Formation of ultrashallow junctions in 500 eV boron implanted silicon using nonmelt laser annealing

Nonmelt laser annealing (NLA) is used to form heavily-doped, ultra-shallow regions in boron implanted crystalline silicon. Results are compared to samples receiving a conventional 1050degC spike anneal. A high-dose non-amorphizing boron implant of 10¹⁵ ions/cm² at 500 eV is used. The implant is laser annealed with between one and 1000 20 ns long pulses or a 1050degC spike anneal. NLA alone produces junction depths from 21 to 25 nm with sheet resistances around 800 W/sq, while spike annealing results in 40 nm junctions at ~ 2400 W/sq. Hall effect measurements produce mobilities around 30 cm²/V-s. Plan-view TEM shows damage from the implant is completely removed after 100 pulses. Thus, nonmelt laser annealing alone can be used to produce shallower junctions with lower resistivity than conventional RTA offering junction characteristics suitable for the 2007 65 nm ITRS technology node