Silicon damage control through the use of aromatic hydrocarbon ion implantation

Abstract

The continuous shrinking of transistor devices calls for precise doping profile control. Generally, monomer carbon (C+) is implanted at doses too low to adequately form an amorphous layer in silicon. Previous experiments used a molecular carbon species combined with dedicated vaporizer-based hardware, but this experiment was carried out using a commercial implanter and source with a liquid precursor material. The use of higher mass molecular carbon ions, such as C7H7+, impart significantly more damage to the silicon than the monomer, and can easily result in a well-defined amorphous layer. There are many species of molecular carbon that can be implanted, but in order to utilize a hot cathode plasma (HCP) ion source some additional criteria must be met. The source feed material should fragment with high-yield of molecular carbon (Cx+, x = 2–8) ions, which could then be extracted at beam currents sufficient to meet production needs using standard ion implant techniques. In this work, we surveyed several candidates for forming the molecular carbon species that could meet the requirements outlined above, reported the performance in plasma formation, and investigated materials properties of the Si after implantation.