HfO₂ and Hf_1–_<i>x</i>Si_<i>x</i>O₂ Thin Films Grown by Metal‐Organic CVD Using Tetrakis(diethylamido)hafnium

Abstract

Abstract Pure tetrakis(diethylamido)hafnium (Hf(NEt 2 ) 4 ) has been synthesized as a precursor for depositing Hf‐compound films. Hf(NEt 2 ) 4 is liquid at room temperature and has sufficient vapor pressure (0.1 Torr at 80 °C) for the CVD of hafnium dioxide (HfO 2 ) and hafnium silicate (Hf 1– x Si x O 2 ). It is stable, not pyrophoric in air, and reacts violently with water. HfO 2 films were grown by low‐pressure (LP)CVD using a Hf(NEt 2 ) 4 /O 2 gas mixture. Although nitrogen atoms tended to remain in the grown films, stoichiometric polycrystalline HfO 2 films with few residual impurities and good step coverage were deposited. By introducing a silicon precursor (such as tris(diethylamino)silane ((NEt 2 ) 3 SiH), tetraisocyanatosilane (Si(NCO) 4 ), or tetraethoxysilane (Si(OEt) 4 )) during HfO 2 LPCVD, amorphous hafnium silicate films were obtained. The amount of residual carbon and nitrogen in the Hf 1– x Si x O 2 was affected by the type of Si precursor used. High‐purity Hf 1– x Si x O 2 films were deposited when Si(OEt) 4 was used as the silicon source.