Rapid Formation of Arsenic-Doped Layer More Than 1.0 µm Deep in Si Using Two KrF Excimer Lasers

Abstract

Sequential irradiation by two KrF excimer lasers (λ=248 nm) has been used to activate arsenic atoms implanted into Si substrates. The 1st laser pulse having 34 ns pulse width followed by the 2nd laser pulse of 23 ns after a time delay was irradiated to the sample. Laser fluences of the 1st laser pulse and the 2nd laser pulse were set at 2.4 J/cm2 and 0.5 J/cm2, respectively. The substrate was heated to 700° C. From Rutherford backscattering spectroscopy (RBS) analysis, the depth of the doped layer is confirmed to be 1.0 µ m. Severely rippled surface was observed by atomic force microscope (AFM) for the sample irradiated without the 2nd laser pulse, but the surface morphology can be improved by the sequential irradiation of two pulses. For a time delay of 150 ns, the minimum values of χmin (4.61%) and sheet resistance (41.43 Ω/\\Box) were obtained.