11. How can resist coatings be removed again?
For the removal of softbaked coatings, polar solvents such as e.g. the respective resist thinner AR 300-12 (methoxy propyl acetate = PGMEA) and the remover AR 600-70 (acetone-based) may be used.
For a wet chemical stripping of coatings baked up to 70 ℃, the organic, highly versatile removers AR 300-70 and AR 300-72 are recommended which do not react with aluminium and may be heated to 80 ℃ to reduce the time for removal. In addition, remover AR 300-72 is particularly suitable for CAR 44 as well as for very persistent thin films.
In semiconductor industries, the removal (stripping) is mostly performed by ashing in a plasma asher.The O2-plasma is generated by microwave excitation and used for an isotropic etching of photoresists.In addition, oxidizing acid mixtures (piranha, nitrohydrochloric acid, nitric acid amongst others) are employed for wet chemical removal procedures.