Investigation on thermal stability of Si_(0.7)Ge_(0.3)/Si stacked multilayer for gate-all-around MOSFETS

摘要

In this study, the thermal stability of a Si0.7Ge0.3/Si stacked multilayer for gate-all-around (GAA) MOSFETS is systematically investigated. Rapid thermal annealing (RTA) treatments at temperatures ranging from 800 degrees C to 1050 degrees C are performed on the Si0.7Ge0.3/Si stacked multilayer samples. Compared with the as-grown sample, the RTA-treated (800 degrees C-900 degrees C) Si0.7Ge0.3/Si stacked multilayer samples attain good crystal quality, a sharp interface between Si(0.7)Ge(0.3)and Si, and minor diffusion of Ge. Furthermore, owing to the rapid diffusion of Ge, the thickness of Si(0.7)Ge(0.3)increases by similar to 6 nm and the Ge concentration of Si(0.7)Ge(0.3)reduces by similar to 3% as the annealing temperature increases to 950 degrees C. The interfaces of the Si0.7Ge0.3/Si stacked multilayer disappear and finally behave like a homogeneous SiGe alloy as the annealing temperature further increases to 1000 degrees C or 1050 degrees C. Therefore, for thermal stability, the highest tolerable temperature of 900 degrees C is proposed for the Si0.7Ge0.3/Si stacked multilayer for the fabrication of the GAA device.