Effective Approach for Hillock Defect Reduction in Cu Metallization Process

Hillock is formed at the film surface in Cu metallization process. During the growth of hillock, the tensile stress built in the copper (Cu) metal film due to the relieved thermal expansion coefficients. These "hillocks" are just areas of localized copper elevation relative to the rest of the surface that can lead to non-uniformity during etch-stop dielectric deposition. It is important to understand how the hillock is created in order to develop an effective preventative process. In this paper, the degas temperature performance and effect on the hillock in Cu metallization process is introduced, then an effective approach to reduce hillock defect is demonstrated.