No abstract

No abstract

No abstract

Nanoindentation, or instrumented indentation, is a versatile technique that is most often used to measure the elastic modulus and hardness of thin film systems. It can also be employed to measure thin film adhesion energies by producing well-defined areas of delamination. When combined with the proper mechanics-based model and characterization of the failing interfaces, nanoindentation-induced delamination is a powerful tool to quantify interfacial fracture. This article highlights new improvements to the technique that build off the work of Marshall and Evans in the 1980s. Indentation-induced delamination in systems with brittle films or substrates can be a balance between causing delamination and causing through-thickness or bulk fracture. Focused ion beam cross-sectioning and confocal laser scanning microscopy were used to characterize failing interfaces, additional fracture events were observed in the load-displacement curves, and the adhesion energy was determined using not only symmetric, ideally shaped buckles, but also irregular-shaped and half-delaminated buckles.

Space-charge-controlled field emission analysis of current conduction in amorphous and crystallized atomic-layer-deposited Al 2 O 3 on GaN

Direct current magnetron sputter deposited Cu films have been grown on Si substrates without and with WTi barrier layers. The combined impact of thermal and kinetic energy activation of film growth on promoting Cu-Si interdiffusion and enhancing Cu3Si formation is illuminated. In addition, the effect of the formed Cu3Si phase on the properties of Cu films in terms of microstructure, residual stress, electrical resistivity, and roughness is highlighted. Finally, the time-dependent self-annealing behavior of residual stresses within Cu films grown at different substrate temperatures is presented and discussed. The formation of a Cu3Si layer at room temperature already during film deposition and the subsequent formation of an additional SiO2 layer deteriorate the long-term stability of residual stresses and electrical resistivity of Cu films directly grown on Si substrates. WTi barrier layers of 100 nm thickness widely prevent such undesired interfacial reactions; however, the first onset of interdiffusion of Cu and Si atoms has been observed at substrate temperatures as low as 474 K.

No abstract

Power semiconductor device architectures require the inclusion of a diffusion barrier to suppress or at best prevent the interdiffusion between the copper metallization interconnects and the surrounding silicon substructure. The binary pseudo-alloy of titanium–tungsten (TiW), with >70 at. % W, is a well-established copper diffusion barrier but is prone to degradation via the out-diffusion of titanium when exposed to high temperatures ([Formula: see text]400 [Formula: see text]C). Here, the thermal stability of physical vapor deposited TiW/Cu bilayer thin films in Si/SiO[Formula: see text](50 nm)/TiW(300 nm)/Cu(25 nm) stacks were characterized in response to annealing at 400 [Formula: see text]C for 0.5 h and 5 h, using a combination of soft and hard x-ray photoelectron spectroscopy and transmission electron microscopy. Results show that annealing promoted the segregation of titanium out of the TiW and interdiffusion into the copper metallization. Titanium was shown to be driven toward the free copper surface, accumulating there and forming a titanium oxide overlayer upon exposure to air. Annealing for longer timescales promoted a greater out-diffusion of titanium and a thicker oxide layer to grow on the copper surface. However, interface measurements suggest that the diffusion is not significant enough to compromise the barrier integrity, and the TiW/Cu interface remains stable even after 5 h of annealing.