Materials Processing

Materials processing by implantation of energetic ions into solid surfaces has been applied in many fields of modern production technologies. For the last 40 years, ion implantation became the key technology especially in semiconductor technology for the production of ultra-large-scale integrated (ULSI) circuits, for example, silicon processors and memory devices. The type and value of semiconductor conductivity can be selected by the type and amount of implanted doping ions, for example, implantation of boron, gallium, or indium ions for p-type doping and of phosphorous, arsenic, or antimony ions for n-type doping of silicon. The necessary dopant concentration to be implanted is below 0.1 at.%. On the other hand by implanting high ion fluences, high impurity concentrations of tens of at.% can be achieved giving the possibility to synthesize buried layers of compound materials, for example SiO2 layers in Si by high fluence oxygen ion implantation. The well-known relations between ion energy and ion penetration depth for all important dopant–semiconductor combinations meet the demands of microelectronic technology for introducing doping concentrations with an error smaller than ±1 %. Lateral doping homogeneities over large wafer areas with an error of ~1 %, multiple implantation steps of different ions without significant interaction of the introduced dopants are standard for the ion implantation technique. Ion implantation is the only doping technique for the fabrication of device structures with dimensions in the nanometer range.