Gas immersion laser doping (GILD) for ultra-shallow junction formation

Gas immersion laser doping (GILD) is a very attractive technique to realize the ultra-shallow and highly doped junctions required by the International Technology Roadmap for Semiconductors (ITRS) for future CMOS technologies. In the present work, gaseous dopant precursors (BCl3) are chemisorbed on the Si surface, and partially incorporated during the melting/recrystallisation of the Si top layer induced by an UV laser pulse (lambda = 308 nm, pulse duration approximate to 25 ns). The resulting thickness and dopant concentration of the doped layer depend on the laser energy density and the number of chemisorption/laser-induced incorporation cycles (up to 200). GILD processed junctions are box-like and exhibit depths ranging from 14 run to 65 nm, with sheet resistances ranging from = 110 to 20 Omega/square (respectively), dopant concentrations well above the B solubility limit in Si (up to 3 X 10(21) at/cm(3)) at local thermodynamic equilibrium (LTE) and abruptness of 5-2 nm/decade. Moreover, in situ optical characterization shows the GILD technique capabilities to realize the sub-10 nm thick shallow junctions needed for the sub-40 nm node ITRS predictions. (C) 2003 Elsevier B.V. All rights reserved.