Photo Resist Stripping

Photo resist stripping or also call ashing is one of the first applications of plasma treatments in semiconductor manufacturing. It came up in the 1970s using pure oxygen plasma to oxidize the organic resist and react it to gasenous $\rm CO_2$ and $\rm H_2O$, which can be pumped off in the vaccum system. Since that time etching and ion implantation have changed quite a lot to fulfill the requirements of the continous shrinking device dimensions. Removing the resist after a high dose ion implant or after a modern via etch is a really difficult task now. In the following we will briefly discuss some basics of resist removal, covering principles, chemistries and special applications.