Last week there was a serious incident involving Tetramethylammonium Hydroxide (TMAH), a chemical that is widely used in the Semiconductor Fab. It is not known what the final outcome is of the 6 individuals that were exposed, 2 were serious. In many large Fabs TMAH is pipe through the facility at various concentrations.

Of all the reactive/pyrophoric or toxic chemicals used in the Fab, TMAH is one of the top 5 that I have a concern with as there appears to be no effective medical treatment protocol. I spoke to Dr. Wu at my 2008 training class on Trichlorosilane Safety and ER in Taiwan.  As a consultant to the Taiwan Poison Control Center he has been involved in TMAH incidents, 3 of which were fatal. He spoke of one in which a worker was alone and was splashed with a 25% solution. He immediately went to the safety shower. He was found 15 minutes later barely conscious. Prior to arrival at the hospital he went into cardiac arrest. He was resuscitated but he slipped into a coma and died 8 days later.

High concentration (25%) exposure of 7% of the body is fatal! Even lower concentration can also be

Park et al., J Occup Health, 2013

• 39 yr old male splashed 8.75% TMAH on his hands, arms and legs
• 12% body surface area affected
• Continued working and went to the shower room 25 mins after the spill
• He was found dead outside the shower ~60 mins later
• Second degree burns on skin

IBM Medical and Safety professionals conducted a detailed review of incidents as well a sponsored extensive animal dermal exposure testing. They presented their findings at the 2011 Semiconductor Environmental Safety and Health Association (SESHA) Conference with an update in 2018. I have summarized the LG Display incident as well as the 2011 IBM presentation to educate those that have limited knowledge of TMAH.  The presentation was updated in 2018. It can be downloaded for free to SESHA members. Membership is free.

My summary can be found on my website https://sites.google.com/a/chemicallyspeakingllc.com/www/home/our-company/files

Eugene Ngai

Chemically Speaking LLC

www.chemicallyspeakingllc.com