Showing papers on "Sputtering published in 1970"

Application of RF discharges to sputtering

Abstract: The operation of rf discharges is described and the internal distribution of voltages is considered. The significance of this with respect to sputtering, particularly of insulators, is then discussed. An equivalent circuit for the discharge is presented and the influence of such parameters as pressure and magnetic field on the components of this circuit is described. Finally, energy distributions for positive ions, electrons, and negative ions incident at the substrate during deposition are given.

Aluminum films deposited by rf sputtering

Abstract: The feasibility of depositing aluminum thin films by means of rf sputtering has been investigated. Film characteristics compatible with the requirements of conductive stripes in integrated circuits have been obtained. The rate of film deposition has been related to rf power dissipation, argon pressure, geometry, and magnetic field. Film characteristics such as electrical resistivity, stress, grain size, and orientation have been studied and compared to the characteristics of films deposited by means of evaporation. The effects of annealing on some of these characteristics have been determined.

Thin foils of non-metals made for electron microscopy by sputter-etching

Abstract: Established techniques of making thin foils of non-metallic materials are reviewed briefly and their inadequacies outlined. The preparation of foils by sputter-etching is described and the effects on the sample of ion current density, and angle of ion incidence are discussed. Results on specimens of ceramics, glasses and minerals are presented. From these it is concluded that sputter-etching is a valuable and nearuniversal thinning technique for non-metals.

Esr and optical absorption studies of ion‐implanted silicon

Abstract: The g value, line shape, and linewidth of an ESR signal in Si layers which have been damaged by ion implantation of Si, P, or As at room temperature are found to be identical to those of the electron states observed in amorphous Si films prepared by rf sputtering. Interference phenomena observed in the optical absorption spectra allow a determination of the depth to which the Si has been damaged by the energetic heavy ions. These two techniques together provide a new tool for investigating lattice disorder in ion‐implanted Si layers.

A System for Determining the Mass and Energy of Particles Incident on a Substrate in a Planar Diode Sputtering System

Abstract: A bakable ultrahigh vacuum system has been constructed to sample the particle flux incident on the substrate of a planar diode sputtering system. A beam of particles from the discharge is extracted into a long mean free path environment where it passes through a 90° deflection electrostatic analyzer into a quadrupole residual gas analyzer. The mass spectra of positive ions incident on a substrate during dc sputtering of copper and aluminum bronze are shown and the influence of hydrogen contamination is illustrated. The energy distribution of the Ar+ ions is presented for several values of the substrate bias.

Application of ion sputtering in preparing glasses and their surface layers for electron microscope investigations

Abstract: The application of a sputtering apparatus suitable for etching as well as for thinning with an ion beam is described. Glasses and glass-ceramics can be etched residue-free by ion sputtering. Inhomogeneities in their structure such as segregations and devitrifications are thereby exposed. The preparation of thin specimens for subsequent investigation with transmission electron microscopy is also possible. It is shown, in particular, that with this method thin surface coatings can be cut perpendicularly to the surface for examination by transmission microscopy. During ion bombardment and investigation in the electron microscope, the temperature increase is so insignificant that no defects in the sections could be observed. The limits of application of this method are explained.

High Resistivity Transparent ZnO Thin Films

Abstract: Zinc oxide (ZnO) is a material which, under ordinary circumstances, has a small oxygen deficiency. This lack of chemical makes ZnO an n-type semiconductor with a typical resistivity of 1–100 Ωcm. In this work crystalline ZnO films with resistivities from 108-1013 Ωcm have been obtained by reactively dc sputtering metallic zinc or rf sputtering ZnO in an argon-oxygen mixture or in pure oxygen. Films were deposited on metallic substrates such as gold or zinc or insulating substrates such as quartz or sapphire maintained at temperatures from −100 °–+200 °C. The high resistivity is thought to result from a decrease in the normal oxygen deficiency of ZnO. Three mechanisms are likely to be involved hi the enhanced oxygen incorporation: (1) oxygen atoms in the discharge, (2) dissociation of oxygen ions on impact with the surface, and (3) implantation of oxygen ions in the film. Although quantitative data are not available at this time it is clear that the effect of oxygen atoms is large since they are formed bot...

Preparation and Epitaxy of Sputtered Films of Ferroelectric Bi4Ti3O12

Abstract: Single crystals of ferroelectric Bi4Ti3O12 are known to possess novel optical properties with potential use in optical memory or display applications. There is interest in duplicating these properties in thin films. Suitability of reactive and rf sputtering for preparation of stoichiometric films has been investigated. Films from stoichiometric targets were Bi deficient. Using Bi-rich targets stoichiometric films were obtained by depositing at substrate temperatures (typically in the range of 500 °–700 °C) high enough to prevent inclusion of the more volatile bismuth oxide in excess of the Bi4Ti3O12 composition. Good quality epitaxial growth has been achieved on MgO and epitaxial Pt substrates.

Preparation of Thin BaTiO3 Films by dc Diode Sputtering

Abstract: Direct current diode sputtering of reduced BaTiO3 ceramic has been applied to the preparation of thin BaTiO3 films. Sputtering was carried out over a range of apparent sputtering rates of ∼500–1200 mg/Ah in atmospheres of argon and air. As the substrate, Pt sheet and fused quartz were principally used. Grain size of the deposited film was ∼1000 A for the Pt substrate at 400°C. The lattice constants were in good agreement with those of ordinary BaTiO3 when the Pt substrate was kept at a temperature above 1000°C, although they were slightly larger for substrates below 900°C. Measurements of optical density and observations of electron micrographs indicated that the sputter‐deposited films have more favorable properties of transparency, uniformity, and crystallization than vacuum‐evaporated films. The film prepared on a Pt substrate at 1000°C in an air atmosphere had a dielectric constant of 1700 and dissipation factor of 1.8% without post‐deposition treatment. However, the remanent polarization was very sma...

Plasma Anodization of Metals and Semiconductors

Abstract: This paper presents a review and analysis of the literature on plasma anodization in the negative glow of the dc discharge. New data by the author on anodic film contamination by reactive cathode sputtering are presented. It is shown that certain anomalous data in the literature may be explained as being caused by cathode sputtering and sputter etching of the anodic film. Some applications of anodization are discussed.

The ejection of atomic particles from ion bombarded solids

Abstract: Considerable interest has developed in the last decade in the study of atomic collisions in solids, particularly single crystal solids. This has been heightened by the observation of channelling and the interest in industrial aspects of ion implantation. In the following article, we present an up-to-date account of the work being done on the particles ejected from a single crystal, following ion bombardment. These particles include sputtered atoms and ions, scattered atoms and ions and secondary electrons. An attempt has been made to indicate the similarities and differences, particularly between the energy and angular distributions of these ejected particles. The major link involving the dependence of these distributions of all particles on crystallography is stressed.

Investigation of the Sputtering of Aluminum Using Atomic‐Absorption Spectroscopy

Abstract: The techniques of atomic‐absorption and emission spectroscopy have been used to detect atoms ejected from an aluminum cathode which is sputtered in a glow discharge in argon. The rate of deposition of the sputtered material is measured using a piezoelectric microbalance which is capable of measuring deposition rates as small as 9.2×10−8 G min−1. The use of atomic‐absorption spectroscopy is shown to be a sensitive and reliable method for the study of the sputtering process. Experimental results indicate that some of the sputtered material in the glow discharge exists in the form of ``molecules.'' However, the absolute numbers of sputtered atoms has not been determined due to uncertainties in the tabulated values of atomic‐transition probabilities.

Post heating of sputtered metal oxide films

Abstract: This invention relates to a novel method of producing electroconductive metal oxide films by cathodic sputtering. It especially pertains to a method of increasing the electroconductivity of sputtered metal oxide films by mildly reducing said films. The reduction step follows sputtering and generally involves heating the metal oxide film in a non-oxidizing or reducing atmosphere for a sufficient period of time to reduce the oxygen content of said film by a minor amount but without substantially reducing the oxide film to metallic form.

RF Sputtered Aluminum Oxide Films on Silicon

Abstract: The physical and electrical properties of aluminum oxide films deposited on silicon by rf sputtering from an alumina target in an argon atmosphere were investigated as a function of sputtering power density in the range from 0.5 to 3 W/cm2. The deposition rates ranged from 20 to 80 Aa/min. The density, index of refraction, and dielectric constant of the films increased while the etch rate decreased with increasing power density. The surface charge at the aluminum oxide‐silicon interface was typically larger than 1012 e/cm2. This charge increased with increasing sputtering power density and could be reduced to by annealing. The films exhibited trapping instabilities at room temperature but no polarization was observed under bias‐temperature stress. The characteristics of composite layers of thermally grown silicon dioxide and sputtered aluminum oxide layers on silicon were also investigated and found to exhibit low surface charge densities, no hysteresis, and a "contact potential" as well as charge stored at the interface between the two insulators.

Surface Composition Analysis by Binary Scattering of Noble Gas Ions

Abstract: Measurement of the energy distribution of backscattered noble gas ions yields information regarding the elemental composition of the first atomic surface layer. An instrument based on this principle and designed for routine surface analysis will be described. This flange-mounted device is comprised of an electron bombardment ion source, an electrostatic energy analyzer, a channel electron multiplier, and a multiple sample holder. Primary ion beam energies range from 100–2000 eV at current densities up to 50 μA/cm2. A depth profile of the surface constituents is obtained by utilizing the probe beam to selectively sputter clean the surface. Observations show the ability to resolve elemental isotopes, such as Cu63 from Cu65. Surface analyses are shown for 304 stainless steel, Cu, Ni, and ZnTe.

Re-emission of sputtered SiO 2 , during growth and its relation to film quality

Abstract: An improved technique for measuring re-emission coefficients is described and data on the effect of temperature are presented. These are discussed in the light of a physical model of film growth during sputtering where in constant re-emission of material throughout deposition occurs. Evidence is then presented that such re-emission is essential if films of high quality are to be obtained. To help assess "quality" in a quantitative fashion use has been made of the PBUT (pin-hole breakup thickness) phenomenon, whichis described in some detail. The influence on PBUT of several system parameters such as sputtering pressure and impurity content is discussed and related to the re-emission coefficient.

Cathode-target assembly for rf sputtering apparatus

Abstract: A TARGET OF A DIELECTRIC MATERIAL IS MOUNTED IN SPACED RELATION TO A CATHODE, WHICH IS ISOLATED FROM THE SPUTTERING CHAMBER AND THE ANODE IN THE SPUTTERING CHAMBER BY THE TARGET AND ITS MOUNTING STRUCTURE. RF ENERGY IS TRANSFERRED FROM THE CATHODE TO THE TARGET, WHICH HAS AT LEAST A PORTION PARALLEL TO THE ANODE, THROUGH THE SPACE BY A DIELECTRIC COOLANT, A LIQUID METAL, OR A METALLIC PASTE. WHEN EITHER THE METALLIC PASTE OR THE LIQUID METAL IS EMPLOYED, THE CATHODE IS COOLED BY CIRCULTING A COOLANT SUCH AS WATER THERETHROUGH.

Structure and Electrical Properties of Sputtered Films of Hafnium and Hafnium Compounds

Abstract: The electrical properties of 2000–3000‐A‐thick films of hafnium, hafnium nitrides, and hafnium dioxide have been studied. The properties of these films can be related to film structure and composition. Conditions were established under which hafnium films can be prepared by dc sputtering in pure argon with density and resistivity approaching that of pure bulk hafnium. Additions of low concentrations of nitrogen to the argon sputtering atmosphere result in the deposition of films consisting of a solid solution of nitrogen in hafnium. At intermediate nitrogen concentrations films of HfN, a compound with metallic properties, are obtained. Higher nitrogen concentrations in the sputtering atmosphere result in films of nonstoichiometric HfN containing excess nitrogen and finally of films of a higher nitride of hafnium having semiconducting properties. Sputtering in argon‐oxygen mixtures above a critical oxygen concentration results in the deposition of HfO2 films with insulating properties.

End point detection method and apparatus for sputter etching

Abstract: The end point in sputter-etching metal layers, for example, from substrates is determined by employing a silicon, quartz, or the like, monitor control wafer in the sputter-etching environment which wafer has been previously coated with said metal, for example, in the same run as that used to fabricate the workpiece substrate. Thus, the monitor control wafer exhibits the same thickness of metal, or the like, as the thickness of the metal layer to be selectively sputter-etched from the substrate. The temperature exhibited by the monitor control wafer during the sputter-etching material removal process in monitored by an infrared radiation thermometer, by way of a quartz window. When the layer of metal, or the like, has been removed from the monitor control wafer, the temperature, as sensed by the infrared radiation thermometer during sputter-etching, declines thereby indicating the end point in the removal process of the metal layer, or the like.

ARGON CONCENTRATION IN TUNGSTEN FILMS DEPOSITED BY dc SPUTTERING.

Abstract: The relative argon concentrations of dc-sputtered tungsten films were determined as a function of argon pressure, target-to-substrate voltage, substrate bias, and target-to-substrate distance, for both the diode and triode configurations. The results for films sputtered in the diode mode support Winters and Kay’s conclusions that the adsorption mechanism is due to entrapment of energetic neutral argon atoms. This model, however, does not. apply for all the argon content in films sputtered in the triode mode. An additional mechanism resulting in a greater entrapment of argon is proposed, namely, the entrapment of low energy argon ions originating from the supporting glow discharge. Measurements of the argon content of the tungsten films were determined using the rf spark-source mass spectrograph.

LOW‐TEMPERATURE EPITAXY OF β‐SiC BY REACTIVE DEPOSITION

Abstract: Epitaxial beta SiC film formation on SiC by reactive evaporation or sputtering at low temperature

Argon content of SiO 2 , films deposited by RF sputtering in argon

Abstract: When SiO2 is deposited by sputtering in an argon rf glow discharge, the films so produced contain considerable amounts of trapped argon, as determined by x-ray fluorescence analysis. This argon content was measured as a function of various sputtering parameters: argon pressure, rf power, electrode spacing, substrate temperature, and magnetic field, the latter two being most influential. A simple theoretical model for the capture and release of argon is presented which explains an observed linear decrease of the argon concentration in SiO2 with increasing temperature. Incorporation of argon into the sputtered SiO2 film does not seem to impair the film's ability to act as a good passivating and insulating layer.

Metal edge coverage and control of charge accumulation in RF sputtered insulators

Abstract: The successful application of rf sputtered SiO2 in the passivation of silicon semiconductor devices depends in part on the proper control of ionic charge migration in the insulator during sputtering, and on the adequate coverage of metal line edges by the insulator. It is shown that an appropriate combination of target purity, substrate temperature control and phosphosilicate blocking layer thickness can be used to achieve ionic charge densities at the silicon-SiO2 interface of less than 1 × 1012, charges per square centimeter. The effects of argon ion bombardment are shown to be acceptably low for typical operating conditions. In a conventional system, the adequate coverage of metal line edges is shown to be influenced primarily by argon pressure and magnetic field. In a special system where the substrate potential can be varied, it has been shown that adequate edge coverage can be obtained at sufficiently negative potentials. These data are consistent with a mechanism requiring some resputtering to obtain the desired film coverage.

Phase Forming Processes in Tantalum Films through Sputtering

Abstract: For the formation of tantalum films by sputtering at a lower gas pressure, α-tantalum is deposited in a contaminative atmosphere, while β-tantalum is deposited in a clean atmosphere. The latter phenomenon can be thought of as the quenching of sputtered tantalum atoms by direct collision with the substrate when no layers of adsorbed impurity gas exist. At a higher pressure, the phase transition to β-Ta can be caused by the incorporation of discharge gas and thermal effect. For tantalum nitride, there is a certain region where the characteristics of the films are insensitive to the nitrogen partial pressure. The extent of nitrization is considered to be determined by the density ratio between the number of nitrogen molecules on the substrate and that of the incoming tantalum atoms. Within this region, the ratio is constant, so a stable film with a low energy state and stoichiometric structure whose main content is Ta2N is formed.

Thin film transistor and method of fabrication thereof

Abstract: A thin film transistor utilizing an insulated gate structure is described wherein the semiconducting layer is formed of defect-nickel oxide having the general formula Ni(1-x)O, wherein x is within the range of 10 7 to 10 2. In a preferred embodiment, the insulating layer overlying the defect-nickel oxide semiconducting layer is formed of stoichiometric nickel oxide thereby reducing the number of steps required in fabrication. The thin film transistor is fabricated within a single system by utilizing reactive sputtering for the formation of the semiconducting and insulating layers. The sputtering takes place in a pure oxygen atmosphere in the absence of inert gases with the result that the characteristics of the deposited nickel oxide films can be varied by controlling the deposition rate during sputtering.