A method for electrically testing a
semiconductor wafer during integrated-circuit fabrication process, the method including: (i) providing a scanning charged-particle
microscope (SCPM), having a defined
scanning plane and operative, while in any one mechanical state, to scan a surface in the
scanning plane within a two-dimensional scanning window, which has a given
maximum size; (ii) providing in association with any layer of the
wafer, it being a test layer, one or more test structures, each
test structure including normally conductive areas within a normally non-conductive background in one or more
layers, which include said test layer, the conductive areas formed as one or more patterns; the patterns in said test layer include one or more clusters of mutually isolated pads; each pad is conductively connected with a corresponding distinct point on the patterns and all the pads in any one cluster are sized and arranged so that at least a significant portion of each pad falls within a common window whose size does not exceed said
maximum size of said scanning window; (iii) with said test layer forming the top surface of the
wafer, placing the wafer on the SCPM and adjusting the mechanical state of the SCPM so that at least a significant portion of each pad in any one of said clusters is within said scanning window; (iv) causing the SCPM, while in said mechanical state, to scan all of the pads of said one cluster and thereby to provide information about the electrical state of the respective
test structure.