화학공학소재연구정보센터
Thin Solid Films, Vol.517, No.24, 6576-6583, 2009
Properties of atomic layer deposited HfO2 thin films
The growth, composition and morphology of HfO2 films that have been deposited by atomic layer deposition (ALD) are examined in this article. The films are deposited using two different ALD chemistries: i) tetrakis ethylmethyl amino hafnium, and H2O at 250 degrees and ii) tetrakis dimethyl amino hafnium and H2O at 275 degrees C. The growth rates are 1.2 angstrom/cycle and 1.0 angstrom/cycle respectively. The main impurities detected both by X-ray Photoelectron Spectroscopy and Fourier transform infrared spectroscopy (FTIR) are bonded carbon (similar to 3 at.%) and both bulk and terminal OH species that are partially desorbed after high temperature inert anneals up to 900 degrees C. Atomic Force Microscopy reveals increasing surface roughness as a function of increasing film thickness. X-ray diffraction shows that the morphology of the as-deposited films is thickness dependent; films with thickness around 30 nm for both processes are amorphous while similar to 70 nm films show the existence of crystallites. These results are correlated with FTIR measurements in the far IR region where the HfO2 peaks are found to provide an easy and reliable technique for the determination of the crystallinity of relatively thick HfO2 films. The index of refraction for all films is very close to that for bulk crystalline HfO2. (C) 2009 Elsevier B.V. All rights reserved.