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, S 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 deg 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 exp 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 > =5 MV /cm. Dielectric constants of kapprox7.6 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 (c) 2002 Elsevier Science B.V.