IMPROVED TiN LINERS FOR ENHANCED W CMP ENDPOINT DETECTION

摘要

Monitoring motor current (friction) is one of popular endpoint detection methods widely implemented in Tungsten Chemical Mechanical Planarization (W CMP) process. However, motor current techniques are very sensitive to CMP consumable sets, process parameters and liner/barrier properties. In this paper, by adjusting the TiN liner deposition parameters, it is demonstrated that reasonable endpoints can be achieved for a W CMP process on a W/TiN/SiO_2 stack structure and therefore the loss in metal and dielectrics due to excess over-polishing can be limited. The TiN film properties are then studied and characterized, and data indicate that changes in surface roughness and grain size might be the factors contributing to the change in friction endpoints when the polishing transitions into TiN layer.