Sem-Based Infrared Contamination Detector
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
An infrared (IR) detection device can detect contamination on patterned wafers, including product debris, while completely ignoring the intended features of the wafer. The apparatus is based on a conventional SEM equipped for wafer inspection with a LaB6 electron filament, an interlocked wafer loader and a motorized wafer stage. The accessories include a PC to drive the wafer stage and the electron beam sweep coils, and for data collection and manipulation, an A/D converter for data digitization and beam sweep coil voltage input, a graphics monitor for displaying the IR image, and an IR collector/detector/preamplifier assembly. The IR collector/detector is detailed in the figure. The wafer is positioned in the lower focal point of tilted ellipsoidal mirror 2 which has a collection efficiency of greater than 50%.