Diffusion Barriers for Mobile Ions in 256M DRAMs

Abstract

AbstractIn this study, we investigate the diffusion of mobile ions through thin PSG or SiN layers using secondary ion mass spectrometry (SIMS). The diffusivity of Na through either layer is about 100,000X slower than through SiO2. Hence, thin layers of these materials are effective barriers for short anneals at 400°C. However, there is significant diffusion of both Na and K through these layers at 550°C. This suggests that improved cleans will be required to remove mobile ion contamination after interconnect processes.