Fluorine Poisoning Compounds

Hydrofluoric acid in the SMFL represents a special danger in that it is a toxic. Death can and has occurred from exposure to hydrofluoric acid. The danger arises from the fluorine ion which reacts with the body's calcium to interfere with the transmission of nervous signals, proper functioning of muscles, and electrochemical imbalance. Concentrated hydrofluoric acid represents the greatest danger of fluorine poisoning, but there are other solutions in the SMFL that also represent a fluorine poisoning hazard.



Tetramethyl Ammonium Hydroxide (TMAH)

TMAH is used in two main areas of semiconductor processing. In higher concentrations (25%) it is used as a crystallographic etch of silicon – similar to KOH etching. In lower concentrations (2.4%), it is used as a positive photoresist developer.

(warning) All concentrations of TMAH solutions pose a toxic threat.



Peroxides are by their nature oxidizing materials.  They are therefore stored separately from flammables and solvents. Hydrogen peroxide can form explosive mixtures with some organic substances.

Another hazard of peroxides is oxygen pressure buildup from decomposition.  Once peroxide is taken from its original container, it should never be put back. 

Used peroxide must be stored in vented cap containers or open containers until decomposition is complete.

The hydrogen peroxide that is found in the SMFL is a 30% solution.  It should not be confused with the 3%  hydrogen peroxide found in stores for treating skin abrasions/cuts/infections. 

Nitric Acid

Nitric acid poses special hazards due to the fact that it is a strong oxidizer.  As such, it should always be kept away from flammables, solvents and metals.

If nitric acid is being used at a manual processing bench, no solvents are allowed on the same bench.

The nitric acid at the SMFL is secured and must be requested by the lab users.