Recrystallization of buried amorphous layers and associated electrical effects in P⁺-implanted Si

Abstract

The recrystallization behaviour of a buried amorphous layer formed by P⁺ implantation in (111) Si has been studied using transmission electron microscopy (TEM), secondary-ion mass spectroscopy (SIMS) and Hall measurements. Special TEM specimen preparation techniques were used to study individual sub-surface damage regions in the as-implanted as well as the annealed samples. The TEM results showed that the recrystallization of the amorphous layer began slowly, increased rapidly above 550°C and was complete at 600°C. At temperatures betweeen 750 and 1000°C, two discrete layers of interstitial a/2 ⟨110⟩ and a/3⟨111⟩ dislocation loops formed below the specimen surface, and the surface region concontained stacking-fault tetrahedra. The SIMS results showed that pronounced segregation of phosphorus atoms occurred in the defect-rich regions at 750°C. At higher annealing temperatures P segregation still occurred, but the magnitude of the segregation was reduced because of diffusive effects. The segregation results correlated with the asymmetry in the inside-outside diffraction contrast results of the dislocation loops. The asymmetry was a maximum in the 750°C annealed specimen, and decreased progressively with increasing annealing temperature. Electrical profiles showed decreases in carrier concentration and/or mobility in the defect-rich regions.