ELECTROMAGNETIC LENS FOR ELECTRON BEAM EXPOSURE APPARATUS

摘要

There is provided an electromagnetic lens which includes an electromagnetic coil wound to be rotationally symmetrical about an optical axis of an electron beam, and a pole piece covering the electromagnetic coil, in which: a gap is integrally formed in either one of an inner wall formed at an inner circumference side of the pole piece and a lower end wall formed in an end portion at an emission side of the electron beam, or a boundary portion between the two walls; the inner wall is formed to be thinnest at a portion close to the gap and to gradually become thicker as a distance from the gap increases; and the electromagnetic lens is formed such that a width in a radial direction thereof is more increased as being closer to the gap along with the change of the thickness of the inner wall.

主权项

1. An electromagnetic lens comprising:
an electromagnetic coil wound to be rotationally symmetrical about an optical axis of an electron beam; and a pole piece including an inner wall covering an inner circumference side of the electromagnetic coil, an upper end wall covering the electromagnetic coil at an entering side of the electron beam, a lower end wall covering the electromagnetic coil at an emitting side of the electron beam, an outer wall covering an outer circumference side of the electromagnetic coil, and a gap formed by cutting out at least a part of the inner wall, the lower end wall, and the upper end wall to be rotationally symmetrical about the optical axis, wherein a thickness of the inner wall is thinnest at a portion close to the gap, and gradually becomes thicker as a distance from the gap increases, and a width of the electromagnetic coil in a radial direction is more increased as being closer to the gap.