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, BF2). 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.