Investigation of thermal stability of Si0.7Ge0.3Si stacked multilayer with As ion-implantation

The effect of As ion implantation on the stability of SiGe/Si multilayer was systematically studied. The atomic percentage of Ge in as-grown SiGe layer was 30% in this work. A thermally stable Si _0.7 Ge _0.3 /Si multilayer with As ion implantation was attained when the rapid thermal annealing (RTA) treatment temperature did not exceed 850 ^o C. Significant Ge diffusion was observed for the SiGe/Si multilayer with As ion implantation when the RTA temperature was 900 °C or above. However, minor Ge diffusion was attained for the SiGe/Si multilayer without As ion implantation when the RTA treatment temperature was 900 °C. Therefore, , compared with samples without As ion implantation, the stability window of the SiGe/Si multilayer with As ion implantation should be further reduced to 850 °C. As ion implantation plays a critical role in the stability of SiGe/Si multilayer, as it promotes the diffusion of Ge. Consequently, based on the stability of the SiGe/Si multilayer, the highest RTA treatment temperature of 850 °C is proposed for the gate-all-around (GAA) device fabrication process.