A hybrid experimental/numerical approach to characterize interfacial adhesion in multilayer low-κ thin film specimens

• Published in: Thin solid films 2010-10, Vol.519 (1), p.337-344
• Main Authors: Kitey, Rajesh, Sottos, Nancy R., Geubelle, Philippe H.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Decompression shock; Dynamic wave propagation; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Laser spallation; Low-κ; Materials science; Mechanical and acoustical properties; Physical properties of thin films, nonelectronic; Physics; Specific materials; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film; Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2010.07.094

The strength of multilayer low dielectric (low-κ) constant organo–silicate glass (OSG) and silicon–carbon–nitride (SiCN) thin film interfaces is characterized by a laser spallation technique. Two specimen sets with different OSG/SiCN stacking sequences are evaluated. The effect of helium (He) pretreatment is also investigated. The stress at the low-κ interface is enhanced through the use of a fused silica backing layer to shape the incident pulse and the addition of a thin gold (Au) top layer to increase inertial force during the dynamic failure event. The weakest interface in the multilayer stack (first to fail) is identified through optical images, profilometry and scanning electron microscope images of the spallation zone. The strength of the failed interface is inferred from the incident stress history in combination with a one dimensional dynamic wave propagation analysis. The adhesion strength of the OSG/SiCN interface (372 MPa) is 32% larger than that of Si/OSG (282 MPa) for specimens with no He pretreatement. The interfacial strength of both interfaces is significantly increased by a He pretreatment, making failure by spallation difficult.