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Nov 1967

Volume 4, Issue 6, pp. 343-385


The Sputtering of Nickel–Chromium Alloys

W. L. Patterson and G. A. Shirn

J. Vac. Sci. Technol. 4, 343 (1967); http://dx.doi.org/10.1116/1.1492560 (4 pages) | Cited 13 times

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Ni-Cr alloys having the compositions (in at. %) Ni-22 Cr, Ni-42 Cr, and Ni-80 Cr were sputtered in argon in a low-pressure supported discharge. Ion energy was varied from 200 to 1000 eV, ion current density from 0.1 to 0.8 mA∕cm2 and pressure from 2 to 6 μ. The ion-pumped sputtering tube was processed as a uhv system. Thin films were deposited on polished silicon, aluminum or sapphire. Results showed that the target composition was preserved in the sputtered films to within ± 1% in each component. Near the surface of the sputtered Ni-22 Cr target, a relative Cr enrichment was found. The alloy sputtering process has been codified in a phenomenological continuity equation, using sputtering yields as parameters. The equation gives quantitatively a transient-state and a steady-state solution. The steady-state solution shows that the sputtered film should have the same composition as the target bulk and that the surface of the target should, in general, change composition.
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81.15.Cd Deposition by sputtering
68.55.Nq Composition and phase identification

The Adsorption of Atmospheric Gases on Molecular Sieves at Low Pressures and Temperatures. The Effect of Preadsorbed Water

S. A. Stern and F. S. DiPaolo

J. Vac. Sci. Technol. 4, 347 (1967); http://dx.doi.org/10.1116/1.1492561 (9 pages) | Cited 7 times

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The adsorption of nitrogen, helium, neon, and air on Molecular Sieves 5A, 10X, and 13X was studied at 77.3 °K and in the pressure range from 102 to 10−6 Torr. The capacities of freshly activated adsorbent samples for nitrogen were found to increase markedly below 10−3 Torr after consecutive adsorption-desorption cycles. This “conditioning effect” may explain the large discrepancies in the data of previous investigators. The nitrogen isotherms can be represented above 10−2 to 10−4 Torr by either the Freundlich or the Dubinin–Radushkevich equations, while the helium and neon isotherms obey Henry’s law. The effect of preadsorbed water is to decrease the adsorptive capacity of Molecular Sieve 5A for nitrogen; when the amount of water exceeds 7 wt%, the capacity for nitrogen is almost completely suppressed. It is suggested that this behavior is due to the migration of hydrated cations, which block the apertures to the cube octahedral cavities of the adsorbent.
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Comparison of Static and Dynamic Calibration Methods for Ionization Gauges

C. Meinke and G. Reich

J. Vac. Sci. Technol. 4, 356 (1967); http://dx.doi.org/10.1116/1.1492562 (4 pages) | Cited 1 time

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Ionization gauges have been calibrated by a static expansion method in the pressure range of 10−2–10−6 Torr with a absolute accuracy of ±3%. The repeatability of the linear calibration curve is 1%. The sensitivity of the gauges thus calibrated has been checked by a dynamic method, comprising a flow measurement through a porous plug and a calculated circular orifice. The accuracy of this method is ± 7%. Evaluation of the measurements of flow and sensitivity is done by an electronic computer. The results agree within the limits of error with those obtained by the static method. The dynamic method can be used for calibrations down to pressures of 10−10 Torr while the static method has its lower limit at 10−6 Torr because of sorption phenomena.
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07.30.Dz Vacuum gauges

Solution of Clausing’s Integral Equation for Molecular Flow

John C. Helmer

J. Vac. Sci. Technol. 4, 360 (1967); http://dx.doi.org/10.1116/1.1492563 (4 pages) | Cited 5 times

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A new solution of Clausing’s equation has been obtained by iterative methods. In long cylindrical tubes it is found that the gradient of the molecular density is higher in the ends of the tube than in the center. Relations are developed for the measurement of the molecular flow rate by pressure gauges mounted in the wall of the tube. A simple function closely approximates the density distribution for both long and short tubes. The gauge position is calculated for the measurement of pumping speed at the end of the tube. The molecular transmission probability is found to agree with the results of Berman to within 0.1%.
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47.45.Dt Free molecular flows

Gold Wire Seals for Ultrahigh Vacuum

Roman A. Hawrylak

J. Vac. Sci. Technol. 4, 364 (1967); http://dx.doi.org/10.1116/1.1492564 (4 pages)

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Advantages of gold as sealing material for ultrahigh vacuum are discussed. A new configuration of unpolarized rotatable uhv flanges, sealed with a gold wire gasket, is described. Use of gold wire for sealing irregularly shaped openings, glass windows, and thin foils in vacuum systems is also discussed.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Present Trends in Condensation and Evaporation Theories

Emile Rutner

J. Vac. Sci. Technol. 4, 368 (1967); http://dx.doi.org/10.1116/1.1492565 (10 pages) | Cited 1 time

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A review is given of theories of nucleation and condensation based on quasi-equilibrium models. Relations between a kinetic theory for nucleation, such as the path-probability method, and the quasi-equilibrium theories are also noted. Theories of condensation and vaporization based on the defect structure of the surface as the site for the processes are also reviewed. The application of absolute-reaction-rate theory to these phenomena is discussed.
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Differentially Pumped, Ultrahigh-Vacuum System Bakeable to 900 °C

C. E. Blahnik

J. Vac. Sci. Technol. 4, 378 (1967); http://dx.doi.org/10.1116/1.1492566 (4 pages)

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A differentially-pumped, ultrahigh-vacuum (uhv) system has been developed that is capable of 900 °C bakeout and can attain pressures below 10−10 Torr in as little as one hour, depending upon the thermal mass of the enclosed apparatus. This paper describes a two-part uhv system and some of the design and materials considerations for mechanical, electrical, and optical couplings through the vacuum walls. Suitable solutions to these and related problems are discussed.
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07.30.-t Vacuum apparatus

Attainment of Ultrahigh Vacua in Small Glass Systems

P. H. Dawson and N. R. Whetten

J. Vac. Sci. Technol. 4, 382 (1967); http://dx.doi.org/10.1116/1.1492567 (2 pages)

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Abstract Unavailable
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07.30.-t Vacuum apparatus

Improved Vapor Pump Operation by Use of a Dual-Expansion Nozzle

C. M. Gosselin and W. W. Longley

J. Vac. Sci. Technol. 4, 383 (1967); http://dx.doi.org/10.1116/1.1492568 (3 pages)

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Abstract Unavailable
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07.30.Cy Vacuum pumps
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