We synthesized very pure tetrakis-diethylamido-hafnium {Hf[N(C2H5)(2)](4):Hf(NEt2)(4)} that can be used as a precursor for depositing Hf-related materials in chemical vapor deposition (CVD). Hf(NEt2)(4) is liquid at room temperature and has a moderate vapor pressure ( 1 torr at 80 degreesC). It is stable, and not pyrophoric in the air. HfO2 film was deposited by low-pressure CVD using the Hf(NEt2)(4)/O-2 gas system. The amount, of residual N and C in the deposited film were decreased when the substrate temperature was increased. Increasing the temperature also improved the step coverage quality of the film deposited on the substrate with a trench. When the film was deposited with Hf(NEt2)(4) and O-2 at 450 degreesC, the resulting stoichiometric HfO2 film. is polycrystalline with a low impurity concentration and has good step-coverage quality.