Showing papers on "Sputter deposition published in 1980"

Preparation of conducting and transparent thin films of tin‐doped indium oxide by magnetron sputtering

Abstract: High‐quality 800‐A‐thick films of tin‐doped indium oxide have been prepared by magnetron sputtering. It is shown that films with low resistivity (∼4×10−4 Ω cm) and high optical transmission (≳85% between 4000 and 8000 A) can be prepared on low‐temperature (40–180 °C) substrates with O2 partial pressures of (2–7)×10−5 Torr.

Compressive stress and inert gas in Mo films sputtered from a cylindrical‐post magnetron with Ne, Ar, Kr, and Xe

Abstract: Previous work by the present authors on metal films sputtered from cylindrical‐post magnetron sources has established the existence of an abrupt transition in internal stress and other properties that occurs as the working pressure is lowered. High compressive stress, maximum reflectance, minimum resistivity, entrapped inert gas, and dense, Zone‐T microstructure were found in a wide variety of pure metals and alloys when sputtered in argon at sufficiently low pressures. The present study reports this same phenomenon for a single metal (Mo) sputtered in a variety of gases (Ne, Ar, Kr, Xe). In this case the transition pressure varies inversely with the mass of the sputtering gas, from less than 0.3 Pa for xenon to over 0.9 Pa for neon. The concentration of inert gas in the films also varies inversely with the mass, increasing by two orders of magnitude from krypton to neon. Deposition through a narrow slit‐aperature established that the entrapped gas comes from the sputtering cathode (backscattered, neutral...

Discharge characteristics for magnetron sputtering of Al in Ar and Ar/O2 mixtures

Abstract: An Al target has been sputtered in a planar magnetron system using argon and argon–oxygen mixtures at pressures from 01 to 2 Pa The characteristics of both dc and rf discharges have been studied In the dc case, the current is given by a relation of the form KVn where V is the applied voltage and K and n are pressure‐dependent parameters Values of n up to 9 were obtained at the higher pressures but n decreased at lower pressures For the rf discharge, the target self‐bias voltage, Vsb, at a given power decreased with decreasing pressure and was related to the average rf power by a relationship of the form CVsb/(Vsb−V) where V was approximately 1000 V and C dereased from 900 to 500 W with increasing argon pressure The deposition rate of Al increased linearly with average dc and rf power and there was good agreement between the values for the same power; the rate was 093 μm/min at the maximum power of 25 kW When sufficient oxygen was added, the target surface was oxidized and the deposition rate of A

Sputtered oxide/indium phosphide junctions and indium phosphide surfaces

Abstract: The reason that sputtered indium‐tin oxide (ITO)/InP solar cells junctions with large lattice mismatch have the same efficiency as CdS/InP junctions with good lattice match is shown to be that sputtered ITO/InP junctions actually consist of n+‐ITO/n‐InP/p‐InP buried homojunctions. To demonstrate this and to show that the homojunction formation is caused by thermal damage to the InP surface during sputtering deposition rather than from impurity diffusion from the oxide, a series of five different metal oxide/InP junctions have been formed by sputtering of the oxide, all with high solar efficiency. Junctions have been prepared both from single‐crystal InP : Cd and from epitaxial crystal films of InP : Zn. The effects of sputter deposition of the oxide have been simulated by sputter etching of the InP surface, and the effects analyzed through measurements of the properties of Au/InP junctions, and of the Hall effect and photoluminescence of InP surfaces. Some heat treatment of the sputtered cells is required...

Electrical Defects in Silicon Introduced by Sputtering and Sputter‐Etching

Abstract: Sputtering a gold contact on n‐silicon or sputter‐etching the silicon surface prior to deposition of gold results in a Schottky barrier which shows a barrier height which depends on the sputtering voltage and time, and is lower than a corresponding barrier obtained by evaporation of a gold contact. On p‐silicon a sputtered gold contact also shows a barrier height influenced by the sputtering conditions. The modifications of the barrier height are caused by a thin positively charged layer formed in the semiconductor near the metal‐semiconductor junction. During sputter etching the silicon surface is subject to bombardment by Ar ions with energies of about the sputtering voltage. If this voltage is high enough charged centers will be introduced. These centers are also observed after sputter deposition at high voltage. We found that damage is caused by etching at 500V but not at 100V. This indicates that the damage found after sputter deposition was caused by rebounded Ar atoms.

Oxidation of an aluminum magnetron sputtering target in Ar/O2 mixtures

Abstract: The oxidation kinetics during sputtering of an Al target in a planar magnetron have been studied by accurate measurement of the total pressure produced by argon/oxygen mixtures. When a 5×8‐in. target is rf sputtered at 500 W with a fixed argon flow, the pressure is constant at 4.6 mTorr until the oxygen flow rate is increased to 2.1 cm3/min. At this critical flow, the total pressure increases to 7.85 mTorr in 100 min and the time dependence is explained by a parabolic oxidation rate. The equilibrium oxide thickness is about 100 nm and has been measured by determining the time necessary to cause a sudden increase from 180 to 290 V in self‐bias voltage. When the target was oxidized, Al2O3 films were deposited at 3 nm/min, whereas Al was deposited in an argon discharge at 70 nm/min. The ratio in sputtering rates of Al and Al2O is a factor of 2 greater than predicted from calculated yield values. Before target oxidation, oxygen added to the system is gettered by the film until, at values just below the critical value, Auger analysis shows the films have a composition AlOx where 1

Plasma spectroscopy control and analysis of a-Si:H deposition

Abstract: Plasma emission spectra have been measured for two different deposition methods, i. e., reactive sputtering of Si and glow discharge decomposition of SiH4. The possibility has been indicated that a-Si:H film can be prepared controllably by measuring the relative intensities of Ar, H2, H and SiH4 emission lines during deposition without disturbance to plasma. Some aspects in deposition kinetics have been discussed by comparing the emission lines during deposition with the properties of the deposited films.

High rate deposition of thick piezoelectric ZnO films using a new magnetron sputtering technique

Abstract: ZnO films were prepared on glass substrates with a new reactive magnetron sputtering technique using a zinc target. A solenoid coil around a bell jar was used to cause an increase in the parallel component of the leakage lines to the target surface. Highly oriented ZnO films (c‐axis orientation) were fabricated on the glass substrates. The deposition rate increases with increasing discharge current, and it attains 15 μm/h for (O2 50%:Ar50%), 11 μm/h for (81.5%:18.5%), and 9 μm/h for 100% oxygen. These films were obtained at a 500‐mA discharge current and a 0.2‐Torr total gas pressure. Resistivities of the films were 106–109 Ω cm. A piezoelectric coupling constant of thick ZnO films (∼30 μm) was obtained by measuring a frequency response of transducer impedance near the fundamental resonance frequency of the interdigital electrode. Experimental results were about 80% of the theoretical values.

Magnetically enhanced sputtering device having a plurality of magnetic field sources including improved plasma trapping device and method

Abstract: A magnetron sputtering device wherein a plurality of magnetic field sources are employed to enhance uniformity of cathode sputtering. Each of the magnetic field sources is independently capable of establishing a discharge at the cathode if the other magnetic field sources are removed so that portions of a V-shaped erosion pattern produced by a primary discharge are also eroded to thus effect the more uniform cathode sputtering. In one embodiment of the invention, a magnetic field dome of a first polarity is disposed over a second magnetic field dome of the opposite polarity, the domes being disposed over the cathode so that a closed plasma loop is established, the loop including a first sputtering path which extends over the cathode and a second non-sputtering return path which is disposed over the sputtering path and between the first and second magnetic field domes. The above technique for trapping plasma between the first and second magnetic field domes is unique and has applications to areas other than sputtering.

Magnetron sputtering apparatus

Abstract: A magnetron sputtering apparatus for producing thin films, which comprises at least two spaced apart opposing electrodes, one of the electrodes having a space therein and being used for mounting a target thereon, from which film-forming atoms are ejected by ion-bombardment, the other electrode being used for mounting a substrate thereon, and a magnet arranged in the space of the target mounting electrode, characterized in that the magnet is mounted on a means for adjusting the distance between the target and the magnet, the means for adjusting said distance being provided in the one electrode on which the target is mounted The magnetron sputtering apparatus of the present invention enables one to adjust the magnetic flux density at the surface of the target by the adjustment of the distance between the target and the magnet, thus making it possible to produce thin films with uniform characteristics, even if the sputtering is repeated many times without exchange of the target

Growth of high‐quality epitaxial GaAs films by sputter deposition

Abstract: Epitaxial GaAs films have been grown on (100) Cr‐doped GaAs substrates by sputter deposition from an undoped GaAs target. Unintentionally doped samples were high resistivity (105–106 Ω cm) n type with room temperature mobilities as high as 5000 cm2/V sec. Residual oxygen and carbon contamination was minimized through the use of a liquid‐nitrogen‐cooled shroud surrounding the discharge during deposition. Excess arsenic was provided to the growing film from an effusion cell. Film doping was accomplished using either an evaporated source (Mn) or the addition of a gas‐phase impurity (H2S) during sputter deposition. Mn‐doped p‐type films were grown with room‐temperature carrier concentrations between 1.3×1017 and 2.5×1018 cm−3 and corresponding hole mobilities of 240–95 cm2/V sec. The S‐doped films were n‐type with S concentrations, as determined by secondary‐ion mass spectrometer (SIMS), up to the solid solubility limit and sharp doping profiles with widths of ∼200 A. In all cases the dopant incorporation pro...

Method of and apparatus for reactively sputtering a graded surface coating onto a substrate

Abstract: A graded surface coating is reactively sputtered onto a tubular substrate by advancing the substrate in an axial direction through a cylindrical sputtering chamber in the presence of a sputter supporting gas. The sputtering chamber includes a cathode liner from which metal is sputtered onto the substrate. A reactive gas is directed into the sputtering chamber from a feed point outside of the chamber, whereby reactive sputtering occurs within the chamber. The reactive gas is induced to flow into the chamber in a direction counter to the direction of advancement of the substrate whereby, as the substrate is progressively advanced through the chamber and the applied coating gradually increases in thickness, the proportion of the reactive gas constituent in the coating increases relative to the metal constituent proportion with increasing thickness of the coating.

A molybdenium source, gate and drain metallization system for GaAs MESFET layers grown by molecular beam epitaxy

Abstract: Molecular beam epitaxy has been used in a continuous growth procedure to form GeGaAs epitaxial structures that were suitable for MESFET fabrication. Near surface doping profiles were engineered such that low resistance ohmic contacts to the GaAs layer were obtained by subsequently depositing a metal overlayer on the Ge surface. Evaporated Au overlayers yielded specific contact resistances of the order of 10−6ω cm2 without heat treatment. Because the conventional alloying procedure now appeared superfluous, metallurgically non-reactive systems were investigated with a view to constructing GaAs MESFETs with entirely refractory metallizations. Sputtered molybdenum has been evaluated for both the formation of ohmic contacts to the Ge/GaAs layers and rectifying contacts to the GaAs layer. Damage introduced as a result of the sputtering deposition process is the probable cause of non-ideality in the as-prepared Schottky barriers. However, forward bias current-voltage ideality factors of n = 1.07 have been obtained after annealing.

Effects of oxygen on properties of rf sputtered NiFe films

Abstract: Oxygen contamination during rf sputter deposition of NiFe films is shown to cause adverse electrical and magnetic properties. This contamination is most pronounced in films deposited at low bias voltages. Although the bias voltage is not a direct cause of these changes, it is a factor which determines the amount of available oxygen in the sputtering gas which is incorporated into the interior of the films. In addition, a thin oxide layer is frequently found on both top and bottom surfaces of the films. It contains as much as 2 at. % oxygen, a concentration which is shown to mark the onset of deteriorating electrical and magnetic properties when occurring uniformly throughout NiFe in films.

Thin-Film CdS/CuInSe2 Heterojunction Solar Cell

Abstract: The development of a polycrystalline, thin-film solar cell utilizing a heterojunction structure based upon N-type CdS and P-type CuInSe2 semiconductor materials is described. The cell, prepared entirely by vacuum deposition and sputtering techniques onto inexpensive substrates, has potential applications as a low-cost mass produced device for photovoltaic power generation systems. A device efficiency of 7.5% under simulated AM-1 illumination is reported. Material and device properties pertinent to the development of the high efficiency cell are reviewed. The electrical, optical, and structural properties of the deposited thin-film materials are described. Results of detailed cell characterization using a variety of electrical, optical, and thermal measurements are presented and analyzed in terms of a photovoltaic cell model dominated by interface state recombinations. Finally, the projected, realistically achievable performance of this thin-film cell is discussed.© (1980) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Nb3Si prepared by high-rate sputtering followed by quenching

Abstract: Nb/sub 3/Si films with the A-15 structure have been prepared by sputtering onto a substrate whose temperature is about 1000/sup 0/C, followed by quenching to liquid nitrogen temperature. All processes were carried out by using magnetron sputtering in a container full of liquid nitrogen. The quenching just after the deposition was achieved by thermal conduction using a sample holder in contact with the liquid nitrogen container. The highest onset temperature T/sub on/ and critical temperature (midpoint of the transition) T/sub c/ of the samples are 17.3 and 16.4 K, respectively, with a sharp transition. X-ray diffraction patterns show fine-grained A-15 structure and give a lattice constant of 5.09 A.

Immobilization of krypton in a metallic matrix by combined ion implantation and sputtering

Abstract: With the increase in nuclear power, it may be necessary to contain for 100–200 years the radioactive 85 krypton released during fuel reprocessing. The ideal method of immobilizing radioactive materials is in the form of stable, monolithic solids which are resistant to the effects of the environment or accidents, and which can retain the radioactivity under all envisaged conditions. Since krypton is a rare gas, not forming thermally stable compounds, conventional methods of storage are not possible. A process is being developed to immobilize the krypton in the form of small gas bubbles in a metal matrix by implanting the gas into a metal layer from a glow discharge and then burying the implanted layer by sputter deposition. By repeating the process, a thick layer of deposit is built up with the krypton dispersed throughout the matrix as bubbles of diameter less than 20 A. This process offers an ideal form of storage since gas in bubbles is not thermally released until the temperature of the matrix...

Deposition of epitaxial layers by ion beam methods

Abstract: The possibilities and the limitations of ion beam sputter deposition are discussed in connection with results obtained for the growth of epitaxial semiconductor films. It turns out that homo‐ and hetero‐epitaxial films of good structural quality can be deposited at relatively low substrate temperatures and that effective doping offers no difficulties. On the other hand, some radiation damage caused by energetic particles must be taken into account. More recently, ion beam deposition methods could be realized under UHV conditions using about the same diagnostic equipment as in MBE. It can be expected that in preparing special film structures combinations between molecular and ion beam techniques might become attractive, while ion beam methods also will stand on its own in synthesizing unusual film phases.

Copper distribution in sputtered Al/Cu films

Abstract: The copper distribution in sputtered aluminum–copper films depends on copper concentration and deposition temperature. At high deposition rates the film temperature is high enough for diffusion to occur without external substrate heating. Targets containing 0.5%, 2%, and 4% copper were used to deposit films by dc magnetron sputtering. No segregation was found in the 0.5% Cu films at film deposition temperatures as high as 460°C. The 2% and 4% Cu films showed segregation, with the peak in the copper content located nearer the film–substrate interface. Auger and SEM data indicate that theta phase particles may form in this region during high rate deposition. These particles apparently redissolve slowly during 500°C postdeposition anneal. In contrast, 4% Cu films deposited by evaporation from a single source showed a similar as‐deposited profile, but a more rapid redistribution of the Cu during anneal. The sputtered films are reported to be more resistant to hillock growth and corrosion than the evaporated f...

Process of bonding sputtering targets to target electrodes

Abstract: In the process of sputter deposition of targets on target electrodes, a gallium-indium eutectic alloy is employed to form a floating bond between the target material and the target electrode. Relatively high radio frequency (r.f.) power density is used to increase the deposition rate without cracking the target.

Bias sputter deposition of PdAuSi and PdSi: Composition and thermal behavior

Abstract: Amorphous films of PdAuSi and PdSi were prepared by bias sputter deposition Variation of the substrate bias voltage used in rf sputter deposition of PdAuSi films produced changes in chemical composition and thermal behavior as observed by differetial scanning calorimetry The amount of Ar incorporated during sputtering initially increases with increasing bias voltage, then decreases to a minimum at approximately −200 V and increases rapidly thereafter Amorphous films of the binary alloy PdSi were prepared by both rf and dc sputter deposition at a single substrate bias voltage of −200 V The heats of crystallization of the ternary sputter deposited films were within 10–20% of those of melt-quenched alloys with similar compositions

Nb3Ge Prepared by High Rate Sputtering in a Container Cooled by Liquid N2

Abstract: Nb3Ge has been prepared by high rate magnetron sputtering followed by quenching just after deposition. A superconducting onset temperature (Ton) above 21~22 K was obtained over a wide band of a substrate temperature (TD) 600°~750°C and that of Ar pressure (Pr) from 0.1 Torr to 0.5 Torr. The highest Ton, Tc (the midpoint of transition) and the transition width were 22.5 K, 21.5 K and 1.5 K respectively. The preparation of a uniform and reproducible sample has become very easy. Associated physical properties of a film are described.