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Pattern Effect on Low-k Channel Cracking

Xiao Hu Liu's picture

Low dielectric constant (low-k) is achieved often at the cost of degraded mechanical properties, making it difficult to integrate the dielectric in the back end of line (BEOL) and to package low-k chips. Development of low-k technology becomes costly and time-consuming. Therefore, more frequently than before, people resort to modeling to understand mechanical issues and avoid failures. In this paper we present three multilevel patterned film models to examine channel cracking in low-k BEOL. The effects of copper features, caps and multilevel interconnects are investigated and their implications to BEOL fabrication are discussed.

Low-k BEOL Mechanical Modeling
Liu, Xiao Hu; Lane, Michael W; Shaw, Thomas M; Liniger, Eric G; Rosenberg, Robert R; Edelstein, Daniel C
Advanced Metallization Conference 2004 (AMC 2004); San Diego, CA and Tokyo; USa and Japan; 19-21 Oct. 2004 and 28-29 Sept. 2004. pp. 361-367. 2005

PDF icon AMC2004.pdf159.47 KB


Zhigang Suo's picture

Now iMechanica has papers on channel cracks in low k dielectrics from several companies: IBM (this post), Intel, and TI. It is fascinating to see how research in mechanics finds creative use in industries.

I first learned about the mechanics of such cracks from Budiansky, and applied it to cracking in layered composites. I didn't know such cracks in composites already had a name: they were called transverse cracks. Instead, I called them tunneling cracks. People liked the name. I even called cracks in thin films tunneling cracks. John Hutchinson corrected my usage: transversely spreading cracks in thin films should be called channeling cracks.

Jack Beuth did the first comprehensive analysis of channel cracks in early 90s as part of his thesis work under John Hutchinson. Perhaps it was Qing Ma at Intel, in late 90s, first applied this concept to thin films in microelectronic industry. These and other references are cited in the above three papers.

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