LBNL Office of science Department of Energy

Ion Beam Technology Group

Lawrence Berkeley National Laboratory

Accelerator Technology & Applied Physics Division

Plasma Applications

Using Plasmas to Tailor-Make Films and Modify Surfaces

Diamondlike-carbon source and twist filter for macroparticles

The twist filter's compactness (several inches long, compared to the meter or so of older filters) is enabled in part by the use of a small cathode, on which the arc spot has much less room to travel. The great reduction in cathode size was enabled by switching to an intense pulsed mode. A shorter filter means less plasma loss (and therefore higher throughput) and also allows this product to be easily fitted into existing coating systems.

Yet another aspect of how IBT expertise can solve diverse problems for the research community may be found in our Plasma Applications Group. Highlights of their work include deposition of advanced coatings and thin films.

In the 1990s, the group developed a technology, the filtered cathodic arc plasma source, for depositing thin films of tetrahedral amorphous carbon—the most diamondlike of all the “diamondlike carbon” materials (DLCs). The films approached the hardness of diamond and are transparent, atomically smooth, chemically inert, and insulating.

Among the many applications, one of the most recent is applying unprecedentedly thin and even films of diamondlike carbon (DLC) to protect the read-write heads of hard disks. This allows the heads to fly closer to the platters, increasing the amount of data that can be stored on the disks—a tiny distance with huge societal implications. This application was recognized with a 2009 R&D 100 award. Additional applications that are being explored include:

  • Durable hard coatings for tools and for low-friction surfaces such as biomedical implants.
  • Less-expensive, indium-free transparent conductive coatings for displays, touch screens, and solar panels.
  • Hard-disk platters as well as heads.
runaway sputtering image

Runaway magnetron sputtering in action This potential breakthrough in high-power impulse magnetron sputtering, now in a developmental stage, achieves runaway self-sputtering, a breakthrough that could be the key to simple, in vacuum deposition of quality coatings of metals.

Several aspects of Plasma Applications Group expertise come together in this recent development: a cathodic arc plasma source (white and gold bands) and open twist filter. The combination has been incorporated into a coating system for hard-drive read/write heads, offered by Veeco, Inc., and now being put into production use by major drive manufacturers. The twist filter conducts a carbon plasma through a helical bend while undesirable macroparticles fly out. Older macroparticle filters had only a single 90-degree bend and were enclosed. They could reflect macroparticles all the way to the head, where they would loom as large in the head's flight over the disk surface as a house on an airport runway.