Showing papers on "Fabrication published in 1990"

Tapered waveguide InGaAs/InGaAsP multiple-quantum-well lasers

Abstract: The use of ultrathin etch-stop techniques to expand the vertical optical mode size adiabatically in 1.5- mu m InGaAs/InGaAsP MQW lasers using a tapered-core passive intracavity waveguide structure is discussed. 30% differential quantum efficiency out the tapered facet, far-field FWHM of approximately 12 degrees and a butt-coupling efficiency into a cleaved fiber of -4.2 dB, with -1-dB alignment tolerances of approximately +or-3 mu m, were achieved. >

NH4Oh-based etchants for silicon micromachining

Abstract: Wet chemical etchants based on ammonium hydroxide-water (AHW) solutions for micromachining monocrystalline silicon are described. The etchants can be applied under clean-room conditions within standard IC fabrication lines. The nature of AHW solutions is discussed with respect to anisotropy and selectivity. At 75 °C and 9 wt.% AHW, a maximum etch rate for (100) silicon of approximately 30μm/h has been determined. (111):(100) etch rate ratios show values around 4%. AHW etchants exhibit an excellent selectivity to SiO 2 , Si 3 N 4 and highly boron-doped silicon. Aluminium will not be attacked by silicon-doped AHW etchants. Therefore, standard IC metallization techniques can be used for device fabrication. The application of AHW solutions to the fabrication of basic micromechanical structures is demonstrated.

Fabrication and applications of piezo-and ferroelectric films

Abstract: Different thin film fabrication techniques of ferro- and piezoelectric materials is described with special emphasis on rf sputtering. The relative advantages and disadvantages of oxide and metallic targets, and the control of stoichiometry by adjusting the target substrate distance and composition of target is described. The possible applications of ferroelectric films in non-volative memories, pyroelectric detectors, electro- and acousto-optic devices is briefly presented. The applications of these films in the fabrication of integrated Surface Acoustic Wave (SAW) devices on Silicon is discussed in some detail. Theoretical calculations of SAW transduction in layered media is used to compare selected ferroelectric (PZT, PbTiO3. LiNbO3 and BaTiO3) and piezoelectric (ZnO, AIN and CdS) films on silicon for their use in SAW devices.

Influence of Magnesium-Aluminum Spinel on the Directed Oxidation of Molten Aluminum Alloys

Abstract: The directed oxidation of some molten aluminum alloys was studied. Alloys containing Si, Zn, and Mg are readily converted into Al2O3/Al composites with the characteristic directed metal oxidation process (DIMOX) metal-channel structure. No reaction took place when alloys without Mg were used. However, when Mg-free melts containing Si and Zn were in contact with bulk spinel (MgAl2O4), the typical reaction product grew from the metal pool, although without formation of the spinel starter layer which was thought to be a prerequisite for DIMOX growth. Furthermore, the growth front was more planar than when Mg-containing alloys were used.

Low-temperature silicon-to-silicon anodic bonding with intermediate low melting point glan

Abstract: Room-temperature silicon-to-silicon bonding has been performed. It is an electrostatic bonding using sputtered low melting point glass as an intermediate layer. Wafers can be bonded at room temperature with an applied voltage of about 50 V. This technique is useful for the fabrication of intelligent sensors and microelectromechanical systems.

Fabrication of Planar and Cross-Sectional TEM Specimens Using a Focused Ion Beam

Abstract: A new technique using a focused ion beam has been developed for the fabrication of transmission electron microscopy specimens in pre-selected regions. The method has been proven in the fabrication of both cross-sectional and planar specimens, with no induced artefacts. The lateral accuracy achievable in the selection of an area for cross-sectional analysis is better than one micrometre. The technique has been applied to a number of silicon and III-V based integrated circuits, and is expected to be suitable for many other materials and structures.

A general model for fabrication processes of channel waveguides by ion exchange

Abstract: A general theoretical approach to the modeling of several different process steps in fabrication of ion‐exchanged channel waveguides is presented. All of the commonly used fabrication processes are included, and the nature of the ion source and the effect of external electric voltage are taken into account. The model uses a numerical finite‐difference calculation of diffusion in the glass with boundary conditions and electrical current distribution chosen according to the process being modeled. A single computer program includes the model, and can be used for simulating a fabrication process with different successive process steps. Several calculated examples are given, all with experimentally obtained parameters for Ag+ ‐Na+ exchange in Corning 0211 glass.

Design and fabrication of highly efficient fan-out elements

Abstract: This paper reports the calculation and fabrication of periodic phase structures for fan-out elements with a theoretical conversion efficiency close to 100% and perfect uniformity. We have measured an efficiency of 92% for a smooth kinoform structure fabricated in photoresist by laser beam writing lithography.

Solid Redox Polymerization Electrodes and Their Use in All-Solid-State Batteries

Abstract: The dramatic proliferation of products based on semiconductor technology is a strong testament to the predictability and reliability of solid-state technology. In a similar vein, advances in materials exhibiting high levels of ionic conduction in the solid state has led to worldwide efforts in the development of all-solid-state rechargeable batteries. Although higher current densities are achievable with liquid electrolytes, all-solid-state cells offer inherent advantages of negligible self-discharge, long cycle life, high reliability, and virtual absence of container corrosion. Elegant work on polycrystalline and vitreous electrolytes has led to solid electrolytes with suitable ionic conductivities for battery development,1,2,3 however, the superior mechanical properties of elastomeric electrolytes combined with the simplicity of fabrication of thin separator films from these materials, has led to very active pursuit of solid-state cells based on solid polymeric electrolytes (SPE's). Although so...

Programmable gate array and methods for its fabrication

Abstract: Circuitry 12 is formed at the face of a layer semiconductor 34. The circuitry includes a plurality of contact points 22 and 24. At least one anti-fuse 14 is formed in a layer vertically displaced from circuitry 12. Anti-fuse 14 is operable to selectively connect together certain ones of said contact points 22 and 24.

Fabrication and characterization of ferroelectric PLZT 7/65/35 ceramic thin films and fibers

Abstract: Integration of ferroelectrics in the current generation of electronic/photonic devices not only enhances the functional capabilities of these devices but also has potential for a variety of new applications. The fabrication of ceramic thin films and fibers is enabled by sol-gel process. This fabrication process is well-controlled, low-cost and compatible with existing fabrication technologies. This study focussed on the fabrication of PLZT 7/65/35 ceramic thin films and fibers from lead acetate hydrate, lanthanum acetate hydrate, zirconium n-propoxide and titanium n-propoxide utilizing acid catalysis. The transformations of the precursors to sol, sol to gel and gel to crystalline phase were characterized using spectroscopy and x-ray diffraction. The films were formed by spin-coating the hydrolyzed precursor sol on various substrates: conductors (Au, Al, Pt), semiconductors (Si [100], Si [111]) and insulators (fused SiO2, Al2O3, MgO). The fibers were drawn from the similar sols. These films and fibers were...

Modeling of an improved Chemical Vapor infiltration Process for Ceramic Composites Fabrication

Abstract: A quasi-steady-state approach is applied to model the pressure-driven, temperature-gradient chemical vapor infiltration (improved CVI process) for ceramic matrix composites fabrication. The deposited matrix in this study is SiC which is converted from the thermal decomposition of methyltrichlorosilane gas under excess hydrogen. A three-dimensional unit cell is adopted to simulate the spatial arrangements of reinforcements in discontinuous fiber mats and three-dimensionally woven fabrics. The objectives of this paper are to predict (1) the temperature and density distributions in a fibrous preform during processing, (2) the advancement of the solidified front, (3) the total fabrication period, and (4) the vapor inlet pressure variation for maintaining a constant flow rate. Furthermore, the effect of boundary temperature and inlet pressure variations on the total proassing period is also studied. The fabrication temperature examined in this paper is in the range between 873 and 1473 K, and the pressure is from 1.0001 to 2.0000 atm (1.0134 × 105 to 2.0265 × 105 Pa). Based upon this analysis, the influence of the reactor condition on the density of the final product in a CVI process can be quantified.

Theory and fabrication of 4 × 4 single-mode fused optical fiber couplers

Abstract: The theory, fabrication, and performance of monolithic 4 × 4 single-mode fused couplers is reported The field coupling matrix is derived and used to show that a device having equal coupling between the four fibers may be obtained The fabrication of such a device is described, and measurements show that the device exhibits excellent coupling uniformity and low excess loss The wavelength response of a device designed for equal coupling at 153 μm is shown between 12 and 16 μm

High temperature metallization system for contacting semiconductor materials

Abstract: A metallization system for contacting semiconductor materials employed in high temperature applications that is thermally stable. The system can be utilized in the fabrication of electronic devices such as diodes, lasers, transistors, solar cells, and integrated circuits comprised of such devices.

The design and fabrication of a magnetically actuated micromachined flow valve

Abstract: In this paper, a magnetically actuated valve, manufactured by silicon and thin-film micromachining, is considered. An analysis of the magnetic circuit is made to determine the critical design parameters, and a fabrication sequence is described. An integrated array of these microvalves, when combined with chemical microsensors, is intended to form the basis of an automated flow distribution and chemical analysis system. The feasibility of magnetic actuation, an addressing scheme, and the fabrication process are discussed.

Ink jet printhead

Abstract: A thermal ink jet printhead having an array of coplanar nozzles in a nozzle face that are entirely surrounded by an insulative polymeric material is disclosed, together with a method of fabrication thereof. The ink channels, nozzles, and reservoir are produced by sequentially depositing and patterning two layers of thick film material, such as Vacrel®, on one substrate containing an array of heating elements and addressing electrodes, so that the heating elements are placed in a pit in the first thick film layer and the channels and reservoir recesses are produced in the overlaying second thick film layer. A second substrate having a third layer of the same thick layer and having a hole processed therethrough to serve as an ink inlet is aligned and bonded to the first substrate to form the printhead, with the second and third film layers bonded together in order to produce the nozzle which are surrounded by the thick film material.

Nanostructure fabrication in InP and related compounds

Abstract: Nanometer‐scale gratings have been fabricated in InP and InGaAs/InP heterostructures using electron‐beam lithography and reactive‐ion etching in methane‐hydrogen plasmas. It is shown that the slight overcut obtained in the etch profiles during a single‐step etch in CH4/H2 is due to polymer formation on inert mask surfaces and edges. Intermittent removal of the deposited polymer film is shown to be effective in obtaining anisotropic profiles. Highly anisotropic 35‐nm‐wide InP lines at 70‐nm pitch demonstrate the potential of this fabrication process. The formation of 100‐nm‐wide free‐standing InP wires is also presented.

The passivation of InP by arsenic surface stabilization and Al2O3 deposition: Correlations between interface chemistry and capacitance measurements

Abstract: A new approach is presented for the development of a metal‐insulator–semiconductor field‐effect transistor technology. It is applied to the optimization of Al2O3/InP structures prepared by the deposition of evaporated Al2O3 on arsenic‐stabilized InP surfaces. Molecular beam epitaxy and surface‐science techniques (reflected high‐energy electron diffraction and x‐ray photoelectron spectroscopy are used to control step by step the fabrication of the structures and to describe the microscopic properties of the interfaces. The optimization of the fabrication process is based on correlations between interfacial physicochemical properties and metal–insulator‐semiconductor capacitor electrical properties. It is shown that an interfacial oxide buffer layer can favor crystallochemical matching between Al2O3 and InP.

Microstructural Designing and Fabrication of Disk Shaped Functionally Gradient Material by Powder Metallurgy

Abstract: The fabrication of disk shaped functionally gradient material with an optimum distribution of composition for thermal stress reduction in a specific material combination of PSZ/Stainless Steel is described. The thermal stress generated during cooling from sintering temperature was analized by finite element method as a function of conpositional distribution and sample size.According to the optimum compositional gradient, the sintered compact of the PSZ /SUS304 functionally gradient material was successfully fabricated.

Method of making stacked surrounding reintrant wall capacitor

Abstract: A stacked surrounding reintrant wall capacitor (SSRWC) using a modified stacked capacitor storage cell fabrication process. The SSRWC is made up of polysilicon structure, having an elongated v-shaped cross-section, located at a buried contact and extending to an adjacent storage node overlaid by polysilicon with a dielectric sandwiched in between. The addition of the polysilicon structure increases storage capability 50% without enlarging the surface area defined for a normal stacked capacitor cell.

Fabrication of microlenses by laser chemical vapor deposition

Abstract: A new laser-based method was developed for fabrication of microlenses on flat quartz plates. In this method, a CO(2) laser is used to heat a quartz surface and induce thermal reactions for source gases of SiH(4) and NO. Even as-grown silicon oxide deposits have the spherical thickness distribution required for a lens at the center and this useful area can be further increased by wet etching. Microlenses were checked on a Fizeau interferometer for surface accuracy and aberrations. As a demonstration, a 14-microm thick microlens was used for collimating light from an optical fiber.

Large-Area Doping Process for Fabrication of poly-Si Thin Film Transistors Using Bucket Ion Source and XeCl Excimer Laser Annealing

Abstract: A large-area doping process for polycrystalline Si (poly-Si) thin-film transistor addressed liquid crystal displays (TFT/LCD's) has been developed. A large ion beam that was extracted from the bucket ion source and a XeCl excimer laser were utilized for impurity doping and impurity activation. A sufficiently low value of sheet resistance (500±25 Ω/\Box) was obtained for an implantation time of 10 s. The poly-Si TFT's fabricated by using this technique have good characteristics and uniformity. This technique seems suitable for the fabrication of large area poly-Si TFT/LCD's.

In Situ Fabrication of Reproducible YBCO/Au Planar Tunnel Junctions with an Artificial MgO Barrier

Abstract: The in situ fabrication of YBCO (YBa2Cu3Oy)/MgO/Au epitaxial planar tunnel junctions with a thin MgO barrier utilizing an electron-beam coevaporation technique is reported. The thickness of the MgO barrier is 3–12 nm and the tunnel resistance shows a strong dependence on barrier thickness. The fabricated tunnel junctions are highly reproducible and controllable. The observed tunnel characteristics contain the gap opening at about 20 mV and the anomaly around zero bias. The tunnel characteristics using the degraded films are also reported.

Performance And Yield Of Pilot-Line Quantities Of Lithium Niobate Switches

Abstract: A large number of single-polarization 2x2 lithium niobate switches have been fabricated for use in a bit serial optical computer. The switches come six to a package and have a single drive voltage of less than 5 volts, insertion loss less than 5 dB, and crosstalk less than -20 dB. At ten chips per 3-inch wafer, a lot of 6 wafers yields as many as 360 switches, making packaging and testing far more costly than chip fabrication. After one die per wafer passed acceptance testing, the rest of the dice were packaged in commercially-made Cu-alloy DTP's without further testing. Standard single-mode fibers were attached twelve at a time using Si-V-groove chips. Exercising our process by making chips in modest volume leads us to conclude that lithium niobate devices are made with a manufacturable process that can be tuned to provide a high yield of packaged devices at a cost comparable to other photonic products.

Micro electro-discharge machining using water as a working fluid 2 : narrow slit fabrication

Abstract: Micro-electro discharge machining (MEDM) using water as a working fluid, with its advantages of high removal rate and low electrode wear without formation of carbonaceous material, for deep micro-hole drilling with large ratios of depth to diameter is applied to the fabrication of narrow slits used for ultra-violet spectrometers. The optimum condition for narrow slit fabrication is investigated concerning the electric discharge circuit and combinations of electrode, workpiece materials and electrode polarity. As a result, it is possible to fabricate fine slits as narrow as 20 μm wide and 3 mm long with fairly fine surface roughness of around 1 μm. Comparative estimation with an optical diffraction method shows that slits made by MEDM and commercially available ones made by photoetching are both of the same level in quality as determined from the higher order spots of the diffraction pattern. The MEDM method is superior to photoetching in fabricating finer and more accurate slits much faster.

Small particle thin electrochemical electrode and method

Abstract: An electrochemical cell electrode such as the cathode element for a high energy density battery cell and its fabrication sequence are disclosed. Material such as finely-divided carbon particles is dispersed over the electrode surface during an ultrasonic energy assisted wet spraying process which produces very thin electrodes that are also low in fabrication cost and increased in uniformity and energy density capability. Fine particle material deposition on both a metal foil electrode and on an insulating member that is later joined to a metal foil electrode are contemplated.