ÒÁÈ˾þÃ

Microchips made in space might work better
(see “Whispering wafers”) but
wherever you make them, it’s a filthy business. Chip makers use thousands of
litres of acid to remove chemical coatings from silicon wafers, then millions of
litres of water to rinse off the acid. Now the Los Alamos National Laboratory in
New Mexico has found a cleaner way—using vinegar. The wafers go into a
pressure vessel containing vinegar (acetic acid) and carbon dioxide. Raising the
temperature and pressure creates a supercritical fluid that penetrates tiny gaps
like a gas while dissolving chemical coatings like a solvent. The process…