Ns laser annealing for junction activation preserving inter-tier interconnections stability within a 3D sequential integration

In this paper, the energy process window of nanosecond (ns) laser annealing for junctions activation has been determined for several dopants (As, P, BF ₂ ). The different recrystallization states observed when tuning laser energy density are explained by numerical simulations. Within these conditions, the laser impact on the thermal stability of ULK/copper inter-tiers interconnections has been evaluated for a 28nm node backend metal 1 design rules technology both from morphological and electrical perspectives. This study highlights the interest of ns laser anneal for CoolCube™ 3D integration.