| 摘要 |
An electron column is provided to facilitate a focusing control by decreasing a voltage, which is used for a focusing process. An uppermost electrode layer(L1) and a lowermost electrode layer(L3) are grounded. A variable voltage is applied on a middle electrode layer(L2) for performing a focusing process. A magnetic lens layer(M) is arranged on the uppermost electrode layer for a pre-focusing process. An electron beam, which is incident on the magnetic lens layer, is pre-focused. A path of the electron beam is focused on a center of the middle electrode layer, on which a focusing voltage is applied. The pre-focusing process is controlled by a voltage and a current, which are applied on the middle electrode layer.
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