Scanning technique with slow electrons for investigation of integrated circuits

An electron-optical method for investigation of conducting and semiconducting surfaces is described. The surface to be investigated is scanned by a low-energy electron beam with a diameter of less than 10 ¿m. This method represents a further development of conventional image-orthicon technique with 625 lines and 25 frames/s. The videosignal is deduced from local differences in surface potential. These differences are used to modulate the beam of a synchronised oscilloscope tube giving a display of the electronic surface. It is possible to investigate semiconductors with protective dielectric films at the surface.