Segregation and activation of Sb implanted in Si by UV nanosecond-laser-anneal-induced non-equilibrium solidification

Abstract

In advanced logic devices, access resistance to transistors is dominated by metal–semiconductor contact resistivity. Recent studies report values below 1 × 10−9 ohm cm2, realizing metastable incorporation of dopants into epitaxially grown semiconductor materials. In this study, we have investigated segregation and activation of antimony (Sb) implanted in silicon (Si) epilayers by using UV nanosecond pulsed laser annealing (LA). The Sb-implanted Si epilayers were partially or fully molten by LA, followed by the analysis of atomic and electrically active dopant concentrations as well as the observation of surface morphology evolution. To discuss the impact of the solute trapping phenomenon on substitutional incorporation of the Sb atoms, we also simulated the evolution of solidification front velocity in the LA-induced non-equilibrium solidification. It is noteworthy that the active level of the Sb atoms largely surpasses their reported equilibrium solubility limit (∼2.6 × 1020 at./cm3 compared to ∼6.8 × 1019 at./cm3) when the non-equilibrium solidification approaches a near-complete solute trapping regime.

3D Simulation for Melt Laser Anneal Integration in FinFET’s Contact

“…This observation supports that the mean SFV in the applied MLA process is smaller than VD. A similar Sb redistribution mechanism during the MLA-induced rapid solidification is also reported in our previous work [13]. Then, one may expect a very high Sb active level which should be at least more than ~2.6 × 10 20 at./cm 3 (equivalent to ~0.5 at.%) [13] and potentially goes up to about 40 at.% (equivalent to ~2 × 10 22 at./cm 3 ).…”

“…A similar Sb redistribution mechanism during the MLA-induced rapid solidification is also reported in our previous work [13]. Then, one may expect a very high Sb active level which should be at least more than ~2.6 × 10 20 at./cm 3 (equivalent to ~0.5 at.%) [13] and potentially goes up to about 40 at.% (equivalent to ~2 × 10 22 at./cm 3 ). This expectation in the V range that we discuss in this work can be supported by a theoretical prediction of MLA-induced substitutional dopant incorporation in Si given by literature [21].…”

“…When V becomes larger than the speed of solute diffusion propagation (VD), kne becomes equal to the unity (i.e., kne = 1 with VD < V) and this regime is called "complete solute trapping" leading to diffusion-less solidification [10]. In our previous works [11]- [13], the degree of surpassing the solid solubility limit (SSL) of the dopants such as Sb and Ga as a function of SFV is systematically studied, using Sb-implanted Si and Ga-implanted Si50Ge50 epilayers. When V becomes larger than ~1 m/s, the dopant active level monotonically increases.…”

“…To enable both MLA-induced surface segregation and activation over SSL of the dopants, V must satisfy ~1 m/s < V < VD (∼15 m/s [13]). Therefore, a process simulation able to extract SFV is necessary to assess the feasibility of MLA integration into contact activation in real devices.…”

Solid Phase Recrystallization in Arsenic Ion-Implanted Silicon-On-Insulator by Microsecond UV Laser Annealing

“…3(b)). When melting of an ion-implanted Si happens, O incorporation is observed even in a nitrogen ambient for a much shorter dwell time (~10 -7 s) [28]. On the other hand, at this possible SPR condition, a clear As segregation towards the surface was observed in the initially amorphized SOI layer (Fig.…”