When a surface of a filter member on a multilayer film is defined as a first surface, a surface of the filter member on an quartz substrate as a second surface, an inner wall surface of a slit which faces the first surface of the filter member as a first inner wall surface, and an inner wall surface of the slit which faces the second surface of the filter member as a second inner wall surface, one or more of the first inner wall surface and the second inner wall surface of the slit, and the second surface of the filter member do not lie parallel to the first surface of the filter member.