Dai and Chen, two young subcontractors, were handling equipment with gloved hands. Unfortunately, those gloves had been contaminated with TMAH (tetramethylammonium hydroxide).
TMAH looks just like water, but on contact with the skin, it penetrates tissue. A single drop of 25% TMAH on your skin kills you. At 2.38%, the watered down version used in chip factories takes just 6 grams on your skin to reach a lethal dose. Roughly a teaspoon.
A worker in Taiwan was splashed with 2.38% TMAH on just 10% of his body. His heart stopped and went immediately into cardiac arrest. [1] Another worker took a 25% splash, showered, and was found unconscious 15 minutes later. He died eight days later, never woke up. One more was splashed with an 8.75% solution, covering 12% of the body surface. He kept working and went to shower 25 minutes later. He was found dead with severe burns one hour after exposure.
The hydroxide ion burns a hole through your skin, and the tetramethylammonium ion, a molecule structurally similar to the neurotransmitter that makes your heart beat, and your lungs breathe, walks straight through that hole into your bloodstream. It then binds to your nerve receptors, paralyzes your respiratory muscles, and stops your heart.
Dai felt a splash on his left wrist and on the right side of his face. Chen caught it on his right palm.
Firefighters spread Diphoterine, a decontamination solution specifically for chemical splashes. The ambulance took them to the nearest hospital with the hope that the damage would not be permanent.
After the initial news cycle, I couldn't find any further media reports about Dai or Chen, their recovery, or anything regarding the aftereffects of the accident.
TMAH is one of the dozens of chemicals that go through Fab 18's complex plumbing system, which carries away the chemical byproducts of chips. This sets the stage for one of the most dangerous floors in the entire fab. The subfab.