Showing papers on "Evaporation (deposition) published in 1981"

Thermalization of sputtered atoms

Abstract: We have calculated the energy distributions of sputtered Nb and Cu atoms ejected from amorphous targets under low‐energy Ar bombardment. A formula based on elementary kinetic gas theory is used to calculate the subsequent energy loss of the ejected atoms due to collisions in the sputtering gas. The energy distributions of the sputtered atoms arriving at the substrate is compared with the distributions obtained using thermal evaporation techniques. This comparison indicates that the preparation of epitaxial metallic films, such as Layered Ultrathin Coherent Structures using sputtering techniques may have fundamental advantages over thermal evaporation.

Heteroepitaxy of vacuum‐evaporated Ge films on single‐crystal Si

Abstract: Heteroepitaxial Ge films on 〈100〉 and 〈111〉 Si substrates have been prepared by vacuum evaporation. The films were deposited in moderate vacuum (10−6 Torr) at a rate of ∼10 A/sec, with the substrates heated to 350–750 °C. The crystalline perfection of the films depends on both substrate orientation and temperature. The best films were obtained on 〈100〉 Si substrates heated to 550 °C. Heteroepitaxial GaAs layers of excellent crystal quality have been grown by chemical vapor deposition on such Ge films. GaAs shallow‐homojunction solar cells with conversion efficiencies up to 12% at AM1 have been successfully fabricated.

Method of and apparatus for manufacturing ultrafine particle film

Abstract: A method and apparatus for manufacturing an ultrafine particle film which has great practical utility when deposited on an appropriate substrate. The particle film is produced from various ultrafine particles of, for example, metals, oxides, nitrides and carbides, and is produced uniformly, effectively and efficiently with a high degree of reproducibility. According to a first method, an atmosphere at a gas of a reduced pressure is formed in a vessel, and a forced flow of the gas is formed unidirectionally from an evaporation source to the substrate, so that the evaporated matters from the evaporation source are forced to move together with the forced flow of the gas, so that ultrafine particles which are formed through interaction between the evaporated matters and the gas deposited on the substrate thereby forming the ultrafine particle film. According to a second method, the evaporation source is disposed within a vessel of having a reduced gas pressure as well as a cylinder surrounded by a high-frequency coil. As the coil is energized, the gas in the cylinder is excited. The evaporated matters are forced to flow through the excited gas atmosphere so that ultrafine particles formed by an interaction between the evaporated matters and the excited gas are deposited on the substrate thereby forming the ultrafine particle layer. A third method is a combination of the first and second methods.

Manufacture of semiconductor device

Abstract: PURPOSE:To selectively leave a metal film on only a diffused film by applying a mask having a double layer constitution of different materials in order to perform a selective diffusion, then covering the whole surface with a metal film and chemically etching only the upper layer film of the mask CONSTITUTION:On an N type InP substrate 1, an Si3N4 film 3 and an SiO2 film 3 are successively piled by the plasma arc coating method The SiO2 is etched by using a mixture of HF and NH4F and the Si3N4 is plasma-etched to form an opening 4 Cd is diffused to form a P type InP layer 5 Because the plasma-formed films 2 and 3, which are piled, have no pinhole, the Cd can be diffused only in the opening 4 After an Au-Zn alloy 6 is deposited by evaporation, the film 3 is etched by using the mixture of HF and NH4F so that the alloy film 6 is left only on the diffused layer 5 Moreover, a heat treatment is applied in a nonoxidative atmosphere to accerelate alloying reaction in order to form an ohmic contact having low resistance By said constitution, the process is largely simplified and a device having high reliability can be obtained at high yield

A study of Ge/GaAs interfaces grown by molecular beam epitaxy

Abstract: Ohmic contacts to n‐GaAs using a Ge/GaAs heterojunction have been developed. Ge layers with free‐electron concentrations above 1×1020 cm−3 have been grown on GaAs by molecular beam epitaxy (MBE). Gold evaporated on such structures forms tunnel contacts through the Ge to the GaAs. The lower barrier height of metals on Ge compared to GaAs and the small barrier at the Ge/GaAs heterojunction facilitates the formation of contacts with specific contact resistances below 10−7 Ω cm2.

Method and apparatus for forming thin film oxide layers using reactive evaporation techniques

Abstract: Apparatus and method for forming high quality thin film oxide layers on a substrate by a reactive evaporation process utilizing an oxygen plasma activation source in the form of a cylindrical boule of insulating material surrounded by a radio frequency coil for generating a radio frequency electromagnetic field in the boule of sufficient magnitude to create a self-igniting oxygen plasma within the boule without evaporating material from the walls thereof.

Formation of protective oxide film on chromium-depleted stainless steel

Abstract: Coupon specimens of a niobium-stabilized 20Cr–25Ni stainless steel were annealed in a dynamic vacuum at 1273K to produce preferential evaporation of chromium. Two sets of specimens, one coarse grain with a surface-chromium concentration of ∼ 14% and the other having a bimodal grain size distribution and surface concentration of ∼ 16%, were subsequently oxidized at 1123 K in a CO2-CO gas mixture. The coarse-grain samples produced uniformly duplex non-protective oxides while those of mixed grain size exhibited a non-homogeneous reaction. Regions of coarse grains on the latter again developed a duplex pitting-type attack but fine grains were protected by a thin chromia-rich layer. The reasons for this difference are discussed. It is argued that the protective film was not produced as a result of a significantly greater supply of chromium ions but was due to easier nucleation on the fine-grain substrate.

Chemical preparation of ultra-fine aluminium oxide by electric arc plasma

Abstract: Ultra-fine aluminium nitride has been obtained by interaction of aluminium and nitrogen in electric-arc plasmA. It has been proved that the rate determining step of the process is the evaporation of the aluminium powder. The most appropriate thermodynamic and kinetic conditions for obtaining pure, finely dispersed product has been determined. The prepared aluminium nitride has dimensions of about 50 nm and specific surface of up to 100 m2g−1. The items made by the baking of this product at 1600 K have zero porosity. The product has a greater chemical reactivity than the one producted by conventional methods.

Thermal stability of Pb‐alloy Josephson junction electrode materials. I. Effects of film thickness and grain size of Pb‐In‐Au base electrodes

Abstract: Pb‐alloy Josephson devices are attractive for potential use as active elements in high‐speed computers. Failures occur in some Pb‐alloy junctions during repeated thermal cycling between 300 and 4.2 K. The failures are believed to be primarily caused by rupture of the ultrathin tunnel barrier oxide between base and counter electrodes when strain in the electrode films induced by thermal‐expansion‐coefficient mismatch between film and substrate is relaxed. The strain relaxation can cause microstructure changes such as grain rotation and hillock formation that can lead to device failure. The effects of film thickness h and grain size g on the strain behavior and microstructure of Pb‐12 wt. % In‐4wt. % Au films similar to those used for a Josephson junction base electrode were studied by x‐ray diffraction, and by transmission and scanning electron microscopy. Films with various combinations of h and g were prepared by evaporation onto oxidized Si substrates at room or liquid‐nitrogen temperature. In the prese...

Process of depositing a hard coating of a gold compound on a substrate for coating jewelry and the like

Abstract: The invention relates to a process of deposition of a coating of a gold compound on a solid substrate. In a vacuum chamber (1), the substrate is fixed on a first substrate electrode (2). A composite target (5) essentially consists of gold and at least one of the metal compounds, such as nitride, carbide and boride of the metals of group IV b of the periodic classification of elements and tantalum. A high-purity argon atmosphere at pressure ranging between 4×10 -4 and 3×10 -2 Torr is then established in the chamber. The deposition of the coating is then carried out by ionic deposition or evaporation in vapor phase at a given rate. The invention may find application to coat articles of jewelry or of watch cases.

Method for making low barrier Schottky devices of the electron beam evaporation of reactive metals

Abstract: A method for making low barrier Schottky devices by the electron beam evaporation of a reactive metal such as tantalum, titanium, hafnium, tungsten, molybdenum, and niobium which is selectively deposited at a semiconductor surface such as n-type silicon using a photoresist mask. The method includes a series of steps during the deposition of the barrier metal for degassing the semiconductor substrate, photoresist mask, reactive metal charge and deposition chamber. More particularly, the method includes steps for preliminarily degassing the substrate, mask and surrounding chamber by infra red heating under vacuum followed by steps for preliminarily degassing the charge and surrounding chamber, while the substrate and mask are shielded by electron beam heating the charge while under vacuum. Thereafter, and prior to deposition, the substrate and mask are finally degassed by irradiation with X-rays produced by electron beam heating the charge to a temperature below evaporation for a predetermined time under vacuum. Upon further heating of the charge, the barrier metal is evaporated and deposited at the semiconductor substrate surface.

Evaporation of High Quality In2 O 3 Films from In2 O 3 / In Source—Evaporation Chemistry and Thermodynamics

Abstract: Highly transparent conductive films can be easily deposited by simple thermal evaporation from an source in a low pressure environment. The important role of In in the evaporation process has been examined. From an analysis of the evaporation chemistry and the thermodynamics of the system, it has been concluded that the incorporation of In in the evaporation source not only significantly enhances the evaporation rate, but also gives rise to a higher concentration of conduction electrons. Many possible reactions in the source region and on the substrate have been considered, and only a few have been found to be of significance, which greatly simplifies the theory. Good qualitative agreement has been found between the theory and several key experimental observations. The theory has also been verified by quantitative comparisons with the experimentally measured film growth rate and the conduction electron concentration.

Platinum losses during high temperature oxidation

Abstract: Platinum reacts with oxygen at high temperatures to form volatile oxides the evaporation of which considerably increases the platinum losses in oxygen-containing atmospheres compared with high vacuum conditions. The metal losses of polycrystalline platinum discs were determined in the pressure range 10−1–10−5 Pa and at high temperatures (1300–1600°C) using a magnetic suspension balance. Marked temperature and pressure dependences were observed. The oxidation mechanism is discussed and the oxidation rates reported in the literature are reviewed. The normal spectral emissivity (λ = 0.645 μm) was also determined.

Improved adhesion of Ni films on X-ray damaged polytetrafluoroethylene

Abstract: The considered investigation shows that the adhesion of evaporated Ni on polytetrafluoroethylene (PTFE) is enhanced by irradiating the PTFE surface prior to evaporation. Evidence obtained with the aid of X-ray photoelectron spectroscopy is presented concerning the association of the enhanced adhesion with an interfacial chemical reaction. Evaporated Ni clearly adheres better to the X-ray damaged PTFE surface than to the undamaged surface. There is evidence that the improved adhesion is not related to the Ni-C bond, but rather to the NiF2. A possible mechanism which may be consistent with the data is the formation of a F-Ni-C complex, where C is a member of the polymer chain.

Highly stable, photosensitive evaporated amorphous silicon films

Abstract: Vacuum‐evaporated pure amorphous silicon films have been successfully hydrogenated in a Theta‐pinch plasma source to give high photoconductivity. Unlike films produced by glow discharge of silane gas, these films are highly stable against heat, intense light illumination, moisture, and other atmospheric contamination. Structural change in the bulk Si matrix being absent, a comparison of properties of films before and after plasma treatment can provide valuable information on pure hydrogenation effects.

Specimen coating for high resolution scanning electron microscopy

Abstract: Thin conducting films, produced by evaporation or soft vacuum sputtering generally show cracks and grain formation, when examined under high resolution scanning electron microscopy (SEM). These artefacts can obscure surface features of coated specimens or cause confusion in the interpretation of micrographs. No such structures have been observed in films produced by ion beam deposition. Ion beam deposition equipment is described in which a cold cathode saddle field ion source, operating at low pressure (15mPa), produces a 2 mm diameter beam of energetic ions (5 keV) and neutrals. With the beam directed onto a target at 30° to glancing incidence, the sputtered material coats the specimens, which are held in a planetary system for good coverage. Conditions favouring fine grain growth are a high nucleation density and low energy transfer to the substrate by thermal conduction or radiation or by particle or photon radiation. These conditions are satisfied by ion beam deposition but evidently not by evaporation or soft vacuum sputtering. With the specimen stationary, sharp shadowing is obtained because the target acts almost as a point source, because of the small diameter of the beam and because there is little scatter at the operating pressure.

Electrical properties of Sn-doped In2O3 prepared by reactive evaporation

Abstract: Sn-doped In2O3 films (ITO) have been prepared by coevaporation of In and Sn on to heated glass substrates at 10-3 Torr O2 and the electrical properties have been investigated. Tin-doping suppresses the oxidation of In under evaporation, and higher substrate temperatures, above 400 degrees C, are necessary to obtain a visible transparent film (80% at 550 nm) than in the case of undoped In2O3 films. By tin-doping, an ITO film with the lowest resistivity rho =6*10-4 Omega cm has been obtained at tin-doping of Sn/In approximately=0.05 atomic ratio, where the carrier concentration is 7*1020 cm-3 and the mobility is 15 cm2 V-1 s-1. All the films show n-type conductivity with complete degeneracy.