| AVS 62nd International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Tuesday Sessions |
| Session NS-TuP |
| Session: | Nanometer-scale Science and Technology Poster Session |
| Presenter: | Cheolsu Han, Korea Basic Science Institute, Republic of Korea |
| Authors: | C. Han, Korea Basic Science Institute, Republic of Korea B. Cho, Korea Research Institute of Standards and Science, Republic of Korea J.-M. Jeong, Korea Basic Science Institute, Republic of Korea J-G. Kim, Korea Basic Science Institute, Republic of Korea |
| Correspondent: | Click to Email |
An electron microscope (EM) such as a scanning electron microscope or a transmission electron microscope are powerful tools in nanometer science and technology.1,2 There are important parameters such as a resolution and a probe current in the EM.2 The optical parameters of an electron source such as a virtual source size and a brightness are strongly relate to the parameters and a performance of the EM. These parameters can be used to design the optical system of EM such as a condenser and an objective lenses and calculate a magnification and a probe current. In order to design an optical system, we have to find the optical parameters of the electron gun. In this work, we describe how to calculate the virtual source size.
To calculate the virtual source size, a homebuilt electron gun testing system (HEGTS) have been developed. Electron beam images have been obtained by the HEGTS which includes an electron gun with tungsten hairpin filament, a movable aperture, and imaging system with CCD camera. Digital image processing techniques such as a noise rejecting filter, a binary image, a pixel operation method, and etc. have been used to calculate the virtual source size.3 And a shadow-image technique also have been used.4 An apparent edge sharpness of the shadow image is determined by the source size. A distance between 25% and 75% of a maximum intensity of electron beam profile can be used to calculate the size.
To obtain the electron beam images by CCD camera (1,600x1,200 pixels), we used a W hairpin filament at a vacuum pressure of 5.5x10-5 Pa. In order to accelerate the generated electron beam, the electron gun system is floated at -10 kV and the filament is heated by adjusting the current flow. A virtual source position was obtained by the movable aperture (100 um) and the beam images. Finally, we calculated the virtual source size of 44.2 um under the conditions.
We demonstrate how to calculate the virtual source size using the homebuilt electron gun testing system without a scanning coil and a secondary electron detector.
[1] A. V. CREWE, D. N. EGGENBERGER, J. WALL and L. M. WELTER, Rev. Sci. Instrum. 39, 567 (1968)
[2] B. B. Williams and C. B. Carter, Transmission Electron Microscopy A Textbook for Materials Science (Springer, NY, 2009)
[3] G. A. Baxes, Digital Image Processing (John Wiley & Sons, Inc, NY, 1994)
[4] O. C. Wells, Proc. the Tenth Annual Scanning Electron Microscope Symposium I, 25 (1977)