| 摘要 |
PURPOSE:To achieve a precise pattern formation, by applying changeable voltage to the first deflection element, deciding on a position divergence by detecting a standard mark by the second deflection element, rectifying the focus of the first lens and forming a cross-over image on the most appropriate point in a deflection plate of the first deflection element. CONSTITUTION:If the point (focus) 20 where the cross-over image is to be formed coincides with the most appropriate deflection point (as assumed deflection point), the position of focus of the workpiece 12 don't move. If the position of the focus 20 gets out of the assumed deflection point, the position of focus of the workpiece 12 moves. In order to coincide the focus 20 to the assumed deflection point 19 of the deflection plate 6, the changeable voltages are applied repeatedly to the first deflection element 6, and the mark is detected by a detector 11 and a circuit 15, and the position divergence is computed 16, and the current to the lens 3 is controlled 18 by the rectifying signals to be made 17 to minimize the divergence. With such an arrangement, even if the configuration of the electron beams is changed, the focus remains stable and stable current density and beam configuration can be obtained on the workpiece, resulting in a precise pattern formation. |
