INVESTIGATION OF PT TA DIFFUSION BARRIER USING HYBRID CONDUCTIVE OXIDE (RUO2) FOR HIGH DIELECTRIC APPLICATIONS/

The Pt/Ta diffusion barrier using hybrid conductive oxide (RuO2) for d ynamic random access memory and ferroelectric random access memory cap acitor bottom electrodes is proposed. The thermal stability of Pt+RuO2 (50 nm)/Ta+RuO2 (50 nm)/TiSi2 /poly-Si/SiO2/Si contact system is inve stigated and compared to that of the Pt(50 nm)/Ta(SO nm)/TiSi2/poly-Si /SiO2/Si contact system. The Pt+RuO2/Ta+RuO2/TiSi2/poly-Si/SiO2/Si con tact system sustained its structure up to 650 degrees C, whereas Pt/Ta /TiSi2/poly-Si/SiO2/Si contact system was completely degraded after an nealing at 650 degrees C. In the former case, the addition of rutheniu m dioxide (RuO2) into the Pt bottom electrode layer led to retardation of the oxygen indiffusion, preventing the indiffusion of oxygen up to 650 degrees C. In addition, the Ta+RuO2 diffusion barrier showed an a morphous structure and RuO2 is bound to the Ta matrix, inhibiting the interdiffusion of O, Pt, and Si through grain boundaries which can act as fast diffusion paths up to high temperatures. Therefore, it appear ed that the barrier properties of Pt/Ta diffusion barrier are improved by using hybrid conductive oxide (RuO2). (C) 1998 American Vacuum Soc iety.