Etch Process Pre-etch Transient Conditioning

The patent applies periodic action by implementing a cyclical etching process that alternates between etching steps and transient conditioning steps. The etching step removes material from the etch layer, while the transient conditioning step restores uniform etch rates by modifying the etch layer surface. This periodic alternation between opposing actions (etching that creates aspect ratio dependence and conditioning that reduces it) enables consistent etching of features with different aspect ratios.

The transient conditioning step serves as a preliminary action performed before the main etching step in each cycle. By conditioning the etch layer surface in advance, the process prepares the surface to receive subsequent etching at a uniform rate, preventing aspect ratio dependent etching from developing during the etching step. This preliminary modification of the etch layer ensures that when etching occurs, all features etch at consistent rates regardless of their aspect ratios.

The cyclical process alternates between etching steps that advance the etch depth and transient conditioning steps that restore etch rate uniformity. By periodically interrupting the etching process to perform conditioning, the system maintains consistent etch rates across features of different widths while still achieving the required etch depth. This periodic intervention prevents the accumulation of aspect ratio dependent effects that would otherwise degrade precision.

The etching process is segmented into discrete cycles, each comprising an etching step and a transient conditioning step. This segmentation divides the continuous etching process into manageable units where precision can be restored periodically. Each cycle is optimized to achieve a specific amount of etch depth while maintaining rate consistency, and multiple cycles are combined to achieve the total required etch depth with uniform precision throughout.