Photoresist Stripping

 

It is the process of removing photoresist and residue from the surface of the wafer. Residue is left behind and hardened after etching. One common method is using heated hydrogen peroxide and sulfuric acid. The mixture produces a volatile exothermic reaction, which removes the photoresist by oxidising the carbon in the photoresist.

 

Carbon is liberated from the photoresist in the form of carbon dioxide. Partial hydrogen peroxide is converted to water, which depending on the bath condition, either remains in the bath or evaporates. The rate at which hydrogen peroxide is exhausted from the bath is dependent on the temperature, photoresist content, and acid concentration.