Advanced Plasma Immersion Technology and Applications
DescriptionPlasma immersion ion implantation and deposition (PIII&D), a proven surface modification technique encompassing the merits of plasma surface treatment and energetic ion bombardment, has widespread applications in microelectronics, metallurgy, nanotechnology, and biomedical engineering. In spite of technological advances heretofore, conventional PIII&D still suffers from a few intrinsic limitations such as ion fluence non-uniformity when dealing with components with a complex geometry and excessive surface damage in materials sensitive to plasma / ion interactions such as polymers. In this project, we aim at developing advanced plasma immersion technologies and new applications that would be difficult or even impossible with the current technology. One method is quasi-DC (direct current) PIII&D in which a continuous low pressure discharge is maintained in the vacuum chamber above a grid and there is no direct contact between the plasma and sample surface thereby reducing overheating and damage to the materials. In addition, the grid can be made with predesigned patterns to perform direct in situ surface patterning in concert with surface modification. The technique can thus be utilized to produce surface patterns and nanostructures in selected areas to tailor local surface properties and achieve desirable and long-term antibiotics and drug delivery effects. The concept can be extended to three-dimensional (3D) PIII by replacing the planar grids with cylindrical, spherical, or other types of 3Dscreens when processing components with a complex geometry like spinal medical implants and hip joints. Another novel idea is enhanced glow discharge PIII (EGD-PIII)in which external plasma sources are not required and the plasma with a density reaching 1E9 to 1E10 cm-3 is produced by self glow discharge. An electron-focusing electric field is formed between the small pointed hollow anode and large tabular cathode inside a dielectric cage when a negative voltage pulse is applied to the sample platen. Consequently, electrons including secondary electrons are all focused to the region near the hollow anode and a higher ionization rate of the species through the hollow anode can be achieved. In addition to better process efficacy, ionization of some solid materials with poor electrical conductivity and some semi-conducting materials that are difficult to ionize in traditional plasma sources can be enhanced. The overall objective of this proposal is to develop new plasma immersion techniques that will propel the technology in the coming decades and to cater to the more stringent requirements demanded by modern and upcoming applications.
|Effective start/end date||1/01/11 → 19/08/14|