Chemical leak at SK Hynix Cheongju plant sends two to hospital

Two workers were taken to the hospital after a chemical leak at SK Hynix's Cheongju plant on Tuesday afternoon. The incident occurred around 3:39 p.m. when a toxic substance, suspected to be Tetramethylammonium Hydroxide (TMAH), leaked from semiconductor equipment being unloaded from a truck.

The affected individuals were a worker responsible for the equipment and a truck driver. They were initially treated with washing at the company's in-house clinic before being transferred to a nearby general hospital. SK Hynix stated that while the workers currently show no symptoms, they are being monitored as a precaution. The company reported that the leak was contained and processed according to standard procedures, with the fire department notified.

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We brought semiconductor equipment from the Icheon plant to install at the M15 plant in Cheongju. When we opened the door of the box truck to unload the equipment, liquid flowed out, and the equipment manager and driver who touched the liquid were moved to the company hospital for washing and then to a nearby general hospital for treatment. There are no symptoms now, but we are monitoring the situation at the hospital in case of any possibility.

TMAH is a highly alkaline and toxic substance commonly used in semiconductor manufacturing for photoresist removal and wafer cleaning. Exposure can lead to rapid systemic absorption, potentially causing severe symptoms including respiratory failure. This incident echoes previous accidents involving TMAH, including a 2021 case in Paju where two workers died and three were injured, and another fatality in Ulsan last June.

This is not the first incident at the Cheongju plant this month. On June 1, a fire broke out in a gas room between the M15 and M15X facilities, exposing 11 workers to chemicals, including fluorine, who received treatment within the SK Hynix campus.

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We contacted the fire department according to the manual and collected and processed all the leaked liquid. We don't know the exact type of liquid, but it could be toxic Tetramethylammonium Hydroxide used in the semiconductor manufacturing process, so related agencies are investigating.