Novel self-assembled ultra-low-k porous silica films with high mechanical strength for 45 nm BEOL technology

Novel ultra-low-k porous silica films were developed by use of a self-assembly technology. The mechanical properties of the porous silica films could be reinforced independently of the dielectric constant by introducing a tetramethyl-cyclo-tetra-siloxane (TMCTS) treatment. High modulus porous silica films, with an elastic modulus of 8 GPa and dielectric constant of 2, can be achieved simultaneously. Ultra-low-k/Cu damascene with sufficient mechanical strength was demonstrated for 45 nm BEOL (back-end-of-line) technology.