Photoresist stabilization for ion implant processing

Abstract

In this study, a non-thermal photoresist stabilization process is considered for ion implant processing. The stabilization process utilizes a flood electron beam system that uniformly exposes the entire thickness of the photoresist film. A photoresist stabilization process is critical for some ion implant processes to reduce out-gassing, provide thermal stability, and facilitate its subsequent removal. Stabilization becomes more critical for advanced photoresists where, due to the high photoactive compound content, the thermal stability of the photoresist is low and the post ion implant removal process becomes more complicated. In this evaluation three i-line photoresists are considered, OiR-32, OiR-32 Medium Dye, and OiR-897 lOi. The non-thermal aspect of the electron beam stabilization process eliminates the shrinkage and flow associated with thermal stabilization processes. Parameters evaluated include critical dimension variation, thermal stability, and post ion implant photoresist removal. The electron beam stabilized photoresist shows significantly reduced post implant shrinkage and critical dimension variation compared to UV/thermal processing. The thermal stability of the photoresist is dramatically improved by the electron beam stabilization process. Finally, the post ion implant removal processing is improved, as indicated by the elimination of popping and contamination during a standard removal process. Thus, the electron beam process is demonstrated to provide improved thermal stability, reduced critical dimension variation, and improved microwave downstream plasma photoresist removal characteristics after ion implant processing.