Mask inspection apparatus and mask inspection method

Patent metadata

Field	Value
Publication number	US-2017235031-A1
Application number	US-201615331575-A
Country	US
Kind code	A1
Filing date	Oct 21, 2016
Priority date	Feb 12, 2016
Publication date	Aug 17, 2017
Grant date	—

Abstract

Provided are a mask inspection apparatus and a mask inspection method that can prevent a reduction in a reflectance of a drop-in mirror, which is caused by carbon contaminants. A mask inspection apparatus according to the present invention includes a drop-in mirror including multi-layer film and a reflective surface. The drop-in mirror is configured to reflect illumination light incident on the reflective surface and illuminate the mask. An area of the reflective surface is configured to be greater than an area of an illuminated spot irradiated with the illumination light on the reflective surface. The drop-in mirror is configured to be movable. A position of the illuminated spot on the reflective surface is configured to be moved when the drop-in mirror is moved.

First claim

1 . A mask inspection apparatus comprising a drop-in mirror comprising:
a multi-layer film; and a reflective surface, wherein the drop-in mirror is configured to reflect illumination light incident on the reflective surface and illuminate a mask, an area of the reflective surface is configured to be greater than an area of an illuminated spot irradiated with the illumination light on the reflective surface, the drop-in mirror is configured to be movable, and a position of the illuminated spot on the reflective surface is configured to be moved when the drop-in mirror is moved.

2 . The mask inspection apparatus according to claim 1 , wherein the drop-in mirror comprises a silicon wafer.

3 . The mask inspection apparatus according to claim 1 , wherein the drop-in mirror is configured to be moved while maintaining a central angle of incidence and a central angle of reflection of an optical axis of the illumination light with respect to the reflective surface.

4 . The mask inspection apparatus according to claim 1 , further comprising:
a first concave mirror configured to collect specularly reflected light, the specularly reflected light being illumination light reflected by the mask; and a second concave mirror configured to collect reflected light from the first convex mirror, wherein a position of the illuminated spot is between the second convex mirror and the mask.

5 . The mask inspection apparatus according to claim 1 , wherein a part that was in the illuminated spot on the reflective surface, which has been moved outside the illuminated spot when the drop-in mirror is moved, is configured to be irradiated with cleaning light including VUV light with a wavelength different from a wavelength of the illumination light.

6 . The mask inspection apparatus according to claim 1 , wherein
the drop-in mirror comprises a rotation axis, and the drop-in mirror is configured to be rotated around the rotation axis.

7 . The mask inspection apparatus according to claim 1 , wherein
the drop-in mirror is configured to be extended in a direction vertical to a surface comprising an optical axis of the illumination light incident on the reflective surface and an optical axis of the illumination light reflected by the reflective surface, and the drop-in mirror is configured to be moved in the direction vertical to the surface.

8 . A mask inspection apparatus comprising a drop-in mirror comprising:
a multi-layer film; and a reflective surface, wherein
the drop-in mirror is configured to reflect illumination light incident on the reflective surface and illuminate a mask,
an area of the reflective surface is configured to be greater than an area of an illuminated spot irradiated with the illumination light on the reflective surface,
the drop-in mirror is configured to be movable,
a position of the illuminated spot on the reflective surface is configured to be moved when the drop-in mirror is moved, and
a part that was in the illuminated spot on the reflective surface, which has been moved outside the illuminated spot, is configured to be irradiated with cleaning light with a wavelength different from a wavelength of the illumination light.

9 . The mask inspection apparatus according to claim 8 , further comprising:
a light source configured to generate light comprising EUV light and DUV light; and a diffraction grating configured to disperse the light into the illumination light comprising the EUV light and the cleaning light comprising the DUV light.

10 . The mask inspection apparatus according to claim 8 , wherein the drop-in mirror is configured to be disposed in an apparatus exhausted by a vacuum pump.

11 . The mask inspection apparatus according to claim 8 , further comprising a condenser lens configured to collect the cleaning light on the part.

12 . A mask inspection method using a drop-in mirror comprising a multi-layer film and a reflective surface, the mask inspection method comprising:
reflecting illumination light incident on the reflective surface and illuminating a mask; making an area of the reflective surface be greater than an area of an illuminated spot, the illuminated spot being a part of the reflective surface irradiated with the illumination light; allowing the drop-in mirror to be movable; and moving the drop-in mirror in order to move a position of the illuminated spot on the reflective surface.

13 . The mask inspection method according to claim 12 , wherein a part that was in the illuminated spot on the reflective surface, which has been moved outside the illuminated spot, is irradiated with cleaning light with a wavelength different from a wavelength of the illumination light.

Assignees

• Lasertec Corp

Inventors

• Takehisa Kiwamu
• Miyai Hiroki

Classifications

• G02B5/1838

  for use with ultraviolet radiation or X-rays · CPC title

• G02B5/0816

  Multilayer mirrors, i.e. having two or more reflecting layers (G02B5/0883, G02B5/0891 take precedence) · CPC title

• G02B7/1821

  for rotating or oscillating mirrors · CPC title

• B08B7/0057

  by ultraviolet radiation · CPC title

• G02B5/0891 Primary

  Ultraviolet [UV] mirrors (apparatus for microlithography exposure G03F7/70; X-ray multilayer structures G21K1/06) · CPC title