THERMAL-PROPERTIES OF VARIOUS TA PRECURSORS USED IN CHEMICAL-VAPOR-DEPOSITION OF TANTALUM PENTOXIDE

The volatilities of various Ta precursors which produce Ta2O5 in chemical vapor deposition (CVD) are investigated by thermogravimetric analysis (TG) and differential thermal analysis (DTA). The Ta precursors studied are Ta(OC2H5)(5), Ta(OCH3)(5), TaCl5 and Ta[N(CH3)(2)](5). The TG and DTA measurements are carried out under both atmospheric pressure (760 Torr) and low pressure (0.6 Torr), and the results are compared. These measurements are also performed after heat treatment for 6 h at 150 degrees C to compare the heat resistance of the precursors. It is shown that the evaporation starting temperature at 0.6 Torr is significantly lower than that at 760 Torr for all Ta precursors studied, which suggests that the pressure in the source bottle is an important deposition parameter. Ta(OC2H5)5 shows 100% volatility and superior heat resistance. It is concluded that Ta(OC2H5)(5) can serve as a good Ta precursor for CVD because of its outstanding volatility and heat resistance.