Laser thermal processing of ion-implanted Si involves melting and recrystallizing an implantation induced amorphous layer containing dopants as a method of producing ultra shallow highly doped junctions in Si. After laser thermal processing there could exist a high concentration of extended defects in the recrystallized region. These defects were commonly in the form of stacking faults and micro-twins that propagate from throughout the region that had been amorphous prior to laser melting. In order to determine the origin of these extended defects, the effect of the dose rate of the Si pre-amorphization implant was studied. A 10keV 1015/cm2 Si+ implant was done into Si at dose rates between 0.06 and 0.48mA/cm2. High-resolution cross-sectional transmission electron microscopy results showed the roughness of the amorphous/crystalline interface increases with increasing dose rate up to 0.24mA/cm2 then decreases because of dynamic annealing. Quantitative plan-view transmission electron microscopy of the defect density after laser thermal processing at 0.75J/cm2 laser power showed a direct correlation between the amorphous crystalline interface roughness and the final defect density. Reduction in amorphous/crystalline interface roughness prior to laser thermal processing results in a dramatic reduction of laser thermal processing recrystallization defects.

Varying Implant Dose Rate for Defect Reduction in Laser Thermal Processing. H.Banisaukas, K.S.Jones, S.Talwar, D.F.Downey, S.Falk: Materials Science in Semiconductor Processing, 2001, 4[4], 339-343