MICROCRYSTALLINE OXIDE-INCORPORATED NEW DIFFUSION BARRIER FOR DYNAMICRANDOM-ACCESS MEMORY AND FERROELECTRIC RANDOM-ACCESS MEMORY CAPACITORELECTRODE

Microcrystalline oxide-incorporated new diffusion barrier for dynamic random access memory (DRAM) and ferroelectric random access memory (FR AM) capacitor electrodes is proposed. The thermal stability of the Pt/ Ta+CeO2/TiSi2/poly-Si/SiO2/Si contact system is investigated and is co mpared to that of the Pt/Ta/TiSi2/poly-Si/SiO2/Si contact system. The Pt/Ta+CeO2/TiSi2/poly-Si/SiO2/Si contact system retained its structure s up to 800 degrees C without increase in electrical resistivity but t he Pt/Ta/TiSi2/poly-Si/SiO2/Si contact system was completely degraded after annealing at 650 degrees C. In the former case, since the additi on of cerium dioxide (CeO2) led to the stuffing of microcrystalline ox ide along the grain boundaries in Ta matrix and CeO2 was much heavier atomic weight than any stuffed elements, it prevented the interdiffusi on of O, Pt, and Si through grain boundaries which can act as fast dif fusion paths to high temperatures. It appears that the barrier propert ies of the microcrystalline oxide-incorporated new diffusion barrier a re superior to polycrystalline transition metal barriers, polycrystall ine nitride barriers, ternary amorphous compound barriers, and N-2- an d O-2-stuffed barriers. (C) 1997 American Vacuum Society.