Optimization of PET (Post Etch Treatment) steps to enlarge queue time and decrease defect counts in Ultra low-k material AIO (all in one) etch processes

To reduce the RC interconnect delays and cross-talk noise associated with the sub-28 nm advanced CMOS technology nodes, Dual Damascene process combined with Ultra low-k material needs to be introduced into Integrated Circuits manufacturing. With pores and low density, Ultra low-k material can be easily damaged. In this paper, we studied how to protect Ultra low-k material (k=2.5) in the Metal Hard Mask AIO Etch (MHM AIO). In order to reduce polymer residue, recovery and protection for the surface of Cu after etch were studied. Stopping Oxygen and moisture from Cu corrosion, Post Etch Treatment (PET) was introduced into AIO etch process. We found that PET could protect Ultra low-k material. PET technology is becoming more critical, because the Queue time (Q-time) between AIO etch process and WET clean need to be enlarged.