Polymer Ion Implantation: Present and Future Prospects
Ljiljana S. Korugic-Karasz and Eufrozina A. Hoffmann
Ion implantation is an effective surface treatment process for various materials such as metals, semiconductors, ceramics, biomaterials and polymers. The ion implantation process directs beams of ions into the materials. The implanted ions lose energy in different ways: Inelastic collisions with bound electrons in the target, elastic collisions with atomic nuclei, elastic electronic collisions, inelastic nuclear collisions, nuclear excitations and reactions. Of these the first two are the most important.
There are a number of types of ion implanters. The conventional ones [1] use an accelerator to produce ions (with typically up to 20–400 keV energy). A relatively inexpensive alternative is plasma enhanced ion implantation, which uses lower energy (a few keV) ions at higher doses. Several variations are in use: Plasma Immersion Ion Implantation (PII), Plasma Source Ion Implantation (PSII) and using a bi-polar high voltage pulses the Plasma Based Ion Implantation and Deposition (PBIID).
The first application of ion implantation, forming the transistors was patented by W. Shockley in 1954. In 1960s major efforts occurred to study effects of implanting dopants into semiconductors. In 1970s fabrication of microelectronic devices based ion implanted silicon started, and the modification of surface properties of metals was studied. In 1980s ion implanted biomedical components reached the market and the ion implantation as a standard technique was established.
Implantation of polymers started in the 1980s as well, making possible the modification of a variety of properties (see Table I) thus enabling new industrial and bio-medical applications. Details of the chemical processes occurring in the polymer host under ion bombardment has recently been reviewed by Sviridov et al. [2].