Lossless Solvent-based Extension Implant Strip

A new approach is presented for resist strip after high-dose implantation of ultra-shallow extensions with minimal loss in the S/D area. For our work, solvents are selected in combination with physical force to remove the resist because of their excellent selectivity towards the sensitive USJ implanted substrates. To enable a more gentle physically enhanced strip of the crusted resist with less risk for damage and less residues left, a short oxidizing pre- and/or post-treatment has to be introduced. Wet O3-based cleans have limited efficiency while UV/O3-exposure and particularly a short plasma step are found to be beneficial. The effect of such an oxidizing treatment on the crusted resist and its removal is presented as well as the effect on highly doped substrates. It is shown that especially after NMOS implantation, a short oxidizing step results in better dopant retention during activation anneal due to the grown oxide.