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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]