Reduction Of Hole Size Research Articles

Improvement of SiC deposition uniformity in CVD reactor by showerhead with baffle

The growth uniformity of silicon carbide (SiC) by halide chemical vapour deposition (HCVD) is influenced by equipment configuration, and a uniform film can be obtained by optimising the chamber structure. An SiC deposition kinetics model is studied in this work, and a detailed chemical reaction mechanism is incorporated into a model reaction chamber to verify the deposition kinetics model. We studied the influence of hole size of showerhead, baffle size, and baffle positioning on the growth uniformity. Further, we then optimised the process parameters using an orthogonal experimental method. Reducing the hole size of showerhead led to a “double peak” in the deposition rate across the substrate from the edge to both sides, which first increased and then decreased. The “double peak” disappeared upon reduction of hole size. With an increase in baffle size, the growth uniformity first increased and then decreased. Moreover, the baffle displacement had little effect on the deposition rate when the baffle-to-showerhead distance was at least 45 mm. Meanwhile, the growth uniformity gradually worsened when the baffle distance was reduced. The showerhead and baffle reduced the extreme difference in deposition rate across the effective deposition area by improving the spatial velocity distribution within the reaction chamber. A uniform SiC film could be obtained using the proposed optimisation method. Furthermore, the results of the orthogonal experimental method showed that the deposition rate increased by 57.8%, and the uniformity of growth standard deviation decreased by 18% compared with the ground state. This study provides theoretical guidance for future optimisations of CVD chambers.

Application of Solid Expandable Tubulars in the Petroleum Industry

The development of solid expandable tubular (SET) technology and products (open hole liner, open hole clad, cased hole liner, liner hanger, internal casing patch, etc.) has enabled operators to plan well design in a new way and solve various problems that arise during drilling and exploitation on land and offshore. By including an expandable open hole liner, monobore open hole liner or monobore openhole clad in well design, it is possible to achieve a slim hole design and/or resolve unwanted situations that occur during the drilling of problem zones with minimal hole size reduction and reach hydrocarbon reserves which cannot be achieved economically by conventional technology. By installing an expandable cased hole liner or internal casing patch in production wells to cover the intervals of a corroded casing or to close old perforations, it is possible to extend the life cycle of a production well and increase the final hydrocarbon recovery and speed up the return on investment. The aim of this paper is to systematically review the relevant literature and give an overview of solid expandable tubular technology and its applications in the petroleum industry, as well as the cementing technology of open hole expandable liners. The available data for 21 case studies of SET application in onshore and offshore wells were analyzed in detail. Based on an extensive review of the literature and analyzed data, it can be concluded that SET technology is being successfully applied worldwide and that expandable liners with a diameter of 114.3 mm to 339.72 mm are being run in wells to ever greater depths (up to 5166 m) and in ever more extreme downhole conditions.

Robust Si3N4 masks for 100 nm selective area epitaxy of GaAs-based nanostructures

A robust shadow mask for fabrication of GaAs-based semiconductor nanostructures via selective area molecular beam epitaxy has been developed. The mask is based on a nano-patterned 100nm thick Si3N4-membrane on a Si(100) support wafer. Into the membrane, holes with diameters down to 100nm have been fabricated. The Si3N4-membranes have been produced by anisotropic etching of the Si(100) by KOH and the membrane itself is patterned by electron beam lithography and reactive ion etching. The masks are fully compatible with ultra-high vacuum and the growth of (In,Ga,Al)As by molecular beam epitaxy. Test depositions of Ga show that one has to minimize the gap between substrate and mask and diffusion has to be suppressed to obtain a localized deposition governed by the hole diameter. Under optimized conditions we were able to deposite Ga in an area with 100nm diameter. A GaAs layer, which is deposited on the front side of the mask, allows an in-situ hole size reduction and can be re-evaporated without damaging the mask.

Metal seed layer sputtering on high aspect ratio through-silicon-vias for copper filling electroplating

Abstract In this experiment, metal (Mo/Cu) seed layers with an aspect ratio of 10:1 were deposited by a conventional sputtering method and then copper filling by electroplating was followed in order to fabricate through silicon vias with a high aspect ratio. With increasing the aspect ratio, it is critical to carefully control the reduction of via's hole size before filling the bottom seed layer. By changing sputtering time, pressure, and power, changes in the thickness of the metal seed layers were investigated. It was found that optimizing the sputtering conditions improved the quality of the seed layer and retarded the speed of the hole size reduction. As a result, a metal seed layer with a via's opening percentage of about 62% and a bottom seed layer thickness of 46.7 nm was fabricated by conventional sputtering. Using this seed layer, Cu filling was successfully carried out by electroplating.

Expandable-Metal Technology Creates a Monobore Well

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 16670, "Using Expandable-Metal Technology To Create a Monobore Well," by Matthew Jabs, SPE, Baker OIl Tools, originally prepared for the 2004 Offshore Technology Conference, Houston, 3-6 May. The introduction of expandable-metal technology into the oil and gas industry in recent years has allowed a change in traditional well-construction design. The advent of this technology is allowing operators to drill wellbores that do not subscribe to the traditional telescoping reduction in casing sizes as well depth increases. This capability allows deep wells to be drilled without sacrificing well hole size, which has many advantages, ranging from lower wellbore construction costs to greater production potential. The full-length paper outlines a method of creating a monobore well over a finite length of well path. Introduction The primary benefit of a monobore well is the ability to reach the desired drilling depth without sacrificing casing size. This capability can allow much deeper or deviated wells to be drilled because of the elimination of the hole-size reduction. Should an unexpected hole problem be encountered while drilling, a monobore-well design provides the ability to set a section of casing across a problem zone and continue wellbore construction without sacrificing hole size. By developing wells from the surface to total depth using a monobore design, it is possible to reduce surface-equipment size. Use of smaller-sized equipment and casing may translate to direct cost savings.

Extraordinary infrared transmission of Cu-coated arrays with subwavelength apertures: Hole size and the transition from surface plasmonto waveguide transmission

The zero-order, infrared transmission spectra were recorded and studied at varying angles of incidence to study the dispersion of the resonances in both the Γ−X and Γ−M reciprocal lattice directions. Reduction of hole size shows dramatic effects on the intensity of transmission, the width of the resonances, the identity of the most prominent resonances, and the dispersion behavior of resonances.

Fabrication of nanohole array on Si using self-organized porous alumina mask

Formation of the ordered array of nanoholes on Si was investigated by the use of the self-organized porous alumina nanoholes array etching mask that is directly formed on the Si substrate by sputtering and subsequent anodic oxidation. Reactive ion etching using chlorine plasma against a porous alumina/thin-SiO2(10 nm)/Si substrate with a high self-bias of rf plasma was revealed to be very effective for pattern transfer to Si. After pattern transference a significant reduction of hole size was observed. In fact, the initial porous alumina hole size of 45 nm is reduced to 13 nm Si holes when the higher aspect ratio of porous alumina nanoholes mask is used. The etching characteristics strongly suggest that not only chemical etching but sputtering occurred, and that redeposition of nonvolatile materials in nanoholes plays an essential role in the reduction of the hole size.

Fabrication of metal field emitter arrays for low voltage and high current operation

This article describes a new fabrication process for a metal field emitter to achieve low voltage and high current operation. The key element of the fabrication process is that the isotropic silicon etching and oxidation process used in silicon tip fabrication are utilized for gate hole size reduction and gate oxide layer formation. A reliable structure with a small gate hole can be easily obtained. Metal field emitter arrays were fabricated in order to demonstrate the validity of the new process and submicron gate apertures were successfully obtained from 2.25-μm-diam disk patterns defined by a conventional contact mask aligner. The required gate voltage to obtain an anode current of a 0.1 μA/tip was 54 V, and emission currents above 20 μA/tip were stable at a gate bias of 96 V without any disruption.

Wellbore Stability

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to informthe general readership of recent advances in various areas of petroleum engineering. Introduction Maintaining a stable wellbore is of primary importance during drilling and production of oil and gas wells. The shape and direction of the hole must becontrolled during drilling, and hole collapse and solid particle influx must be prevented during production. Wellbore stability requires a proper balance between production. Wellbore stability requires a proper balance between the uncontrollable factors of earth stresses, rock strength, and pore pressure, andthe controllable factors of wellbore fluid pore pressure, and the controllable factors of wellbore fluid pressure and mud chemical composition. pressure andmud chemical composition. Wellbore instabilities can take several forms (Fig.1). Hole size reduction can occur when plastic rock is squeezed into the hole, and hole enlargement can be caused by caving shales or hard rock spalling. If the wellbore fluid pressure is too high, lost circulation can occur as a resultof unintentional hydraulic fracturing of the formation; if it is too low, the hole may collapse. Excessive production rates can lead to solid particlein flux. Hole instabilities can cause stuck drill pipe as well as casing or liner collapse. These problems can result in side tracked holes and abandoned wells. Since 1940 considerable effort has been directed toward solving rock mechanics problems associated with wellbore instabilities, and much progress has beenmade during the past 10 years toward providing predictive analytical methods. Some of the literature representative of this work is discussed in thisarticle. Emphasis here is on understanding factors that influence wellbore stability in open holes, prediction of wellbore failures, and applications of rock mechanics concepts to control wellbore stability, A brief historical overview is followed by discussion of various types of wellbore instabilities and descriptions of studies of field wellbore stability problems. Stresses Around Wellbores H.M. Westergaard published a paper entitled "Plastic State of Stress Arounda Deep Well" in 1940. This now-classic paper defined the wellbore stability problem as follows. The analysis that follows is a result of conversations with Dr. KarlTerzaghi who raised this question: What distributions of stress are possible inthe soil around an unlined drill hole for a deep well? What distributions of stress make it possible for the hole not to collapse but remain stable for sometime, either with no lining or with a thin "stove pipe" lining of small structural strength? Westergaard uses stress functions in cylindrical coordinates to solve the elastic-plastic wellbore problem for zero pressure in the hole and all normal stress components equal to the overburden far from the hole. Hooke's law was applied for the elastic region and a Coulomb yield condition* where "the limiting curve for Mohr's circle is a straight line" was assumed for the plastic region. His conclusions were: The plastic action makes it possible for the great circumferential pressures that are necessary for stability to occur not at the cylindrical surface of the hole but at some distance behind the surface, where they may be combined with sufficiently great radial pressures. The formulas that have been derived serveto explain the circumstances under which the drill hole for a deep well may remain stable. Westergaard's elasticity solution agrees with the Lame solution for a thick-walled cylinder subjected to the same boundary conditions. Hubbert and Willis (1957) demonstrated how earth stresses can vary from regions of normal faulting to those with thrust faulting. On the basis of a Coulomb failure model, they suggest that the maximum value of the ratio of the maximum to the minimum principal stress in the earth's crust should be about 3:1. JPT P. 889

Dynamics of the holes in human erythrocyte membrane ghosts.

Osmotic lysis of human erythrocytes creates in each membrane a single large hole which subsequently contracts to a size determined largely by the buffer, typically 7-140 A in radius. Cations, but not anions, stimulated the rate and extent of hole size reduction with simple saturation behavior; the potency of Ca2+ exceeded M&+, which greatly surpassed Na+. The hole size was minimal at pH 5.5. Hole size change was greatly accelerated by increasing temperature between 0 and 50 “C. Whatever its size, the hole radius was stable to 21-2 A over several days at 0 “C. Cationic amphipaths such as chlorpromazine promoted hole closure in a salt-dependent fashion, while anionic amphipaths such as 2,4-dinitrophenolate or hexanoate opposed hole closure. Hole size thus appears to be determined by a balance between the force expanding the hole (electrostatic repulsion among anionic groups on the membrane) and the force driving hole closure (perhaps the hydrophobic effect of the lipid/ water interface at the hole perimeter and/or membrane elasticity). Hole size was initially completely reversible; however, the extent to which holes were able to expand and contract gradually diminished in parallel until the oles became fixed at an ambient size. The rate of this process increased directly with temperature, pH, and the presence of hexanol, and inversely with cation concentration. A 30% reduction in membrane cholesterol greatly accelerated the loss of hole sealing. Glutaraldehyde at 0.5 l ~ l ~ (0.005%) blocked hole closure (but not hole expansion) without cross-linking membrane proteins significantly. Once lost, the ability to expand hole size could be regenerated by osmotically stressing sucrosefilled ghosts. We infer that hole size dynamics. reflect metastable configurations of the membrane bilayer which can be reversibly altered, dissipated, and restored by experimental manipulations. Applications of the hemolytic hole as a continuously tunable molecular filter are suggested.