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Magnetic multipole line-cusp plasma generator for neutral beam injectors
Classified abstracts 43054312 the film morphology became discontinuous, leading to a welldeveloped island structure. Desorption energies of 0.33 eV on Al and sapphire and 0.40 eV on glass were obtained from the temperature dependence of the sticking fraction. G Abowik and L B Leder, J Yuc Sci Techtrol, 15 (5), 1978, 1746-I 75 I. 30 4305. Quantitative AES analysis of coevaporated Cu/Ni films and the effects of ion sputtering on them: experiments at liquid nitrogen and room temperature. (USA) Samples of various concentrations were made by coevaporation of Cu and Ni. The coevaporation was carried out by simultaneous controlled electron bombardment heating of independent evaporation sources. The Auger-electron spectroscopy (AES) measurements were made by using a CMA and could be done following coevaporation or ion sputtering without moving the sample in the uhv system. The absolute composition of the sample was measured by atomic absorption spectroscopy (AAS). A linear relation was found between the AES measurements (700-IOOOeV) and the results of AAS when the coevaporation was made onto the substrate at almost liquid nitrogen temperature. It should bementioned that samples of homogeneous concentration from the surface to the bulk could be obtained, making quantitative AES possible. On the other hand, coevaporation onto substrates at room temperature resulted in Cu-rich surfaces being obtained. Quantitative AES analysis using lower-energy Auger peaks (80-120eV) was also made using the same samples and results similar to those calculated from the higher-energy Auger transitions (700-1000 eV) were obtained. Samples coevaporated near liquid nitrogen temperature were sputtered by argon ions of 500-2000 eV and no significant difference was observed between sputtering near liquid nitrogen temperature or after allowing the sample to warm to room temperature. The surface of a 60 at.‘% Cu film became Ni-rich by 4, 8, and I2 at.% for ion energies of 500, 1000, and 2000 eV, respectively. (Japan) K Gota et al, J vuc Sci Tcchnol, 15 (5). 1978, 1695-1700. 30 4306. Pressure-operated shutter for thin-film monitor. (GB) This article describes a gas-pressure-operated shutter interfaced to a Sloan 1000 digital thickness monitor and suitable for operation under ultra-high vacuum. (Australia) R B Turkentine and I S Williams, J P/?,JsE: Scient fm~um, I2 (I), 1979, 17.
31. SPUTTERING 4307. End-effects in cylindrical magnetron sputtering sources. (USA) J A Thornton, J Yac Sci Techno/. 16 (I), 1979, 79-80.
31
31 4308. Vertical electrode configuration to avoid contaminating particles in sputtered ZnO thin films. (GB) Sputtering of ZnO thin films, both from a ZnO target and from a Zn target with a reactive atmosphere, by means of a horizontal electrode configuration with the target up, yielded films contaminated by ZnO particles of various sizes (1ooO-0.1 pm). Defects in the thin ZnO layer on the ZnO target and on the Zn target in the reactive sputtering process, are the main source of contaminating particles. We set up a vertical electrode configuration and installed it in the sputtering system and obtained clear and homogeneous ZnO films (the particles’ diameter was smaller than 0.5 pm). The contaminating particles were found on the horizontal sputtering table, which was just underneath the vertical system. A description of the vertical electrode configuration is presented. (Israel) S Maniv and 1 Berman, Yucu~rm, 28 (l2), 1978, 529-532. 31 4309. Cadmium selenide thin-film transistors. (USA) Vacuum deposited CdSe thin-film transistors (TFT’s) with reproducible good stability, performance, uniformity, and yield were made using sputtered SiO, gate insulator, Cr source-drain (s-d) electrodes, and postdeposition annealling in Nz. These materials and procedures permit the use of multiple pumpdown fabrication methods with no loss in ac characteristics and little sacritice in dc stability. Promising results were obtained using photolithography (PL) to delineate 200
s-d electrodes, further simplifying fabrication. The dc instability is electron-trapping type and the drain current decay exhibits a logarithmic time dependence. The slope of this decay curve is used as a parameter to describe device stability and its dependence on the fabrication methods studied: M = 0.03-0.06 for one pumpdown devices, 0.05-0.08 for multiple pumpdown TFT’s, and 0.1-0.2 for TFT’s with PL delineated s-d electrodes. Preliminary reliability studies show that suitably encapsulated TFT’s have long time stability comparable to the good short time stability observed for fresh devices, indicating the absence of built-in failure mechanisms and the capability for a satisfactory operating life. J C Erskine and A Cserhati, J Vuc Sci Techrrol, 15 (6), 1978, 1823-l 835. 31 4310. An XPS study of the adherence of refractory carbide, silicide and boride rf sputtered wear-resistant coatings. (USA) Radio frequency sputtering was used to deposit refractory carbide, silicide and boride coatings on 440-C steel substrates. Both sputter etched and pre-oxidized substrates were used and the films were deposited with and without a substrate bias. The composition of the coatings was determined as a function of depth by X-ray photoelectron spectroscopy combined with argon ion etching. Friction and wear tests were conducted to evaluate coating adherence. In the interfacial region there was evidence that bias may produce a graded interface for some compounds. Biasing, while generally improving bulk film stoichiometry, can adversely affect adherence by removing interfacial oxide layers. Oxides of all film constituents except carbon and iron were present in all cases but the iron oxide coverage was only complete on the preoxidized substrates. The film and iron oxides were mixed in the MoSi, and MozC films but layered in the Mo2B, films. In the case of mixed oxides, preoxidation enhanced film adherence. In the layered case it did not. W A Brainard and D R Wheeler, J Vuc Sci Terh/rol, 15 (6), 1978, 1800-l 805.
32. EVACUATION
AND SEALING
4311. Gas evolution and gettering in high pressure discharge lamps. (G?) The use of getters within the jacket of metal halide lamps is necessary to prevent the deleterious influence of gaseous impurities on their performance. A number of experimental metal halide lamps (400 W) were produced using the St IO1 getter alloy (8454 Zr-167; Al). Analysis of the jacket atmosphere and the getter gives information about the impurity load and the gas release dynamics. About 35 Pa I of hydrogen and 7 Pa I of CO and lower quantities of CO, and CH, are evolved. The release seems to be complete within about 1000 h of operation. Practical results confirm that the St IO1 alloy, because of its gettering properties and its ability to withstand the contaminating ambient during lamp production, is particularly suited for use in the outer jacket of discharge lamps. (Italy) M Borghi and L Rosai, Vacrtrn~~, 29 (2). 1979, 67-72.
33. NUCLEONICS 33 4312. Magnetic multipole line-cusp plasma generator for neutral beam injectors. (USA ) The magnetic multipole line-cusp device developed by MacKenzie and associates has been adapted for use as a neutral beam ion source. It has produced high-density, large volume, quiescent, uniform hydrogen plasmas, which makes it a potential candidate for use as a plasma generator for neutral beam injectors. The device is a water-cooled cylindrical copper discharge chamber (25 cm in diameter by 36 cm long) with one end enclosed by a set of extraction grids with a 15 cm-dia multi-aperture pattern. The chamber wall serves as an anode and is surrounded by an external system of rare-earth cobalt magnets arranged in a line-cusp geometry of I2 cusps; plasma is produced by electron emission from a hot cathode assembly. This source has achieved extracted beam currents of I2 A at 18.5 kV, radial plasma density uniformities of +Sv/ over a I5 cm dia, noise levels of less than +0.5%, and arc efficiencies (beam current/arc power) of 0.6 A kW-‘. W L Stirling et al, Reo scietrt Itrsrrrm, 50 (I ), 1979. 102-108.
31. SPUTTERING 4307. End-effects in cylindrical magnetron sputtering sources. (USA) J A Thornton, J Yac Sci Techno/. 16 (I), 1979, 79-80.
31
31 4308. Vertical electrode configuration to avoid contaminating particles in sputtered ZnO thin films. (GB) Sputtering of ZnO thin films, both from a ZnO target and from a Zn target with a reactive atmosphere, by means of a horizontal electrode configuration with the target up, yielded films contaminated by ZnO particles of various sizes (1ooO-0.1 pm). Defects in the thin ZnO layer on the ZnO target and on the Zn target in the reactive sputtering process, are the main source of contaminating particles. We set up a vertical electrode configuration and installed it in the sputtering system and obtained clear and homogeneous ZnO films (the particles’ diameter was smaller than 0.5 pm). The contaminating particles were found on the horizontal sputtering table, which was just underneath the vertical system. A description of the vertical electrode configuration is presented. (Israel) S Maniv and 1 Berman, Yucu~rm, 28 (l2), 1978, 529-532. 31 4309. Cadmium selenide thin-film transistors. (USA) Vacuum deposited CdSe thin-film transistors (TFT’s) with reproducible good stability, performance, uniformity, and yield were made using sputtered SiO, gate insulator, Cr source-drain (s-d) electrodes, and postdeposition annealling in Nz. These materials and procedures permit the use of multiple pumpdown fabrication methods with no loss in ac characteristics and little sacritice in dc stability. Promising results were obtained using photolithography (PL) to delineate 200
s-d electrodes, further simplifying fabrication. The dc instability is electron-trapping type and the drain current decay exhibits a logarithmic time dependence. The slope of this decay curve is used as a parameter to describe device stability and its dependence on the fabrication methods studied: M = 0.03-0.06 for one pumpdown devices, 0.05-0.08 for multiple pumpdown TFT’s, and 0.1-0.2 for TFT’s with PL delineated s-d electrodes. Preliminary reliability studies show that suitably encapsulated TFT’s have long time stability comparable to the good short time stability observed for fresh devices, indicating the absence of built-in failure mechanisms and the capability for a satisfactory operating life. J C Erskine and A Cserhati, J Vuc Sci Techrrol, 15 (6), 1978, 1823-l 835. 31 4310. An XPS study of the adherence of refractory carbide, silicide and boride rf sputtered wear-resistant coatings. (USA) Radio frequency sputtering was used to deposit refractory carbide, silicide and boride coatings on 440-C steel substrates. Both sputter etched and pre-oxidized substrates were used and the films were deposited with and without a substrate bias. The composition of the coatings was determined as a function of depth by X-ray photoelectron spectroscopy combined with argon ion etching. Friction and wear tests were conducted to evaluate coating adherence. In the interfacial region there was evidence that bias may produce a graded interface for some compounds. Biasing, while generally improving bulk film stoichiometry, can adversely affect adherence by removing interfacial oxide layers. Oxides of all film constituents except carbon and iron were present in all cases but the iron oxide coverage was only complete on the preoxidized substrates. The film and iron oxides were mixed in the MoSi, and MozC films but layered in the Mo2B, films. In the case of mixed oxides, preoxidation enhanced film adherence. In the layered case it did not. W A Brainard and D R Wheeler, J Vuc Sci Terh/rol, 15 (6), 1978, 1800-l 805.
32. EVACUATION
AND SEALING
4311. Gas evolution and gettering in high pressure discharge lamps. (G?) The use of getters within the jacket of metal halide lamps is necessary to prevent the deleterious influence of gaseous impurities on their performance. A number of experimental metal halide lamps (400 W) were produced using the St IO1 getter alloy (8454 Zr-167; Al). Analysis of the jacket atmosphere and the getter gives information about the impurity load and the gas release dynamics. About 35 Pa I of hydrogen and 7 Pa I of CO and lower quantities of CO, and CH, are evolved. The release seems to be complete within about 1000 h of operation. Practical results confirm that the St IO1 alloy, because of its gettering properties and its ability to withstand the contaminating ambient during lamp production, is particularly suited for use in the outer jacket of discharge lamps. (Italy) M Borghi and L Rosai, Vacrtrn~~, 29 (2). 1979, 67-72.
33. NUCLEONICS 33 4312. Magnetic multipole line-cusp plasma generator for neutral beam injectors. (USA ) The magnetic multipole line-cusp device developed by MacKenzie and associates has been adapted for use as a neutral beam ion source. It has produced high-density, large volume, quiescent, uniform hydrogen plasmas, which makes it a potential candidate for use as a plasma generator for neutral beam injectors. The device is a water-cooled cylindrical copper discharge chamber (25 cm in diameter by 36 cm long) with one end enclosed by a set of extraction grids with a 15 cm-dia multi-aperture pattern. The chamber wall serves as an anode and is surrounded by an external system of rare-earth cobalt magnets arranged in a line-cusp geometry of I2 cusps; plasma is produced by electron emission from a hot cathode assembly. This source has achieved extracted beam currents of I2 A at 18.5 kV, radial plasma density uniformities of +Sv/ over a I5 cm dia, noise levels of less than +0.5%, and arc efficiencies (beam current/arc power) of 0.6 A kW-‘. W L Stirling et al, Reo scietrt Itrsrrrm, 50 (I ), 1979. 102-108.