HfO2 and Hf1–xSixO2 Thin Films Grown by Metal‐Organic CVD Using Tetrakis(diethylamido)hafnium

Pure tetrakis(diethylamido)hafnium (Hf(NEt2)4) has been synthesized as a precursor for depositing Hf‐compound films. Hf(NEt2)4 is liquid at room temperature and has sufficient vapor pressure (0.1 Torr at 80 °C) for the CVD of hafnium dioxide (HfO2) and hafnium silicate (Hf1–xSixO2). It is stable, not pyrophoric in air, and reacts violently with water. HfO2 films were grown by low‐pressure (LP)CVD using a Hf(NEt2)4/O2 gas mixture. Although nitrogen atoms tended to remain in the grown films, stoichiometric polycrystalline HfO2 films with few residual impurities and good step coverage were deposited. By introducing a silicon precursor (such as tris(diethylamino)silane ((NEt2)3SiH), tetraisocyanatosilane (Si(NCO)4), or tetraethoxysilane (Si(OEt)4)) during HfO2 LPCVD, amorphous hafnium silicate films were obtained. The amount of residual carbon and nitrogen in the Hf1–xSixO2 was affected by the type of Si precursor used. High‐purity Hf1–xSixO2 films were deposited when Si(OEt)4 was used as the silicon source.