Wet Resist Strip Capability vs. Implant Energy

Abstract

Implant doses greater than 5E14 atoms/cm2 can create an amorphous carbon like damage layer (crust) that is difficult to dissolve with wet chemistries. During the wet strip, the undamaged and lightly-damaged resist is dissolved quickly, undercutting and releasing most of the crust. The portions of crust that contact the silicon, however, cannot be undercut, and must be dissolved. The most extensive and difficult to dissolve regions of crust typically occur near the edge-bead-removal (EBR) region. This work uses the SRIM (Stopping Range of Ions in Matter) computer simulation to investigate the characteristics of the crust for a range of implant conditions including dose, energy and implant species. Techniques to prevent the formation of attached crust near the edge bead region are also discussed.