The integration of low-k dielectric material hydrogen silsesquioxane (HSQ) with nitride thin films as barriers

HSQ (hydrogen silsesquioxane) is one of the promising low-k materials used in VLSI technology as an intra-metal dielectric to reduce capacitance-related issues. Like any other dielectrics, the integration of HSQ in multilevel interconnect schemes has been of considerable importance. In this study, the compatibility of HSQ with different nitride barrier layers, such as PVD and CVD TiN, PVD TaN, and CVD W ₂N, has been investigated by using a variety of techniques. The refractory metal barriers, Ti and Ta, are also included for a comparison. The degradation of HSQ films indicates a strong underlying barrier layer dependence. With CVD nitrides or refractory metals as barrier, HSQ exhibits a better structural and property stability than that with PVD nitrides. The possible mechanisms have been discussed to account for these observations.