Stress analysis of dielectrics using FEM for Analyzing the cause of cracking observed after W-CMP

This study examined the cause of the mechanical fracture (cracking) of dielectrics observed after chemical mechanical polishing (CMP) in the damascene interconnect process for W/oxide structures through the stress analysis of dielectrics with the finite element method (FEM). The analysis, performed considering polishing pressure during CMP and residual film stress, revealed that the stress in dielectrics generated by polishing pressure during CMP was approximately 2% of that generated through W film removal. This result suggests a high likelihood that the cracking of dielectrics observed after CMP is caused by the release of residual stress in W film through CMP. To prevent the mechanical fracture of dielectrics, it is thus important to reduce defects in the deposition of dielectrics and to decrease residual film stress.