Diamond-like amorphous carbon layer film by an inductively coupled plasma system for next generation etching hard mask

Amorphous carbon layer (ACL) deposited by the capacitively coupled plasma (CCP), plasma-enhanced chemical vapor deposition (PE-CVD) is widely used in etching hard masks in the semiconductor industry. As the feature size of semiconductor devices decreased below 30 nm, a carbon hard mask film with high etching selectivity and high transparency is required. However, it is very difficult to deposit the amorphous carbon film with both high etching selectivity and high transparency by CCP type PE-CVD. In this study, ACL films were deposited by an inductively coupled plasma (ICP) type deposition system. We selected the ICP deposition method because it allows independent control of the plasma density and ion impingement energy. The ACL films deposited by the ICP system had higher film density than the density of ACL films deposited by PE-CVD system. Moreover, Raman spectroscopy analysis of the ICP-made ACL films showed diamond-like properties with a high ratio of sp3 bonding, which could be due to the optimal bias power in ICP during deposition. The dry-etching selectivity of ACL films linearly increased with the density of the film. These studies confirmed that ICP is an effective method for the deposition of carbon hard masks with high etching selectivity.