SEM Hole Filling by Pulsed Gas Flow for Uniform Delayering

The patent applies preliminary action by filling the high aspect ratio channel holes with deposition material before performing the delayering milling process. This pre-filling step ensures that when milling occurs, the material is removed uniformly from both the solid portions and the channel hole regions, preventing sputtering through the walls and achieving consistent metrology across the wafer surface.

The patent applies local quality by selectively depositing material only within the channel hole regions rather than uniformly across the entire wafer. The deposition process targets specific locations (the high aspect ratio holes) to modify their properties locally, ensuring they mill at the same rate as the surrounding solid portions during delayering.

The patent applies periodic action by pulsing the deposition gas flow in synchronization with the charged particle beam scanning. The gas flow is turned on and off in periodic cycles, allowing material to be deposited in controlled increments. This prevents continuous deposition that would cause clogging in high aspect ratio holes while maintaining an overall high deposition rate through repeated pulsing cycles.

The patent applies dynamics by making the deposition gas flow dynamic rather than static. The gas flow rate and timing are adjusted in real-time based on the beam position and deposition progress. This dynamic control allows the system to adapt deposition conditions to prevent clogging while maximizing deposition rate, achieving both speed and uniformity.