Illumination system for an euv lithography device and facet mirror therefor

Patent metadata

Field	Value
Publication number	US-2016004164-A1
Application number	US-201514796164-A
Country	US
Kind code	A1
Filing date	Jul 10, 2015
Priority date	Feb 22, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

The invention relates to an illumination system for an EUV lithography device, comprising: a first facet mirror having facet elements that reflect EUV radiation, and a second facet mirror having facet elements for reflecting the EUV radiation reflected by the first facet mirror onto an illumination field. At least one of the facet elements of the first facet mirror or of the second facet mirror is designed as a diffractive optical element for diffracting the EUV radiation. In particular, at least one of the facet elements of the second facet mirror is designed as a diffractive optical element for illuminating only a part of the illumination field. The invention also relates to an EUV lithography device comprising such an illumination system, and to a facet mirror comprising at least one diffractive facet element.

First claim

1 .- 18 . (canceled)

19 . An illumination system, comprising:
a first facet mirror comprising facet elements configured to reflect EUV radiation; a second facet mirror comprising facet elements configured to: a) reflect the EUV radiation after the EUV radiation reflects from facet elements of the first facet mirror; and b) reflect the EUV radiation onto an illumination field of the illumination system, wherein:
a first facet element is a diffractive optical element configured to diffract the EUV radiation;
the first facet element is a facet element of the first facet mirror or the second facet mirror;
a second facet element is configured to illuminate only a part of the illumination field;
the second facet element is a facet element of the second facet mirror; and
the illumination system is an EUV lithography illumination system.

20 . The illumination system of claim 19 , wherein the part of the illumination field comprises first and second partial regions of the illumination field, and the first partial region is non-contiguous with the second partial region.

21 . The illumination system of claim 20 , wherein:
a first plurality of the facet mirrors of the second facet mirror are configured to illuminate the first partial region; a second plurality of facet elements of the second facet mirror are configured to illuminate the second partial region; and the first plurality of facet elements of the first facet mirror is different from the second plurality of facet elements of the second facet mirror.

22 . The illumination system of claim 21 , wherein:
the facet elements of the first facet mirror are switchable between first and second positions; in the first position, the facet elements of the first face mirror are configured to reflect the EUV radiation onto the first plurality of facets of the second facet mirror; and in the second position, the facet elements of the first facet mirror are configured to reflect the EUV radiation onto the second plurality of facets of the second facet mirror.

23 . The illumination system of claim 22 , wherein the facet elements of the second facet mirror define a grid arrangement in which facet elements of the first plurality of facet elements alternate with facet elements of the second plurality of facet elements.

24 . The illumination system of claim 23 , wherein the first diffractive facet element comprises:
a substrate comprising a profiled surface; and a multilayer coating supported by the profiled surface, the multilayer coating configured to reflect EUV radiation.

25 . The illumination system of claim 20 , wherein:
the facet elements of the first facet mirror are switchable between first and second positions; in the first position, the facet elements of the first face mirror are configured to reflect the EUV radiation onto a first plurality of facets of the second facet mirror; in the second position, the facet elements of the first facet mirror are configured to reflect the EUV radiation onto a second plurality of facets of the second facet mirror; and the first plurality of facet elements of the second face mirror is different from the second plurality of facet elements of the second facet mirror.

26 . The illumination system of claim 25 , wherein the facet elements of the second facet mirror define a grid arrangement in which facet elements of the first plurality of facet elements alternate with facet elements of the second plurality of facet elements.

27 . The illumination system of claim 20 , wherein the first facet element is a diffractive optical element configured to deflect EUV radiation onto a radiation sensor.

28 . The illumination system of claim 20 , wherein at least one of the facet elements comprises a planar surface.

29 . The illumination system of claim 20 , wherein the first facet element comprises:
a substrate comprising a profiled surface; and a multilayer coating supported by the profiled surface, the multilayer coating configured to reflect EUV radiation.

30 . The illumination system of claim 29 , wherein the profiled surface comprises a multi-step surface profile.

31 . The illumination system of claim 20 , wherein the first facet element comprises a grating structure having a lateral extent of the order of magnitude of a wavelength of the EUV radiation.

32 . The illumination system of claim 19 , wherein the first facet element is the same as the second facet element.

33 . The illumination system of claim 19 , wherein the first facet element is different from the second facet element.

34 . The illumination system of claim 33 , wherein the first facet element is a facet element of the second facet mirror.

35 . The illumination system of claim 19 , wherein the first facet element is a facet element of the first facet mirror.

36 . The illumination system of claim 19 , wherein the first facet element is configured to deflect EUV radiation onto a radiation sensor.

37 . The illumination system of claim 19 , wherein at least one of the facet elements comprises a planar surface.

38 . The illumination system of claim 19 , wherein the first diffractive facet element comprises:
a substrate comprising a profiled surface; and a multilayer coating supported by the profiled surface, the multilayer coating configured to reflect EUV radiation.

39 . The illumination system of claim 38 , wherein the profiled surface comprises a multi-step surface profile.

40 . The illumination system of claim 19 , wherein the first facet element comprises a grating structure having a lateral extent of the order of magnitude of a wavelength of the EUV radiation.

41 . A lithography device, comprising:
an illumination system according to claim 19 ; and a projection lens, wherein the lithography device is an EUV lithography device.

42 . A method of using an EUV lithography device comprising an illumination system and a projection lens, the method comprising:
using the illumination system to illuminate a portion of a structured object; and using the projection lens to image at least a portion of the illuminated structured object onto a substrate, wherein the illumination system comprises an illumination system according to claim 19 .

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Ruoff Johannes
• Saenger Ingo
• Zimmermann Joerg
• Kraehmer Daniel
• Hennerkes Christoph
• Schlesener Frank

Classifications

• G03F7/70158 Primary

  Diffractive optical elements · CPC title

• G03F7/70091

  Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA] · CPC title

• G03F7/70116

  Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets · CPC title

• G03F7/70075

  Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection · CPC title

• G02B26/0833

  the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B) · CPC title