Plasma immersion ion implantation using polymeric substrates with a sacrificial conductive surface layer

Conventional ion beam implantation has been shown to modify the surface properties of polymers, giving an improvement in such qualities as hardness, conductivity and biocompatibility. Plasma immersion ion implantation (PIII) offers an alternative to conventional ion beam implantation, with the advantages of high implantation rates and conformal treatment of three-dimensional surfaces. There are, however, problems inherent to the application of PIII to non-conducting materials, such as the transfer of the high-voltage bias to the polymer and surface charging. To overcome these difficulties, we have developed a technique whereby a thin conductive film is deposited on the substrate prior to implantation. The film is contacted to the high-voltage pulser and ions from the plasma are implanted through the conductive film and into the underlying polymer. If required, the conductive film can be subsequently removed by etching, revealing the modified polymer surface beneath. Cross-sectional TEM results are presented, showing the extent of the implantation. Surface conductivity measurements show an increase with implantation time. The advantages and limitations of the technique are discussed.