The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Yasunori Ohtsu - One of the best experts on this subject based on the ideXlab platform.
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characteristics of a rotational windmill shaped radio frequency magnetron sputtering plasma for effective Target Utilization
Vacuum, 2020Co-Authors: Yasunori Ohtsu, Takahiro Nakashima, Rei Tanaka, J SchulzeAbstract:Abstract A rotational windmill-shaped radio frequency magnetron plasma source has been developed for improving the Target Utilization rate. Two kinds of magnet arrangements are designed by taking into account the E × B drift motion of electrons using simulated magnetic field profiles, where the electric field, E, is vertical to the Target and the magnetic field, B, is parallel to the Target, respectively. It is found that the Hall parameters of the electrons in the magnetron area have a higher value ranging from 12 to 110 for both magnet arrangements. This is high enough to magnetize electrons, while the electron Larmor radius is as low as 0.3–2.8 mm. The Target Utilization rate has attained approximately 65 % and 70 % for an initial and for an improved magnet arrangements, respectively. The improved magnet arrangement has a uniform profile of the Target erosion compared with the initial magnet arrangement.
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outer ring shaped radio frequency magnetized plasma source for Target Utilization in specific area
IEEE Transactions on Plasma Science, 2018Co-Authors: Md Amzad Hossain, Yasunori OhtsuAbstract:A capacitively coupled radio frequency outer ring-shaped magnetized plasma discharge has been proposed with a concentrically monopole arrangement of magnets to erode the Target in a specific area, especially, near the chamber wall. The three concentric monopole magnet arrangements with a center magnet and magnets in setups: 1) three circles; 2) two circles; and 3) one circle were investigated. From the magnetic flux lines profiles, it was found that the magnetic flux density in component parallel to the Target surface has a peak magnitude in the outer circle of magnets for all setups. Ring-shaped plasma in the specific outer area was observed. The ion saturation current, $I_{\text {isat}}$ were 0.6, 0.79, and 0.46 mA, for setups 1)–3), respectively, at $r = 47$ mm, where $r = 0$ mm is the center of the Target. It was found that $I_{\text {isat}}$ is very high in the outer Target region near the chamber wall for setups 1) and 2), where $I_{\text {isat}}$ for setup 3) decreases slowly. The results showed that the Target Utilization could be controlled in the outer specific area near the discharge chamber wall.
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rotational cross shaped magnetized radio frequency sputtering plasma source for uniform circular Target Utilization
Journal of Vacuum Science and Technology, 2017Co-Authors: Md Amzad Hossain, Yutaro Nakamura, Yasunori OhtsuAbstract:A rotational cross-shaped magnetized radio-frequency (RF) sputtering plasma source was developed for uniform circular Target Utilization. The cross-shaped magnetized RF plasma was attained by inducing a linear E × Br drift motion using a cruciform arrangement of neodymium magnets, where E and Br are the electric field perpendicular and magnetic field parallel to the Target, respectively. A two-dimensional magnetic field simulation clarified that the electrons are strongly magnetized by the Hall parameter at a magnitude 20 times that of the ions. Strong cross-shaped plasma discharges are observed. The temporal evolutions of the ion saturation current were measured by a Langmuir probe at various radial positions, and the time-averaged ion saturation current was found to decrease from the center to the outer area of the Target. The Target Utilization percentage was found to increase from 73.6% to 86.3% when Fe pole pieces were incorporated on the cruciform arrangement of neodymium magnets.
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Outer Circular Ringshaped RF Magnetized Plasma for Specificarea Target Utilization by Magnetic Monopole Arrangement
2017 IEEE International Conference on Plasma Science (ICOPS), 2017Co-Authors: Amzad Hossain, Yasunori OhtsuAbstract:We have proposed a radio frequency (RF) magnetized outer circular ring-shaped plasma sputtering source with a concentrically monopole arrangement of magnets with each gap of $d =5$mm for specific area Target Utilization [1–3]. The three setups, that is, with a center magnet, and type (a): magnet arrangement with three circles, type (b): magnet arrangement with two circles, and type (c): magnet arrangement with one circle are investigated from the point of view of specific area Target Utilization. The experiments were performed in stainless-steel cylindrical RF discharge chamber with outer diameter of 235 mm, inner diameter of 160 mm and 195 mm in height, where Ar gas pressure of 1.50 [Pa], and RF power of 50 [W] at 13.56 [MHz] are used to produce the plasma. From the 2D magnetic flux lines and their profiles, it is found that the magnetic flux density in component parallel to the Target surface has a peak outside the exterior circle of magnets for all setups. Ring-shaped plasma in the specific outer area is observed at the position with the peak magnetic flux density and its diameter depends on a number of magnet circles. The results show that the Target Utilization can be controlled in the outer specific region near the wall. The typical RF magnetized plasma discharge, the RF discharge voltages, the self-bias dc voltages and the radial profiles of ion saturation currents, electron temperature and plasma density have been also investigated.
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plasma characteristics and Target erosion profile of racetrack shaped rf magnetron plasma with weak rubber magnets for full circular Target Utilization
Surface & Coatings Technology, 2016Co-Authors: Yasunori Ohtsu, Tatsuo Tabaru, Shohei Tsuruta, Morito AkiyamaAbstract:Abstract We have developed the racetrack-shaped RF magnetron plasma with weak rubber magnets (ferrite and neodymium) for the full Utilization of the circular Target and the reduction of the magnet weight. The magnetic field simulations are analyzed for the ferrite rubber magnets, the neodymium rubber magnets, and the neodymium rubber magnets including the neodymium metal magnets. The magnetic flux density indicates a mountain like profile between the magnets, having a maximum for the neodymium rubber and metal magnets. It is found that the ion flux to the Target has a peak in the gap between two rubber magnets and the value remarkably increases with the addition of neodymium metal magnets. The erosion of the circular copper Target, with 100 mm in diameter, has been studied by rotating the racetrack-shaped RF magnetron plasma for the neodymium rubber magnets including the neodymium metal magnets. It is seen that radial profile of the erosion depth keeps roughly constant until r = 20 mm and then decreases gradually away from the center for RF power of 40 W, Ar gas pressure of 2 Pa and sputtering time of 4 h. The Target Utilization is approximately 72% estimated from the erosion profile.
Morito Akiyama - One of the best experts on this subject based on the ideXlab platform.
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plasma characteristics and Target erosion profile of racetrack shaped rf magnetron plasma with weak rubber magnets for full circular Target Utilization
Surface & Coatings Technology, 2016Co-Authors: Yasunori Ohtsu, Tatsuo Tabaru, Shohei Tsuruta, Morito AkiyamaAbstract:Abstract We have developed the racetrack-shaped RF magnetron plasma with weak rubber magnets (ferrite and neodymium) for the full Utilization of the circular Target and the reduction of the magnet weight. The magnetic field simulations are analyzed for the ferrite rubber magnets, the neodymium rubber magnets, and the neodymium rubber magnets including the neodymium metal magnets. The magnetic flux density indicates a mountain like profile between the magnets, having a maximum for the neodymium rubber and metal magnets. It is found that the ion flux to the Target has a peak in the gap between two rubber magnets and the value remarkably increases with the addition of neodymium metal magnets. The erosion of the circular copper Target, with 100 mm in diameter, has been studied by rotating the racetrack-shaped RF magnetron plasma for the neodymium rubber magnets including the neodymium metal magnets. It is seen that radial profile of the erosion depth keeps roughly constant until r = 20 mm and then decreases gradually away from the center for RF power of 40 W, Ar gas pressure of 2 Pa and sputtering time of 4 h. The Target Utilization is approximately 72% estimated from the erosion profile.
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production of radio frequency magnetron plasma by monopole arrangement of magnets for Target uniform Utilization
Vacuum, 2014Co-Authors: Yasunori Ohtsu, Morito Akiyama, Masakazu Shigyo, Tatsuo TabaruAbstract:Abstract The monopole magnet arrangement under sputtering Target has been proposed to improve Target Utilization in radio frequency magnetron plasma. Magnetic field analysis simulation indicates that a magnetic tunnel on the sputtering Target for the monopole arrangement increases twice as much as that for the conventional arrangement. The profiles of the ion flux to the Target and the Target erosion depth has been investigated at three magnet spacings of 10, 30 and 70 mm. It is found that radial profile of the ion flux is almost similar to radial profile of the magnetic flux density in radial direction which is an important component for magnetron discharge at all magnet spacings. The ion flux profile has become uniform with decreasing the spacing although the ion flux decreases with reducing the spacing. The erosion profile of the Target corresponds to the ion flux profile near the Target at three spacings. The Cu Target Utilization percentage increases with decreasing the spacing and attains the highest value of 59% at the spacing 10 mm. It is obtained that the resistivity of Cu thin film deposited is approximately 4.6 × 10 −8 Ωm, which is almost of the same order with the bulk resistivity.
Tatsuo Tabaru - One of the best experts on this subject based on the ideXlab platform.
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Magnetron sputtering cathode for inward enlargement of doughnut-shaped plasma discharge area
Vacuum, 2019Co-Authors: Taisei Motomura, Tatsuo TabaruAbstract:Abstract A unique magnetron sputtering cathode with a pinhole-centered permanent magnet has been developed for an inward enlargement of doughnut-shaped plasma discharge. Both a pinhole-centered permanent magnet and a tilt of magnetization vector to the normal to the top surface of the Target play an important role for the inward enlargement of the plasma discharge area. The radial differentiated radial component of magnetic field strength, d | B r | / d r , near the center is useful to explain the inward enlargement of the plasma discharge area. By the means of the tilt of magnetic field lines at 45° to the normal to the Target surface, the magnetic field lines are compressed near the Target center compared with conventional magnetron cathodes, and which also provides strong magnetic mirror configuration near the Target center. The Target Utilization efficiency by volume ratio was ~ 50 % in the use of proposed magnetron cathode. An aluminum deposition rate of ~ 6.7 nm/min was obtained under experimental conditions with a Target-substrate distance of 150 mm, Ar gas pressure of 0.2 Pa, and DC input power of 100 W.
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plasma characteristics and Target erosion profile of racetrack shaped rf magnetron plasma with weak rubber magnets for full circular Target Utilization
Surface & Coatings Technology, 2016Co-Authors: Yasunori Ohtsu, Tatsuo Tabaru, Shohei Tsuruta, Morito AkiyamaAbstract:Abstract We have developed the racetrack-shaped RF magnetron plasma with weak rubber magnets (ferrite and neodymium) for the full Utilization of the circular Target and the reduction of the magnet weight. The magnetic field simulations are analyzed for the ferrite rubber magnets, the neodymium rubber magnets, and the neodymium rubber magnets including the neodymium metal magnets. The magnetic flux density indicates a mountain like profile between the magnets, having a maximum for the neodymium rubber and metal magnets. It is found that the ion flux to the Target has a peak in the gap between two rubber magnets and the value remarkably increases with the addition of neodymium metal magnets. The erosion of the circular copper Target, with 100 mm in diameter, has been studied by rotating the racetrack-shaped RF magnetron plasma for the neodymium rubber magnets including the neodymium metal magnets. It is seen that radial profile of the erosion depth keeps roughly constant until r = 20 mm and then decreases gradually away from the center for RF power of 40 W, Ar gas pressure of 2 Pa and sputtering time of 4 h. The Target Utilization is approximately 72% estimated from the erosion profile.
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production of radio frequency magnetron plasma by monopole arrangement of magnets for Target uniform Utilization
Vacuum, 2014Co-Authors: Yasunori Ohtsu, Morito Akiyama, Masakazu Shigyo, Tatsuo TabaruAbstract:Abstract The monopole magnet arrangement under sputtering Target has been proposed to improve Target Utilization in radio frequency magnetron plasma. Magnetic field analysis simulation indicates that a magnetic tunnel on the sputtering Target for the monopole arrangement increases twice as much as that for the conventional arrangement. The profiles of the ion flux to the Target and the Target erosion depth has been investigated at three magnet spacings of 10, 30 and 70 mm. It is found that radial profile of the ion flux is almost similar to radial profile of the magnetic flux density in radial direction which is an important component for magnetron discharge at all magnet spacings. The ion flux profile has become uniform with decreasing the spacing although the ion flux decreases with reducing the spacing. The erosion profile of the Target corresponds to the ion flux profile near the Target at three spacings. The Cu Target Utilization percentage increases with decreasing the spacing and attains the highest value of 59% at the spacing 10 mm. It is obtained that the resistivity of Cu thin film deposited is approximately 4.6 × 10 −8 Ωm, which is almost of the same order with the bulk resistivity.
Tadahiro Ohmi - One of the best experts on this subject based on the ideXlab platform.
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3.2: Invited Paper: Application of Rotation Magnet Sputtering Technology to a‐IGZO Film Depositions
SID Symposium Digest of Technical Papers, 2014Co-Authors: Tetsuya Goto, Shigetoshi Sugawa, Tadahiro OhmiAbstract:We developed new magnetron sputtering equipment called rotation magnet sputtering (RMS), where multiple moving plasma loops are exited on the planar Target surface, obtaining high Target Utilization. The moving plasma loops also worked efficiently to homogenize the spatial distribution of a-IGZO film qualities by time-averaged homogenization effect.
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56.2: Deposition of a‐InGaZnOx by Rotation Magnet Sputtering
SID Symposium Digest of Technical Papers, 2012Co-Authors: Akihiko Hiroe, Tetsuya Goto, Shigetoshi Sugawa, Tadahiro OhmiAbstract:We have developed a new magnetron sputtering equipment called Rotation Magnet Sputtering (RMS), and realized the Target Utilization rate of more than 60%. We applied this new system to the deposition of a-InGaZnOx films. Comparison of the spatial distribution of the film characteristics between RMS and conventional magnetron sputtering revealed that film quality near erosion area is better than the rest presumably due to the heating from plasma. It was also revealed that this spatial distribution is smaller for RMS than conventional magnetron sputtering, which can be another merit of RMS.
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Rotation magnet sputtering: Damage-free novel magnetron sputtering using rotating helical magnet with very high Target Utilization
Journal of Vacuum Science and Technology, 2009Co-Authors: Tetsuya Goto, Takaaki Matsuoka, Tadahiro OhmiAbstract:Novel magnetron-sputtering equipment, called rotation magnet sputtering (ROT-MS), was developed to overcome various disadvantages of current magnetron-sputtering equipment. Disadvantages include (1) very low Target Utilization of less than 20%, (2) difficulty in obtaining uniform deposition on the substrate, and (3) charge-up damages and ion-bombardment-induced damages resulting from very high electron temperature (>3eV) and that the substrate is set at the plasma excitation region. In ROT-MS, a number of moving high-density plasma loops are excited on the Target surface by rotating helical magnets, resulting in very high Target Utilization with uniform Target erosion and uniform deposition on the substrate. This excellent performance can be principally maintained even if equipment size increases for very large-substrate deposition. Because strong horizontal magnetic fields (>0.05T) are produced within a very limited region just at the Target surface, very low electron-temperature plasmas (
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rotation magnet sputtering damage free novel magnetron sputtering using rotating helical magnet with very high Target Utilization
Journal of Vacuum Science and Technology, 2009Co-Authors: Tetsuya Goto, Takaaki Matsuoka, Tadahiro OhmiAbstract:Novel magnetron-sputtering equipment, called rotation magnet sputtering (ROT-MS), was developed to overcome various disadvantages of current magnetron-sputtering equipment. Disadvantages include (1) very low Target Utilization of less than 20%, (2) difficulty in obtaining uniform deposition on the substrate, and (3) charge-up damages and ion-bombardment-induced damages resulting from very high electron temperature (>3eV) and that the substrate is set at the plasma excitation region. In ROT-MS, a number of moving high-density plasma loops are excited on the Target surface by rotating helical magnets, resulting in very high Target Utilization with uniform Target erosion and uniform deposition on the substrate. This excellent performance can be principally maintained even if equipment size increases for very large-substrate deposition. Because strong horizontal magnetic fields (>0.05T) are produced within a very limited region just at the Target surface, very low electron-temperature plasmas (<2.5eV for Ar p...
Md Amzad Hossain - One of the best experts on this subject based on the ideXlab platform.
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outer ring shaped radio frequency magnetized plasma source for Target Utilization in specific area
IEEE Transactions on Plasma Science, 2018Co-Authors: Md Amzad Hossain, Yasunori OhtsuAbstract:A capacitively coupled radio frequency outer ring-shaped magnetized plasma discharge has been proposed with a concentrically monopole arrangement of magnets to erode the Target in a specific area, especially, near the chamber wall. The three concentric monopole magnet arrangements with a center magnet and magnets in setups: 1) three circles; 2) two circles; and 3) one circle were investigated. From the magnetic flux lines profiles, it was found that the magnetic flux density in component parallel to the Target surface has a peak magnitude in the outer circle of magnets for all setups. Ring-shaped plasma in the specific outer area was observed. The ion saturation current, $I_{\text {isat}}$ were 0.6, 0.79, and 0.46 mA, for setups 1)–3), respectively, at $r = 47$ mm, where $r = 0$ mm is the center of the Target. It was found that $I_{\text {isat}}$ is very high in the outer Target region near the chamber wall for setups 1) and 2), where $I_{\text {isat}}$ for setup 3) decreases slowly. The results showed that the Target Utilization could be controlled in the outer specific area near the discharge chamber wall.
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rotational cross shaped magnetized radio frequency sputtering plasma source for uniform circular Target Utilization
Journal of Vacuum Science and Technology, 2017Co-Authors: Md Amzad Hossain, Yutaro Nakamura, Yasunori OhtsuAbstract:A rotational cross-shaped magnetized radio-frequency (RF) sputtering plasma source was developed for uniform circular Target Utilization. The cross-shaped magnetized RF plasma was attained by inducing a linear E × Br drift motion using a cruciform arrangement of neodymium magnets, where E and Br are the electric field perpendicular and magnetic field parallel to the Target, respectively. A two-dimensional magnetic field simulation clarified that the electrons are strongly magnetized by the Hall parameter at a magnitude 20 times that of the ions. Strong cross-shaped plasma discharges are observed. The temporal evolutions of the ion saturation current were measured by a Langmuir probe at various radial positions, and the time-averaged ion saturation current was found to decrease from the center to the outer area of the Target. The Target Utilization percentage was found to increase from 73.6% to 86.3% when Fe pole pieces were incorporated on the cruciform arrangement of neodymium magnets.
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high density radio frequency magnetized plasma sputtering source with rotational square shaped arrangement of rod magnets for uniform Target Utilization
Vacuum, 2016Co-Authors: Md Amzad Hossain, K Ikari, Yasunori OhtsuAbstract:Abstract We have developed a high-density radio frequency (RF) magnetized sputtering plasma source with a rotational square-shaped magnet arrangement for uniform Target Utilization. Eight neodymium rod magnets of 30 × 5 × 3 mm, where the connection between N-pole and S-pole magnets is one side of the square, are mounted on a circular iron yoke disc and an iron cover of 5 × 3 × 1 mm is also used for magnetic shielding of otiose magnetic fields from the permanent magnets. The magnetic field simulation, the measurement of the Target erosion and the time-averaged ion flux to the Target have been investigated (a) without iron cover and no air gap between N-pole and S-pole magnets, (b) with iron cover and no air gap, and (c) with iron cover and 5 mm air gap, respectively. It is found that the iron covers suppress the horizontal magnetic flux density and the copper Target Utilization percentage increases from 74.15% to 87.49%. Moreover, by decreasing the air gap between the shielded magnets, the copper Target Utilization percentage rises from 83.85% to 87.49%. The Target Utilization as well as the time-averaged ion flux to the Target is optimum for case (b).
