Ashing of Organic Compounds with Spray-Type Plasma Reactor at Atmospheric Pressure

We examined the ashing treatment at atmospheric pressure by means of three spray-type reactors fed with O2/He or O2/Ar mixture gases. These differed in the size or the shape of their nozzles. Such reactors were able to ash an organic compound (OFPR-800; a photoresist) even at atmospheric pressure. The results showed that the following procedures are important for increasing the ashing rate: to make the gas speed after blowing out fast; to decrease the O2 content while increasing the gas speed; and to use a gas mixture which has a slow decay rate of the active species, such as the oxygen radicals. Especially, when we used O2/Ar mixture gas for the ashing treatment, the ashing rate became quite fast and was as fast as that of a general low pressure glow plasma.