Showing papers on "Pulsed laser deposition published in 1982"

Ar+ laser induced chemical vapor deposition of Si from SiH4

Abstract: For the first time polycrystalline silicon has been grown by using the visible light of an Ar+ laser for pyrolytical decomposition of SiH4. With a laser irradiance of 3600 W/mm2 a deposition rate of 30 μm/s was obtained. The temperature dependence of the deposition rate was investigated. The kinetically controlled regime is characterized by an activation energy of 44±4 kcal/mole.

Preparation of PbTiO 3 Ferroelectric Thin Film by Chemical Vapor Deposition

Abstract: Chemical vapor deposition of PbTiO3 thin film on the substrate of Pt plate has been successfully made. (100)- and (001)-oriented PbTiO3 film has been obtained under a certain deposition condition. Surface of the film is smoother and the deposition rate of 8.3 µm/h is much higher, as compared with those of conventional sputtering method.

Laser Photolytic Deposition of Thin Films

Abstract: An excimer laser is used to photochemically deposit thin films of silicon dioxide, silicon nitride, aluminum oxide, and zinc oxide at low temperatures (100–350deg;C). Deposition rates in excess of 3000 A/min and conformal coverage over vertical walled steps were demonstrated. The films exhibit low defect density and high breakdown voltage and have been characterized using IR spectrophotometry, AES, and C-V analysis. Device compatibility has been studied by using photodeposited films as interlayer dielectrics, diffusion masks, and passivation layers in production CMOS devices. Additionally, we have deposited metallic films of Al, Mo, W, and Cr over large (>5 cm 2 ) areas using UV photodissociation of trimethylaluminum and the refractory metal hexacarbonyls. Both shiny metallic films as well as black particulate films were obtained depending on the deposition geometry. The black films are shown to grow in columnar grains. The depositions were made at room temperature over pyrex and quartz plates as well as silicon wafers. We have examined the resistivity, adhesion, stress and step coverage of these films. The films exhibited resistivities at most ∼20 times that of the bulk materials and tensile stress no higher than 7 × 10 9 dynes/cm 2

Method and apparatus for laser-stimulated vacuum deposition and annealing technique

Abstract: A method and apparatus for vacuum deposition and annealing wherein specimens 18 and 20 of coating material within a vacuum chamber 2 are evaporated by a laser beam 24, while the substrate 16 is scanned by another laser beam 36 to cause localized heating of the substrate and deposited coating materials to an energy slightly below the bonding energy of the coating materials to promote annealing of the coating materials and to drive off contaminant materials.

Laser Induced Chemical Vapor Deposition of Hydrogenated Amorphous Silicon

Abstract: Some results on hydrogenated amorphous silicon growth by CO 2 laser photodissociation of silane are reported. A 100 W CW CO 2 laser was used as the excitation source. A horizontal configuration was adopted, where the laser beam is sent parallel to the substrate surface inside a flux reactor, and its energy is used to excite and dissociate the silane molecules flowing near the solid surface. The laser has no direct heating effect on the substrate, which is independently heated by an oven. The photoproduced radicals by interacting with the surface grow a film at a rate strongly depending on silane pressure, substrate temperature and laser intensity. This experimental configuration allows depositions on large areas, owing to the large number of reactant molecules involved in the photochemical process. Moreover, material can be produced with a continuously variable hydrogen content, since the substrate temperature required for obtaining depositions can be as low as room temperature and adjusted independently of the other process parameters. The film properties are similar to those of the glow discharge deposited material. The film amorphousness and the hydrogen presence either in monohydride and dihydride groups are evidenced by x-ray patterns and ir spectra. Results on the electrical and optical properties are also reported.

Direct Writing Using Laser Chemical Vapor Deposition

Abstract: Metal, dielectric and semiconductor films have been deposited by laser chemical vapor deposition (LCVD) using both pulsed and cw laser sources on a variety of substrates. For LCVD on substrates such as quartz, the deposition was monitored optically in both transmission and reflection using a collinear visible laser and the depositing CO2 laser. Deposition initiation and rate were correlated with irradiation conditions, the laser generated surface temperature, and the changing optical properties of the filmμsubstrate during deposition. Single crystallites of W greater than 100 pm tall were deposited using a Kr laser on Si substrates.

Forming method for pattern

Abstract: PURPOSE:To form a substance changing section corresponding to a desired pattern on a substrate by making energy beam itself possess necessary pattern information or pattern distribution. CONSTITUTION:An insulating film alpha2 made of SiO2 is shaped onto the Si substrate alpha1, and an amorphous Si film alpha3 is further deposited. Partial pulse laser annealing is conducted to the film 3. That is, the film alpha3 is changed into poly Si as a substance change through a melting reaction by giving energy beam itself the pattern information and irradiating the film alpha3, and a poly Si pattern is formed. An island alpha4 mde of poly Si is shaped according to the difference of the speed of etching through dry etching. Consequently, a process can be turned in a resistless dry process.

Laser-initiated Ga-deposition on quartz substrates

Abstract: The deposition of Ga on quartz substrates by photodissociation of trimethylgallium has been investigated Light from a frequency doubled Ar-ion laser beam (2572 nm) was focused onto quartz substrates The Ar-ion laser was operated under CW or mode-locking conditions The deposition rate has been investigated as a function of averaged UV power densities in the range of 18-1750 W/cm2 and is shown to depend critically on the laser operating mode For CW operation, the maximum growth rate within the focal zone is limited to 17 A/s whereas under mode-locking conditions, no saturation is observed and the growth rate increases linearly with the laser power up to 70 A/s at 175 kW/cm2

A simple optical thin film deposition monitor using LED’s and fiber optics

Abstract: A thin film deposition monitor is described which can be used to monitor the rf‐sputter deposition of dielectric and thin metallic films on transparent substrates in a multi‐target system. The monitor uses a green and a red LED as a light‐source, a bundle of optical fibers to transmit the light into and out of the sputtering chamber and Si‐photocells as detectors. The LED’s are pulsed at two different frequencies and phase‐sensitive detection allows the simultaneous monitoring of the substrate reflectivity at two different wavelengths. Applications of the deposition monitor include the exact control of individual layers in multilayer dielectric filter structures and monitoring the deposition of very thin, semitransparent metallic films.

Laser-Induced Lateral, Vertically-Seeded Epitaxial Regrowth of Deposited Si Films over Various SiO2Patterns

Abstract: The difference in bridging epitaxy of Si over SiO2 by pulse ruby laser and cw-scanned Ar laser irradiation has been investigated using TEM and SEM. Pulse laser induced lateral regrowth over SiO2 is governed by uniform heat flow from the oxide window edges to the SiO2 center during a melting time of ~100 ns. The regrowth length is limited to ~2.5 µm and straight crystal boundary is formed in regrown layers when SiO2 stripe patterns are used. On the other hand, when cw-scanning laser is utilized, single crystal film is formed without crystal boundary over the whole 5 µm width oxide stripe pattern.

Dual beam pulse laser experimental set-up for measuring attenuation coefficients of liquids: application to distilled water in the 414-662 nm spectral range

Abstract: A double beam laser method for measuring attenuation coefficients of sea-water throughout the 414-662 nm wavelength region is presented. The radiant source is a pulsed wavelength-tunable dye laser, with a spectral width of 0.01 nm. A test with de-ionised filtered distilled water is described.

Pulse‐laser‐induced supersaturation of indium and antimony in germanium

Abstract: A pulsed ruby laser has been used to produce enhanced solubilities of indium and antimony in germanium. Lower limits for the solubilities have been obtained using Rutherford backscattering spectrometry and electrical measurements. The values obtained are ≳5.3×1020 cm−3 for indium and ≳6.2×1020 cm−3 for antimony.

Growth by Vacuum Evaporation, Sputtering, Molecular Beam Epitaxy and Chemical Vapor Deposition

Abstract: Thickness homogeneity and chemical purity of thin film deposition by vacuum evaporation with point and planar sources are discussed High pressure, low pressure, and assisted sputtering methods (deposition of atoms having 10 to 103 times higher energy than evaporated atoms) are presented and their relative advantages discussed The discussion of molecular beam epitaxy is focused mainly on surface kinetic studies performed to gain more insight of the GaAs deposition process Finally, the chemical vapor deposition of {100| GaAs in a Ga - AsC13 - H2 system and of {lll|Si from silane diluted in hydrogen at reduced pressures are analysed on the basis of surface reactions

Measuring method for heat transmission factor of thin film

Abstract: PURPOSE:To reliably measure a heat transmission factor of a thin film element on a substrate, by a method wherein a known material, being low in a melting point and absorbing a laser light, is formed in a filmy manner on a surface of an object to be measured, and the work is irradiated with a pulse laser light. CONSTITUTION:In an optimum design of an integrated circuit element and other film electronic element and a design of a radiating heat transmission object, a film 3 of a known material, e.g., Sn, Pb, being low in a melting point and absorbing a pulse laser light, is formed in about 500Angstrom thickness on a thin film 2 to be measured on a substrate 1 by a vacuum evaporation method. The heat transmission factor of the thin film 2 is found by computing it by a given heat diffusion equation from an energy value obtained until the film 3 is molten for the deformation through the irradiation with a pulse laser light 4 from the location above the film 3. This causes to perform a reliable measurement of the heat transmission factor of the thin film 2, being in the thickness of 1mu or less, with a minimum of the influence affected by the substrate.

Laser amplifying device

Abstract: PURPOSE:To ensure a maximum output energy by a method wherein the diameter of a laser beam travelling through laser amplifiers is aligned with the diameter of the cross section of laser activating solid substance housed in said amplifiers. CONSTITUTION:Located between a pulse laser oscillator 1 and a laser amplifier 4 containing laser activating solid substance 5 is an optical system 3 whose function is to align the diameter of a laser beam emitted by the oscillator 1 and the cross section diameter of the solid activating substance 5. The multiplication factor is expressed by the ratio between the cross section diameter of the substance 5 and the beam diameter, and is set at 0.96 by design. Another optical system 7 is provided between the laser amplifier 4 and 8, again to match the diameter of the laser beam to that of the cross section of the activating substance 5. This setup maximizes a laser amplifier output.

Characterization of Defects in As-Implanted and Laser-Annealed Si Layer together with Electrical Properties of As Atoms

Abstract: A TEM study on defects in pulse and cw laser-annealed Si layers is described. The type and distribution of defects at the beam periphery in pulse laser annealing depend on the pulse duration, whereas dislocation loops are distributed homogeneously in cw laser annealing. The periodic change in the defect density at the periphery was thoroughly investigated with five different laser beams, and it was concluded to be due to laser beam interference. A dislocation network is observed in the melted silicon layer in cw laser annealing at sufficiently high power. Dislocations interact with each other, and result in Cottrell sessile dislocations. The properties of implanted As atoms were also examined by RBS and electrical measurements, and the results for pulse and cw laser annealing are compared.

Metalorganic chemical vapor deposition of very thin (≂2 μm), oriented GaAs layers on tungsten substrates

Abstract: This letter describes a novel technique for the deposition of very thin (≂2 μm), pinhole‐free gallium arsenide layers, with large grains (≂ 7 μ) and (110) preferred orientation, on tungsten substrates, by the metalorganic chemical vapor deposition process (MOCVD) The deposition was performed at ∼930 °C with a controlled undercooling of 2°/min, and under a high trimethylgallium flux, corresponding to a gallium arsenide growth rate of 04 μm/min The deposition process is explained by the vapor‐liquid‐solid growth mechanism in which gallium arsenide, in the chemical vapor deposition environment, is formed as in solution growth The need for undercooling during the deposition process is outlined in terms of gallium arsenide nucleation It is proposed that such nucleation in CVD occurs by a priori nucleation of gallium, and by subsequent supersaturation of these gallium nuclei by arsenic