| AVS 66th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Tuesday Sessions |
| Session PS+EM-TuA |
| Session: | Advanced BEOL/Interconnect Etching and Advanced Memory and Patterning |
| Presenter: | Xinghua Sun, TEL Technology Center, America, LLC |
| Authors: | X. Sun, TEL Technology Center, America, LLC A. Raley, TEL Technology Center, America, LLC J. Lee, IBM Research Division, Albany, NY J.C. Arnold, IBM Research Division, Albany, NY K. Taniguchi, TEL Miyagi Limited M. Edley, TEL Technology Center, America, LLC K. Lutker-Lee, TEL Technology Center, America, LLC D. O'Meara, Tokyo Electron America, Inc. K. Tapily, TEL Technology Center, America, LLC Y.-T. Lu, TEL Technology Center, America, LLC P.E. Biolsi, TEL Technology Center, America, LLC |
| Correspondent: | Click to Email |
Aggressive metal pitch scaling of back end of line (BEOL) interconnect for future nodes leads to increased sensitivity to via overlay and critical dimension (CD) errors, resulting in yield loss. Spacing between top and bottom metal layers in via chain macros are reaching the limits of current materials, such that device reliability may become compromised due to metal shorting or dielectric breakdown. The technique of 1-D self-aligned via (SAV) constrained by top metal hard mask (MHM) is widely used to control one direction of via CD. 2-D fully aligned via (FAV) was recently introduced to mitigate the drawbacks of SAV at via bottom. In FAV, vias are constrained with spacers resulting from recessed metal in the orthogonal direction to the MHM, thereby increasing the margin of error allowed due to CD variations and overlay shifts. However, one of the biggest challenges in successfully integration of FAV in the BEOL is maintaining the integrity of these spacers during via etch. Etch selectivity, landing on conformably deposited Nblok based cap layers, is far from sufficient to maintain good self-confinement that demonstrates adequate FAV behavior. High selectivity etch stop layers (ESL) along with compatible etches that promote soft landing on these films are required.
In this presentation, we demonstrate that etch and film can collaboratively work to make FAV a competitive solution for sub-7nm nodes. Different ESL materials and film properties are investigated in conjunction with unique via and trench etch processes to achieve optimized FAV corner shape. This work shows a multifaceted approach to successful implementation of FAV as a valuable scaling booster for advanced BEOL nodes.