Magnetic Contrast in the Scanning Electron Microscope with a Control Grid

Abstract

A differential detection system of magnetic contrast with control grid in the scanning electron microscope is proposed, and its application to the magnetic contrast improvement for perpendicularly recorded magnetization is discussed. The system consists of two symmetrically placed detectors and a differential amplifier. The output voltage of each detector is fed back to a control grid placed between magnetic film and detector.
It is shown that the detected signal amplitude of the system with control grid is 3 times greater than that of the system without control grid for perpendicularly recorded magnetization on Co-Cr film. The differential amplitude of the twin detectors is twice the amplitude of each detector in the system. Perpendicularly recorded magnetization of 3 micron bit length on Co-Cr film is detected with the system. These results suggest that the system may provide a convenient means to observe recorded pattern on magnetic films and show a step towards an electron beam readout in high density recording.