DIRECT MEASUREMENT OF SURFACE CHARGING DURING PLASMA-ETCHING

An on-wafer surface potential probe was developed for the direct real- time measurement of the local charging on a wafer surface during plasm a etching. Pressure and rf power dependencies of the surface charging potential were measured in a nonuniform magnetron plasma by this probe . The variation in etching profiles was also observed by scanning elec tron microscopy (SEM). The measured surface charging potential was con sistent with previously expected values from the profile distortion an d device damage results. The local surface charging and the profile di stortion increased as the pressure was reduced, while they were insens itive to the rf power change.