Investigation of interconnect design on interfacial cracking energy of Al/TiN barriers under a flexural load.

Abstract: The integration of thin film technology into the fabrication of semiconductor transistors has given rise to significant challenges in the design of multi-level back-end-of-line interconnects. The interfacial adhesion between Al metal and TiN barrier is one of the major factors that affect interconnect reliability. Analyzing the effect of the interconnect structures of Al/TiN barriers on interfacial cracking energy under flexural loading is an interesting research direction. This work proposes a robust estimation of interfacial cracks by simulation-based methods to satisfy the mechanical design requirements for multi-level interconnect systems. A constant bending moment can be generated with the framework of the four-point bending test (4-PBT). A 4-PBT simulation model can be used in finite element analysis, combined with the J-integral method and the modified virtual crack closure technique, to accurately predict the interfacial fracture energy of Al/TiN films. Preliminary results indicate a considerable increase in energy release rate. Energy is released as a crack along the interface of the Al/TiN films passes through the region above the parallel metal lines of patterned interconnects, especially for a Cu/SiLK material system. The results also show that dielectrics can serve as stress buffer layers that inhibit crack growth. [Copyright &y& Elsevier]