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DS: Dünne Schichten
DS 5: Internal Symposium “Functional thin films - future applications and challenges”
DS 5.5: Invited Talk
Monday, March 27, 2006, 17:15–18:00, GER 37
Measurement of nanomechanical properties of low-k dielectric films — •H. Geisler, D. Chumakov, L. Jiang, P. Hofmann, C. Streck, U. Mayer, R.-Q. Su, and E. Zschech — AMD Saxony LLC & Co. KG, Wilschdorfer Landstr. 101, D-01109 Dresden, Germany
Interlayer dielectric (ILD) thin films with permittivities of k=3 are currently implemented in advanced integrated circuits to reduce the interconnect signal delay. According to the International Roadmap for Semiconductor Industries, a long-term goal is the fabrication of ILDs with k-values as close as possible to the physical limit k=1. One possible approach to approximate this target is to integrate nano-porous organo-silicate glass materials. As a drawback, low-k and ultra low-k materials possess much lower Young’s modulus and hardness values than conventional SiO2 glasses which have been used so far. This is a critical issue since ILD films must withstand patterning, chemical mechanical polishing, etching, thermal cycling and chip-packaging. Their adhesion inside multilayer interconnect stacks must be as good as possible to prevent reliability issues or delamination. As a consequence, the mechanical properties of (ultra) low-k thin films have to be characterized carefully to improve performance and to maintain reliability. Since ILD film thicknesses and Cu-low-k structure sizes are typically in the range of a few hundred nanometers or below, suitable mechanical characterization techniques need to be operated on the nano scale. It is shown that nanoindentation with in-situ probe scanning, special force-modulation AFM as well as global and local adhesion measurement techniques can fulfill this task.