Patent ID: 8653477

Claim:
A lithography apparatus comprising: a stage on which a target object is placed; a chamber in which the stage is arranged and which has at least one side surface in which an opening having a size which is enough to carry the stage in or out is formed and at least one side surface in which an opening is not formed, the opening being closed with an independent lid; an electro-optic lens barrel arranged on the chamber; and at least one rib portion formed to have a shape that is convex on an upper portion of each of the at least one side surface of the chamber in which the opening is formed, the rib portion being formed integrally with the chamber, as an integral extension of the at least one side surface of the chamber in which the opening is formed, to increase rigidity of the at least one side surface of the chamber, wherein the chamber has four side surfaces, and the at least one rib portion is formed along a whole border line between the each of the at least one side surface, in which the opening is formed, of the four side surfaces of the chamber and an upper surface of the chamber; wherein the rib portion does not surround the opening.