High Aspect Ratio Carbon Hard Mask Etch Process for Profile and LCDU Control

Improving the bowing profile and LCDU in HAR etching is challenging due to ion sputtering, insufficient sidewall protection, and uneven polymer deposition. To address these challenges, we investigated the gas ratio in deep hole etching of ACL, the effect of new polymer gas on sidewall protection, and the effects of different descum steps and their addition times and BRF parameters on LCDU. From the results, it can be seen that using more COS in the early stage of etching and adding polymer gas SiCl4 all have varying degrees of improvement on bowing profile. Using a descum step containing CHF3, adding it earlier and using lower BRF resulted in different levels of improvement in LCDU.