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Influence of Interfacial Delamination on Channel Cracking of Brittle Thin Films

Yaoyu Pang's picture

Channeling cracks in low-k dielectrics have been observed to be a key reliability issue for advanced interconnects. The constraint effect of surrounding materials including stacked buffer layers has been studied. This paper analyzes the effect of interfacial delamination on the fracture condition of brittle thin films on elastic substrates. It is found that stable delamination along with the growth of a channel crack is possible only for a specific range of elastic mismatch and interface toughness. An effective energy release rate is defined to account for the influence of interfacial delamination on both the driving force and the fracture resistance, which can be significantly higher than the case assuming no delamination.

This paper is presented at 2007 MRS Spring Meeting at San Francisco on Wednesday, April 11, 2007. The attached manuscript will be submitted to the MRS Proceedings for Symposium B: Materials, Processes, Integration, and Reliability in Advanced Interconnects for Micro- and Nano-Electronics.

Update on August 16, 2007: This paper has been published in: Materials, Processes, Integration and Reliability in Advanced Interconnects for Micro- and Nanoelectronics, edited by Q. Lin, E.T. Ryan, W-L. Wu, D.Y. Yoon (Mater. Res. Soc. Symp. Proc. Vol. 990, Warrendale, PA, 2007), B06-04.

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Hi, Yaoyu, this is a very nice work. When N. Cordero studied the channel cracking in hermetic coating for flexible electronics, we realized that we needed to do more to consider the coupling of channel cracking and interfacial delamination. Otherwise, the deformation in substrate around the channel crack front on the interface is too large and distorted, which is easily observed in FEM. Now you did this nice work before we move forward. And this is a nice paper.

Besides, I want to ask a question: how can you verify the whole crack front morphology, including the channeling front and the delaminated front, esp. around the vicinity of channeling crack front? You assume the shape is like that in Fig.1(b). Of course, your method circumvents this subtlety. I am just curious if you considered this point?

Yaoyu Pang's picture


In the present work, we actually considered the coupling situation for steady state channel cracking, putting aside any complexities around the crack fronts and scenarios during the intermediate stage. So a 2D plane strain FEM model was set up and calculated, which I think is quite different from what N.Cordero have been doing.

But you did raise some interesting issues. Thanks for your nice input.

Rui Huang's picture

A renovated version of this work has been submitted to International Journal of Fracture


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