| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Tuesday Sessions |
| Session PS-TuM |
| Session: | Advanced BEOL / Interconnect Etching I |
| Presenter: | Gerardo Delgadino, Lam Research Corp. |
| Correspondent: | Click to Email |
Cu resistivity increase at smaller geometries and the use of lower κ dielectrics forced several changes on BEOL integration. Susceptibility of ULK material to strip damage drove the adoption of TiN hard mask integration starting with a few players at 65nm node to full adoption at 32nm for advance logic.
TiN hard mask demonstrated good selectivity during dielectric etch but concerns arise as we move to smaller pitch: 1- TixFy residues may compromise metallization of small features and 2- Residual compressive stress in the TiN may induce line wiggling. This last concern is the focus of this work.
We develop a simple analytical model based on Energy balance to predict wiggling onset based on geometrical and mechanical properties of the materials. We showed that the wiggling onset aspect ratio reduces with the pitch. We also shown that even when at the end of the process the no-wiggling condition is satisfied, wiggling might have occurred during etch causing feature distortions.