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Shunted Cathode Enhancement
With the aid of magnetic modeling software, Soleras has developed a low-cost method to improve older cathode designs. By modeling existing magnetic profiles and adding magnetic “shunts” into the cooling plates of cathode assemblies, magnetic profiles can be altered for process improvement. The shunt flattens the magnetic field lines above the target face. The modification offers two distinct benefits: longer target life, and a more stable plasma impedance. |
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Standard Magnetron Configuration |
Enhanced Configuration |
| The purpose of the magnetic field in any magnetron arrangement is to intensify and confine electrons above the face of the target causing a high gas ionization rate. Material removal is most efficient where the magnetic field lines run parallel to the target face. See the diagram above. The ideal magnetic configuration would have parallel lines across the entire target face. In a normal magnet arrangement (shown on left), as the target erodes, the magnetic strength of the electron capture field becomes stronger. This intensifies and confines the plasma into a small, confined space leading to narrow erosion grooves, low target utilization, and a lower yield. Voltage must be increased over the target lifetime to maintain a consistent product. In a “shunted” arrangement (shown on right), as the target erodes, the magnetic strength of the electron capture field remains more constant. The plasma is not confined to a small erosion area and voltage is more stable over the target lifetime. This leads to a stable process and more consistent product. |
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