Suppression of dislocation multiplication inside contact holes

Ion implantation into contact holes has been regarded as an effective method to lower the contact resistance in microelectronics devices. However, implantation into contact holes after contact opening usually result in residual defects during post-implantation annealings. In this study, it was found that mask edge defects (MEDs) were formed at the edge area of contact holes of small size (0.5 /spl mu/m) and high aspect ratio (a/c>4). Nucleation and multiplication of tertiary defects from MEDs were also observed inside contact holes after back-end processing. The dislocations were identified to be Schockley partial dislocations and stair-rod dislocations on inclined [111]Si planes.