Two workers at SK Hynix's Cheongju facility were hospitalized after coming into contact with a chemical substance believed to be tetramethylammonium hydroxide (TMAH) while moving equipment.
According to fire authorities and SK Hynix, the incident occurred at 3:58 p.m. on June 10 at the company's fourth campus in Cheongju. The workers were transported to the hospital, but reports indicate they showed no unusual symptoms at the time of transfer.
TMAH is a highly alkaline chemical widely used in the semiconductor and display manufacturing processes for cleaning and developing silicon wafers. It can cause severe damage upon contact with skin, eyes, or respiratory systems, and even minor skin exposure can be fatal.
Authorities suspect that TMAH leaked from equipment being transported. Initial tests did not detect any toxic substances. Investigators are considering the possibility that TMAH mixed with water during the transportation of equipment that had not been completely dried after cleaning.
Recent incidents at SK Hynix's Cheongju site have raised concerns. On June 1, a fire broke out in a gas room connecting the M15 and M15X plants, resulting in a small amount of fluorine being released. Additionally, on May 27, sparks from semiconductor processing equipment in the M11 plant forced employees to evacuate for about an hour. Earlier, on January 19, five workers were exposed to phosphoric acid that fell from overhead piping during maintenance work.
* This article has been translated by AI.
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