Suppression of boron diffusion using carbon co-implantation in DRAM

Abstract

In this paper, germanium pre-amorphization implantation (PAI) and carbon co-implantation (Ge+C co-IIP) were applied to suppress boron diffusion. The corresponding characteristics were investigated in terms of the dopant diffusion, device performance, and its application to dynamic random access memory (DRAM). A shallow dopant profile was indicated and the threshold voltage (VTH) was reduced by approximately 45mV by Ge+C co-IIP. In the DRAM device, the VTH mismatch of the sense amplifier NMOS pairs was reduced by approximately 15% and the write characteristics were improved two-fold.