Improved process flows and methods are provided herein for forming a passivation layer on sidewall surfaces of openings formed in an amorphous carbon layer (ACL) to avoid bowing during an ACL etch process. More specifically, improved process flows and methods are provided to form a silicon-containing passivation layer on sidewall surfaces of the openings created within the ACL without utilizing atomic layer deposition (ALD) techniques or converting the silicon-containing passivation layer to an oxide or a nitride. As such, the improved process flows and methods disclosed herein may be used to protect the sidewall surfaces of the ACL and prevent bowing during the ACL etch process, while also reducing processing time and improving throughput.