Patent ID: 9455123
Filing Date: 2016-09-27
CPC Classification: H01J

Claim Text:
1. A current regulation method of multiple beams comprising: acquiring a current density distribution of multiple beams formed by letting portions of an electron beam emitted from a thermal-electron gun assembly having a Wehnelt electrode respectively pass through a corresponding opening of a plurality of openings; selecting at least one beam whose current density is equal to or more than a threshold from the multiple beams used for writing a pattern on a target object by referring to the current density distribution; measuring a current value of the at least one beam whose current density is equal to or more than the threshold respectively by varying a voltage applied to the Wehnelt electrode of the thermal-electron gun assembly and acquiring a correlation between the voltage applied to the Wehnelt electrode and the current value of the at least one beam selected from the multiple beams used for writing the pattern on the target object; moving a stage to a position where the at least one beam is allowed to enter a current detector arranged on the stage each time writing of a stripe region obtained by virtually dividing a writing region of the target object in a thin rectangular shape is completed while the pattern is being written on the target object arranged on the stage; measuring, after moving the stage, a current value of the at least one beam each time the writing of the stripe region is completed by allowing the at least one beam to enter the current detector while beams of the multiple beams whose current density is less than the threshold are blocked; operating a target voltage value applied to the Wehnelt electrode to cause the current value measured to be a target current value by using the correlation; and applying the target voltage value to the Wehnelt electrode.