Charged particle beam lens and exposure apparatus using the same

An electrostatic charged particle beam lens comprising:

• an electrode including a flat plate having a first surface having a normal line extending in a direction of an optical axis and a second surface opposite to the first surface, the electrode having a through-hole extending from the first surface to the second surface,
• wherein, when an opening cross section is defined as a cross section of the through-hole taken along a plane perpendicular to the normal line and a representative diameter is defined as a diameter of a circle obtained by performing regression analysis of the opening cross section, a representative diameter of the opening cross section in a first region that is on the first surface side and a representative diameter of the opening cross section in a second region that is on the second surface side are each larger than a representative diameter of the opening cross section in a third region that is a region in the electrode disposed between the first surface and the second surface,
• wherein, when an incircle and a circumcircle are respectively defined as two concentric circles having a smaller radius and a larger radius between which the opening cross section is disposed and having the smallest difference in the radii, a difference in the radii of the incircle and the circumcircle of the opening cross section in the first region and a difference in the radii of the incircle and the circumcircle of the opening cross section in the second region are each larger than a difference in the radii of the incircle and the circumcircle of the opening cross section in the third region, and
• wherein the representative diameter in the first region and the representative diameter in the third region are different from each other at an interface between the first region and the third region, and the representative diameter in the second region and the representative diameter in the third region are different from each other at an interface between the second region and the third region.