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The growth of tungsten nitride carbide (WNxCy) films obtained by atomic layer deposition using triethylboron, tungsten hexafluoride, and ammonia precursors is determined by the density and type of reactive sites. The film properties change as a function of thickness. On silicon dioxide and silicon carbide, growth is initially nonlinear such that the transient regimes are characterized by island formation, as evidenced by a parabolic tungsten growth curve extending to film thicknesses of up to 5 nm. Such films have low densities of ∼4–6 g cm-3 corresponding to only ∼30%–45% of the bulk density of ∼13.1 g cm-3 determined for a WN0.45C0.55 composition. X-ray reflectivity, thermal desorption, and elastic recoil detection spectroscopies reveal surface roughening and compositional and density differences close to the substrate surface. The offset from linear growth in the case of WNxCy films deposited on silicon dioxide is induced by the initial reaction of silanol and siloxane groups with triethylborane resulting in passivating ethylsilyl groups on the surface. A transient regime is not observed for WNxCy growth on hydrogen-terminated silicon with the initial growth being dominated by the reduction of tungsten hexafluoride to tungsten. On silicon nitride a short transient regime is observed relative to the carbide and oxide surfaces attributed to the enhanced binding of the triethylboron precursor. [ABSTRACT FROM AUTHOR]

The short-ranged bonding structure of organosilicate glasses can vary to a great extent and is directly linked to the mechanical properties of the thin film material. The combined action of ultraviolet (UV) radiation and thermal activation is shown to generate a pronounced rearrangement in the bonding structure of thin organosilicate glass films involving no significant compositional change or film densification. Nuclear magnetic resonance spectroscopy indicates loss of –OH groups and an increase of the degree of cross-linking of the organosilicate matrix for UV-treated films. Fourier transform infrared spectroscopy shows a pronounced enhancement of the Si–O–Si network bond structure, indicating the formation of more energetically stable silica bonds. Investigation with x-ray reflectivity and ellipsometric porosimetry indicated only minor film densification. As a consequence, the mechanical properties of microporous organosilicate dielectric films are substantially enhanced while preserving the organosilicate nature and pristine porosity of the films. UV-treated films show an increase in elastic modulus and hardness of more than 40%, and a similar improvement in fracture energy compared to untreated films. A minor increase in material dielectric constant from 3.0 to 3.15 was observed after UV treatment. This mechanism is of high relevance for the application of organosilicate glasses as dielectric materials for microelectronics interconnects, for which a high mechanical stability and a low dielectric constant are both essential film requirements. [ABSTRACT FROM AUTHOR]

Gaseous precursors for the atomic layer deposition (ALD) process can penetrate and deposit inside porous dielectrics. Understanding the relationship between the substrate porosity and the size and shape of precursor molecules used for the ALD of dielectric or metal films on these substrates is crucial for the formation and fabrication of reliable nanostructures. Sealing the surface pores is highly desirable to prevent the deposition of gaseous ALD precursors inside the porous network. In this study, in-diffusion of precursors is investigated using x-ray reflectivity, transmission electron microscopy, and Rutherford backscattering spectrometry for different porous substrates and binary (TaN) and ternary (WNC) ALD systems. Experimental observations are complemented with computational molecular modeling performed in the framework of the density-functional-theory formalism to determine the size and shape of ALD precursors. Pore sealing treatments are used to prevent a precursor penetration and to provide a suitable starting surface for the nucleation and growth of ALD films. [ABSTRACT FROM AUTHOR]

On nanoscale laminate structures, the interface cannot be identified any longer as the separation between two films of bulk materials. The formation of the interface defines the final composition and structure of the laminate structure. As such, the characterization of the interface becomes an important challenge. In this work the nanoscale laminate structures were formed by atomic layer deposition (ALD) of tungsten nitride carbide and tantalum nitride thin films on dense dielectrics [silicon carbide and silicon oxide (SiO2)]. The laminates were studied using x-ray reflectivity. The starting substrate surface is a primary factor in determining the density of the ALD layer. Moreover, in some cases, electron-density perturbations are observed in the vicinity of the interfacial region. A characterization strategy, using a density contrast layer between the silicon substrate and the SiO2 dielectric is presented. Depending on the chemical nature of precursors and substrate, ALD processes can either form specific interfacial organization or induce dielectric modifications, in any case, leading to unexpected metal-dielectric interactions. [ABSTRACT FROM AUTHOR]

Subcritical cracking of thin glass films caused by stress-corrosion phenomena cannot be neglected when it comes to application and manufacturing processes that involve exposure to aqueous environments. A protocol is introduced to allow for a quantitative study of stress corrosion through channel cracking experiments. By this method, an exponential dependence of the crack propagation rate on the pH of the aqueous environment is revealed. Therefore, this behavior should be accounted for through the use of an appropriate pre-exponential factor in the expression of channel cracking rate. This factor should reflect the reduced crack resistance of the glass film caused by the weakening of the silica bonds behind the crack tip in the aqueous environment. A direct comparison between commercial slurries and reference solutions confirms that the crack resistance is a function of the pH of the ambient. [ABSTRACT FROM AUTHOR]

It is known that porous organosilicate glass (OSG) dielectrics tend to lose functional groups and become denser upon the chemical and physical action of the plasmas, but an accurate analysis and estimation of the depth and degree of film densification is not straightforward. In this study, we show that the combination of techniques like x-ray reflectivity, surface acoustic waves, and nanoindentation in depth-sensing and modulus mapping mode allow a complete and self-consistent physical analysis of the damage induced by the direct exposure of porous OSG films to different plasma ambients in reactive ion etching mode. We demonstrate for the chosen dielectric that the characteristics of the damage regions such as density and elastic modulus are very similar regardless of the reducing or oxidizing nature of the plasma. Nevertheless, the physical depth of the damage region shows large variation. Capabilities and limitations of each of the chosen analysis techniques are also discussed. [ABSTRACT FROM AUTHOR]