The electrical manifestations of Cu on silicon surfaces were investigated using Contact Potential Difference (CPD) and ac-Surface Photovoltage (SPV) measurements of Si intentionally contaminated with Cu. The corresponding physical model involves Cu-induced surface states. The Cu-induced negative surface charge is manifested by an increase of the work function and a decrease of the surface depletion barrier,Vsb, in p-type Si and an increase in n-type Si. The SPV manifestation of Cu is a decrease of the surface lifetime, tau s. These manifestations should enable Cu monitoring within the 1e8 atom/cm2 range. In practice, this limit is not reached because only a small fraction of surface Cu is electrically active. This obstacle is overcome using an optical surface treatment that electrically activates surface Cu and isolates the Cu contribution. With this approach we demonstrated Cu detection in the 1e9 atoms/cm2 range using Vsb and in the 1e10 atoms/cm2 range using tau s.
