In plasma processing, especially during the etching process in microel
ectronics, and as the feature size decreases, charging damage to thin
gate oxides can be produced which does not occur when wet chemical pro
cesses are used, It is currently believed that such damage occurs when
excess charge is deposited on a wafer because of nonuniformities in t
he plasma parameters across the surface of the wafer, To predict the o
ccurrence of charging damage, unpatterned wafers are exposed to a plas
ma in which nonuniformity is introduced across the wafer surface. Surf
ace photovoltage (SPV) and contact potential difference (CPD) techniqu
es can be used to determine the regions where excess charge is deposit
ed and thus where the potential for charging damage exists, Wafer maps
of these measurements are made to show the difference between uniform
and nonuniform charge distributions.