Jeannette M. Jacques

Effects of elastic modulus on the fracture behavior of low-dielectric constant films

A model that predicts channel-crack propagation behavior in silica-based low-/spl kappa/ dielectrics (low-/spl kappa/) was developed. A solid-mechanics theory that governs fracture behavior was used to obtain low-/spl kappa/ material constants. These fracture parameters were used to predict crack behaviors in five low-/spl kappa/ films with distinct elastic moduli. The model developed demonstrates that crack propagation rate is extremely sensitive to modulus, especially when the material is compliant.

Environmental Effects on Crack Characteristics for OSG Materials

To improve capacitance delay performance of the advanced back-end-of-line (BEOL) structures, low dielectric constant organosilicate glass (OSG) has emerged as the predominant choice for intermetal insulator. The material has a characteristic tensile residual stress and low fracture toughness. A potential failure mechanism for this class of low-k dielectric films is catastrophic fracture due to channel cracking. During fabrication, channel cracks can also form in a timedependent manner due to exposure to a particular environmental condition, commonly known as stress-corrosion cracking. Within this work, the environmental impacts of pressure, ambient, temperature, solution pH, and solvents upon the channel cracking of OSG thin films are characterized. Storage under high vacuum conditions and exposure to flowing dry nitrogen gas can significantly lower crack propagation rates. Cracking rates experience little fluctuation as a function of solution pH; however, exposure to aqueous solutions can increase the growth rate by three orders of magnitude.

Fracture Property Improvements of a Nanoporous Thin Film via Post Deposition UV Curing

As silicon-based microelectronic devices continue to aggressively scale down in size, traditional BEOL dielectric materials have become obsolete due to their relatively high dielectric constant. Organosilicate glass (OSG) materials have emerged as the predominant choice for intermetal dielectrics in advancing technology nodes. A potential failure mechanism for this class of low-k dielectric films during the manufacturing process is catastrophic fracture due to channel cracking. To improve the mechanical strength and stability of these silicon-based materials, the use of post-deposition curing processes is under evaluation. In this work, the effects of UV curing on the properties of OSG films were characterized. After UV curing, film hardness and elastic modulus are improved, with no change in the residual film stress. The average film density increases linearly as a function of UV exposure time. Channel crack propagation velocities decrease with UV exposure. The improvements in the mechanical properties of OSG films are believed to correlate with the increasing Si-O-Si bond population. Comparisons between post-deposition UV and Electron Beam curing processes are provided.