Deep Level Transient Spectroscopy (DLTS) has been applied to Metal-Oxide-Semiconductor (MOS) capacitors fabricated on crystalline silicon n- and p-type substrates, with a SiO2 or a SiO2/SiNx passivation stack, covered by an Al gate. It is shown that similar interface state distributions are obtained in both cases, from which it is concluded that the SiNx deposition does not degrade the interface. It is also shown that a rather large density of dangling bond defects is present at the Si/SiO2 interface, which is related to the absence of a post metallization forming gas annealing. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3568952] All rights reserved.