loadlock

A loadlock is a vacuum chamber that attaches to a larger process chamber to enable loading and unloading of samples without exposing the main chamber to atmospheric air. It provides a controlled interface for substrates such as semiconductor wafers, cassettes, or other sample types, helping to maintain the cleanliness and vacuum integrity of the processing environment.

Typically, a loadlock connects to the main chamber through a gate valve and includes its own pumping system, often comprising a roughing pump and a high-vacuum pump. It may also house a transfer mechanism, such as a robotic arm, to move substrates between the loadlock and the main chamber via a dedicated transfer chamber. Many systems include purge gas lines (commonly nitrogen) and sensors to monitor pressure, contamination, and gas composition. Some loadlocks provide two-stage functionality or “double door” configurations to further minimize gas load during transfers.

Operation generally follows two modes. In vacuum transfer, the loadlock is pumped down to match the main chamber pressure, the gate valve opens, and the substrate is moved into the main chamber without exposing it to air. In vented or purge modes, the loadlock is vented to atmosphere and purged with inert gas before transfer, reducing the risk of oxidation or moisture contamination when the main chamber would otherwise be exposed to air.

Applications are common in semiconductor fabrication and surface science instruments, including deposition, etching, and analysis systems, where preserving vacuum and cleanliness is critical. Benefits include reduced pump-down time for the main chamber, minimized contamination risk, and protection of sensitive pumps and process gases; drawbacks can include added system complexity and potential leak paths if not properly maintained.