Mask defect imaging system using backscattered electron images

The optical inspection system has been applied for mask inspection. The small but fatal detects on the mask can not be detected minutely by the optical system because of the limitations of optical resolution. We have developed the Defect Imaging System (DIS-05) using Backscattered Electron Images (BSI). DIS-05 is composed of 3 units: (1) SEM with a newly developed Backscattered Electron detector, (2) CAD computer to create CAD Image and, (3) Main computer to control the SEM and CAD computer. One of key technologies for DIS-05 is the technique of detecting BSI at a high contrast. Moreover, we herewith describe "Superimposed Image", which compares BSI with CAD one. Finally, we also report the possibility of detecting "haze on masks" using DIS-05.