SEM/EDS analysis method for bare silicon particle monitor wafers

A method for effectively utilizing a Scanning Electron Microscope (SEM) for defect review and identification of unpatterned silicon particle wafers, following inspection on a laser-scanning defect inspection tool, is presented. The method involves pre-patterning of bare silicon wafers at the extreme edges, typically less than 3 mm from the edge of a 200 mm wafer, using standard (I-Line) photolithographic processing. The registration marks created in this process are used for stage correlation between the SEM and laser-scanning wafer inspection tools. Use of these marks is demonstrated to result in a 50% improvement in particle location accuracy (mean+2 sigma) over previously reported results. Further optimizations, including modeling and removal of systematic error sources through data transformations, demonstrate the additional improvements in particle location accuracy that are possible.