Defect formation during W chemical-vapor deposition on TiN/Ti is studied using a variety of TiN/Ti annealing and TiN deposition conditions. Most of the defects observed on the W surfaces are associated with a great change of TiN film stress toward tensile direction after the rapid thermal annealing. Dense TiN (sputtered at a chamber pressure of 5.1 mTorr) produces a stress change of the TiN/Ti stack from -0.52 - 109 to 2 - 109 Pa, while porous TiN (sputtered at a chamber pressure of 12.8 mTorr) produces a stress change from -0. 11 x 10(9) to 0.95 x 10(9) Pa. When the porous TiN is used for the diffusion barrier, defect counts on the W films are minimized (< 100 ea. per wafer) and even comparable with those of the W films on unarmealed TiN/Ti. Microcracks or pinholes caused by a huge stress change of the TiN provide a pathway for WF(6) reaction with underlying Ti and forming the titanium fluoride, such as TiF(3) and TiF(4). Large stress developed due to volume expansion during fluorination of the Ti layer results in local delamination or abnormal growth at the W/Ti and the Ti/SiO(2) interfaces. (c) 2008 Elsevier B.V. All rights reserved.