| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultracompact SEM using a permanent magnetic lens in which change of the number of stages of condensing lens can be achieved relatively easily according to an accelerating voltage due to magnetic saturation. SOLUTION: In Fig.1, as for the electron lens at an acceleration voltage 5 kV, an auxiliary condensing lens 3 is detached. At the acceleration voltage 5 kV, there is no magnetic saturation of a condensing lens, and two-stage lens can be used. Then, when the acceleration voltage is made 15 kV, the condensing lens of two stages has magnetic saturation and sufficient reduction ratio can not be obtained, thereby, the auxiliary condensing lens 3 is inserted between a condensing lens (1) 4 and an anode. Thereby, the reduction portion of this reduction ratio at the condensing lens (1) 4 and the condensing lens (2) 5 is supplemented by this auxiliary lens, and the condensing lens as a whole has no reduction in the reduction ratio. COPYRIGHT: (C)2008,JPO&INPIT
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