MICROLITHOGRAPHY PROJECTION OPTICAL SYSTEM AND METHOD FOR MANUFACTURING A DEVICE
In some embodiments, a catoptric microlithgraphy projection optical system includes a plurality of reflective optical elements arranged to image radiation from an object field in an object plane to an image field in an image plane. The image field can have a size of at least 1 mm×1 mm. This optical system can have an object-image shift (OIS) of about 75 mm or less. Metrology and testing can be easily implemented despite rotations of the optical system about a rotation axis. Such a catoptric microlithgraphy projection optical system can be implemented in a microlithography tool. Such a microlithography tool can be used to produce microstructured components.
1 . A system, comprising:
a plurality of reflective elements configured to image radiation from an object field in an object plane of the system to an image field in an image plane of the system,
wherein the system has an object-image shift of about 75 mm or less, the image field has a size of at least 1 mm×1 mm, and the system is a catoptric microlithography projection optical system.
2 . The system of claim 1 , wherein at least one of the plurality of reflective elements has a rotationally asymmetric surface positioned in a path of the radiation, and the rotationally asymmetric surface deviates from a best-fit rotationally symmetric surface by at least λ at one or more locations, where λ is the wavelength of the radiation.
3 . The system of claim 2 , wherein the best-fit rotationally asymmetric surface deviates by about 0.1× or less from a surface corresponding to the equation:
z
=
cr
2
1
+
1
-
(
1
+
k
)
c
2
r
2
+
∑
j
=
2
α
C
j
x
m
y
n
where
j
=
(
m
+
n
)
2
+
m
+
3
n
2
+
1
,
z is the sag of the surface parallel to an axis, c is the vertex curvature and k is the conical constant, C j is the coefficient of the monomial x m y n , and α is an integer.
4 . The system of claim 2 , wherein the rotationally asymmetric surface deviates from the best-fit rotationally symmetric surface by about 10λ or more at the one or more locations.
5 . The system of claim 2 , wherein the rotationally asymmetric surface deviates from the best-fit rotationally symmetric surface by about 20 nm or more at the one or more locations.
6 . The system of claim 1 , wherein the plurality of reflective elements define a meridional plane and the plurality of reflective elements are mirror symmetric with respect to the meridional plane.
7 . The system of claim 1 , wherein the plurality of reflective elements comprises two elements that are reflective elements and that have rotationally asymmetric surfaces positioned in a path of the radiation.
8 . The system of claim 1 , wherein the plurality of elements includes at most two reflective elements that have a positive chief ray angle magnification.
9 . The system of claim 1 , wherein the plurality of elements includes at most one reflective element that has a positive chief ray angle magnification.
10 . The system of claim 1 , wherein the microlithography projection optical system has an image-side numerical aperture of about 0.2 or more.
11 . The system of claim 1 , wherein the system has a rectangular field at the image plane, and the rectangular field in each orthogonal direction has a minimum dimension of about 1 mm or more.
12 . The system of claim 1 , wherein static distortion at the image field is about 10 nm or less.
13 . The system of claim 1 , wherein wavefront error at the image field is about λ/14 or less, where λ is the wavelength of the radiation.
14 . The system of claim 1 , wherein a path of the radiation though the system is characterized by chief rays that are non-parallel to an object plane normal at the object plane.
15 . The system of claim 1 , wherein chief rays are parallel to each other to within 0.05° at the object plane.
16 . The system of claim 1 , wherein chief rays diverge from each other at the object plane.
17 . The system of claim 1 wherein, for a meridional section of the system, chief rays have a maximum angle of incidence on a surface of each of the elements of less than 20°.
18 . The system of claim 1 , wherein the system is telecentric at the object plane.
19 . The system of claim 1 , wherein the system is telecentric at the image plane.
20 . The system of claim 1 , wherein:
a path of the radiation through the system is characterized by chief rays;
for a meridional section of the optical system, a chief ray of a central field point has a maximum angle of incidence on a reflective surface of each of the plurality of reflective elements of θ degrees;
the optical system has an image side numeral aperture, NA, of more than 0.3; and
a ratio θ/NA is less than 68.
21 . The system of claim 1 further comprising a radiation source configured to provide the radiation to an object plane, wherein a wavelength of the radiation is about 30 nm or less.
22 . The system of claim 21 further comprising an illumination system comprising one or more elements arranged to direct radiation from the radiation source to an object positioned at the object plane, wherein the illumination system comprises an element positioned at a location corresponding to an entrance pupil of the system.
23 . The system of claim 1 , wherein the system is free of pupil obscuration.
24 . A tool, comprising:
an illumination system comprising one or more optical elements; and
a catoptric microlithography projection optical system, comprising:
a plurality of reflective elements configured to image radiation from an object field in an object plane of the catoptric microlithography projection optical system to an image field in an image plane of the catoptric microlithography projection optical system,
wherein the catoptric microlithography projection optical system has an object-image shift of about 75 mm or less, the image field has a size of at least 1 mm×1 mm, and the tool is a microlithography tool.
25 . The tool of claim 24 , wherein the illumination system is configured to direct the radiation from a radiation source to an object positioned at the object plane of the catoptric microlithography projection optical system.
26 . The tool of claim 25 , further comprising the radiation source.
27 . A method, comprising using the microlithography tool of claim 24 to produce microstructured components.