HfO2 films have been grown by an atomic layer deposition method using a high-purity tetrakis(ethylmethylamido)hafnium (TEMAH). TEMAH, which has been used as a source material for HfO2 film formation, is likely to include zirconium (Zr) or titanium (Ti) atoms as impurities in the manufacturing process, and further purification was difficult. We succeeded in synthesizing a high-purity TEMAH with a reduced Zr concentration of impurities. The electrical properties of HfO2 films were investigated, and the breakdown voltage and leakage current were improved by decreasing Zr impurities. (C) 2008 The Electrochemical Society.