Plasma ashing

From ArticleWorld

Plasma ashing refers to a technique in semiconductor manufacturing involving the removal of photoresist from an already etched wafer. Reactive species, most commonly oxygen or fluorine, are made to combine with the unwanted photoresist to produce ash. This ash is taken away with the help of a vacuum pump.

This technique essentially involves the use of plasma which is formed remotely and directed to the wafer. Damage to the wafer surface by free radicals accompanying the reactive plasma of oxygen and fluorine is prevented as there is enough time for them to recombine. A large part of the active specie is lost due to recombination, with the result that process times may take longer than expected. The temperature of the reaction region may have to be increased to compensate for this.