Showing papers on "Fabrication published in 1989"

Hexagonal boron nitride: Fabrication, properties and applications

Abstract: The production methods for α-BN powders and dense shapes, their physical and chemical properties, industrial uses and potentialities are reviewed.

Efficient multichannel integrated optics star coupler on silicon

Abstract: The design and fabrication of a 19*19 star coupler suitable for lightwave distribution in high-capacity local area networks with a measured efficiency of 55% at a wavelength of 1.3 mu m is reported. The coupler consists of two arrays of channel waveguides separated by a slab waveguide fabricated on a silicon substrate using SiO/sub 2//Si technology. The integrated optics design is well suited to manufacture. It is argued that the coupler performance does not depend critically on the fabrication accuracy. In fact, the efficiency is primarily determined by the radiating element pattern, whose effective angular aperture is essentially determined by the width Omega of the first Brillouin zone, and, therefore, it is not greatly influenced by the fabrication process. >

Fabrication of detectors and transistors on high-resistivity silicon

Abstract: A new process for the fabrication of silicon p-i-n diode radiation detectors is described. The utilization of backside gettering in the fabrication process results in the actual physical removal of detrimental impurities from critical device regions. This reduces the sensitivity of detector properties to processing variables while yielding low diode reverse-leakage currents. In addition, gettering permits the use of processing temperatures compatible with integrated-circuit fabrication. P-channel MOSFETs and silicon p-i-n diodes have been fabricated simultaneously on 10 k..cap omega../center dot/cm silicon using conventional integrated-circuit processing techniques. 25 refs., 5 figs.

Fabrication of thin‐film metal nanobridges

Abstract: Thin‐film fabrication techniques for forming three‐dimensional ‘‘point contacts’’ are presented. As‐fabricated nanobridges can be modified using electromigration to make the constriction region smaller or dirtier. Scientific applications to quantum transport studies, 1/f noise, and electromigration are discussed.

Laser direct writing of channel waveguides using spin‐on polymers

Abstract: A focused argon‐ion laser beam (λ=350 nm) is used to fabricate optical channel waveguides on oxidized silicon wafers using a commerically available spin‐on polymer. The polymerization process is photon induced, thus allowing the reaction to occur in a room‐temperature ambient. This allows the fabrication of waveguides on a variety of substrates including those with low melting points. The losses in these waveguides are typically less then 1 dB/cm, making them applicable to a variety of optical interconnect problems. In particular, we demonstrate their use in the fabrication of an optical power tap.

Fabrication and testing of uranium nitride fuel for space power reactors

Abstract: Abstract Uranium nitride fuel was selected for previous space power reactors because of its attractive thermal and physical properties; however, all UN fabrication and testing activities were terminated over ten years ago. An accelerated irradiation test, SP-1, was designed to demonstrate the irradiation performance of Nb-1 Zr clad UN fuel pins for the SP-100 program. A carbothermic-reduction/nitriding process was developed to synthesize UN powders. These powders were fabricated into fuel pellets by conventional cold-pressing and sintering. The pellets were loaded into Nb-1 Zr cladding tubes, irradiated in a fast-test reactor, and destructively examined after 0.8 at% burnup. Preliminary postirradiation examination (PIE) results show that the fuel pins behaved as designed. Fuel swelling, fission-gas release, and microstructural data are presented, and suggestions to enhance the reliability of UN fuel pins are discussed.

Method for the fabrication of field emission type sources, and application thereof to the making of arrays of emitters

Abstract: Disclosed is a method for the fabrication of field emission peaks using a monocrystalline substrate with a suitable orientation coated with an insulating layer where square-shaped elementary zones with a suitable orientation with respect to the substrate have been removed. Silicon is deposited by selective epitaxy in these zones. The epitaxial growth of silicon, at high speed parallel to the substrate and at low speed along faces of the substrate at 45° to the substrate, enables the making of pyramidal peaks which, afater being coated with tungsten, form emitting peaks.

Fabrication of intermetallic matrix composites

Abstract: Research into the fabrication of intermetallic matrix composites is presented using the Ni 3 AlAl 2 O 3 system as the baseline. The approach combines reactive sintering, powder injection molding, and hot isostatic compaction to form an aligned fiber composite. The individual components to this process are described with example microstructures and mechanical properties. The initial successes and problems are described. The paper concludes with a description of the major remaining processing challenges in the fabrication of intermetallic matrix composites.

Grain-oriented fabrication of bismuth titanate ceramics and its electrical properties

Abstract: The concept of grain-oriented fabrication in ceramics, which utilizes anisotropy either in morphology or some specific property of the particle, is reviewed. A fabrication method, which maximizes the grain orientation, is described for Bi/sub 4/Ti/sub 3/O/sub 12/. The process utilized plate-like morphology of Bi/sub 4/Ti/sub 3/O/sub 12/ particles and yielded a ceramic with an X-ray density of 95.4% and an unprecedented value of 100% for Lotgering's orientation factor in the direction of orientation. The dielectric and piezoelectric properties of this ceramic are described and compared to single crystal values. Complex impedance analysis of the ceramics was used to explain the dielectric relaxations at elevated temperatures. The use of grain-oriented fabrication as a practical technique for making polycrystalline ceramics with electrical properties close to those of single crystals (in the direction of orientation) is emphasized. The use of grain-oriented Bi/sub 4/Ti/sub 3/O/sub 12/ ceramics as a high-temperature piezoelectric transducer is suggested. >

Transistor manufacturing process using three-step base doping

Abstract: In a transistor fabrication process, the use of a three-step base doping technique enables the characteristics of a vertical bipolar transistor to be controllably reproduced at highly optimal values from run to run. Insulating spacers (52A) are employed in forming a self-aligned base contact zone (58B). A shallow emitter (46) is created by outdiffusion from a patterned non-monocrystalline semiconductor layer (38A) that serves as the emitter contact. The fabrication process is compatible with the largely simultaneous manufacture of an insulated-gate field-effect transistor of the lightly doped drain type.

Optical properties of SiC for crystalline/amorphous pattern fabrication

Abstract: The optical contrast between crystalline and ion beam amorphized regions in SiC has been studied by transmission spectrometry for photon energies ranging up to the ultraviolet. The working range of such an optical device with crystalline/amorphous patterns, e.g., for use as a photolithographic mask, is extended to considerably higher photon energies than with Si as a recording material. Thus, SiC, in the form of thin crystalline layers on a transparent substrate, is a promising candidate for submicron structuring in various fields of application.

Enhancement in Thermal Oxidation of Silicon by Ozone

Abstract: It is demonstrated, that the thermal oxidation of silicon, which is one of the important processing steps in the fabrication of integrated circuit devices, can be enhanced without introducing additional impurities.

Laser chemical processing for microelectronics

Abstract: This book describes the application of laser processing techniques in the fabrication of semiconductor materials and devices for the microelectronics industry. It comprises a collection of reviews of interest to those involved with a semiconductor fabrication facility.

Internal stress minimization in the fabrication of transmissive multilayer x‐ray optics

Abstract: Transmissive multilayer optics have a potential application in the development of high‐resolution x‐ray microscope and spectrometer systems. Difficulties encountered in the sputter deposition of these multilayer optical structures can be overcome by careful control of the fabrication parameters. The deleterious effects of compressive or tensile intrinsic stresses can be minimized by optimizing both substrate temperature and working gas pressure during the deposition process. This study specifically considers the Al/Ta multilayer combination.

Electron Beam Lithography And Resist Processing For The Fabrication Of T-Gate Structures

Abstract: This paper will discuss direct-write electron beam lithography and multilayer resist processing for the fabrication of T-shaped gates. Gates whose length at the bottom of the "T" are less than 100 nm have been fabricated by this method using a multilayer of polynethylnethacrylate and lift-off. Because of the large cross-section of the T-gate, the resistance is reduced. The end-to-end resistance of the 100 nm T-shaped lines was less than 25) Ohninin as compered to 2000 Ohm/nin for a 100 nm conventional gate, i.e., an eight-fold decrease. In order to facilitate the fabrication of these gates a series of computer programs were written to simulate the development process in a multilayer of electron resists. These programs are based on a string development model of resist development. They allowed rapid prediction of the resist profiles. As a demonstration of the increased device performance made possible by this prociss, modulation-doped field effect transistors (HOLEY) have been fabricated using these T-gate structures . The extrapolated unity current gain frequency (ft) of these transistors is 113 Gilz.

A New Fabrication Process for High-Tc Superconducting Oxide Ceramic Fibers

Abstract: A new fabrication process for superconducting oxide ceramic fibers, the alginate method, is proposed. This process is based on a gelation of a sodium alginate aqueous solution by sodium ion exchange with protons or multivalent metal ions. Dense Y-Ba-Cu-O superconducting fibers have been successfully fabricated by firing Y-Ba-Cu-alginate fibers at temperatures above 900°C. The fibers have shown a tensile strength of 192 MPa and an end-point critical temperature of 85 K.

Self aligned registration marks for integrated circuit fabrication

Abstract: In order to reduce alignment errors arising in the fabrication of semiconductor integrated circuits using electron beam lithography, enhanced registration marks--(i.e., registration marks that are more easily and accurately detectable by the electron beam)--are formed at the edges of oxide layers, located at the surface of a silicon body, by means of forming metal silicide layers having edges coincident with the edges of the oxide layers. Advantageously, the enhancing of the registgration marks by forming the metal silicide is performed subsequent to any high temperature processing steps, whereby the integrity of the marks is maintained.

Rapid fabrication of lightweight ceramic mirrors via chemical vapor deposition

Abstract: Lightweight Si/SiC mirrors of nominal diameter 7.5 cm have been fabricated via a scalable and rapid CVD process to demonstrate the CVD mirror fabrication technology. These mirrors consist of a faceplate of either Si or Si-coated SiC and a lightweight backstructure made of either Si or SiC. The mirrors were polished to a figure better than 1/5th of a wave at 0.6328 A and a finish of better than 10 A rms. A procedure for fabricating these mirrors is described. The CVD fabrication process is fast and has the potential to yield several mirrors in a few weeks time from a single reactor. The CVD mirror fabrication technology is quite general and can be extended to include mirrors of other ceramic materials such as TiB2 and B4C.

Thin-base bipolar transistor fabrication using gas immersion laser doping

Abstract: Gas immersion laser doping (GILD) is used to fabricate the base and emitter regions of narrow-base n-p-n bipolar transistors. The GILD process is unique in that it allows simple fabrication of box-like impurity profiles which can be placed very accurately in the vertical dimension (+or-100 AA). Transistors with base widths ranging from 700 to 1200 AA and DC forward current gains greater than 50 are fabricated. >

Monolithic 4×4 single-mode fused coupler

Abstract: The fabrication and performance of a monolithic 4×4 single-mode fused coupler is reported. Measurements show that the device exhibits excellent coupling uniformity together with low excess loss. Two propagation paths are seen to be wavelength-flat between 1.2 μm and 1.6 μm, and two paths have a small coupling variation which may be minimised by fabrication technique.

Monolithic silicon membrane device fabrication process

Abstract: The method of fabrication of a monolithic silicon membrane structure in which the membrane and its supporting framework are constructed from a single ultra thick body of silicon. The fabrication sequence includes the steps of providing a doped membrane layer on the silicon body, forming an apertured mask on the silicon body, and removal of an unwanted silicon region by mechanical grinding and chemical etching to provide a well opening in the silicon body terminating in the doped membrane.

Superconducting thin film fabrication

Abstract: An improved fabrication of superconducting films is disclosed whereby a multi-phase Y-Ba-Cu-O compound is utilized. The film is formed by sputtering of a target material consisting of the superconducting 123 phase Y1Ba2Cu3O7 onto the green 211 phase Y2BaCuO5. After annealing, the superconducting characteristic, of the formed film, in terms of transition width and Tc, are improved over those using other oxide compounds as substrates.

Fabrication of high density multichip modules

Abstract: A novel high-density multilayer interconnect (HDMI) technology has been shown to provide very high functional densities and a fabrication platform for extremely compact and complex systems. The technology comprises an interconnect fabrication method for microelectronic circuits based on vacuum thin-film metallization and polymeric insulation between layers. The HDMI technology makes wafer-scale integration realistic by using a hybrid concept. Semiconductor devices can be built to the practical limit of reasonable yields, then regrouped on a substrate to achieve the desired level of integration. The technology is discussed in connection with photolithography, the effect of three-dimensional topography, alternatives for the definition of metal patterns, and the pattern of polymers. >