Ultra-shallow junction formation on 3D silicon and germanium device structures by ion energy decoupled plasma doping

Abstract

Advanced inductively coupled plasma techniques and surface treatments have been used to demonstrate 5 nm conformal shallow junctions at low energy with no structure damage for both silicon (Si) and germanium (Ge). N-type PH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> 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 with a junction depth (Xj) of less than 5 nm was achieved with low incident energy condition without bias power. Adding Antimony (Sb) in the plasma-assisted doping step when using the decoupled plasma condition was found to enhance the phosphorous (P) dopant level and the activation level dramatically. Various annealing techniques were compared to understand the impact to dopant activation and levels to form shallow junctions of less than 5 nm.