Annealing of ultrashallow p+/n junction by 248 nm excimer laser and rapid thermal processing with different preamorphization depths

Ultrashallow $p^{+}\mathrm{/n}$ junctions formed by ${\mathrm{B}}^{\mathrm{+}}$ -ion implantation and annealed by spike rapid thermal annealing (RTA) or laser annealing were studied. The effect of the preamorphizing depth on the redistribution of boron atoms after annealing has also been investigated. Our results show that for ultrashallow junctions formed by ultra-low-energy ion implantation and spike RTA, the depth of the preamorphizing implant has very little impact on the junction depth. By optimizing the laser fluence and preamorphization depth, a highly activated, ultrashallow, and abrupt junction can be obtained using a 248 nm excimer laser. The secondary-ion-mass spectrometry results clearly indicate that a step-like profile with a junction depth of 370 Å (for a ${\mathrm{B}}^{\mathrm{+}}$ implant at 1 keV) can be formed with a single-pulse laser irradiation at 0.5 J/cm².