Improvement of type-I method for observing magnetic contrast using scanning electron microscope under tilting-deceleration condition

Abstract

We developed a method of observing SEM images with a clear magnetic contrast without anisotropy using a scanning electron microscope (SEM). Directional-selective detection of secondary electrons (SEs) is needed to obtain SEM images with a clear magnetic contrast using a type-I method that utilizes changes in the number of detected signals due to a deflection of SEs by the stray magnetic fields of specimens. By combining beam deceleration and specimen tilting (hereinafter “tilting deceleration”), we achieved a directional-selective detection condition for SEs that is preferable for the type-I method. We found that the tilting deceleration method has high sensitivity for fine magnetic domain structures and can visualize submicron-sized magnetic domain structures in a vertically magnetized region of Nd2Fe14B specimens. Furthermore, we synthesized two SEM images with different directional information to reduce the anisotropy of magnetic contrast obtained by the asymmetric detector configuration. As a result, we obtained SEM images with isotropic magnetic contrast, which is similar to that of an SEM image acquired by a spin-SEM equipped with a Mott-type spin-polarization detector.