Mechanical property analyses of porous low-dielectric-constant films for stability evaluation of multilevel-interconnect structures

Abstract

The mechanical properties of porous low-dielectric-constant (low- k) thin films have been investigated for the stability evaluation of multilevel-interconnect structures using nanoindentation, microscratch, and four-point bending tests. Stress–strain curves of these films are proposed to predict their strengths and to explain their deformation behaviors. Real stress–strain behaviors are analyzed and confirmed by combining the experimental data obtained from nanoindentation and microscratch tests. Soft low- k films exhibit large plastic deformation, while hard and brittle films fracture early. The interfacial adhesion strengths and delamination behaviors between thin-film layers have been also studied using microscratch and four-point bending tests. The mechanical failure of interconnect structures depends on the inferiority of film strength or interfacial adhesion.