Implantation characteristics by boron cluster ion implantation

Recently, boron cluster implantation (i.e. decaborane: $B10Hx+$⁠) is regarded as a promising technology for the formation of P‐type Ultra Shallow Junction (USJ) because of the equivalent high beam current with less beam divergence compared to the conventional B⁺ or $BF2+$ implantation. Also as‐implanted and after‐annealing characteristics are different due to the appearance of self‐amorphized layer by the cluster ion bombardment, which suppresses the channeling and enhances the boron activation. However, it is anticipated that the properties caused by this amorphous layer will vary with different implantation conditions or a presence of Pre Amorphization Implantation (PAI) process, which should be understood well to maintain a good process control. From this point of view, we have measured the decaborane implantation characteristics by a couple of different related conditions, for instance, the beam energy and current. Sheet resistance vs junction depth (Rs‐Xj) are also evaluated in different annealing methods with combination of PAI processes. In addition, a brief comparison is made by implanting the different boron cluster ions (i.e. $B8Hx+$⁠) by mass selecting the ions extracted from decaborane ionization chamber. In this paper, these characteristics of boron cluster implantations are reviewed.