Lateral Straggling of Ion Implantation Distributions in 4H-SiC Investigated by SIMS

Abstract

Ion implantation is a crucial step in the process of SiC device fabrication. Precise and predictable doping distributions are necessary for reduced cell pitches and integrated circuit development. However, straggling due to ion channeling affects this goal. Even though vertical channeling has been investigated successfully, lateral straggling remains unclear. Therefore, two-dimensional SIMS concentration distributions are used to investigate lateral straggling of Al and P implanted in 4H-SiC. Results, for both Al and P, show that there is a significant influence of the crystal orientation showing that some channels lead to a few micrometers more lateral straggling than others. High implantation doses increase the amount of amorphization, which leads to more dechanneling and, thus, less straggling. Even though elevated implantation temperatures increase lattice vibrations and thus act in favor of dechanneling, the implantation distributions show significant lateral straggling as amorphization is suppressed.