(38a) Atomic-Scale Modeling of the Mechanical Behavior of Ultra-Low-Dielectric-Constant Mesoporous Amorphous Silicate Films: Effects of Straining Mode and Pore Morphology and Orientation | AIChE

(38a) Atomic-Scale Modeling of the Mechanical Behavior of Ultra-Low-Dielectric-Constant Mesoporous Amorphous Silicate Films: Effects of Straining Mode and Pore Morphology and Orientation

Authors 

Gungor, M. R. - Presenter, University of Massachusetts Amherst
Maroudas, D. - Presenter, University of Massachusetts
Watkins, J. J. - Presenter, University of Massachusetts


Latest-generation technologies in microelectronics require ultra-low-dielectric-constant (ULK) dielectric materials to eliminate the capacitive coupling between closely spaced interconnect lines due to the larger-scale integration of transistors in increasingly smaller areas (on the order of 109 cm-2). The ULK dielectric materials must also withstand certain challenging thermo-electro-mechanical conditions, which can cause cracking and delamination, as well as thermal and electrical breakdown. Additionally, these materials should be compatible with lithographic processing during chip manufacturing. Mechanical strength is particularly important for the structural integrity and overall reliability of the microelectronic devices under the thermomechanical loading conditions characteristic of semiconductor manufacturing processes, chip packaging, and device service. Among materials that are being developed for ULK applications, porous amorphous silicate films are primarily considered due to their compatibility with current semiconductor manufacturing technologies.

In this presentation, we report results of molecular-dynamics (MD) simulations aiming at a fundamental understanding of the physical mechanisms that control the mechanical behavior of film structures of mesoporous amorphous silica with pore diameters of a few nanometers, as well as prediction of the response of such structures to various mechanical loading conditions. The MD simulations employ a realistic classical potential that includes two-body and three-body interatomic interactions. The normal-density amorphous silica structures are prepared through MD starting from a beta-cristobalite crystalline structure and following a thermal processing sequence that includes melting, rapid quenching, and a thermal annealing schedule. We have generated ?regular? and ?disordered? mesoporous structures through the introduction of various geometric arrangements of spherical or cylindrical pores by removal of atoms from the normal-density amorphous silica matrix and subsequent thermal annealing at the temperature of interest to ensure proper structural relaxation.

We present a systematic analysis of the mechanical response of regular mesoporous amorphous silica structures with spherical and cylindrical pores under applied strains within the elastic limit near room temperature; the analysis employs large-size computational supercells and is based on MD simulations of dynamic straining followed by isostrain MD simulations. We have computed the elastic moduli of mesoporous structures with spherical pores arranged in simple cubic lattices and cylindrical pores in square and hexagonal lattice arrangements and analyzed the stability of these structures under tensile and compressive straining as a function of density and pore diameter. Furthermore, we have analyzed the effects of high-temperature thermal treatment of the mesoporous amorphous structures on their structural stability and mechanical strength in correlation with the underlying microstructural evolution.