Monitor system for determining orientations of mirror elements and euv lithography system

Patent metadata

Field	Value
Publication number	US-2015198894-A1
Application number	US-201514665420-A
Country	US
Kind code	A1
Filing date	Mar 23, 2015
Priority date	Oct 5, 2012
Publication date	Jul 16, 2015
Grant date	—

Abstract

An EUV lithography system 1 has an EUV beam path and a monitor beam path 51.
The EUV beam path comprises a mirror system 13 having plurality of mirror elements 17 , the orientations of which can be changed.
The monitor beam path comprises a monitor radiation source 53 , a screen 71 and a spatially resolving detector 77 , wherein the mirror system is arranged in the monitor beam path between the monitor radiation source and the screen.
Each one of the mirror elements generates an image of the monitor radiation source in an image plane associated with the respective mirror elements, wherein distances B between the image planes and the screen have a maximum distance, distances A between each one of the mirror elements and the image plane have a minimum distance, and wherein the maximum distance B is less than half of the minimum distance A.

First claim

1 - 22 . (canceled)

23 . An optical system, comprising:
a mirror system comprising a plurality of mirror elements, orientations of the mirror elements being settable independently of each other; and a monitor system configured to determine the orientations of the mirror elements, the monitor system comprising:
a monitor radiation source configured to illuminate the plurality of mirror elements with light having a plurality of different wavelengths;
a monitor lens having an object plane, an image plane, and a pupil plane between the object plane and the image plane;
a color filter having wavelength-dependent transmission properties which differ from one another at different positions of the color filter; and
a light detector configured to spatially resolve light and to wavelength-resolve light, the light filter having a detection area,
wherein:
the mirror elements are arranged in a region of the object plane of the monitor lens;
the detection area of the light detector is arranged in a region of the image plane of the monitor lens; and
the color filter is arranged in a region of the pupil plane of the monitor lens.

24 . The optical system of claim 23 , further comprising a controller configured to analyze light intensities detected by the light detector and to determine orientations of the mirror elements, wherein, for each individual mirror element, the orientation of the mirror element is determined depending on wavelengths detected at a position on the detection area of the light detector associated with the mirror element.

25 . The optical system of claim 24 , wherein the mirror system comprises a plurality of actuators configured to change the orientation of at least some of the mirror elements relative to other mirror elements, and the controller is configured to actuate the actuators based on the determined orientation of at least one of the mirror elements.

26 . The optical system of claim 23 , wherein the monitor radiation source has a diameter of less than 2.0 mm, and in particular of less than 1.0 mm.

27 . The optical system of claim 23 , wherein the monitor radiation source has a diameter of less 1.0 mm.

28 . The optical system of claim 23 , wherein the monitor system comprises a plurality of monitor radiation sources arranged at a distance from one another.

29 . The optical system of claim 28 , wherein each of the plurality of monitor radiation sources is configured to emit radiation having a predetermined temporal intensity modulation, and the temporal intensity modulations of at least two monitor radiation sources are different from one another.

30 . The optical system of claim 23 , wherein:
the monitor system comprises:
a plurality of monitor lenses;
a plurality of color filters; and
a plurality of light detectors,
the mirror elements are arranged in a region of the object plane of each of the monitor lenses; the detection area of each of the plurality of light detectors is arranged in a region of the image plane of each of the monitor lenses; and one of the plurality of color filters is arranged in a region of the pupil plane of each of the monitor lenses.

31 . The optical system of claim 23 , wherein a mask having perforations is arranged in the beam path upstream of the detection area, and the perforations are arranged at positions corresponding to the positions of the mirror elements.

32 . The optical system of claim 23 , wherein the color filter has a linear spatially dependent profile for at least one wavelength, and values of a degree of transmission of the color filter to light of the at least one wavelength change linearly with a value of a spatial coordinate on the color filter.

33 . A lithography system having an EUV beam path, the lithography system comprising:
imaging optics arranged in the EUV beam path and configured to image an object plane into an image plane; an optical system according to claim 31 ; and an EUV radiation source, wherein the mirror elements are in the EUV beam path between the EUV radiation source and the object plane of the imaging optical unit.

34 . The lithography system of claim 33 , wherein the mirror system comprises more than 1000 mirror elements.

35 . The lithography system of claim 33 , wherein mirror areas of the mirror elements are next to each other within an overall mirror area, an a diameter of the overall mirror area is greater than 100 mm.

36 . The lithography system of claim 33 , wherein mirror areas of the mirror elements are next to each other within an overall mirror area, an a diameter of the overall mirror area is greater than 150 mm.

37 . The lithography system of claim 33 , wherein the mirror areas of the mirror elements in each case have an area of less than one square millimeter.

38 . The lithography system of claim 33 , wherein the orientation of at least one of the mirror elements is changeable by more than ±0.05 rad.

39 . The lithography system of claim 33 , wherein the orientation of at least one of the mirror elements is changeable by more than ±0.1 rad.

40 . The lithography system of claim 33 , wherein the orientation of the mirror elements is changeable in two linearly independent directions.

41 . The lithography system of claim 33 , wherein an absolute value of a linear magnification of the image of the object plane of the monitor lens in the image plane of the monitor lens is less than 0.6.

42 . The lithography system of claim 33 , wherein an absolute value of a linear magnification of the image of the object plane of the monitor lens in the image plane of the monitor lens is less than 0.3.

43 . The lithography system of claim 33 , wherein the monitor lens has an image-side numerical aperture NA such that 0.1<NA<0.9.

44 . The lithography system of claim 33 , wherein the monitor lens has an image-side numerical aperture NA such that 0.3<NA<0.8.

45 . The lithography system of claim 33 , wherein the light detector has a plurality of detector pixels, and a number of the detector pixels is greater than 5 times a number of mirror elements arranged in an object field of the monitor lens.

46 . The lithography system of claim 33 , wherein the light detector has a plurality of detector pixels, and a number of the detector pixels is greater than 10 times a number of mirror elements arranged in an object field of the monitor lens.

47 . The lithography system of claim 33 , wherein the light detector has a plurality of detector pixels, each detector pixel comprises a color filter, and directly adjacent detector pixels have color filters that are different from each other.

48 . The lithography system of claim 33 , wherein:
the light detector comprises a plurality of detector pixels; the light detector comprises a dichroic beam splitter; and at least two groups of detector pixels arranged in different beam paths in the beam path are downstream of the dichroic beam splitter.

49 . The lithography system of claim 33 , wherein the color filter comprises at least 2000 mutually different spectral transmission properties which are resolvable by the light detector.

50 . The lithography system of claim 33 , further comprising a vacuum vessel, wherein the mirror elements are arranged within the vacuum vessel, and the monitor radiation source and/or the monitor lens is/are arranged outside of the vacuum vess

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Wangler Johannes
• Eisenmenger Johannes
• Deguenther Markus
• Patra Michael

Classifications

• G03F7/70033 Primary

  by plasma extreme ultraviolet [EUV] sources · CPC title

• G01M11/005

  Testing of reflective surfaces, e.g. mirrors · CPC title

• G01B11/14

  for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) · CPC title

• G03F7/70075 Primary

  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

• G03F7/70116

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