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Study on the Scan Field of Modified Octupole and Quadrupole Deflector in a Microcolumn

마이크로칼럼에서 변형된 4중극 디플렉터와 8중극 디플렉터의 스캔 영역 비교

  • Kim, Young Chul ;
  • Kim, Ho-Seob ;
  • Ahn, Seong Joon ;
  • Oh, Tae-Sik ;
  • Kim, Dae-Wook
  • 김영철 ;
  • 김호섭 ;
  • 안승준 ;
  • 오태식 ;
  • 김대욱
  • Received : 2018.08.02
  • Accepted : 2018.11.02
  • Published : 2018.11.30

Abstract

In a microcolumn, a miniaturized electrostatic deflector is often adopted to scan an electron beam. Usually, a double octupole deflector is used because it can avoid excessive spherical aberrations by controlling the electron beam path close to the optical axis of the objective lens and has a wide scan field. Studies on microcolumns have been performed to improve the low throughput of an electron column through multiple column applications. On the other hand, as the number of microcolumns increases, the number of wires connected to the components of the microcolumn increases. This will result in practical problems during the process of connecting the wires to electronic controllers outside of the vacuum chamber. To reduce this problem, modified quadrupole and octupole deflectors were examined through simulation analysis by selecting an ultraminiaturized microcolumn with the Einzel lens eliminated. The modified deflectors were designed changing the size of each electrode of the conventional Si octupole deflector. The variations of the scan field and electric field strength were studied by changing the size of active electrodes to which the deflection voltage was to be applied. The scan field increased linearly with increasing deflection voltage. The scan field of the quadrupole deflector and the electric field strength at the center were calculated to be approximately 1.3 ~ 2.0 times larger than those of the octupole deflector depending on the electrode size.

Keywords

MEMS;Microcolumn;Octupole deflector;Quadrupole deflector;Scan field

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Acknowledgement

Supported by : 한국연구재단