Optimization of ion implantation using trim software for the formation of shallow n+/p junction in germanium substrate

摘要

Silicon (Si) device down-scaling is facing a big challenge to maintain its high drive current capability along with lower leakage current. Due to its similarities with Si, the interest has been focused on Germanium (Ge) as a substitute for device substrate. However, there are major problems in fabricating complementary metal-oxide semiconductor (CMOS) devices i.e. poor dopant solubility, low dopant activation and large dopant diffusion coefficient. These required further optimization on fabrication parameters involving ion implantation process. This paper reports the optimization of ion implantation parameters such as energy and dose. Co-implantation technique employing two atoms with different size will be adopted for forming the shallow n+/p junction in Ge. The stress associated with atomic size is expected to be introduced into the Ge lattice. This stress will be manipulated to enhance dopant activation while controlling the diffusion. Low energy of dopant-ion implantation is selected to achieve high dopant concentration near the surface. The simulation parameters of two atoms were arranged to get such result where the effect of stress from co-implantation process can be manipulated.