Millisecond annealing induced by atmospheric pressure thermal plasma jet irradiation and its application to ultra shallow junction formation

We have developed millisecond annealing technique using an atmospheric pressure DC arc discharge thermal plasma jet (TPJ). Noncontact monitoring of wafer surface temperature is performed on the basis of transient reflectivity of silicon wafer observed during TPJ irradiation. As and B implanted silicon wafers were annealed and the impurity activation was investigated. In the case of As⁺-implanted samples, efficient dopant activation was observed at a temperature higher than 1000 K, while it was observed at a temperature higher than 1400 K in the case of B-implanted samples. The sheet resistance (R_S) of B-implanted samples monotonically decreases with temperature, and no significant dependence on heating rate (R_h) or cooling rate (R_c) is observed. On the other hand, As⁺-implanted samples show significant dependence of R_S on R_h and R_c. We have performed TPJ annealing on an As₂⁺-implanted sample, and obtained an ultrashallow junction (USJ) with a junction depth (X_j) of 11.9 nm and a R_S of 1095 Ω/sq. B USJ is also obtained with a X_j of 23.5 nm and a R_S of 392 Ω/sq. Precise control of R_h and R_c in addition to annealing temperature is quite important for achieving highly efficient doping in USJ.