Effects of post deposition annealing of evaporated Copper and Aluminium on MSQ low-k dielectric spin on glass

The organic Methylsilsesquioxane (MSQ) exhibits low dielectric constant and is an important and promising material to reduce the capacitive coupling between metal layers in semiconductor integrated circuits. However, MSQ has lower film density and therefore more porous than the traditional SiO₂ film and could pose reliability issues. The aim of this paper is to study the effect of post deposition annealing of Copper and Aluminium using evaporation method. Electrical characterisation employing high-frequency C-V and bias-temperature stress (BTS) were employed to study the effect of MOS capacitor (MOSC) structures annealed at different temperatures. The results showed that the leakage current of MOSC with Aluminium and Copper gate increases as the annealing temperatures increases. In addition, MOSC with Aluminium gate has greater reliability compared to MOSC with Copper gate when subject to BTS. However, the leakage current of MOSC with Aluminium gate is much greatly affected by the operating temperature. These concerns need to be addressed and overcome to ensure that MSQ can be a viable interlayer dielectric (ILD) for integrated circuits (IC).