Backscattered electrons topographic mode problems in the scanning electron microscope.

The application of several backscattered electron (BSE) detectors makes it possible to separate topographic (TOPO) contrasts and material (COMPO) contrasts in a 'scanning' electron microscope (SEM). The BSE signals from six p-i-n diodes were used to investigate some artifacts connected with the reconstruction of real topography. The location of these diodes had been predicted theoretically to obtain algebraic formulas for the appropriate mixing of the BSE signal from the detectors. The specimen surface was specially prepared for estimation of the surface reconstruction quality. The TOPO mode in the SEM was realized with the use of analog and digital methods. The experimental and theoretical analysis indicates that the signal difference from the detector placed at higher angles (in relation to x axis) is preferable for topography reconstruction. The goal-of this paper is to discuss some ways of eliminating the artifact that-the structures parallel to the connection lines of diametral detectors can only be imaged with less contrast.