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The effect of porosity on the stiffness and fracture energy of brittle organosilicates

Li Han's picture

Integrating porous low-permittivity dielectrics into Cu metallization is one of the strategies to reduce power consumption, signal propagation delays, and crosstalk between interconnects for the next generation of integrated circuits. However, the porosity and pore structure of these low-k dielectric materials also strongly affects other important material properties besides their dielectric constant.

In this paper, we investigated the impact of porosity on the stiffness and cohesive fracture energy of a series of porous organosilicate glass (OSG) thin films using the nanoindentation technique and the double-cantilever beam (DCB) test. The OSG films were deposited by plasma-enhanced chemical vapor deposition (PECVD), and had a porosity in the range of 7~45%. The experimental results were compared with micromechanics models and finite element method (FEM) calculations. It was demonstrated that both the level of porosity and pore microstructure affect the stiffness of the OSG films significantly; in contrast, the cohesive fracture energy is determined by the level of porosity only and decreases linearly with increasing porosity.

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Li Han's picture

 

Li Han

Aaron Goh's picture

Li Han, do you think if you could also apply percolation theory to your data? I am also wondering if the analysis by Sudduth 1995 J. Materials Sci. 4451 might apply to your data. 

Li Han's picture

Dear Aaron, you are rising an excellant point. Indeed, we did think of percolation theory in interpreting our data; however, the difficulty is that such theory in one way or another depends on the shape of the pore that we do not have direct information about. Any idea in mind?

Thank you for your interest in our work and for point out a nice reference. 

Li Han

Li Han's picture

We'd like to update the original manuscript with the final version accepted for publication in JMR.

Li Han

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