Physical Process Parameters Research Articles

Critical tasks in high aspect ratio silicon dry etching for microelectromechanical systems

The process of pattern transfer of desired topological features into silicon plays a critical role for the production of microelectronic and photonic devices, and micro- and nanoelectromechanical systems. Any deviation from the desired shape of the pattern limits density, yield, and reliability of these devices. Gas reactivity, pressure, ion, electron, and reactant transport to the surface, and product transport away from the surface, have all been identified as important issues that control the microscopic uniformity in high aspect ratio etching. When etch-inhibiting chemistry by the gas chopping deep reactive ion etching (RIE) was employed, it caused enormous complications in the scaling of etching rates, with increasing aspect ratio. Using an energy-resolving quadrupole mass spectrometer assembled into the cathode, specially designed test features, and etching simulation models, we establish the link between etch process parameters such as pressure, rf power, etching gas chemistry, temperature, and the physical and chemical process parameters like energy and angular distribution of ions and neutrals, radical sticking, and surface charging. The most significant effects like RIE lag, notching, bowing, faceting, microtrenching, profile shape dependence, etc. will be discussed in this article. 2003 American Vacuum Society.

Statistical artefacts in the determination of the fractal dimension by the slit island method

This paper comments upon some statistical aspects of the slit island method which is widely used to calculate the fractal dimension of fractured surfaces or of materials’ features like grain geometry. If a noise is introduced when measuring areas and perimeters of the islands (experimental errors), it is shown that errors are made in the calculation of the fractal dimension and more than a false analytical relation between a physical process parameter and the fractal dimension can be found. Moreover, positive or negative correlation with the same physical process parameter can be obtained whether the regression is performed by plotting the variation of the noisy area versus the noisy perimeter of the considered islands or vice versa. Monte-Carlo simulations confirm the analytical relations obtained under statistical considerations.

Correlations of MOSFET transconductance: Its physical origins and relevance to analog MOSFET modeling and operation

The correlations of MOSFET transconductance across the full operating regime were studied on a statistically significant number of devices. This is to our knowledge the first time such a measurement is reported. We present "device operation phase diagrams" summarizing our findings: there are only a few, typically two, highly intracorrelated regions of the transconductances in the V/sub g/ - V/sub d/ plane. The diagrams aid analog design by clearly depicting the relative process induced variations of the transconductance between any two operating points. Though crucial for analog design, this correlation structure is not typically captured, nor to our knowledge understood, by circuit design and modeling methodologies. The results also suggest that in order to track, at production, the transconductance process induced variations in the full MOSFET operating regime, it is sufficient to select only a few operating points, sampling each intracorrelated region. Finally, a simple, physics based picture is presented, tracing the origin of the correlation patterns back to the variations of a few physical process parameters common to all modern technologies. We can therefore predict our observations are general, and will extend beyond the 0.25-/spl mu/m technology we examined.

Grey box modelling for model predictive control of a heating process

This paper presents a rational modelling procedure of a pilot heating process by using the grey box modelling method. A simplified nonlinear continuous model, based on the conservation of energy, is formed and unknown parameters of the model are estimated by using measured data from an experiment with the process. The model is expanded with a wider model structure by testing formulated hypothesis about the process. The model is also expanded in an engineering way by considering the shape of the residuals. During the model expansion the Likelihood ratio test is applied for falsification tests. The study uses the continuous model for both estimating the states of the process and controlling the system. A continuous-discrete extended Kalman filter estimates the model states and time varying disturbances. The model predictive controller is based on the continuous process model, but the optimisation of the control performance index is made at discrete sampling instances. The control law compensates for changing temperature references and compensate for varying load situations. Besides using the model for control purposes the case demonstrate the possibility of using the grey box modelling technique to estimate physical process parameters such as the thermal diffusivity of the process.

Conjugate Parameters of Physical Processes and Physical Time

All physical phenomena run in nature with the continuous transformation of the kinetic field into the potential field, and vise versa, i.e., they have the wave character. For this reason, the structure of expressions representing these fields (both real physical space and physical time space) must be potential-kinetic. Contemporary physics satisfactory describes the kinetic field, but the complete description of the potential subfield is absent. In this paper we partially fill in this gap, beginning from the description of harmonic oscillations (of a material point) and the physical time wave field-space.

Exploring natural and anthropogenic variation of climate

AbstractThis lecture discusses the low‐frequency variability of surface temperature using a coupled ocean‐atmosphere‐land‐surface model developed at the Geophysical Fluid Dynamics Laboratory/NOAA. Despite the highly idealized parametrization of various physical processes, the coupled model simulates reasonably well the variability of local and global mean surface temperature. The first half of the lecture explores the basic physical mechanisms responsible for the variability. The second half examines the trends of local surface temperature during the last half century in the context of decadal variability simulated by the coupled model.

Cosmoparticle physics as the physical basis for modern cosmology

Abstract Cosmoparticle physics has appeared as a natural result of the internal development of cosmology, looking for physical grounds for inflation, baryosynthesis and nonbaryonic dark matter, and of particle physics, going beyond the standard model of particle interactions. Its aim is to study the physical basis of modern cosmology in the combination of indirect cosmological, astrophysical and physical effects. The ideas of new particles and fields, predicted by particle theory, and on their cosmological impact are discussed, as well as the methods of cosmoparticle physics to probe these ideas are considered with special analysis of physical mechanisms for inflation, baryosynthesis and nonbaryonic dark matter. These mechanisms are shown to reflect the main principle of modern cosmology, putting instead of formal parameters of cosmological models physical processes governing the evolution of Big Bang Universe. Their realization on the basis of particle theory induces additional model-dependent predictions, accessible to various methods of cosmoparticle physics. The power of these methods is illustrated in the example of a gauge model with broken family symmetry, on which the horizontal unification is based, possessing quantitatively date physical grounds for inflation, baryosynthesis and effectively multicomponent dark matter scenarios.

Revision of convection, radiation and cloud schemes in the ECMWF integrated forecasting system

AbstractRevisions to the convection, radiation and cloud schemes recently introduced into the European Centre for Medium‐Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS) are described, together with discussion of their impact upon model performance. Seasonal simulations with observed sea surface temperatures (SSTs) for June/July/August 1987 and December/January/February 1987/88 with a low‐resolution (T63) version of the model are used to assess the impact of the revised schemes, concentrating upon tropical climate and variability. While the revisions improve the physical basis of the schemes, and each improves aspects of the seasonal climate, overall improvement does not result until the changes are combined. Biases in simulated temperature and top‐of‐atmosphere and surface energy budgets are reduced, leading to a substantial decrease of an equatorial SST cold bias in coupled ocean‐atmosphere simulations used in seasonal forecasting. At higher resolution (T213) changes to temperature and wind fields are similar to those found in seasonal simulations, with little impact upon medium‐range forecast performance in mid latitudes, although these forecasts proved a more critical test of the impact of the schemes upon mid‐latitude flows. The paper demonstrates the methodology used in the development of parametrizations of physical processes at ECMWF, and points to the need to balance parametrization improvements especially between schemes which are highly interactive.

Precision Laser Deburring and Acoustic Emission Feedback

Sensor feedback for process control is one of the essential elements in an automated deburring procedure. This paper presents the implementation of acoustic emission (AE), which has been developed as a feedback sensing technique for precision (mechanical) deburring, in a precision laser deburring process. AE signals were sampled during laser machining/deburring under various experimental conditions and analyzed using several signal processing methods including AE rms and spectral analysis. The results, such as the sensitivity of AE signals to different laser cutting depths, edge detection capability and the frequency analysis show a clear correlation between physical process parameters and the AE signals. A subsequent control strategy for deburring automation is also briefly discussed.

Volcanic lake systematics I. Physical constraints

Volcanic lakes have a wide range of characteristics, and we make an attempt to delineate the limiting physical conditions for several lake classes. The ratio between heat input and heat dissipation capacity of a lake constrains the temperature for perfectly mixed steady-state volcanic lakes. Poorly mixed lakes are also conditioned by this ratio, but their temperature structure is also strongly influenced by the hydrodynamics resulting from different mechanisms of heat transfer. The steady-state temperatures of volcanic lakes are largely determined by the magnitude of the volcanic heat influx relative to the surface area of the lake. Small lakes have only a small capacity for heat dissipation and their temperature rises quickly with only small heat inputs; large lakes are buffered against variations in heat input. Both the heat dissipation and meteoric water input into a lake are functions of lake surface area and therefore each lake water temperature demands a certain precipitation rate for mass conservation, independent of lake size. The results of energy/mass-balance modeling shows that under common atmospheric conditions, most steady-state volcanic lakes are unlikely to maintain a temperature in excess of 45–50 °C. Validation of the volcanic lake model was performed using published data from Yugama Lake (Japan) and the Keli Mutu lakes (Indonesia). Also, the model was applied to 24 natural systems to provide a baseline assessment of energy fluxes under the model assumptions so future work on those systems can identify nuances in individual systems that deviate from the simple model conditions. We recommend the model for use in assessing temperature variations and volcanic lake stability in settings with known physical and atmospheric conditions. Application of the energy/mass balance calculations of model lakes provides a genetic classification scheme largely based on physical process parameters.

Étude expérimentale du séchage infrarouge et convectif de peintures automobiles modèle sur supports plastiques ou métalliques

This work aims to study car paint drying and to better understand the complex physico-chemical transformations which occur during this process. Two different model painting systems were studied: • - a water-based epoxy-amine paint applied on steel support; • - a solvent based polyurethane paint applied either on sheet molding compound support (SMC) or on steel support. In these two cases, drying is an important step and determines significantly the final paint film quality. Indeed, water is a solvent which is difficult to evaporate and SMC supports are plastic and porous materials which can induce the apparition of bubbles on the dry paint film. After the description of the two paint systems and of the near infrared and convective laboratory drier, we will sum up the different results obtained for different experimental conditions, in terms of drying kinetics and dry paint film quality. These experiments show the influence of the physical process parameters (air temperature and velocity), of the infrared flux density, of the paint system (film thickness, chemical properties...) and of the supports properties.

Predicting plasmaspheric radial density profiles

A principle question concerning storm time convection is, What physical process or measurable parameter controls the location of the equatorward edge of the large‐scale convection zone expansion during magnetic storms and hence the plasmapause location? Experimental data on convection and particle precipitation consistently show that in the evening to midnight local time sector, the inner boundary of the high‐latitude westward ion convection band colocates with the equatorward boundary of soft electron precipitation (SEB). Low‐energy electron precipitation is usually absent, or very weak, above the lower‐latitude band of the disturbed‐time double‐peaked convection pattern. It follows that large‐scale convection streamlines carrying plasma sheet particles do not enter the polarization jet band which lies on the opposite (inner) side of the Alfven layer, which limits the inward expansion of hot plasma and convection by polarizing the edge of the inner magnetosphere plasma population. We conclude that the SEB (measured and/or modeled) can be used in plasmasphere density models as a substitute for the convection boundary. A time‐dependent convection‐driven plasmaspheric density model (CDPDM) is introduced to describe plasmaspheric thermal density profiles. The CDPDM is based on the convection drift and refilling rate prehistory calculated for a particular plasma flux tube, and its most important ingredient is a realistic convection model for disturbed times. Sharp density gradients (plasmapauses) on the radial profiles are indicators of preceding convection boundary locations outside of which the thermal plasma content was lost. We compare the predictions of the model with storm time ionospheric observations with the Millstone Hill radar and conclude that the CDPDM can be used to predict the locations of plasma density radial gradients, including the plasmapause.

A non-hydrostatic version of the NMC's regional Eta model

A non-hydrostatic version of the regional Eta model used operationally at the National Meteorological Center (NMC) has been developed by implementing the ideas of Juang (1992) and Laprise (1992), who independently recommended a hydrostatically based, vertical coordinate for a fully compressible set of equations. The grid-point model dynamics is based on perturbation equations in the η-vertical coordinate; the base state may be taken from the operational NMC model, and thus updated with time. The non-hydrostatic model uses a stepwise treatment of terrain present in the operational version, eliminating the pressure-gradient-term error associated with sigma-coordinate models over steep topography. The compressible equations are written in a form that allows conservation of energy in a horizontally closed domain with appropriate advective schemes. A two-dimensional version of the model, without parametrizations of physical processes, has been used successfully to simulate ascending warm bubbles and collapsing cold bubbles at high resolutions.

A non‐hydrostatic version of the NMC's regional Eta model

AbstractA non‐hydrostatic version of the regional Eta model used operationally at the National Meteorological Center (NMC) has been developed by implementing the ideas of Juang (1992) and Laprise (1992), who independently recommended a hydrostatically based, vertical coordinate for a fully compressible set of equations. The grid‐point model dynamics is based on perturbation equations in the η‐vertical coordinate; the base state may be taken from the operational NMC model, and thus updated with time.The non‐hydrostatic model uses a stepwise treatment of terrain present in the operational version, eliminating the pressure‐gradient‐term error associated with sigma‐coordinate models over steep topography. The compressible equations are written in a form that allows conservation of energy in a horizontally closed domain with appropriate advective schemes.A two‐dimensional version of the model, without parametrizations of physical processes, has been used successfully to simulate ascending warm bubbles and collapsing cold bubbles at high resolutions.

Analyse der Steuer- und Beobachtbarkeit linearer Systeme mit unsicheren Parametern

In this paper two structural measures as quantitative criteria for controllability and observability respectively are proposed. Fuzzy arithmetic together with conventional interval calculations is used. So one can get more insight into a systems characteristics than by using graph-theoretic methods or interval arithmetic. The Fuzzy Hadamard condition measure introduced in the sequel enables the decision whether there are parameter combinations possible which lead to a loss of controllability or observability respectively and whether further analysis seems to be useful. The following analysis identifies on the one hand those physical parameters which are decisive in the loss of the systems structural characteristics. In addition a measure called physical margin rank is defined which specifies the range the physical process parameters may vary without a loss of controllability or observability respectively

Effect of integration parameters on high-performance liquid chromatographic method development and validation

An HPLC method is defined as a specific setting of the physical, chemical and data processing parameters which control the chromatographic analysis. During the development or validation of a method no special attention is usually given to the data processing parameters. However, it turns out that HPLC methods for complex samples can be very sensitive to minor changes in certain numerical integration parameters such as the threshold. A series of statistically designed Chromatographic runs for a dyestuff with a very large number of peaks is presented where the interpretation of the data depends crucially on which threshold parameter value is chosen. It is therefore recommended that for development or validation of an HPLC method, especially in the context of quality control of complex substances, greater attention should be paid to the integration parameters.

Chemical and thermodynamic influences in ion beam assisted thin film synthesis

The main parameter of ion beam assisted deposition of compound films is the ratio γ of impacting ions to condensing atoms. It determines the energy input into the growing film and influences the composition of the film. When highly reactive elements such as transition metals are involved in the process, the elemental composition of the film may also be influenced by the presence of reactive gas molecules, and their partial pressure in the vacuum system. The corresponding process parameter is the ratio δ of impinging gas molecules to condensing atoms. In this case, the final phase and elemental composition of the film is strongly affected by chemical and thermodynamic influences. This is shown by a comparison of ion beam assisted deposition of TiN, VN and CrN. The according metal was evaporated and the growing film irradiated with energetic nitrogen ions. The physical process parameters such as evaporation rate, ion current density and ion energy were the same for all three elements. X-ray phase analysis shows that, whereas it is easily possible to synthesize TiN over a wide range of γ-values, CrN requires a very high irradiation intensity or high γ-value to be deposited as a monophase. VN is intermediate in its behaviour between TiN and CrN. This result is in accordance with the reactivity of the metals towards nitrogen gas and the thermodynamic stability of the resulting nitride. It shows that besides the physical parameters of the process chemical driving forces also play an important role.

Estimates of surface fluxes from global operational numerical weather predictions

The success of coupled models of the ocean-atmosphere system depends in part on their ability to estimate the momentum, heat and water vapour fluxes at the interface accurately. Their accuracy as now calculated by atmospheric numerical forecast models with relevant variables at the sea surface given is uncertain. The achievement of an acceptable accuracy in this simpler situation is an essential preliminary to a solution of the more difficult interactive problem. The ISCU/WMO Joint Scientific Committee (JSC) for the World Climate Research Programme (WCRP) considered how best to obtain surface flux values primarily for running large-scale ocean models. They concluded that the most promising approach was to extract them from numerical prediction models whose capabilities in terms of assimilating observations of many diverse kinds and of quality controlling meteorological information, have reached a high level of development and are being improved continuously. The committee requested its Working Group on Numerical Experimentation (WGNE) to investigate and report on the accuracies now achieved. In the absence of measurements of surface fluxes suitable for validation, the WGNE decided that the first step was to compare surface fluxes as estimated by state-of-theart global prediction models. The ECMWF (European Centre for Medium-Range Weather Forecasts) and Meteorological Office models were considered suitable, and have the advantage of employing different approaches to data assimilation, model configuration and the parametrization of physical processes. This report will outline the results obtained by the two models for a first comparison period, May-June 1987.

The oil spill behaviour model of the Canadian atmospheric environment service Part I: Theory and model evaluation

Abstract This paper describes a model to simulate the behaviour of oil spills in marine environments. The model includes parametrizations of various physical processes representing the movement and weathering of an oil slick. The movement of the slick is affected by wind‐driven, tidal and residual water currents. Turbulent dispersion is an important mechanism influencing the horizontal spreading of the slick for time periods greater than about a day. The model is used to simulate successfully the movement of spill‐following buoys deployed in the Bay of Fundy, where some of the strongest tidal currents in the world occur. The ability of the model to simulate the horizontal spreading of an oil slick was evaluated with observed data from the Argo Merchant oil spill for a 10‐day period. It was found that the observed shape and extent of the spill could be fairly well described by the parametrization of turbulent dispersion effects.

A fundamental study of polymer melt devolatilization: III More experiments on foam‐enhanced DV

AbstractA systematic, experimental study was conducted on the elementary process of devolatilization (DV) of volatile contaminants from polymer melts. Emphasis was placed on foam‐enhanced DV from rolling melt pools, which are present in rotating machinery. All experiments were conducted in a specially designed apparatus at room temperature using poly(dimethyl siloxane) to simulate the melt, and methyl chloride together with several chlorofluorocarbons as the contaminants. The special apparatus was devoid of the flow complexities present in industrial equipment and permitted independent control of all pertinent operating parameters. Physical properties and process parameters examined include feed composition and vapor pressure of contaminant, applied vacuum level, rotational speed of the pool, viscosity of the melt, and the effect of air entrainment.