| AVS 62nd International Symposium & Exhibition | |
| Applied Surface Science | Thursday Sessions |
| Session AS-ThP |
| Session: | Applied Surface Science Poster Session |
| Presenter: | In-Yong Park, KRISS, Korea |
| Authors: | I.-Y. Park, KRISS, Korea B. Cho, KRISS, Korea C. Han, KBSI, Korea D. Lee, KRISS, Korea S.J. Ahn, KRISS, Korea |
| Correspondent: | Click to Email |
Most of the charged particle instruments (CPBIs) have the gun which generates a charge particle beam and column which controls a beam direction. In CPBIs, the precise alignment between gun and column is very important to get a best performance, such as high imaging resolution and patterning resolution. Generally, mechanical moving and electro-magnetic deflection are adopted to adjust beam path relatively in the each component. Most mechanical alignment operations use sliding single O-ring or thin metal bellows, which allow motion while preserving the internal vacuum. However, single O-ring allows the only small changes of shifting and tilting. For the double-deflector, an electronic part controlling the applied voltage or current is necessary, a fairly difficulty to assemble double-deflector part inside a vacuum chamber included. In this work, we center around on a simple and cheap electron gun alignment method in the laboratory experiment and early stages of CPBIs development.
To monitor the electron beam movement controlled by flange motion, we use a thermionic electron source and maintained a vacuum pressure of approximately 10-5 Pa with a combination of a rotary pump and a turbo-molecular pump which ran in tandem. In order to accelerate the generated electron beam, the electron gun system is floated at a negative 20 kV and the filament is heated by adjusting the current flow. Finally, the accelerated electrons hit the phosphor screen and make the visible light. We stacked ten O-rings and insert the metal center rings between O-rings to maintain the structure stably. We assembled four identical structures, all of which can shift the gun flange vertically and horizontally with clamping screws and separate it azimuthally with an equal space on the flange, which is under the O-rings. We monitored the beam position at the phosphor screen in real time shifting and tilting the flange on which electron gun is installed. Also, we get the nearly identical values comparing the experiment result and theoretical calculation result. This means that we can control the electron beam direction precisely with O-ring stack system maintaining the inside vacuum pressure steadily. We demonstrate a tilting angle of ±2.55° with shifts of ±2 mm experimentally1, values which are generally sufficient for application to CPBI gun alignment, as this adjustable range can cover the error range when the parts are made and assembled. It can also be applied when insulation is needed between the flanges while maintaining some degree of freedom.
[1] I.-Y. Park, B. Cho, C. Han, S. Shin, D. Lee and S. J. Ahn, Rev. Sci. Instrum. 86, 016110 (2015).