Abstract
Process integration feasibility of UV nanosecond melt laser annealing (MLA) in 14 nm node generation FinFET's contact for dopant surface segregation and activation is assessed by using a 3D TCAD simulation tool. In a n-type source/drain (S/D) in-situ phosphorous doped epilayer, Sb ion implantation is performed, considering the advantage of its surface segregation in lowering of the contact resistivity. The simulation results show that the heat sources created by the laser irradiation are confined mainly in the replacement metal gate (RMG) part, suggesting a potential interest of controlling the polarization of laser light to enlarge the process window by reducing the laser absorption in the RMG part. Also, the estimated solidification front velocity (V) in the MLA-induced epilayer regrowth (~4 m/s) satisfies the requirements (~1 m/s <; V <; ~15 m/s) to enable the surface segregation and metastable activation of the dopants. The surface segregation is also experimentally confirmed in the FinFET contact module.
Highlights
Nowadays, the area of transistors is so small that metalsemiconductor contact resistivity dominates parasitic components of access resistance [1]
The required breakthrough is demonstrated for p-type contact by using gallium (Ga) as the dopant in high germanium (Ge) content silicon-germanium (SiGe) alloys [3], [4] and pure Ge [4], where a key phenomenon is dopant surface segregation during non-equillibrium solidification induced by nanosecond melt laser annealing (MLA)
The lowest melting energy density (ED) for the a-Si:P can be explained by its much lower the same melting point (Tmelt) than the Si:P, whereas the lower melting ED of the Si Fin channel w.r.t. the Si:P is consistent with the heat transfer pathway from the heat source generated in the replacement metal gate (RMG) region
Summary
The area of transistors is so small that metalsemiconductor contact resistivity dominates parasitic components of access resistance [1]. The required breakthrough is demonstrated for p-type contact by using gallium (Ga) as the dopant in high germanium (Ge) content silicon-germanium (SiGe) alloys [3], [4] and pure Ge [4], where a key phenomenon is dopant surface segregation during non-equillibrium solidification induced by nanosecond melt laser annealing (MLA). Ga has a very small equilibrium segregation coefficient (k0) in both Si (0.008 [5]) and Ge (0.071 to 0.078 [6], [7]). Antimony (Sb) can be a candidate for n-type contact because its reported equilibrium segregation coefficient is very small in Si (0.023 [8])
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