Plasma immersion ion implantation: From microelectronics to biomedical engineering

Plasma immersion ion implantation (PHI) is a very useful technique in the fabrication of silicon-on-insulator and high-k dielectrics and is commercially used to produce shallow junctions in deep-sub micro meter integrated circuits. The applications of PHI are in fact much broader covering many other areas such as metallurgy and particularly biomedical engineering. Many of the innovations and protocols developed for PHI in semiconductor applications have been translated to the processing of biomedical components. In this invited talk, our recent work of PHI related to biomedical science and engineering is reviewed. As an important material in bioMEMS, the biocompatibility of single-crystal silicon must be improved. Our experiments indicate the osteo-compatibility of crystalline silicon can be improved by hydrogen plasma immersion ion implantation. The ability to grow apatite (bone) on silicon stems from the hydroxyl bonds on the silicon surface after hydrogen PHI and the amorphous surface created by ion bombardment. The concept has been expanded to hip joints with a plasma-sprayed titania and improved surface biocompatibility can indeed be attained by hydrogen PHI, nano-powder plasma spraying, and irradiation with ultra-violet light. Our recent work on materials which are used as both high-k dielectrics in microelectronics and biomedical coatings on biomedical implants is described. By means of plasma immersion ion implantation, the surface osteo-compatibility of high-k materials such as Zrθ2 can be improved. The mechanism of the improvement will be discussed. A couple of new innovations in this area such as plasma treated polymers and medical devices used to automatically correct spinal problems such as scoliosis will be presented in this invited talk. The latter has in fact gone into clinical trials with a number of patients having been implanted with the correction devices surgically.