Surface modification by negative-ion implantation

We have developed a negative-ion implantation technique for surface modification of materials together with the development of high-intensity negative-ion sources and negative-ion implanters. In the negative-ion implantation, we have the advantage of a nearly “charge-up-free” property for the implanted surface of insulators or insulated materials. The charging voltage on the implanted surface is no greater than plus or minus a few volts. By virtue of this merit, negative-ion implantation can include more excellent applications than those accessible only by positive-ion implantation. Negative-ion implantation enables us to open various applications, such as ion implantation to large scale integrated circuits (LSIs) without an electron shower neutralizer, surface modification of micrometer-sized powders by implantation without scattering, and formation of metal nanoparticles by implantation in a thin insulator film without damage. Besides, this technique makes possible the manipulation of nerve cell growth by precise control of the biocompatibility of a polymer surface. In this paper, novel surface modification applications by negative-ion implantation are reviewed.