The Morphological Evolution For A Void In Thin-film Interconnect Of Integrated Circuit Analyzed By Phase-field Method

A typical failure mode of the thin-film interconnect in integrated circuit is that voids nucleate, grow and change their shape to form crack-like slits oriented perpendicular to the line, which cause an open circuit.In this thesis, the governing equations which simulate morphological evolution of a void in interconnect are firstly developed based on sharp interface method and phase-field method, and then we examine the applicability of the phase-field model by use of asymptotic expansion of an order parameter which controls the width of the interface phase.Secondly, the governing equation for morphological evolution of an elliptic void driven by surface energy is established by the method of conformal transformation, which overcomes the difficulty of the boundary value problem for an elliptical void.Then using the phase-field theory, a simplified model is established to describe the morphological evolution of a circular void via surface diffusion and bulk diffusion driven by surface tension and applied biaxial stress. The governing equation for this mode is derived and solved numerically by the FTCS(forward for time; center for space) difference scheme.Finally, a theoretical formula is established, which describes the rule and stability condition of the morphological evolution for a void under mechanical and thermal load.