TaO x film formation by a photo-CVD method using TaCl5 as a source material is examined. The deposition rate increases with increasing growth temperature and decreasing chamber pressure down to 1 Torr. The leakage current of the formed TaO x film decreases drastically with annealing in the presence of both UV-irradiation and an oxygen ambient after deposition (p-O2 annealing), when the underlying layer contains Si. The leakage current density is 10-8 A/cm2 at the 4 MV/cm electric field. The dielectric constant for MIS structure capacitors decreases with decreasing TaO x thickness, but does not decrease much with p-O2 annealing. In addition, the mechanisms of reduction of the leakage current with p-O2 annealing are discussed.

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Recent VLSI requires materials with high dielectric constant in order to reduce their storage capacitor areas. We attempted to form a tantalum oxide film from Ta(OCH3)5 at a low temperature by photo-CVD method. Our evaluation shows that the photo-CVD film obtained in this study has good step coverage, high dielectric constant (20–24), and low leakage current, and is superior to the thermal-CVD film in various characteristics.

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