Duv-Resist Stripping with Ozonated Water in Semiconductor Industry : Process chemistry and analytical aspects

The ongoing miniaturisation in the semiconductor industry places many major challenges for materials as well as the process design. A very important step is the residue-free and gentle stripping of photo-resists. The standard process is a sequence of plasma etching and wet chemical cleaning. Hence, with actual structures of 32 nm and new materials for high- and low-k dielectrics, the aggressive plasma etching has come to its limits. For the future it is thus essential to find a non-destructive wet cleaning method. Such alternatives already exist originated from the standard SPM, modified to SOM and finally to ozonated water. This chemistry not only is cost efficient and eco-friendly, it has also proven its feasibility with i-line resists. The challenge now is to adapt this chemistry to currently applied DUV-resists which essentially differ in their structures. All-important is to find a way to remove the crust generated on the resists during implantation steps, being impossible by wet chemistry yet. The eventual purpose of this work is to achieve an understanding of all the parameters involved, in order to be able to design individual solutions for each resist and process step.