The effect of implantation, energy, and dose on extended defect formation for MeV phosphorus implanted silicon

Abstract

The effect of dose and energy on postannealing defect formation, for high energy (MeV) phosphorus implanted into epitaxially grown silicon, has been studied by etch pits and transmission electron microscopy (TEM). The phosphorus dose was varied from 1×1013 to 5×1014 cm−2 and the energy was varied from 180 to 5000 keV. After implantation, the wafers were processed through subsequent annealing cycles which simulates a typical advanced complementary metal–oxide–semiconductor process to understand the formation of the defects in the near surface and projected range. For phosphorus energies above 500 keV, the threading dislocation density (TDD), increases dramatically with increasing dose from below the minimum detection limit (5×103 cm−2) at a dose of 1×1013 cm−2 to a maximum above 1×106 cm−2 for a dose of 1×1014 cm−2. However, with further increases in dose, the TDD decreases back close to the minimum detection limit. Plan-view TEM suggests that with increasing dose, the formation of extended defects at the projected range reduces the TDD. For a fixed dose of 1×1014 cm−2, the TDD exhibits a superlinear increase of nearly 3 orders of magnitude as the implant energy is increased from 180 to 2000 keV. With further increases in implant energy, the TDD saturates at a value around 2×106 cm−2. The marked effect of dose and energy on the TDD can be partially understood from homogeneous nucleation theory.