]

The sodium dodecylsulphate (SDS) binding capacities of secalin, gliadin and gluten in the presence of a very low SDS concentration were determined and compared to the SDS binding capacities of bovine serum albumin (BSA), beta-lactoglobulin, ovalbumin und beta-casein. The SDS binding capacities of endosperm proteins determined in phosphate buffer (pH 6.0) are very low. Only 0.6 microgram .. 0.8 microgram SDS were bound to 500 micrograms of the proteins. This low SDS binding capacities do not correlate with the expected hydrophobicity of these proteins. In comparison, 500 micrograms of ovalbumin, beta-lactoglobulin and BSA each bind 0.5, 5.9 and 13.5 micrograms SDS, respectively. According to literature the SDS binding capacities of these proteins are in correlation with the surface hydrophobicity determined with cis-parinaric acid using the fluorescence probe method. The SDS binding capacities of endosperm proteins increased in the presence of 0.1 N acetic acid and consequently 6.2 micrograms .. 6.9 micrograms SDS were bound to 500 micrograms of the corresponding proteins. beta-casein described as a highly hydrophobic protein binds only 0.9 micrograms SDS to 500 micrograms of it in phosphate puffer (pH 6.0) and 1.2 micrograms SDS in 0.1 N acetic acid, respectively.     

Using a Three-Phase Deterministic Model for the Columnar-to-Equiaxed Transition

In order to overcome the limitations of previous columnar-to-equiaxed (CET) models, which neglect melt convection and the movement of free equiaxed grains, this article presents a three-phase deterministic CET model. With appropriated multiphase volume-averaging approaches, it is possible to account for nucleation and growth of equiaxed grains ahead of a growing columnar front, the influence of melt convection, and grain sedimentation, and the occurrence of a CET in a casting of engineering scale. Special modeling assumptions ensure that both CET mechanisms, namely, “hard” and “soft” blocking, are tackled. It is highly recommended that both mechanisms should be considered, especially in the situation where grain sedimentation and melt convection are present. Although the current model incorporates almost all the physical variables relevant to a CET event, under special condition of a one-dimensional case, the model still reproduces the results of Hunt’s classical CET approach. This article is based on a presentation made in the symposium entitled “Solidification Modeling and Microstructure Formation: In Honor of Prof. John Hunt,” which occurred March 13–15, 2006, during the TMS Spring Meeting in San Antonio, Texas, under the auspices of the TMS Materials Processing and Manufacturing Division, Solidification Committee.