In semiconductor manufacturing plasma ashing is the process of removing the photoresist (light sensitive coating) from an etched wafer.
Using a plasma source, a monatomic (single atom) substance known as a reactive species is generated.
The reactive species combines with the photoresist to form ash which is removed with a vacuum pump.
Monatomic oxygen is electrically neutral and although it does recombine during the channeling, it does so at a slower rate than the positively or negatively charged free radicals, which attract one another.
Because a large portion of the active species is lost to recombination, process times may take longer.