Ultra Shallow Junction Formation by Cluster Ion Implantation

Abstract

ABSTRACTImplantation of B cluster ions into Si using decaborane (B10H14) has been demonstrated. SIMS measurements show that the depth distribution of boron atoms implanted with a monomer ion is exactly matched by that of boron atoms implanted from decaborane ions, if the cluster ion has an order of magnitude larger acceleration energy. According to the Langmuir-Child equation, two orders of magnitude larger space-charge limited ion beam current is possible when decaborane ions are used. Implanted boron atoms from decaborane ions are electrically activated after annealing. Junction depth of the implanted layer with 3 keV decaborane ions is approximately 20nm after annealing at 900°C. Molecular dynamic caluculations show that implantation efficency of boron monomer ions and decaborane ions are the same. However, the number of displaced silicon atoms per implanted boron atom from a decaborane ion impact is 4 times larger than that by boron monomer impact so that a heavily damaged region is created near the impact zone by decaborane ion penetration.