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The thermal conductivity measurement of films with submicrometer thicknesses is difficult due to their exceptionally low thermal resistance, which makes it challenging to accurately measure the temperature changes that occur as heat flows through the film. Thus, specialized and sensitive measurement techniques are required. 3ω method is a widely used and reliable tool for measuring the thermal conductivity of films. However, the high in-plane thermal conductivity in thin films results in rapid heat dissipation across the thin film, resulting in poor measurement sensitivity and making it difficult to accurately measure the temperature gradient with the traditional 3ω method. Also, the traditional 3ω method requires cross-plane thermal conductivity to derive the in-plane counterpart. Here, we introduce a dual-domain 3ω method that adopts AC-modulated heating and electrode arrays facilitating surface temperature profiling: (1) the sensitivity was significantly improved due to the employment of low-thermal-conductivity-substrate, and (2) cross-plane thermal conductivity is not required for the analysis of in-plane counterpart. This measurement platform allows us to control heat penetration in depth via varied heating frequencies as well as spatial temperature detection through laterally distributed electrodes on the thin film surface. By utilizing the described method, we have determined the in-plane thermal conductivity of a copper film, having a thickness of 300 nm, which was found to be 346 Wm−1K−1 and validated by the Wiedemann–Franz law.

Interfacial debonding of multi-layer thin film systems in microelectronics can severely affect device functionality and reliability. There is great engineering value to quantitatively evaluate the interface adhesion strength so as to control the adhesion quality. It has been known that the formation energy of new crack surfaces along an interface and the plastic dissipation occurring in the bulk materials are the two major energy contributions to the total interface toughness. The total interface toughness is the only quantity measurable in a fracture experiment To understand the adhesion strength of interfaces, one has separate the two energy contributions to the total toughness. This can be achieved by computational modeling of the failure process. In this paper, the fracture process zone model is used to specify the properties of the interface, in which the major parameters are the work of separation and peak strength. This model is readily incorporated into a finite element analysis which can be used to predict interfacial decohesion and crack advance along the interface. There is no need to introduce an additional failure criterion and this is an attractive feature of the above approach. We have analysed interface crack growth in a Cpoint bend specimen. Interfacial crack growth occurs under mixed mode. The crack growth resistance and the contribution of plastic dissipation to the total interface toughness are calculated for crack growth along one of the interfaces of a ductile thin film joined with two elastic substrates. The effects of the thickness of the ductile thin layer, the peak separation strength and work of separation on the total work of fracture and the steady-state work of fracture are discussed.