Patent ID: 6822245
Filing Date: 2004-11-23
Classification: H01J

Abstract:
An ion beam apparatus comprising an ion beam optical system including an ion source, an objective lens for focusing an ion beam emitted from said ion source, and a scanning and deflecting unit for scanning said ion beam on a sample, a detector for detecting secondary particles generated from the sample under the irradiation of said ion beam, and a control unit for controlling said ion beam optical system,wherein said control unit controls to change a focusing condition of said objective lens in accordance with a current value of said ion beam when section processing of said sample is executed; wherein when the current value of said ion beam is less than the predetermined value, said control unit sets the focusing condition of said objective lens so that a Gauss image plane of said ion beam is more flush with a surface of said sample than the case that the current value of said ion beam is not less than the predetermined value; and wherein when the current value of said ion beam is not less than the predetermined value, said control unit changes the focusing condition of said objective lens to set the focusing condition of said objective lens so that a plane of said ion beam on which a least circle of confusion is formed is more flush with a surface of said sample than the case that the current value of said ion beam is less than the predetermined value.