Surface treatment for high-quality Al2O3 and HfO2 layers deposited on HF-dipped surface by atomic layer deposition

Abstract

Al 2 O 3 and HfO 2 thin layers were deposited on either 0.7-nm chemical SiO 2 surface layers, HF-dipped Si surfaces or on HF-dipped Si surfaces with an innovative Cl 2 surface treatment. This chemical treatment leads to the formation of one mono-layer of -OH groups on the silicon surface without any SiO x growth. Thicknesses, composition, and structure of the high-k layers as well as the nature of their interfaces with silicon were studied using spectrometric ellipsometry, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). While deposition on a HF-dipped Si surface led to a nucleation retardation and to a 3-dimensional growth mode, high-quality, uniform Al 2 O 3 layers were obtained on a Cl 2 -treated Si surface. XPS and ATR analyses showed a very small SiO x regrowth, less than 0.26 nm during deposition.