A novel correction scheme for quantitative voltage contrast measurements using low extraction fields in the scanning electron microscope

Abstract

A novel correction technique combined with a lock-in peak detection scheme for quantitative voltage contrast measurements using low extraction fields in the scanning electron microscope has been developed. This technique was found to be more accurate than the conventional feedback technique for quantitative voltage contrast measurements. Local field effects (of both types I and II) can be accounted for by this correction scheme without the use of very high extraction fields of 500-1000 V mm-1. The use of a low extraction field of 50 V mm-1 is especially advantageous for specimens that are sensitive to high fields and for measurements on specimens surrounded by regions of insulating material, which may charge up under high extraction fields. This scheme also allows the possibility of correction for minor charging due to a contaminant layer forming as a result of sample exposure to air or under electron beam bombardment.