Annealing of phosphorus-ion-implanted silicon using a CO2 laser

Annealing behavior of phosphorus implanted in silicon layers under cw CO2 laser irradiation is investigated. The irradiation time required for full electrical activation is found to depend on the dopant concentration of the substrate. This is because absorption of CO2 laser light is a function of free-carrier concentration in the crystalline substrate. During the experiment, an enhancement of annealing efficiency is observed in the case of a low-resistivity substrate or with bias light (Xe lamp) irradiation. This supports the above explanation.