公开(公告)号：US20200182803A1

公开(公告)日：2020-06-11

申请号：US16709630

申请日：2019-12-10

Applicant: Lasertec Corporation

Inventor： Tetsuya SENDODA ,  Kiwamu TAKEHISA ,  Takayuki ISHIDA

IPC: G01N21/88 ,  G01N21/956 ,  G01N21/21

Abstract: A mask inspection apparatus according to the present disclosure includes: a field stop unit capable of switching between a field stop for an optical mask configured to emit an incident illumination light while maintaining the polarization state thereof and a field stop for an EUV mask configured to change the polarization state of a part of the incident illumination light and to cause an illumination light including an S-polarized light and a P-polarized light; a beam splitter unit capable of switching between a PBS for an optical mask and a non-polarized BS; an objective lens configured to collect an illumination light reflected in the beam splitter unit in a mask to be inspected and collect a reflected light obtained by reflecting an illumination light in the mask to be inspected; and a λ/4 plate that can be provided in an optical path of an illumination light and a reflected light.