An Introduction to Plasma Source Ion Implantation

What is ion implantation?

Ion implantation is a process by which ions are accelerated to a target at energies high enough to bury them below the target's surface. Depending on the application, the acceleration energies can range from a few keV to MeV.

What is ion implantation used for?

Ion implantation was developed as a means of doping the semiconductor elements of integrated circuits. Because of the speed, accuracy, cleanliness and controllability of the process, it has become the standard for this type of work.

In the early 1970s, it was found that ion implantation of metal surfaces could improve their wear, friction and corrosion properties. Ion implantation of specific tools is now preferred over other types of coating technologies because the ion implanted layer doesn't delaminate, doesn't require high processing temperatures to produce, and doesn't add more material on the surface (which would change the size of critical components).

Ion implantation is now used regularly to implant specific tools and equipment (e.g. score dies for aluminum can pop-tops and artificial knee and hip joints). Studies have shown considerably more applications can benefit from ion implantation, however, the expense of the process prevents it from becoming cost-effective for those applications.

What is Plasma Source Ion Implantation?

Plasma Source Ion Implantation (PSII), developed by Professor John Conrad at the University of Wisconsin - Madison, is a different approach to ion implantation.

Conventional ion implantation setups extract a stream of ions from an ion source, accelerates and focuses them into a beam, which is rastered onto the target. Often the ion beam must be partially masked to prevent the ions from striking the target at above 30 degrees off-normal. This insures that most of the ions are being implanted and reduces sputtering (effectively, atomic-scale sand blasting). In addition, the sample must often be rotated and manipulated in the vacuum to insure all parts have been treated.

PSII places the target inside the ion source itself. No ion beam is extracted and none needs to be manipulated or focused. High voltage negative pulses applied to the target attract positive ions in the plasma which naturally strike all parts of the target at normal incidence (the optimal angle for ion implantation).

The PSII Laboratory at the University of Wisconsin - Madison.

At the PSII Laboratory, we help develop new applications for ion implantation and often work with companies to try to bridge the gap between university research labs and factory production lines.

Plasma Source Ion Implantation Laboratory
Department of Nuclear Engineering and Engineering Physics
University of Wisconsin - Madison
1500 Engineering Drive
Madison, WI 53706-1687
Phone: (608) 263-1609 Fax: (608) 263-4739