Study of the Removal of Ion-Implanted Resists Using Wet Ozone

Abstract

We have investigated the removal of novolac resists into which B and P ions had been implanted with a dose of 5×1014 atoms/cm2 at acceleration energies of 10, 70, and 150 keV (ion-implanted resists), using wet ozone. Also, we confirmed the presence of the surface hardened layer of ion-implanted resists by cross-sectional observation using scanning electron microscopy (SEM), the stripping of the hardened layer using chemicals, and the measurement of the plastic-deformation hardness of the resists by nanoindentation. The removal rate for a resist using wet ozone decreased with increasing acceleration energy because the hardness of the resist increased with increasing acceleration energy. Moreover, we clarified by time-of-flight secondary ion mass spectrometry (TOF-SIMS), that the ion intensity of C10H- (m/z 121.01) for the hydrocarbon component, which has the unsaturated bonds as a component of the surface hardened layer increased with increasing acceleration energy. Cresol novolac resin was destroyed and carbonized by ion implantation. Therefore, the removal of ion-implanted resists became difficult with increasing acceleration energy.