The incorporation of fluorine into SiO2 has been shown to reduce the dielectric constant of the existing materials by reducing the electrical polarizability. However, the incorporation of fluorine has also been shown to decrease film stability. Therefore, new efforts have been made to find different ways to further decrease the relative dielectric constant value of the existing low-k materials. One way to reduce the dielectric constant is by decreasing its density. This reduces the amount of polarizable materials. A good approach is increasing porosity of the film. Recently, fluorinated silica xerogel films have been identified as potential candidates for applications such as interlayer dielectric materials in CMOS technology. In addition to their low dielectric constants, these films present properties such as low refractive indices, low thermal conductivities, and high surface areas. Another approach to lower k is incorporating lighter atoms such as hydrogen or carbon. Silsesquioxane based materials are among them. However, additional integration issues such as damage to these materials caused by plasma etch, plasma ash, and wet etch processes are yet to be overcome. This dissertation reports the effects of triethoxyfluorosilane-based (TEFS) xerogel films when reacted with silylation agents. TEFS films were employed because they form robust silica networks and exhibit low dielectric constants. However, these films readily absorb moisture. Employing silylation reactions enhances film hydrophobicity and permits possible introduction of this film as an interlayer dielectric material. Also, this work describes the effects of SC-CO2 in combination with silylating agents used to functionalize the damaged surface of the ash-damaged MSQ films. Ashed MSQ films exhibit increased water adsorption and dielectric constants due to the carbon depletion and modification of the properties of the low-k material caused by interaction with plasma species. CO2 is widely used as a supercritical solvent, because of its easily accessible critical point, low cost, and non-hazardous nature. Its unique diffusion and surface tension properties make SC-CO2 a good candidate for treatment of porous ultra low-k materials.

Avec la miniaturisation continue des circuits intégrés et le remplacement de l’oxydede silicium par des diélectriques low-κ poreux à base de SiOCH, la fiabilité des circuitsmicroélectroniques a été fortement compromise. Il est aujourd’hui extrêmement importantde mieux appréhender les mécanismes de dégradation au sein de ces matériaux afin deréaliser une estimation précise de leur durée de vie.Dans ce contexte, ces travaux de thèse ont consisté à étudier les mécanismes de dégradationau sein du diélectrique afin de proposer un modèle de durée de vie plus pertinent.Par une étude statistique du temps à la défaillance sous différents types de stress électrique,un mécanisme de génération des défauts par impact est mis en évidence. En l’associantau mécanisme de conduction au sein du diélectrique, il a été possible de développer unmodèle de durée de vie cohérent pour les interconnexions permettant une estimation de ladurée de vie plus fiable que les modèles de la littérature. L’impact du piégeage de chargesdans le diélectrique a ensuite été analysé grâce à ce modèle. / With the constant size reduction of integrated circuits and the replacement of silicon dioxide with porous SiOCH, the reliability of interconnects has been sharply reduced. A better understanding of degradation mechanisms is now required in order to have a precise estimation of product lifetime. In this work, degradation mechanisms have been studied in order to propose a more accurate lifetime model. A statistical study of times to failure under various electrical stresses is used to explain the physical mechanisms involved in defect creation. Combining these degradation mechanisms and Poole-Frenkel conduction mechanism enables the use of a new lifetime model. This model leads to a better estimation of the lifetime than existing models. Finally, the effects of charge trapping on lifetime in these materials have been studied.