The exothermic reaction and temperature measurement for tungsten CMP technology and its application on endpoint detection

A novel in-situ endpoint detection method used pad temperature measurement to control the polishing tungsten and barrier metal Ti/TiN is proposed. The metal chemical-mechanical polishing (CMP) process includes chemical reaction. It is an exothermic process as the polishing slurry reacts on tungsten and Ti/TiN films. Therefore, the pad temperature increases as tungsten and barrier metal films are polished, but will drop dramatically when metal layers are polished and touch the oxide layer. A non-contact thermal sensor system was installed on our CMP tool to measure the pad temperature. From the in-situ pad temperature curve, the endpoint can be detected clearly and the polishing process stops at the oxide layer. This method can also be used to study the reactions between the pad temperature curve and the effects of CMP process conditions such as down force, platen speed as well as polishing performance such as removal rate and uniformity. (C) 1998 Elsevier Science S.A.