Showing papers on "Isotropic etching published in 1978"

Device fabrication by plasma etching

Abstract: High density fine-line integrated structure fabrication is expedited by use of plasma etching systems which assure straight vertical walls (absence of undercutting). Critical to the sytems is choice of appropriate plasma chemistry. Appropriate systems are characterized by inclusion of recombination centers, as well as active etchant species. Recombination centers which effectively terminate etchant species lifetime in the immediate vicinity of resist walls afford means for controlling etching anisotropy. Use is foreseen in large scale integrated circuitry (LSI) and is expected to be of particular interest for extremely fine design rules, i.e., in Very Large Scale Integrated circuitry.

Mechanism of silicon etching by a CF4 plasma

Abstract: The mechanisms for the reactive ion etching of silicon by CF4 plasma are investigated A model is proposed whereby silicon is etched by chemical reaction with free fluorine to produce a volatile species, and also by physical sputtering The chemical etching is shown to be enhanced by ion bombardment of the reacting surface This etching process, together with a model for cracking CF4 in the plasma, is evaluated by comparison to actual etch rates Experimentally, the silicon etch rate is observed to decrease with increasing silicon area, by what is called the loading effect The functional form of the loading effect, as predicted by the model, is fitted to experimental loading curves The contributions of the various etching components are separated, to yield empirical values for the enhancement of the chemical reaction by physical sputtering

Method of forming thin film interconnection systems

Abstract: A method for forming thin film interconnection patterns atop substrates, particularly semiconductor substrates. It features the use of the passivation layer itself, typically glass, as a stable masking material to etch the conductive lines. Conversely, the metal conductor is used as a stable mask in etching the glass to form via holes. The process provides a practical resist system which is compatible with reactive ion etching or other dry etching process.

Reactive ion etching of aluminum and aluminum alloys in an rf plasma containing halogen species

Abstract: An etching method capable of producing vertical‐walled high‐resolution patterns in aluminum and aluminum alloy films is described. The process consists of rf sputter etching in a plasma containing ion species, which react with the metal to form volatile or easily sputtered compounds. The presence of reactive species greatly enhances the etch rate, while the electric field maintains the directionality inherent in the sputtering process. Halogen ion species, as obtained in rf plasmas containing a partial pressure of Cl2, Br2, HCl, HBr, or CCl4, were used to produce reactive ion etching of Al. The etch rate in a CCl4 plasma at a power input of 0.6 W/cm2 is as high as 5000 A/min. Variations in reaction rate with rf power, reactant concentration, reactant flow rate, temperature, gas pressure, batch size, and residual gas contamination are discussed. Etch rate data for various materials found suitable for masking are also presented.

Patterned multi-layer structure and manufacturing method

Abstract: A patterned multi-layer structure for a stripe filter used for a photoelectric pickup tube, comprises a protective layer preventing a substrate from being etched by reactive sputter etching and a multi-layer optical filter formed on the protective layer patterned by reactive sputter etching into a stripe pattern. The etching rate of the protective layer by an etching gas agent is not greater than that of the multi-layer filter.

The effect of hf acid etching on the morphology of quartz inclusions for thermoluminescence dating

Abstract: The assumption of isotropic etching in hydrofluoric acid of quartz grains prepared for thermoluminescence dating has been tested by optical and scanning electron microscopy. We have found that the rate of etch is very irregular over the surface of many grains and that some grains are attacked much more severely than others. The uncertainty introduced into TL dating by this effect is discussed.

Effects of ion etching on the properties of GaAs.

Abstract: Effects of ion etching on the optical properties and lattice disorder of GaAs were studied by means of photoluminescence, He backscattering, and enhanced chemical etching. The photoluminescence intensity excited by a He–Cd laser (3250 A), which penetrates a distance of approximately 150 A into GaAs, is decreased to less than 20% of the initial value after ion etching by 100-eV Ar and recovered almost completely by 450° C annealing. Helium backscattering and electron diffraction pattern indicate the existence of an amorphous layer, the thickness of which is 20% larger than the value estimated by LSS theory. Photoluminescence measurement shows that beyond this amorphous region there are distributed a lot of nonradiative recombination centers as well as radiative recombination centers which diffuse into the bulk. The depth of this distribution is larger than that of the amorphous region by 1 order of magnitude.

Negative electron resists for direct fabrication of devices

Abstract: The Bell Laboratories electron‐beam exposure system (EBES) is currently being used to fabricate master masks and experimental devices using a negative resist based on poly(glycidyl methacrylate‐co‐ethyl acrylate) (COP) and a positive resist, poly(butene‐1‐sulfone) (PBS). COP was designed to have a sensitivity of 2–4×10−7 C cm−2 and good wet chemical etching resistance for a variety of thin‐film conductors and insulators. The resolution obtained with a 0.6‐μm initial COP film exposed with EBES and processed on a routine line is 2.0 μm. These characteristics are satisfactory for current requirements; soon however, machine improvements, smaller device geometries, and new processing procedures are going to place increasing demands on resist systems. In addition to resolution requirements, it is desirable to have a resist which is resistant to ion beam milling, plasma etching, or other dry etching techniques. Each of these requirements will be discussed in detail. This paper summarizes the results of the synth...

PNAF Etchant for aluminum and silicon

Abstract: A chemical etchant and a process for chemically etching thin films of aluminum, silicon, and aluminum-silicon alloy on composite structures which may be, for example, integrated circuit devices The etching process utilizes a mixture of phosphoric acid, nitric acid, acetic acid, a fluoroborate anion containing compound such as fluoroboric acid for providing fluoride ions, a surfactant, and water This PNAF etchant may be used in fabricating a wafer of integrated circuit devices without lifting photoresist maskant thereon The formulation provides relatively rapid dissolution of silicon as compared to its etch rates for silicon oxide and silicon nitride In addition, the etchant has been found suitable for relatively long term use in a production environment

Isolated bump circuitry on tape utilizing electroforming

Abstract: A process for electroforming a bump circuit and a lead circuit on a tape to be used for making contact with integrated circuit chips and the like. By means of the process, an inverse bump pattern is produced. To this end, a first metal plate is coated with a photoresist on one surface and suitable apertures are made in the photoresist in a conventional manner. Now indentations are chemically etched, partly through the uncovered metal surface to form a bump circuit. Next the photoresist is completely removed and the metal plate is again covered with a layer of photoresist. After the photoresist is developed again to form a lead circuit, the metal is chemically etched partly through the uncovered metal to form a lead circuit while at the same time further etching the bump circuit indentations. These indentations are now covered with metal by various plating steps. For example, the indentations may be covered successively with layers of gold, nickel, copper, and an additional layer of gold. The original metal is then removed by chemical etching. Either the remaining photoresist may remain or else the remaining photoresist is completely removed and a new layer of photoresist is applied over the entire structure before the original metal is removed by chemical etching. The final product is an electroformed lead and bump circuit on a tape to provide a flexible carrier.

Process for etching holes

Abstract: A method for etching at least one aperture having a defined crystallographic geometry in single crystals which includes masking the crystal to protect predetermined portions thereof from being etched, and then anisotropically etching with a mixture of sulfuric acid and phosphoric acid.

Selective chemical etching of poly(ethylene terephthalate) using primary amines

Abstract: Several primary amines have been examined as selective degradative etchants for the investigation of poly(ethylene terephthalate) (PET) morphology. The objective is to remove less ordered regions, leaving crystals intact. The amines include 40% and 20% aqueous methylamine, 70%–40% aqueous ethylamine and pure and 40% aqueous n-propylamine. Weight-loss and x-ray diffraction data show that certain concentration of aqueous amine solution simultaneously degrade and crystallize PET. This observation indicates the hazard of using some of these amine reagents to characterize PET morphology since the crystalline structure found after etching is likely to be a result of solvent-induced crystallization during degradation. Data for 40% aqueous methylamine used at room temperature shows that crystallization does not occur during etching, and in light of earlier research indicates the favorable nature of this reagent as a selective degradative medium for PET. Application of this reagent disclosed that in oriented PET fibers chemical stress cracking occurs, causing the degradative reagent to lose its selectivity.

Vacuum interlock system for molecular beam epitaxy.

Abstract: A vacuum interlock system which permits rapid loading of substrates for molecular beam epitaxy crystal growth is described. Substrates are introduced through a separate, independently pumped, loading chamber while maintaining the main growth chamber under vacuum, thereby minimizing contamination of the evaporation sources and reducing the downtime of the system between successive growth runs. The design permits outgassing of the substrates prior to their insertion in the growth chamber, and has provisions for a later addition of a separate sputtering or chemical etching capability.

Light emission element and its manufacturing method

Abstract: PURPOSE:To obtain heat resistent GaN light emission elements without connecting the stem the metal post and the ohmic electrode of the light emission element with metallic wire. CONSTITUTION:On a sapphire substrate 11, an n-type GaN layer 12 including light emitting impurities and a semi-insulating i-type GaN layer 13 are laminated. On the layer 13, concave parts reaching the layer 12 are formed and Al or Al alloy thin film 16 is evaporation-deposited. On the concave parts 19 and a part of the layer 13, Ni or Cu thin film 17 is selectively formed. If this wafer is dipped in a bath of solder including Pb, solder bumps 18 are formed on the film 17. At this time, the Al or Al alloy thin film 16 exposed on the wafer surface is eaten away by the solder and remaining parts 16' are removed by chemical etching. Finally, the wafer is cut into pieces so that each piece may have a pair of an ohmic electrode 14 and an i-type layer electrode 15, and GaN light emission elements 10 are completed. By so constructing, the element has two electrodes on its same side and is mass-productive, and it is highly reliable having no wire connection.

Method for manufacturing semiconductor structures by anisotropic and isotropic etching

Abstract: Semiconductor integrated circuit structures and manufacturing methods wherein isolation grooves are etched into a semiconductor body by first bringing an anisotropic etchant in contact with portions of the surface of the body which are exposed by windows formed in an etch-resistant mask to form grooves with side walls which intersect the surface at acute angles. Next, an isotropic etchant is brought in contact with the walls of the etched grooves to remove portions of the body which are underneath the etch-resistant mask such that the mask extends over the side walls of the resulting grooves, the bottom walls of such grooves are disposed under the windows and the side walls maintain acute angle intersection with the surface. Junction isolation regions are formed by ion implanting particles into the bottom walls of the grooves, the mask shielding the side walls from such particles. This self-aligning process accurately controls the placement of the junction isolation regions and thereby reduces the depth required for the grooves in providing dielectric isolation. Because the grooves have side walls which intersect the surface at acute angles, and because the grooves are relatively shallow because of the addition of accurately placed junction isolation regions, subsequent metallization processing is more readily controllable.

Chemical Etching of Fission Tracks in Polyfluoro Plastics

Abstract: A method has been developed for the chemical etching of fission tracks in polyfluoro plastics. The formation of fine holes several tens of nanometers in diameter in polyvinylidene fluoride films, bombarded by fission fragments in oxygen and etched in 5-normal sodium hydroxide solution at 85°C, was confirmed by electron microscopy.

Process of etching with plasma etch gas

Abstract: A method of etching aluminum in a planar plasma etcher is disclosed wherein a first plasma of carbon tetrachloride is developed followed by a second plasma of carbon tetrachloride and chlorine. By generating the specific claimed plasmas at specific partial pressures in two steps, the selectivity of the etching operation is greatly enhanced while disadvantages encountered in etching aluminum with prior art techniques are greatly reduced.

Method of fabricating semicondcuctor device

Abstract: PURPOSE: To perforate a fine hole at an insulating film without ouver-etching by determining etching end time from electrochenical reaction of specimen in etching liquid. CONSTITUTION: A dummy specimen 10 and a platinum film 11 are contained in a tank 12 filled with NH 4 F liquid. A semiconductor device 13 selectively coated with resist on an insulating film 8 is selectively etched at the film 8. Then, nonporous alumina 7 is etched in phosphoric acid and chromic acid mixture. No change occurs at a voltmeter 14 while the alumina 7 is coated on an aluminum wire 5 at the dummy specimen 10, but when the alumina 7 is etched to make the aluminum wire 5 contact with the etching liquid, there occurs an electrode reaction to generate voltage at the voltmeter 14. When this occurs, it is decided as an end of etching. After predetermined time is elapsed from this end, the device 13 is removed from the etching liquid to thereby finish the etching to thus form a fine hole 9 thereat. Thus, the device can be exactly and accurately stopped etching. COPYRIGHT: (C)1980,JPO&Japio

Plasma etching of polypropylene films and fibres

Abstract: The introduction of a ∼1000 A scale corrugated structure, aligned perpendicular to the filament axis, into oriented semi-crystalline polymers on plasma etching is shown to result from restructuring of the partially etched surface and not, as has previously been proposed, to correspond to morphological detail in the unetched material. The detail exposed on plasma etching polypropylene is shown to vary extensively with the etching conditions used. The exposed surface is compared with those resulting from peeling and chromic acid etching. Plasma etching is, however, shown to be useful in exposing coarse morphological detail such as spherulites, and in providing a convenient route for rapidly stripping the polymeric sample. The restructured partially etched surface may then be removed easily by, for example, a brief chromic acid treatment, exposing the sample interior to microscopic examination.

Semiconductor substrate and its manufacture

Abstract: PURPOSE:To obtain a substrate featuring the reduced crystalline defects by giving the mechanical grinding to the back of the Si substrate before the mechanical/ chemical mirror surface polishing to form the working distortion and then giving the chemical etching to form the heat oxide film on the back of the substrate respectively CONSTITUTION:First, the working distortion layer is formed via the grindstone to the water The depth of the distortion increases as the size of the abrasive grain increases, and the depth on the (111) surface features about 08 times as much as that on the (100) surface If the heat treatment is applied immediately, the displacement is caused at the distortion layer And the depth of the displacement increases suddenly at 15mum or more of the distortion layer, giving the evil effect to the characteristics While a large curving is produced when the grinding is given only to one surface of the wafer, resulting to the crack occurrence at the mirror surface working time as well as to the uneven thickness When the distortion layer is etched off about 05mum with the 1000 degC heat treatment applied, the curvature can be reduced down almost to zero Thus, a flat substrate can be obtained with the reduced crystalline defects

Method of making a thin film thermal print head

Abstract: A thin film thermal print head is fabricated using radio frequency (rf) or direct current (DC) sputtering within a vacuum chamber into which is introduced a partial pressure of argon and nitrogen. Without breaking the vacuum, three consecutive layers comprising respectively tantalum nitride, gold, and tantalum nitride are sputter deposited and a diffusion barrier formed on a glazed substrate material. After these steps the desired land patterns are formed by photo lithographic techniques and chemical etching and finally sealant and abrasion resistant coatings are applied.

Method of epitaxial deposition of an A{HD III {B B{HD V{B -semiconductor layer on a germanium substrate

Abstract: The method makes possible the manufacture of luminescence diodes on the basis of GaAsP or other ternary semiconductor layers deposited on a Ge substrate of n-type conductivity, followed by a zinc diffusion. In the method, a resist layer is deposited on the backside of the Ge substrate to passivate the backside to an extent such that it becomes thermally and chemically stable and does not release any Ge to the ambient atmosphere, and the front side of the Ge substrate is chemo-mechanically polished to microsmoothness. Immediately before the epitaxial deposition, the polished front side is subjected to a very weak chemical etching to a removal depth of 500 A units without eliminating the polish or microsmoothness and, thereupon, the substrate is heated, in a high purity hydrogen atmosphere, to a temperature between about 680 DEG C and 720 DEG C and a GaAs layer is deposited on the front side. The temperature is then increased and there is deposited, on the GaAs layer, a ternary AIII BV compound including a third, additive component whose proportion increases in the direction away from the GaAs layer and which consists of either an AIII element or a BV element. The increase in concentration of the third component is continued to a predetermined final value determined by either the band gap or the corresponding wavelength of the emitted light, and then a third relatively thick layer of the ternary component is deposited, and the composition thereof is maintained constant at the predetermined final value of the second layer.

Method of ion etching Cd-Hg-Te semiconductors

Abstract: A method of etching comprises etching a cadmium-mercury-telluride semiconductor layer by means of an ion beam.

Etchant for electrolytic etching of a ferrite for a magnetic head and method of producing a magnetic head

Abstract: An etchant comprising an electrolytic liquid which comprises sulfuric acid as a main component and water in such amount that the weight ratio of sulfuric acid to water is between 9:1 and 2:1. The ferrite surface having been electrolytically etched by using this etchant is smooth. Thus, this etchant makes it possible to etch a ferrite to a large depth, and thereby easily shape a ferrite by electrolytic etching, e.g. to define the track width of a magnetic head.