Chemical vapour deposition of the oxides of titanium, zirconium and hafnium for use as high-k materials in microelectronic devices. A carbon-free precursor for the synthesis of hafnium dioxide

A brief survey of the precursors used for the chemical vapour deposition of the dioxides of titanium, zirconium and hafnium is presented. The review c overs precursors used for the closely related process known as atomic layer chemical vapour deposition (ALCVD or ALD), Precursors delivered by standar d carrier gas transport and by direct liquid injection (DLI) methods are in cluded, The complexes fall into four classes based upon the ligands: halide s, alkoxides, acetylacetonates (acac) and nitrates. Compounds bearing a mix ture of ligand types have also found application in this area. The impact o f the ligand on the microstructure of the metal oxide film is greatest at l ower temperatures where the deposition rate is limited by the surface react ivity, The first use of anhydrous hafnium nitrate, Hf(NO3)(4), to deposit f ilms of hafnium oxide on silicon is reported. The films are characterized b y Rutherford backscattering and X-ray photoelectron spectroscopy, X-ray dif fraction and transmission electron microscopy, Copyright (C) 2000 John Wile y & Sons, Ltd.