Investigation of lanthanum and hafnium-based dielectric films by X-ray reflectivity, spectroscopic ellipsometry and X-ray photoelectron spectroscopy

• Published in: Thin solid films Vol. 516; no. 22; pp. 7974 - 7978
• Main Authors: Edon, V., Hugon, M.-C., Agius, B., Durand, O., Eypert, C., Cardinaud, C.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 30.09.2008; Elsevier Science; Elsevier
• Subjects: Condensed Matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Dielectric thin films; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Diffusion barrier; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; High-κ dielectric materials; Interfacial layer; Materials Science; Methods of deposition of films and coatings; film growth and epitaxy; Optical models; Photoemission and photoelectron spectra; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Interfacial layer; Diffusion barrier; High-κ dielectric materials; Optical models; Amorphous material; Spectroscopic ellipsometry; Roughness; X-ray reflection; Lanthanum oxide; Thin films; Cathode sputtering; Hafnium; Physical vapor deposition; Silicon; Lanthanum; Aluminium oxide; Annealing; Semiconductor materials; High-K dielectric materials; Interfaces; Diffusion barriers; Silicon oxides; Lanthanum aluminate; Dielectric thin films; High k dielectric; X-ray photoelectron spectra
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2008.04.006

LaAlO 3 and HfAl x O y thin films have been deposited by magnetron sputtering for replacement of SiO 2 in new Complementary Metal Oxide Semiconductor applications. A three-layer model was found both in X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) analysis to be the best optical model for these two high-κ materials. It was composed of an interfacial layer, covered by a layer of pure LaAlO 3 or HfAl x O y , and a surface-roughness layer. In the case of LaAlO 3 and HfAl x O y directly deposited on Si, the interfacial layer is a mixture of high-k material and amorphous-Si inclusions, which thickness is growing after post-deposition annealing (PDA) in O 2 at 600 °C. On the contrary, for films deposited on thermally nitrided Si, the SiON-like interface did not change significantly after a PDA in O 2. XRR analysis showed that the dielectric/Si interface of HfAl x O y /SiON/Si structure had a significantly smaller roughness than those of HfAl x O y /Si. When being deposited on SiON/Si substrates, HfAl x O y , and to a lesser extent LaAlO 3, demonstrate superior diffusion barrier properties pointed out by X-ray photoelectron spectroscopy.