Dependence of the minimal PVD TA(N) sealing thickness on the porosity of Zirkon TM LK Dielectric films

The understanding of the parameters and mechanisms playing a role in sealing the surfaces of porous dielectrics is fundamental for an effective integration of these new materials in the interconnect processing. This study focuses on the correlation between the porosity of Zirkon™ low-k dielectric films and the physical vapom deposition (PVD) Ta(N) thickness needed to achieve an efficient sealing of the dielectric surface. A clear dependence of the minimal Ta(N) sealing thickness on the porosity of the Zirkon dielectric films has been observed. Since the average pore size of the films remains approximately constant for the different porosity formulations, this effect is most probably attributed to a partial conversion of the initial 'closed pore' structure into an 'open pore' one for the highest porosity films.