On the Mechanism of the Step Coverage of Blanket Tungsten Chemical Vapor Deposition

In this study, computer modeling of the contact fill process with chemical vapor deposition, (CVD) of tungsten is usedto show the importance of several details on the quality of the fill process. The effect of surface curvature on the stepcoverage of CVD-W has been investigated. It is shown that for contacts with an aspect ratio smaller than one, the effect ofsurface curvature is substantial and actually improves step coverage. Therefore, surface curvature for features with aspectratios smaller than one, should be accounted for in computer simulations of the fill process. For contacts with aspect ratioslarger than one the effect of surface curvature is negligible. It is shown that the size of the void (which will be formed incases of step coverage less than 100%) is a better way to describe the quality of the deposition and the repercussions of thevoid on subsequent process steps such as tungsten etch back. In addition, the size of the void depends for a given set ofdeposition conditions solely on the depth of the contact rather than the contact diameter (for aspect ratios larger than 1.0)

The role played by public enterprises: how much does it differ across countries?

This article studies the extent to which governments produce goods for the market (that is, the extent of public enterprise production). It concludes that the current literature dramatically understates the role of public enterprises in many low-productivity countries. The current literature focuses on the total value of goods produced by public enterprises. This article focuses on the types of goods they produce. While the total value of goods produced by public enterprises (as a share of total output) differs a bit across countries, the types of goods they produce differ much more dramatically. In many low-productivity countries, the government produces a large share of the country's manufactured goods. In nearly all high-productivity countries, the government stays out of the manufacturing sector altogether. Therefore—and because the manufacturing sector plays a special role in economies—this article concludes that public enterprises play a very large role in many low-productivity countries.Government-sponsored enterprises ; Industrial policy

A generalized Schroedinger equation for loop quantum cosmology

A temporally discrete Schroedinger time evolution equation is proposed for isotropic quantum cosmology coupled to a massless scalar source. The approach employs dynamically determined intrinsic time and produces the correct semiclassical limit.Comment: 5 pages, to appear in the Proceedings of the Eleventh Marcel Grossmann Meetin

A Modeling approach for analysis and improvement of spindle-holder-tool assembly dynamics

The most important information required for chatter stability analysis is the dynamics of the involved structures, i.e. the frequency response functions (FRFs) which are usually determined experimentally. In this study, the tool point FRF of a spindle-holder-tool assembly is analytically determined by using the receptance coupling and structural modification techniques. Timoshenko’s beam model is used for increased accuracy. The spindle is also modeled analytically with elastic supports representing the bearings. The mathematical model is used to determine the effects of different parameters on the tool point FRF and to identify contact dynamics from experimental measurements. The applications of the model are demonstrated and the predictions are verified experimentally

Transitions in turbulent rotating Rayleigh-B\'enard convection

Numerical simulations of rotating Rayleigh-B\'enard convection are presented for both no slip and free slip boundaries. The goal is to find a criterion distinguishing convective flows dominated by the Coriolis force from those nearly unaffected by rotation. If one uses heat transport as an indicator of which regime the flow is in, one finds that the transition between the flow regimes always occurs at the same value of a certain combination of Reynolds, Prandtl and Ekman numbers for both boundary conditions. If on the other hand one uses the helicity of the velocity field to identify flows nearly independent of rotation, one finds the transition at a different location in parameter space

Early progress on the "problem of economic development"

This study describes recent attempts to solve what Lucas has called the "problem of economic development"—the problem of accounting for the great disparity in per-capita output across countries. The study examines a number of economic development theories, including the neoclassical theory of growth, which relies on cross-country differences in physical capital per person to explain the disparity, and newer theories, which stress cross-country differences in human capital, or education. It is argued that these models cannot account for observed per-capita output diversity. More promising theories are those that stress differences in incentives for entrepreneurs to create businesses (i.e., business capital) and adopt new technologies.Economic development

A new circuit technique for reduced leakage current in Deep Submicron CMOS technologies

Modern CMOS processes in the Deep Submicron regime are restricted to supply voltages below 2 volts and further to account for the transistors&apos; field strength limitations and to reduce the power per logic gate. To maintain the high switching performance, the threshold voltage must be scaled according with the supply voltage. However, this leads to an increased subthreshold current of the transistors in standby mode (<i>V</i>_<i>GS</i>=0). Another source of leakage is gate current, which becomes significant for gate oxides of 3nm and below. </p><p style=&quot;line-height: 20px;&quot;> We propose a <b>S</b>elf-<b>B</b>iasing <b>V</b>irtual <b>R</b>ails (SBVR) - CMOS technique which acts like an adaptive local supply voltage in case of standby mode. Most important sources of leakage currents are reduced by this technique. Moreover, SBVR-CMOS is capable of conserving stored information in sleep mode, which is vital for memory circuits. </p><p style=&quot;line-height: 20px;&quot;> Memories are exposed to radiation causing soft errors. This well-known problem becomes even worse in standby mode of typical SRAMs, that have low driving performance to withstand alpha particle hits. In this paper, a 16-transistor SRAM cell is proposed, which combines the advantage of extremely low leakage currents with a very high soft error stability