OXIDATION RESISTANCE OF TANTALUM-RUTHENIUM DIOXIDE DIFFUSION BARRIER FOR MEMORY CAPACITOR BOTTOM ELECTRODES

The effect of the RuO2 addition into a Ta film on the oxidation resist ance of a diffusion barrier for the Ta+RuO2/Si system was investigated . The Ta+RuO2/Si system was sustained up to 800 degrees C without an i ncrease in resistivity, while the Ta/Si structure completely degraded after annealing at 450 degrees C. The Ta+RuO2 diffusion barrier showed an amorphous microstructure for an as-deposited state and formed a co nductive RuO2 phase after annealing. Ta was sufficiently bound to oxyg en of RuO2 for an as-deposited state, but RuO2 was divided into Ru and Ru-O binding slates. Ta-O bonds showed a little change compared to th e as-deposited state with increasing annealing temperature, whereas Ru -O bonds significantly increased. Therefore, the Ta layer deposited by the RuO2 addition effectively prevented the indiffusion of oxygen up to 800 degrees C and its oxidation resistance was superior to those of polycrystalline nitride (TIN, TaN) and ternary amorphous (TaSiN) barr iers reported by others. (C) 1998 American Institute of Physics.