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Ultra-stable system for rf sputtering with rf-induced substrate bias
Classified
abstracts
1484-l
492 30
1484. Ion implantation during film growth and its effect on the superconducting properties of niobium. (USA) Low-energy (5500 eV) Kr+ ion bombardment during film growth and its consequences on superconducting properties of Nb are studied in a triode glow discharge sputtering configuration. Tc is depressed from the bulk value at a rate of -O.l9’C/a~ % dissolved in the lattice. The residual resistivity shows an increase of 3.4 FQ cm/at.% Kr. It is shown that radiation damage due to ion bombardment dominates the superconducting properties up to 0.2 at.:< dissolved, whereas above this Kr concentration, up to -2 at.?< Kr, the noble-gas content dominates the transport properties. All films show a dilated la&e which is mainly caused by energetic bombardment during film growth rather than subsequent trapping of the Kr gas. G Heim and E Kay, J App/Phys, 46 (9), l975,4006-4Ol2. 31
1485. Redeposition of sputtered species during ion etching of Cu, Ag, and Au. (USA) The redeposition of sputtered, Au, Ag, and Cu onto glass surfaces, which are in the same plane as bombarded metal foils, has been established by ion scattering spectrometry. Sites near the sputtering centre were analysed with sensitivities of 0.0008-0.001 monolayers after neon bombardment of the foils for up to two hours. From the data, the redeposition coverage is estimated to be from 0.009d to 0.04z monolayers after two hours of Ne bombardment at I500 eV. The electric field of the incident ion beam, acting on low-energy sputtered ions, is a likely cause of the redeposited material.
A C Miller 1086-1087.
and A W Czanderna, J Vuc Sri T&no/,
12 (5), 1975, 31
1486. Low-voltage triode sputtering with a confined plasma. Part It: Plasma characteristics and energy transport. (USA) The plasma characteristics of a triode low-voltage sputtering (LVS) system have been measured. The curren&voltage relationships in the confined plasma discharge, of the target and of thesubstrate table, have been investigated as a function of pressure for Ar and Xe, with and without an axial magnetic field. The power dissipation and steady-state temperature at the target and substrate table were also measured as a function of operating conditions. From these measurements the plasma potential and target current densities could be deduced. The application of these results to sputter deposition is considered.
T C Tisone and P D Cruzan, J Vuc Sci Techno/, 12 (5), 1975, 10581066. 31
1487. Ultra-stable bias. (USA)
system for rf sputtering with &induced
substrate
Radio-frequency sputtering with rf-induced substrate bias has been shown to be extremely valuable in tailoring the properties of many thin films. The use of this process has been inhibited by the lack of availability of simple equipment to implement it. We have designed a system which (1) is very rugged and reliable; (2) has no sensitive or critical tuning controls; (3) is insensitive to phase relationships; (4) is insensitive to fluctuations in gas discharge ympedance, (5) is extremely stable, reproducible, and repeatable for long periods of time under a variety of sputtering conditions; and (6) can be operated, literally, in “push-button” fashion. J L Vosen and J J O’Neitl, j Vat Sci Techol, 12 (S), 1975,lO52-1057.
33. NUCLEONICS 33
casts. A monitor of the transmitted CO2 laser pulse indicates very incomplete coupling of laser radiation inlo the plasma column with the field applied, presumably due to refraction losses at the entrance boundary of the breakdown. A A Offcnbergcr and N H Burnett, cfftt J P/IJW, 53 ( 14). 1975, 13601366.
34. ELECTRONICS TECHNOLOGY
AND
HIGH
ALTITUDE
AND 34
1489. Plasma-cathode electron gun. (USA) The plasma-cathode electron gun is a new type of electron source which is suitable for applications requiring a large area, high-energy electron beam. It employs a plasma generated within a cold lowvoltage, hollow-cathode discharge as the source of electrons. Plasma cathode devices are characterized by their simplicity and versatility, and they offer a number of advantages over other designs. An electron gun producing a beam with dimensions of 5 x I25 cm has been developed for use with high-power cw gas lasers. This device has been operated at beam energies of I50 keV and cw beam current densities of 0.1-0.2 mA/cmz. J R Bayless, Rer Sci /m/rwn, 46 (9), 1975, I 158-l 160. 34 1490. Vacuum ultraviolet radiometry with hydrogen arcs. 2: The high
power arc as an absolute standard of spectral radiance from 124 nm to 360 nm. (USA) A wall-stabilized hydrogen arc can be utilized as a standard source of spectral radiance since the continuum emission coefficient is calculable to within a few percent. Previous elTor& to apply this concept have been impeded by relatively large uncertainties associated with the plasma diagnostics. The present approach yields absolute intensities independent of other radiometric standards or the accuracy of any plasma diagnostics. The hydrogen arc is operated at high temperatures where the continuum emission coefficient reaches a broad, unique, and calculable maximum. Comparisons with other primary standards are consistent with the estimated uncertainty in the arc continuum intensities. W R Ott et al, App/ Opf, 14 (9). 1975,2l2l-2128. 34
1491. Excitation-energy-dependent resonances in X-ray emissions under near-threshold electron excitation of the Ce 3 d and 4 d levels. UJSAI Soft X-ray appearance potential spectra of the 3 d and 4 d levels of polycrystalline cerium metal are reported in this paper. Resonant X-ray emissions are observed when the electron-excitation energy sweeps through the ionization energies of the 3 d and 4 d levels. The resonant X-rays excited at the 3 d-level onsets are considerably more intense and are excited at a lower electron-excitation energy than the 3 d-series characteristic X-rays. In the neighbourhood of the 4 delectron thresholds, four line-like structures extend to -8 eV below the 4 d-electron binding energies, while two broad and more intense structures occur above the 4 d onsets, with the largest one reaching a peak intensity at I2 eV above the 4 d thresholds. The resonant emissions apparently arise from the decay of threshold-excited states which are bound to the inner vacancy and have core configurations /z d94j3, (n = 3,4). The exchange interaction between the three 4 y electrons and the respective &orbital vacancy spread the 4 d-threshhold structures over a 20-eV range of excitation energies and the 3 d-threshold structures over a much smaller range.
M B Chamberlain and W L Baun, J Vuc Sci Techo/, 12 (5), 1975,
1488.
CO2 laser induced breakdown and heating of hydrogen in a magnetic mirror field geometry. (Canada)
1047-1051.
At 1 GW, 125 J CO2 laser pulse focused by a 10 cm f.1. parabolic mirror has been used to induce breakdown and heating in 15 torr hydrogen along the axis of a short 50 kG magnetic mirror field. Evolution of the breakdown plasma thus produced has been studied by high speed photography, ruby laser Thomson scattering, and a Mach-Zehnder interferometer. Results indicate an efficient radial confinement of plasma by the mirror field with an electron temperature much enhanced over that resulting from a fieldfree breakdown. Interferometric measurements show that breakdown results in a cylindrical plasma with an electron density minimum on axis in both
1492. X-ray emission from COz-laser-produced to ~10” W crnmz for 26 elements. (GB)
86
PHYSICS
34
plwmas at powers up
The X-ray emission from COz-laser-produced plasmas has been studied for target elements covering the atomic number range Z = 6-92. For irradiations of ~7 x 1O’O W cmsz the X-ray yield was less than -3 x 10d6. Plasma temperature has been measured as a function of incident power over the range (2-8) x lOlo W cmwz for carbon and titanium and is typically 100-150 eV. J A McMordie and A C Simmons, J Whys. D: Appl. Whys, 8 (12), 1975, Ll33-Ll36.
abstracts
1484-l
492 30
1484. Ion implantation during film growth and its effect on the superconducting properties of niobium. (USA) Low-energy (5500 eV) Kr+ ion bombardment during film growth and its consequences on superconducting properties of Nb are studied in a triode glow discharge sputtering configuration. Tc is depressed from the bulk value at a rate of -O.l9’C/a~ % dissolved in the lattice. The residual resistivity shows an increase of 3.4 FQ cm/at.% Kr. It is shown that radiation damage due to ion bombardment dominates the superconducting properties up to 0.2 at.:< dissolved, whereas above this Kr concentration, up to -2 at.?< Kr, the noble-gas content dominates the transport properties. All films show a dilated la&e which is mainly caused by energetic bombardment during film growth rather than subsequent trapping of the Kr gas. G Heim and E Kay, J App/Phys, 46 (9), l975,4006-4Ol2. 31
1485. Redeposition of sputtered species during ion etching of Cu, Ag, and Au. (USA) The redeposition of sputtered, Au, Ag, and Cu onto glass surfaces, which are in the same plane as bombarded metal foils, has been established by ion scattering spectrometry. Sites near the sputtering centre were analysed with sensitivities of 0.0008-0.001 monolayers after neon bombardment of the foils for up to two hours. From the data, the redeposition coverage is estimated to be from 0.009d to 0.04z monolayers after two hours of Ne bombardment at I500 eV. The electric field of the incident ion beam, acting on low-energy sputtered ions, is a likely cause of the redeposited material.
A C Miller 1086-1087.
and A W Czanderna, J Vuc Sri T&no/,
12 (5), 1975, 31
1486. Low-voltage triode sputtering with a confined plasma. Part It: Plasma characteristics and energy transport. (USA) The plasma characteristics of a triode low-voltage sputtering (LVS) system have been measured. The curren&voltage relationships in the confined plasma discharge, of the target and of thesubstrate table, have been investigated as a function of pressure for Ar and Xe, with and without an axial magnetic field. The power dissipation and steady-state temperature at the target and substrate table were also measured as a function of operating conditions. From these measurements the plasma potential and target current densities could be deduced. The application of these results to sputter deposition is considered.
T C Tisone and P D Cruzan, J Vuc Sci Techno/, 12 (5), 1975, 10581066. 31
1487. Ultra-stable bias. (USA)
system for rf sputtering with &induced
substrate
Radio-frequency sputtering with rf-induced substrate bias has been shown to be extremely valuable in tailoring the properties of many thin films. The use of this process has been inhibited by the lack of availability of simple equipment to implement it. We have designed a system which (1) is very rugged and reliable; (2) has no sensitive or critical tuning controls; (3) is insensitive to phase relationships; (4) is insensitive to fluctuations in gas discharge ympedance, (5) is extremely stable, reproducible, and repeatable for long periods of time under a variety of sputtering conditions; and (6) can be operated, literally, in “push-button” fashion. J L Vosen and J J O’Neitl, j Vat Sci Techol, 12 (S), 1975,lO52-1057.
33. NUCLEONICS 33
casts. A monitor of the transmitted CO2 laser pulse indicates very incomplete coupling of laser radiation inlo the plasma column with the field applied, presumably due to refraction losses at the entrance boundary of the breakdown. A A Offcnbergcr and N H Burnett, cfftt J P/IJW, 53 ( 14). 1975, 13601366.
34. ELECTRONICS TECHNOLOGY
AND
HIGH
ALTITUDE
AND 34
1489. Plasma-cathode electron gun. (USA) The plasma-cathode electron gun is a new type of electron source which is suitable for applications requiring a large area, high-energy electron beam. It employs a plasma generated within a cold lowvoltage, hollow-cathode discharge as the source of electrons. Plasma cathode devices are characterized by their simplicity and versatility, and they offer a number of advantages over other designs. An electron gun producing a beam with dimensions of 5 x I25 cm has been developed for use with high-power cw gas lasers. This device has been operated at beam energies of I50 keV and cw beam current densities of 0.1-0.2 mA/cmz. J R Bayless, Rer Sci /m/rwn, 46 (9), 1975, I 158-l 160. 34 1490. Vacuum ultraviolet radiometry with hydrogen arcs. 2: The high
power arc as an absolute standard of spectral radiance from 124 nm to 360 nm. (USA) A wall-stabilized hydrogen arc can be utilized as a standard source of spectral radiance since the continuum emission coefficient is calculable to within a few percent. Previous elTor& to apply this concept have been impeded by relatively large uncertainties associated with the plasma diagnostics. The present approach yields absolute intensities independent of other radiometric standards or the accuracy of any plasma diagnostics. The hydrogen arc is operated at high temperatures where the continuum emission coefficient reaches a broad, unique, and calculable maximum. Comparisons with other primary standards are consistent with the estimated uncertainty in the arc continuum intensities. W R Ott et al, App/ Opf, 14 (9). 1975,2l2l-2128. 34
1491. Excitation-energy-dependent resonances in X-ray emissions under near-threshold electron excitation of the Ce 3 d and 4 d levels. UJSAI Soft X-ray appearance potential spectra of the 3 d and 4 d levels of polycrystalline cerium metal are reported in this paper. Resonant X-ray emissions are observed when the electron-excitation energy sweeps through the ionization energies of the 3 d and 4 d levels. The resonant X-rays excited at the 3 d-level onsets are considerably more intense and are excited at a lower electron-excitation energy than the 3 d-series characteristic X-rays. In the neighbourhood of the 4 delectron thresholds, four line-like structures extend to -8 eV below the 4 d-electron binding energies, while two broad and more intense structures occur above the 4 d onsets, with the largest one reaching a peak intensity at I2 eV above the 4 d thresholds. The resonant emissions apparently arise from the decay of threshold-excited states which are bound to the inner vacancy and have core configurations /z d94j3, (n = 3,4). The exchange interaction between the three 4 y electrons and the respective &orbital vacancy spread the 4 d-threshhold structures over a 20-eV range of excitation energies and the 3 d-threshold structures over a much smaller range.
M B Chamberlain and W L Baun, J Vuc Sci Techo/, 12 (5), 1975,
1488.
CO2 laser induced breakdown and heating of hydrogen in a magnetic mirror field geometry. (Canada)
1047-1051.
At 1 GW, 125 J CO2 laser pulse focused by a 10 cm f.1. parabolic mirror has been used to induce breakdown and heating in 15 torr hydrogen along the axis of a short 50 kG magnetic mirror field. Evolution of the breakdown plasma thus produced has been studied by high speed photography, ruby laser Thomson scattering, and a Mach-Zehnder interferometer. Results indicate an efficient radial confinement of plasma by the mirror field with an electron temperature much enhanced over that resulting from a fieldfree breakdown. Interferometric measurements show that breakdown results in a cylindrical plasma with an electron density minimum on axis in both
1492. X-ray emission from COz-laser-produced to ~10” W crnmz for 26 elements. (GB)
86
PHYSICS
34
plwmas at powers up
The X-ray emission from COz-laser-produced plasmas has been studied for target elements covering the atomic number range Z = 6-92. For irradiations of ~7 x 1O’O W cmsz the X-ray yield was less than -3 x 10d6. Plasma temperature has been measured as a function of incident power over the range (2-8) x lOlo W cmwz for carbon and titanium and is typically 100-150 eV. J A McMordie and A C Simmons, J Whys. D: Appl. Whys, 8 (12), 1975, Ll33-Ll36.