| 摘要 |
In a scanning electron microscope a primary electron beam (20b) emitted from an electron source (1) is scanned on a sample (18) and a scanning image is obtained from a detection signal produced by secondary electron and/or backscattered electrons. By applying a negative voltage to the sample, a retarding static field is produced with respect to the primary electron beams. Detecting means (26, 25) having a detection plane for receiving the secondary electrons and the backscattered electrons is provided between the electron source (1) and the objective lens (17), the detection plane intersecting the primary electron beam (20b) and having an aperture (33) for passing through the primary electron beam. In order to selectively detect only the backscattered electrons, the invention suggests a filtering voltage means (34, 25, 28) for generating a potential filter which selectively let pass through the backscattered electron accelerated by the retarding static field and which repels the secondary electrons accelerated by the retarding static field, the filtering voltage means having a mesh (34) provided between the detection plane and the sample. |
