Lateral undermask penetration of Al + ions implanted in 4H-SiC is investigated by computer simulation based on Monte Carlo binary collision approximation. Results show that a small fraction of ions, implanted normal to a (0001) 4H-SiC wafer miscut of 8° toward the {112̅0}, is scattered and become channeled in all the directions perpendicular to the axis, traveling long distances along these directions. Due to this phenomenon, channeling tails in ion distributions, with concentration ≤ 10 -4 of the peak value, can extend laterally for a few micrometers below the edge of a SiO 2 mask.