Chemical risks in semiconductors industry?
Semiconductors are materials having an intermediate electric conductivity between metals and insulators.
The semiconductors industry is essential for the field of electronics.
These compounds make it possible to control at the same time and thanks to various ways, the quantity of power likely to cross them as well as the direction this power can take. Semiconductors are essential to the good functioning of many modern appliances and are key products in the electronic systems.
Liquid chemicals are use in the semiconductors industry in many applications such as the manufacture of microchips and the growth of crystals. The production requirements of this High Tech industry impose the massive setting up of clean rooms for the various processes of manufacture and treatments including chemical ones. Wet chemistry is one of the most important technological stages in the realization of electronic devices. Semiconductors chemistry is mainly organized around the chemical treatment by solvents and acid-base attacks of semiconductors.
- Chemistry of solvents : the main chemicals used during this stage are trichloroethylene, acetone, isopropanol and also other alcohols such as denatured ethanol. The typical applications are the cleaning, the degreasing of the semiconductors and the shrinkage of residual resins (acetone).
- Chemistry of acids and bases : the acid chemical agents used can be sulphuric acid, nitric acid, orthophosphoric acid, hydrochloric acid, hydrobromic acid or even citric acid. Solutions prepared associate sometimes a base (to oxidize the semiconductor) to an acid (to attack this oxide): hydrogen peroxide, ammonium hydroxide, sodium hydroxide or potasium hydroxide (mainly used for the attack of silicon).
Acids and bases are mainly used to carry out attacks of semiconductors or to carry out surface preparations (deoxidation) and regeneration. A few acids used can sometimes be corrosive and toxic such as hydrofluoric acid, the mixtures containing iodine, bromine or bromide ions.
Particularity of hydrofluoric acid
In the electronic industry, especially the one dealing with the semiconductors production, hydrofluoric acid is the key product for manufacturing silicon components. Its capacity to attack the silicon oxide and to change it into a soluble compound is the starting point or many other application for cleaning and engraving. Hydrofluoric acid is used in association with nitric acid to engrave silica in a mix with an ammonium fluoride solution, and also diluted as a cleaning agent or to remove residual oxides.