Physical and electrical characteristics of atomic-layer deposition-HfO2 films deposited on Si substrates having different silanol Si-OH densities J. Vac. Sci. Technol. A 31, 01A132 (2013); 10.1116/1.4769206 Low temperature growth of high-k Hf-La oxides by remote-plasma atomic layer deposition: Morphology, stoichiometry, and dielectric properties J. Vac. Sci. Technol. A 30, 01A147 (2012); 10.1116/1.3665419 X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy investigation of Al-related dipole at the HfO 2 / Si interface J. Appl. Phys. 105, 024102 (2009); 10.1063/1.3066906 Photoelectron spectroscopic analysis of Hf-silicate/ Si O 2 ∕ Si stacks deposited by atomic layer chemical vapor deposition J.The authors investigated in situ the initial stages of the atomic layer deposition (ALD) growth of HfO 2 on Si(001)/SiO 2 substrates by using tetrakis-di-methyl-amino-Hf and H 2 O as precursors. The surface morphology and the chemical and electronic properties of HfO 2 ultrathin films were studied after each ALD cycle by surface-sensitive techniques. Atomic force microscopy image analysis was performed by analyzing the height-height correlation function (HHCF), the root mean square surface roughness, and the surface fractal dimension, as function of the number of ALD cycles. Parameters directly related to HHCF, e.g., surface width, correlation length, local slope, and roughness exponent, were calculated and used for determination of scaling exponents. A complex behavior of all parameters up to the eighth ALD cycle was evidenced. High-resolution synchrotron radiation photoemission spectroscopy was applied to characterize the chemical nature of Si/SiO 2 /HfO 2 interface. Changes arising in the Si 2p, O 1 s, and Hf 4f core level lines after each ALD cycle up to the complete formation of two layers of HfO 2 were observed. The thickness of the growing HfO 2 layer was calculated to estimate the growth per cycle to approximately 0.1 nm/cycle. By means of ultraviolet photoemission spectroscopy, variations of valence band maximum and secondary electron cutoff after each ALD cycle were observed and the presence of an interfacial dipole was pointed out. Finally, the loss function onset of electron energy loss spectroscopy changed during ALD because of bandgap variations from SiO 2 to HfO 2 . By combining all experimental results a new and fully comprehensive growth model of ALD during the initial stages was developed.
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