Electron Beam Inspection System for Semiconductor Wafer Based on Projection Electron Microscopy -Ⅱ

摘要

Electron beam inspection systems based on a scanning electron microscopy (EBI-SEM) had been developed and used for the yield management in the semiconductor process because of its high resolution. However, they have the restriction of inspection speed due to the space charge effect of the electrons in the focused electron beam. We have been developing the electron beam inspection system based on the projection electron microscopy (EBI-PEM), and reported the results which revealed the possibilities of detecting the defect size of less than 100nm and the data rate 600MPPS, last year. We have further improved the EBI-PEM on its secondary electron optical system (2’nd EO) for obtaining smaller aberrations and distortion. The aberrations and distortion of the improved EBI-PEM optical system have been estimated by calculation using conventional simulation program. Obtained aberration values were small enough than one necessary for attaining the spatial resolution of the target specification and a resolution has been confirmed by the experiments.