Ni-Silicided Deep Source/Drain Junctions Formed by Solid Phase Epitaxial Regrowth
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Ni-Silicided Deep Source/Drain Junctions Formed by Solid Phase Epitaxial Regrowth Anne Lauwers1, Richard Lindsay1, Kirklen Henson1, Simone Severi1, Amal Akheyar2, Bartek J. Pawlak3, Muriel de Potter1 and Karen Maex1 1 IMEC, Kapeldreef 75, 3001 Leuven, Belgium 2 Affiliate researcher at IMEC from Infineon 3 Philips Research Leuven
ABSTRACT Making use of SPER (Solid Phase Epitaxial Regrowth) As and B deep source/drain junctions with high activation can be obtained at temperatures below 700ºC. However, higher thermal budget is required to regrow and activate the dopants in the poly gates. Low junction leakage and low contact resistance can be obtained for Ni-silicided As and B SPER junctions making use of deep As and B implants. Because of the low thermal budget source/drain junctions obtained by SPER are an attractive alternative to conventional spike annealed junctions for technologies making use of metal gates.
INTRODUCTION The introduction of high-K dielectrics, metal gates and advanced extension junctions in a conventional CMOS process imposes limitations on the thermal budget that can be allowed to activate the deep source/drain junctions. It was demonstrated that low resistive and very abrupt extension junctions can be obtained by solid phase epitaxial regrowth (SPER) of a doped amorphous region, obtained by As implantation or by Ge amorphisation implantation followed by B implantation.[1,2] Regrowth of the amorphous region at temperatures below 700ºC results in a high activation level of the dopants. Due to insufficient activation of the dopants beyond the amorphous region, a very abrupt profile can be obtained with the junction depth being determined by the amorphous depth. This paper reports on the use of SPER for the formation of low thermal budget As and B deep source/drain junctions with a junction depth ranging between 20 and 100 nm. The dopant profile and activation was investigated by SIMS (secondary ion mass spectroscopy) and SRP (spreading resistance probe). The resistance of the unsilicided active and poly was studied. The junction leakage and silicide/diffusion contact resistance was measured on Ni-silicided SPER junctions and compared to a conventional spike annealed junction.
EXPERIMENTAL B SPER junctions were obtained by a combination of an amorphising 1E15 Ge implant and a B implant followed by a 1 min anneal at 650ºC. The Ge implant energy was varied between 20 keV and 50 keV and the B implant energy was varied between 3 keV and 10 keV. The amorphous depth (Table I) is determined by the Ge implant energy and can be varied independently of the B profile.
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As SPER junctions were obtained by 4E15 As implantation followed by a 1 min anneal at 650ºC or a 0 sec anneal at 750ºC or 850ºC. The As implant energy (varied between 10 keV and 60 keV) determines at the same time the amorphous depth and the dopant profile. As has almost the same atomic mass as Ge but because of the higher As dose, the amorphous depths are estimated to be 10-20% higher compared to the values listed in Table I
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