Abstract: With the decreasing feature size and increasing patterned layers of ultra large scale integration, dielectric constant of low-k materials decreases accordingly. Due to poor mechanical strength for porous low-k materials, peeling or delamination of Cu/Ta/low-k or ultra low-k is the key issue for chemical mechanical polishing (CMP). An interfacial fracture mechanics model is constructed for single-level structure and multi-level structures during CMP. Numerical calculation based on fracture mechanics and finite element method is employed to analyze the stress distribution and interface crack fracture strength in the Si/Cu/Ta/Low-k interface. Crack energy release rate is used to describe expansion of the crack. According to analytic method of crack energy release rate, effects of crack length, material properties and number of patterned layers on the fracture and delamination of interface during the crack expansion are researched. Simulation is made on the influence of crack length, material properties and number of patterned layers on the crack energy release rate, stress distribution and phase angle. The effects of lower modulus, higher initial crack length of low-k materials, and multiple levels of patterned films are found to increase energy release rate.

Key words: Chemical mechanical polishing, Energy release rate, Interface crack expansion, Phase angle