Chemical vapor deposition of HfO2 thin films using the novel single precursor hafnium 3-methyl-3-pentoxide, Hf(mp)(4)

Abstract

Hafnium oxide films have been deposited on silicon substrates by metal organic chemical vapor deposition using the novel single precursor, hafnium 3-methyl-3-pentoxide {Hf[OC(CH3)(C2H5)(2)](4), Hf(mp)(4)}, with no additional oxygen source, and the deposition mechanism was elucidated. Hf(mp)(4) is a liquid at room temperature and has a moderate vapor pressure comparable to that of hafnium tertbutoxide, Hf((OBU)-B-t)(4), and a lower residual weight (< 10%) in thermogravimetric analysis. The deposition rate was found to be similar to 27 angstrom/min at 400 degrees C, and the activation energy was 68.1 kJ/mol, which is higher than those of other hafnium alkoxide and hafnium amide precursors. By gas chrornatography/mass spectroscopy and nuclear magnetic resonance analyses of the thermally decomposed vapor phase products collected during the deposition of HfO2 films, it was clearly found that they are grown via P-hydrogen elimination processes of the Hf(mp)(4) single precursor. Negligible carbon incorporation Of the HfO2 films, examined by X-ray photoelectron spectroscopy and depth-profiling Auger electron spectroscopy, indicates that, except for the beta-hydrogen elimination processes, no additional decomposition and/or recombination processes contributed to the HfO2 film growth. The morphology, crystallinity, and electrical properties of the HfO2 films were characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, and capacitance-voltage and current-voltage measurements.