Electron beam device
View Patent ↗Disclosed here is a high resolution scanning electron microscope having an in-lens type objective lens. The microscope is structured so as to detect transmission electrons scattering at wide angles to observe high contrast STEM images according to each sample and purpose. A dark-field detector is disposed closely to the objective lens magnetic pole. The microscope is provided with means for moving the dark-field detector along a light axis so as to control the scattering angle of each detected dark-field signal.
1. An electron beam device, comprising:
means for accelerating an electron beam emitted from an electron source;
an objective lens for focusing said accelerated electron beam on a sample;
means for scanning said electron beam on said sample two-dimensionally;
a transmission electron detector for detecting electrons transmitting said sample; and
means for recording or displaying said sample with signals output from said transmission electron detector;
wherein said transmission electron detector is a dark-field detector through a center portion of which transmission electrons pass; and
wherein said electron beam device also includes detector moving means for moving said dark-field detector along a light axis in an area under a lower magnetic pole of said objective lens.
2. The electron beam device according to claim 1 ,
wherein said dark-field detector is structured so as to transmit electrons through its center portion; and
wherein said electron beam device also includes a bright-field detector disposed under said dark-field detector, said bright-field detector being used to detect electrons transmitting said center portion of said dark-field detector.
3. The electron beam device according to claim 2 ,
wherein said device further includes:
a bright-field iris having two or more apertures and being disposed between said dark-field detector and said bright-field detector; and
alignment means for controlling the positions of electrons transmitting said center portion of said dark-field detector on said bright-field iris so that said electrons pass one of said apertures of said bright-field iris.
4. The electron beam device according to claim 1 ,
wherein said dark-field detector is divided into two or more partial detectors in the circumferential direction; and
wherein said electron beam device further includes a calculation device for selecting any of signals detected by partial detectors or adding/subtracting signals detected by said partial detectors to/from a signal to be output.
5. A method for measuring a sample comprising:
focusing an electron beam;
scanning a sample with the focused electron beam two-dimensionally;
detecting transmission electrons that have passed through the sample with a detector; and
recording or displaying a sample image,
wherein the detector is a dark-field detector through a center portion of which transmission electrons pass, said method further comprising moving said dark-field detector along the optical axis, positioning said dark-field detector at a particular position within a movable range of said dark-field detector, detecting transmission electrons that have passed through said sample, and recording or displaying a sample image.