A systematic study to investigate the fundamental cause for wet etch variation of ultrathin titanium nitride (TiN) film as a function of the deposition technique such as physical vapor deposition, chemical vapor deposition, and atomic layer deposition is presented. For this study, 10 nm TiN films were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, X-ray reflectometry, and absolute ellipsometry. It is shown that the deposition method plays an important role on the final TiN crystallography and properties. However, it is demonstrated that the dominating factor defining etch rate is the resulting film strain. (c) 2006 The Electrochemical Society.