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Volume 42, Issue 10
Displaying 1-9 of 9 articles from this issue
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Yuko HIROHATA1999 Volume 42 Issue 10 Pages 879-885
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
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Takayuki TAKAHAGI, Hiroyuki SAKAUE1999 Volume 42 Issue 10 Pages 886-891
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
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Kazuyuki UEDA1999 Volume 42 Issue 10 Pages 892-896
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
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Study of Behavior of Deuterium Atoms and Defects in Graphite by ERD and Positron Annihilation MethodEiichi KURAMOTO, Noboru TSUKUDA, Minoru TAKENAKA, Hideaki OHKUBO, Taka ...1999 Volume 42 Issue 10 Pages 897-904
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
JOURNAL FREE ACCESSBehavior of deuterium atoms implanted in graphite has been investigated by ERD (elastic recoil detection) method and the defect behavior has also been studied by positron annihilation method. It was found that diffusion of deuterium atoms shows a significant anisotropy, i.e., very high diffusivity along the direction parallel to the basal plane and very low diffusivity along the direction perpendicular to the basal plane. Deuterium atoms are considered to be trapped at the boundaries between adjacent crystallites and the sites of radiation induced defects and are released from the specimen through three stages in the isochronal annealing process depending on the depth of the trapping potential. The isochronal annealing curve of the positron lifetime for HOPG irradiated with electrons at 77 K can be divided into two stages, i.e., below 1200°C and above 1200°C. In the former the increase of positron lifetime corresponding to the growth of interstitital type loops is observed and in the latter that corresponding to the growth of vacancy type loops (and also to interstitial type loops) is observed. Positron lifetime calculation for a vacancy and vacancy clusters was made and the comparison with the experimental results was also made to clarify the fundamental aspects of radiation induced defects in graphite.View full abstractDownload PDF (994K) -
Koji NAKAYAMA, John H. WEAVER1999 Volume 42 Issue 10 Pages 905-909
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
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Satoshi KUROKOUCHI, Masayuki OKABE, Mitsuyoshi SAITO, Satsuo SHINODA, ...1999 Volume 42 Issue 10 Pages 910-917
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
JOURNAL FREE ACCESSA ConFlat seal mechanism is most widely used in small and/or middle-sized ultrahigh vacuum system. The existing model on its seal mechanics, however, is somewhat curious and is undoubtedly to be reconsidered.
Our experiments indicated that capturing with the contact of a disk gasket and a retaining counter is not a key factor for the sealing. We tested a taper-seal mechanism, which was newly designed to improve the inefficiency of the ConFlat mechanism. It was remarked under the tightening torque of 50 kgf cm that the seal area on a taper-seal type gasket was 3 times larger than that of a conventional disk gasket. High sealing reliability was thus achieved as expected which is mainly due to its wide seal contact area realized even for rather a hard gasket material.View full abstractDownload PDF (1187K) -
Satoshi KUROKOUCHI, Masayuki OKABE, Shinsaku MORITA1999 Volume 42 Issue 10 Pages 918-922
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
JOURNAL FREE ACCESSThe “capture” model, which is dependent on the compression of a gasket between the knife edge and the retaining counter of the flange, has been the rationale of ConFlat seal mechanism. Our numerical analyses of stress distributions in a tightened gasket indicate that the capture increases the seal pressure less than 2%. The seal pressure is mainly related to the compressive stress between 20° tapers of a pair of flanges. Numerical results also show that maximum stress in the conventional disk gasket can be over 3 times larger than that in the taper-seal gasket. This fact implies that excessive high stresses in the conventional disk gasket prevent achievement of a wide seal area, resulting in a gasket creep during baking. Newly designed taper-seal gasket realizes highly stable seal pressure even under a lower tightening torque and consequently shows a good seal performance as expected.View full abstractDownload PDF (1079K) -
Yoshitsugu TSUTSUMI, Hideki TOMIOKA, Yoshio OKAMOTO1999 Volume 42 Issue 10 Pages 923-928
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
JOURNAL FREE ACCESSWith regard to semicondutors, thin films that are manufactured for DRAM (Dynamic Random Access Memory) capacitors with high dielectric constant will be used for 256M-or 1G-DRAMs. Sources of these thin films are in liquid phase at normal condition. In order to deposit thin films on a complicated structure of DRAM cells, it is necessary to vaporize these sources. A new type of vaporizer which vaporizes these sources inside of the reactor was studied. This vaporizer, celled direct injection vaporizer, injects these sources directly into a reactor, makes very fine droplets, and vaporizes these droplets by radiation from a susceptor and thermal conduction from gases in the reactor. In this paper, the method of measurement for vaporization was studied. The measurement for diameters and the ratio of vaporization of droplets that were injected in a vacuum chamber were conducted with a substitutional liquid of PET (Penta-Ethoxy Tantalum). The results indicated that it is possible to vaporize the liquid sources using the direct injection vaporizer.View full abstractDownload PDF (895K) -
Akiko N. ITAKURA, Tetsuya NARUSHIMA, Takayuki KURASHINA, Masahiro KITA ...1999 Volume 42 Issue 10 Pages 929-932
Published: October 20, 1999
Released on J-STAGE: October 20, 2009
JOURNAL FREE ACCESSWe present the evolution of surface stress of Si (100) at the oxide film thickness from 0 to 5 nm. Using micromechanical cantilevers, we have measured surface stress evolution during plasma oxidation with applying positive bias to the samples and observed five stages in surface stress. The stress curve depending on oxidation time showed a quick buildup of compressive stress, followed by a tensile stress formation, gradually changed to tensile one and compressive stress appeared again. In the second stage, the formation of tensile stress suggests a oxygen-bridged dimer structure. Only the last compressive stress have been known as a intrinsic stress in silicon oxide film of 10 nm to 1000 nm, which due to the lattice mismatch of Si and SiO2. For the cases of oxidation with applying negative biases, stress curves showed different time dependence from that with positive bias. They showed three stages, the first two stages which were observed in the case of positive bias did not appear.View full abstractDownload PDF (575K)
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