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| Sierra Applied Sciences offers both round and rectangular cathodes in a multitude of sizes ranging from 2” round to 12” round, and 2” to 11” wide up to 140” long, and in any fractional length increment. In addition to interface and size options, there are options for: target configurations; target clamping; target-water membranes; ground shield configurations; cooling water connections; high flow rate water connections; power connections; gas manifolds; magnets for magnetic targets; and magnets for high B field applications. We only discuss target clamping and mounting options here, but our sales/engineering team can answer any specific questions you might have (Select type of cathode below and place cursor over the various components for more info). |
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Internal Cathodes are mounted inside the vacuum chamber. The water and power are delivered via an atmospheric connection, such as NW50 tubing. The advantages of this style of cathode are that it can be mounted on the chamber wall as well as far away from the wall, and that the atmospheric seal to the power and water have small and easy-to-maintain seal surfaces. A disadvantage is that it may take up too much space within the chamber. For most models, the dark space gap is adjustable. We recommend a gap of 0.125". Internal cathodes are made to adapt to an NW fitting (place cursor over components to see specific information).
Flange Mount Cathodes mount from outside the chamber wall. This allows them to be sealed directly to the chamber with a metal flange and single o-ring instead of a teflon insulator/seal. It is possible to inject process gas through the sealing flange behind the cathode similarly to the internal cathodes with their gas manifolds (place cursor over components to see specific information).
Target
Sierra's cathodes can be built to accommodate unmodified, stepped, bonded, or indirectly cooled targets (click target for more details).
Target Clamps
Clamps come in a variety of styles depending on target style and mounting configuration (click clamp for more details).
Water Channel
Sierra's cathodes come standard with a water channel designed to operate with a flow of ~2gpm @ 30psi. We also offer a High-Flow model which is designed to operate with a flow of 15-20 gpm @ 30psi (click water channel for more details).
(Note: High-Flow models are NOT designed to be run at 2gpm and will experience cavitations at low flow rates).
MagPack
The cathode's magnet pack is what determines the performance of that cathode. MagPacks are designed with 3 major considerations: film uniformity, target utilization, and the magnetic permeability of the target material (click magpack for more details).
Cathode Body
body overText (click cathode body for more details)
Water Fittings
Sierra's water fittings are brazed directly into the cathode body and are made of either 304 SS or brass. Typical water fitting styles include pipe thread, Pisco®, Swagelock®, and unmodified. However, almost any type of connection can be accommodated.
Water Tubes
Sierra's water tubes are brazed directly into the cathode body and are made of either 304 SS or brass. Typical water tube fitting styles include pipe thread, Pisco®, Swagelock®, and unmodified. However, almost any type of connection can be accommodated.
Insulator Seals
Sierra's cathodes come with insulator seals made of either Delrin® or Teflon® and use Viton® O-Rings.
Flange
flange overText (click flange for more details)
Shields
Sierra's cathodes came standard with 304 SS top shields and 6061 AL side shields. We suggest a 1/8" dark space gap, although this is ultimately decided by the customer (click shield for more details).
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Unmodified - a standard target design requiring no modifications to the target, cutting down on material costs. These cathodes are designed to cool the target directly, allowing the water to come into direct contact with the target, sealing with a Viton O-Ring.
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Stepped - a stepped target has material removed from the substrate side of the target, creating a step which the target clamp recesses into. Because the clamps are recessed, they don't protrude into the plasma region. This allows for a wider erosion path, thereby increasing target utilization and decreasing film contamination.
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Bonded - targets can be bonded to a Copper backing plate if the target material doesn't have much native structural integrity. Special "lipless" clamps can be used on bonded targets, but standard clamps are suggested. Bonded targets can also be stepped.
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Indirectly cooled - If there is concern with water contamination during target changes, a copper membrane can be placed underneath the target and be sealed with a Viton O-Ring and a separate set of clamps. Although this ensures that there is no possibility of accidentally getting water in the chamber, the target is less effectively cooled.
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Standard Clamp
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Two-Piece Membrane Clamp
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Clamp for Bonded Target
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(graph of water flow)
Standard - the basic magnet configuration. Offers maximal target utilization while maintaining a film uniformity of (?95%?)
High Uniformity - the magnet pack can be designed to accommodate incredibly high demands for film uniformity. The magnet configuration shown can achieve uniformities of ~%, but not without a significant trade-off in utilization (?25%?).
High Utilization - the magnet pack can be designed to accommodate incredibly high demands for target utilization. The magnet configuration shown can achieve target utilizations of ~%, but without t a significant trade-off in film uniformity (?85%?).
Magnetic Materials - The magnet packs can be designed to accommodate materials with high magnetic permeabilities (iron, cobalt, nickel, etc.). Sierra's magnetic desgins minimize the effects of magnetic pinching that occur in those types of materials.
body clickText
flange clickText
(image of dark space gap between target and top shield + labels of top shield and side shield)
