Electrical characterization of thin Al sub(2)O sub(3) films grown by atomic layer deposition on silicon and various metal substrates

• Published in: Thin solid films 2002-06, Vol.413 (1-2), p.186-197
• Main Authors: Groner, M D, Elam, J W, Fabreguette, F H, George, Steven M
• Format: Article
• Language: English
• ISSN: 0040-6090

Al sub(2)O sub(3) films with thicknesses ranging from 30 to 3540 A were grown in a viscous flow reactor using atomic layer deposition (ALD) with trimethylaluminum and water as the reactants. Growth temperatures ranged from 125 to 425 degree C. The Al sub(2)O sub(3) ALD films were deposited successfully on a variety of substrates including Au, Co, Cr, Cu, Mo, Ni, NiFe, NiMn, Pt, PtMn, Si, stainless steel, W, and ZnO. Electrical properties were characterized by current-voltage and capacitance-voltage measurements using a mercury probe. These measurements focused mainly on Al sub(2)O sub(3) ALD films deposited on n-type Si(1 0 0) and on Mo-coated Si(1 0 0) substrates. Excellent insulating properties were observed for nearly all of the Al sub(2)O sub(3) films. For a typical Al sub(2)O sub(3) ALD film with a 120 A thickness, leakage currents of < 1 nA/cm super(2) were observed at an applied electric field of 2 MV/cm. Fowler-Nordheim tunneling was observed at high electric fields and dielectric breakdown occurred only at greater than or equal to 5 MV/cm. Dielectric constants of k[similar to]7.6 were measured for thick Al sub(2)O sub(3)ALD films. The measured dielectric constant decreased with decreasing Al sub(2)O sub(3) film thickness and suggested the presence of a thin interfacial oxide layer. For Al sub(2)O sub(3) ALD films grown on n-type Si(1 0 0), capacitance measurements were consistent with an interfacial layer with a SiO sub(2) equivalent oxide thickness of 11 A. Spectroscopic ellipsometry investigations also were in agreement with a SiO sub(2) interfacial layer with a 13 A thickness. copyright 2002 Elsevier Science B.V. All rights reserved.