Formation of 5 nm Ultra Shallow Junction on 3D Devices Structures by Ion Energy Decoupled Plasma Doping

Advanced inductively coupled plasma techniques and surface treatments have been used to demonstrate 5 nm conformal shallow junctions at low energy with no silicon structure damage. N-type PH3 plasma-assisted doping was characterized by dopant diffusion and electrical activation with increasing wafer temperature. Plasma-assisted doping at high wafer temperature showed no structure damage even at a high incident energy condition with a bias power applied to the wafer, while a shallow junction of less than 5 nm of Xj formation was achieved with low incident energy condition without bias power. Adding a silicon surface modification step when using the decoupled plasma condition prior to PH3 doping was found to enhance the dopant level and lower Rs dramatically. Various annealing techniques were compared to understand the impact to dopant activation and levels to form shallow junctions of less than 5 nm.