Subcritical debonding of polymer/metal interfaces has important implications for the reliability of a range of modern device technologies containing thin layered structures, although the physics of the underlying crack-growth mechanisms are not well understood. This study investigates the effect of moisture on subcritical debonding at the interface between a silica-filled epoxy resin and a copper substrate electroplated with a nickel layer. Subcritical debond-growth rates in the range of 10−5 to 10−11 m/s were characterized as a function of the applied strain energy release rate, GA. Particular attention was given to the relationship between the debond tip strain energy release rate, Gtip, and the measured debond growth rates. The kinetics of interfacial debond growth were rationalized in terms of a stress-dependent chemical reaction and mass transport of the environmental species to the debond tip. The order of the chemical reaction with respect to water was determined and found to be surprisingly high (n∼5). In the transport-controlled region, the rate of debond growth was found to increase linearly with the partial pressure of water vapor. The effects of salient interface parameters including the peak stress in a cohesive zone used to model the fracture mechanism were explored.

The reliability of microelectronic components is profoundly influenced by the interfacial fracture resistance (adhesion) and associated progressive debonding behavior. In this study we examine the interfacial fracture properties of representative polymer interfaces commonly found in microelectronic applications. Specifically, interface fracture mechanics techniques are described to characterize adhesion and progressive bebonding behavior of a polymer/metal interface under monotonic and cyclic fatigue loading conditions. Cyclic fatigue debond-growth rates were measured from ~10−11 to 10−6 m/cycle and found to display a power–law dependence on the applied strain energy release rate range, ΔG. Fracture toughness test results show that the interfaces typically exhibit resistance-curve behavior, with a plateau interface fracture resistance, Gss, strongly dependent on the interface morphology and the thickness of the polymer layer. The effect of a chemical adhesion promoter on the fracture energy of a polymer/silicon interface was also characterized. Micromechanisms controlling interfacial adhesion and progressive debonding are discussed in terms of the prevailing deformation mechanisms and related to interface structure and morphology.

The interfacial fracture properties of a representative polymer/metal interface commonly found in microelectronic applications are examined. The double cantilever beam (DCB) configuration was used to investigate the effects of environmental variables on interfacial adhesion and progressive delamination under monotonic and cyclic fatigue loading conditions. The steady-state interfacial fracture energy, Gss, taken from the plateau of the R-curve, of a representative silica-filled Phenol-Novolac epoxy on a Nielectroplated Cu substrate showed little sensitivity to the presence of moisture. On the other hand, both the initiation interfacial fracture energy, Gi, and the entire progressive debond curve under fatigue loading were remarkably sensitive to moisture and temperature, respectively. Debonding is modeled in terms of interface structure, chemistry using chemical reaction rate theory, and relaxation process at the debond tip. The activation energy for stage I debond growth is found to be 140 kJ/mol and 63 kJ/mol for stage II for the current polymer/metal interface.

The reliability of microelectronic components is profoundly influenced by the interfacial fracture resistance (adhesion) and resistance to progressive debonding of interfaces. In this study we examine the interfacial fracture properties of representative polymer interfaces commonly found in microelectronic applications. Specifically, interface fracture mechanics techniques are described to characterize adhesion and progressive debonding behavior of a polymer/metal interface under cyclic fatigue loading. Cyclic fatigue debond-growth rates were measured from ∼10−10 to 10−6 m/cycle and found to display a power-law dependence on the applied strain energy release rate range, ΔG. Fracture toughness test results show that the interfaces typically exhibit resistance-curve behavior, with a plateau interface fracture resistance, Gss, strongly dependent on the interface morphology and the thickness of the polymer layer. The effect of a chemical adhesion promoter on the fracture energy of a polymer/silicon interface was also characterized. Micromechanisms controlling interfacial adhesion and progressive debonding are discussed in terms of the prevailing deformation mechanisms and related to interface structure and morphology.

Lower RC delay is vital to achieve optimal and competitive circuit performance and hence drives the endlessly pursued BEOL integration scheme advancement. To date low-k dielectric materials, i.e., fluorine-doped oxides, carbon-doped oxide (SiCOH), to porous carbon-doped oxides (p-SiCOH) have been implemented. However, due to the process integration challenges with inherently weak low-k materials, the trend to pursue lower k dielectrics has come to a plateau as technology nodes scale down past 20/14nm. On the other hand, the trend of geometry layer thickness shrinking down, such as trench CD and height, via CD and height, etc., still continues for each advanced technology node. In the BEOL stack adhesion layers (oxide + gradient layers) (ALs) with higher k value were introduced to enhance interface adhesion strength between SiCOH/p-SiCOH and dielectric cap film (SiCN), which offset the intrinsic RC benefit from low-k dielectric material. At more advanced nodes and beyond, the combined ALs and cap film could be up to via or trench height, which poses a huge challenge to meet desired RC performance and technology node scaling. Therefore, the thickness reduction of ALs and cap film becomes necessary for further technology node scaling. In this study, samples with interfacial full ALs, reduced ALs and bulk only (no ALs) for p-SiCOH (k=2.75) on various cap films were prepared, such as SiCN, SiCN/ODC, SiCN/AlONx, etc. TOF-SIMS analyses was used to confirm the composition of the dielectric stacks and later check the debonded surface morphology. Four-point bend adhesion tests were conducted to evaluate interfacial adhesion strength. Results show the interfacial adhesion strength on samples with reduced Als and bulk only (no ALs) is dropped by ~20% and ~30%, respectively. Additional ODC layer on top of SiCN would increase the interfacial adhesion strength by ~10%. It is suggested that reduced ALs may be adequate to satisfy overall CPI requirement for the BEOL integration scheme of p-SiCOH on advanced dielectric cap films (AlN + ODC). The coupling capacitance reduction for a combined reduced ALs and advanced dielectric cap can be up to 16% at M0 level and 10% at Mx level for a 40nm metal pitch.