Market / Customer Need
What it is, what it does, why initiated.
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Exothermics are a provider of specialty materials and thin films. Their primary business activities focus on the development/manufacture of hot isostatically pressed (HIP’ed) alloys and refractory compounds, as well as sputtered films. One of their customers had a need to combine multilayer functional ferromagnetic layers in a single product. After smaller scale testing conducted in collaboration with Gencoa, they then approached Gencoa again to fulfil the requirement to provide cathodes for a new larger-scale production machine.
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Project Details
What project involves R&D, design, testing ….
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The project involved converting one of their existing vacuum vessels into a sputtering system that could deposit films onto larger substrates. The two primary challenges encountered concerned the fact that one of the target materials was ferro-magnetic, while the other target installation called for a large area RF cathode to sputter from insulating ceramic targets.
The particular problem with ferro-magnetic targets in large scale production is the requirement for use of thick targets along with high target utilization.
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Initial Requirements
Materials, performance specs, standards, testing..
The requirement was to take an existing vacuum system and create a production worthy process for highly novel multi-layer structures. Gencoa as the cathode provider worked with Exothermics to device the optimum solution. As no oxygen gas could be tolerated in the chamber, the decision was made to use a non-reactive oxide process based upon the use of different types of insulating target materials. The ferro-magnetic target materials of interest for Exothermics were non-standard and hence B/H curve data had to be measured before accurate magnetics modelling was possible.
The ideal solution for the ferro-magnetic targets was the Gencoa LOOP cathode design with the aim to use 10mm thick nickel alloy targets.
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Difficulties Experienced
What uncertainty, materials, process, testing, cost implications
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Although the LOOP technology is well established and patented, each time a different cathode size or ferro-magnetic target material is required, there is a need for extensive modelling work to ensure an optimum solution. Also, modelling and plasma / target predictions for LOOP cathode is much more challenging than standard cathodes using non-magnetic target materials. Uncertainty will also exist if the B/H data for a measured sample of the target material does not match the as manufactured material for the target.
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Hence, the actual plasma tests showed that to optimise target use further small changes to the target designs are needed and iterations was the best approach as one solution for one material may not be the best solution for a new material blend. The new system produced product from the initial turn-on and Gencoa and Exothermics worked together to fine tune the process to give the maximum cost efficiency. This ultimately resulted in a thinner target (6mm) with higher target use being preferred to the initial 10mm thickness delivered.
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Innovation
New innovative features – over state of the art for Gencoa / industry
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The LOOP technology is exclusive to Gencoa and the choice of target materials for Exothermics meant this was a new design of target. The LOOP technology provides a clear advantage compared to the conventional approach but is more challenging. It is also the first time to our knowledge that a dielectric or semiconducting plus magnetic layer stack has been produced in a large scale production environment.
Also, large area RF powered cathodes are not trivial and Gencoa designed with care the RF circuit, the Faraday cage and the RF matching unit interface. As both the RF and DC processes were positioned side-by-side in the deposition chamber, two RF blocking filters had to be installed on the DC cathodes to prevent damage to the DC power supplies.
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Technology Improvement
How project has advanced tech / scientific knowledge
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The project has further advanced the LOOP cathode technology as new materials have been successfully sputtered.
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