Characterization of Residual Stress Change of Dielectrics in W-CMP Process Using Finite Element Method Analysis

Inhalt:
We simulated stresses in inter-metal dielectrics in a W/oxide structure before CMP, during CMP, and after CMP by the finite element method analysis. As a result, the stress in the inter-metal dielectrics after releasing the residual stress in the tungsten film was about 100 times larger than the stress caused by CMP. Consequently, it is most likely that releasing the residual stress in the tungsten film by CMP leads to a cracking of the dielectrics observed after CMP. Therefore, we consider it is important to reduce defects in dielectrics and to decrease a residual stress in a W film for preventing the dielectrics from the cracking.