Direct patterning of nanometer-scale silicide structures on silicon by ion-beam implantation through a thin barrier layer

CoSi₂ structures were formed by focused ion-beam implantation. Patterned suicide lines with dimensions down to 150 nm were produced on (100) silicon. The process involved the ion implantation of 200 keV As⁺⁺ through a cobalt (34 nm)/oxide (~2 nm) thin film structure. The thin oxide at the Si/Co interface acted as a selective reaction barrier. Ion-beam mixing disrupted the oxide layer to allow silicidation to proceed during subsequent rapid thermal anneal treatments. Reactions were inhibited in nonimplanted areas. A threshold dose of 3 × 10¹⁵ cm^-2 was required for process initiation. Electrical measurements resulted in resistivities ranging from 15 to 30 μΩ cm.