Delamination Behavior of Cu-Low-k Stack Under Different Slurries
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DELAMINATION BEHAVIOR OF Cu-LOW-k STACK UNDER DIFFERENT SLURRIES A. K. Sikder1, S. Thagella1,2, P. B. Zantye1,3, and Ashok Kumar1,3 1
Nanomaterials and Nanomanufacturing Research Center, 2Department of Industrial Engineering 3 Department of Mechanical Engineering, University of South Florida, Tampa, FL-33620
Abstract Lower mechanical strength, reduced cohesive strength and lack of compatibility with other interconnect materials, are the major challenges involved in chemical mechanical polishing (CMP) of Cu metallization with ultra low-k materials as interlayer dielectrics. In this study we have investigated the polishing behavior of patterned Cu samples with underneath different low-k materials using two different slurries and a wide range of machine parameters. CMP micro tribometer was used to polish the samples with different rotations of platen (50 to 250 RPM) and down forces (1-6 PSI). Friction co-efficient and wear behavior were also investigated at different conditions. Optical and scanning electron microscopy was used to investigate the polished surface. It was observed that the two different Cu slurries used for polishing have marked effects on the polishing of Cu-low-k stack with respect to wear and delamination. I. Introduction IC manufacturers are fundamentally redesigning their chips to take full advantage of the speed offered by combining copper and low-k dielectrics. The major challenge faced by IC manufacturers is the integration of novel low-k materials with copper [1]. The International Technology Roadmap for Semiconductors (ITRS) predicts a need for dielectrics with a bulk k value of
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