Using molecular-dynamics simulations, we examine the mechanical behavior of mesoporous amorphous silicas that are considered as ultralow-dielectric-constant materials in microelectronics. We study structures with a regular array of spherical pores and densities between 88% and 72% of the amorphous silica normal density. We find that the Young modulus depends on density according to a sublinear power-law scaling relationship and decreases with decreasing mesopore size. Upon uniaxial compression, an elastic instability is triggered in structures with less-than-critical density or mesopore size.
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