Solid phase phosphorous activation in implanted silicon by excimer laser irradiation

The activation mechanism in phosphorous implanted silicon under excimer laser irradiation is investigated. The activation efficiency in the solid phase has been measured in a wide range of irradiation conditions, tuning the laser fluence in the sub-, partial, and total melting regime. Moreover, fixing the fluence, the activation as a function of the shot number has been analyzed. The total active fraction varies by several orders of magnitude and shows a complex trend depending on the process conditions. Our model, based on the interaction between defects and the active/inactive impurities, explains this scenario. In particular, it predicts experimental P active profiles, thus demonstrating that the status of the defect system rules the activation phenomenon, where the coupling between dopant and defect clusters at the early irradiation stage plays a crucial role.