Thin film selection for Diamond/Nickel interface

  1. Hello everyone. My task is to select a thin film and deposition method that will achieve a few goals.
    The thin film will be sandwitched between a diamond and nickel alloy. The thin film needs to:

    • Adhere to a diamond and nickel alloy strongly without inter diffusion.
    • Stay together up temperatures of 700K, and be decently thermally conductive.

    The film can be deposited via standard methods like sputtering, Evaporation, JDC, CVD, ect...

    I know that diamond and nickel have similar bond structures (sp3) and a thin film with a similar structure would help maintain a strong bond.

    Any info would be greatly appreciated!
  2. jcsd
  3. Typical film structure put down on diamond to enable solder attachment is Ti/Pt/Au. The Ti reactively bonds with the diamond surface, the Pt prevents inter diffusion, and the Au makes a good bond with solder.

    There's some work with Cr as the first layer on diamond. It forms a carbide, so adheres to diamond. Don't know how it would stick to nickel, nor do I know about its inter diffusion barrier properties.

    Most of the diamond adhesion systems I worked with were put on by sputtering. You have to have a good (low oxygen background pressure) sputtering system to successfully deposit Ti because it's very reactive and forms a super stable oxide if you have any background oxygen in the chamber.

    An alternative might be active brazing alloys, which contain a little bit of Ti that combines with diamond and whatever else you're bonding to the diamond when the braze melts. I used some products from S-bond to attach copper microprocessor heat spreaders to CVD diamond plates and it worked reasonably well. I think there are active braze alloys that might make your 700°C requirement, but I'm not sure. I used the S-bond material because it was easier than waiting through the out of house sputtering service turnaround.

    It probably doesn't help with adhesion that diamond and Ni have similar crystal systems. Ni doesn't form a carbide under normal conditions. Diamond abrasive makers sell Ni-coated diamond abrasives, so clearly they can stick Ni to diamond very well. They use fluidized-bed deposition, but I have no idea what the interface chemistry is.

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