Supercritical CO2 clean with novel solution for 65 nm and beyond BEOL performance improvement

Supercritical CO₂ (SCCO₂) clean/modification performance on a 300 mm tool with promising physical, electrical and reliability results for 65 nm low k dual damascene is successfully demonstrated in this work. The process is optimized to remove post-ash residues and modify the dielectric film damaged by O₂ plasma ash. The low-k value dielectric (LKD) surface is modified from hydrophilic to hydrophobic by the SCCO₂ treatment. Dielectric constant measurements before and after treatment show effective modification only on porous CVD LKD films. Leakage performance with 55% reduction and capacitance performance with 11% reduction by the process with respect to the conventional process demonstrate the benefits. The process is compatible with the 8 layer scheme. Promising electro-migration (EM), stress migration (SM) performance and better time-dependent dielectric breakdown (TDDB) results indicate that the process is more robust than the conventional one for future interconnects. For 65 nm generation and beyond, SCCO₂, clean/modification is demonstrated as a promising solution for Cu/low k integration.