OPTICAL ARRANGEMENT FOR THREE-DIMENSIONALLY PATTERNING A MATERIAL LAYER
The disclosure relates to an optical arrangement for three-dimensionally patterning a radiation-sensitive material layer, such as a projection exposure apparatus for microlithography. The optical arrangement includes a mask for forming a three-dimensional radiation pattern, a substrate with the radiation-sensitive material layer, and a projection optical unit for imaging the three-dimensional radiation pattern from the mask into the radiation-sensitive material layer. The optical arrangement is designed to compensate for spherical aberrations along the thickness direction of the radiation-sensitive material layer in order to generate a stigmatic image of the three-dimensional radiation pattern.
1 . An optical arrangement, comprising:
a mask configured to form a three-dimensional radiation pattern;
a substrate;
a radiation-sensitive material layer supported by the substrate, the radiation-sensitive material layer having first and second planes in a thickness direction of the radiation sensitive material layer, the first plane being different from the second plane; and
a projection optical unit configured to image the three-dimensional radiation pattern from the mask into the radiation-sensitive material layer,
wherein the optical arrangement is configured to compensate for spherical aberrations at the same time at least within the first and second planes to generate a stigmatic image of the three-dimensional radiation pattern in the radiation-sensitive material layer, and
wherein the optical arrangement is configured to be used in a projection exposure apparatus for microlithography.
2 . The optical arrangement according to claim 1 , wherein the first and second planes are oriented perpendicular to the thickness direction of the material layer.
3 . The optical arrangement according to claim 1 , wherein the first and second planes are separated from each other by a distance that corresponds to more than twice a depth of focus of the projection optical unit.
4 . The optical arrangement according to claim 1 , wherein the mask has a three-dimensionally patterned material layer.
5 . The optical arrangement according to claim 4 , wherein, for an imaging scale β of the projection optical unit, a refractive index n r of the radiation-sensitive material layer and a refractive index n m of the material layer of the mask, the following holds true: β=n m /n r .
6 . The optical arrangement according to claim 4 , wherein an imaging scale β of the projection optical unit can be set in a manner dependent on a refractive index of the radiation-sensitive material layer and a refractive index of the material layer of the mask.
7 . The optical arrangement according to claim 4 , wherein an imaging scale β of the projection optical unit can be set in a manner dependent on a refractive index of the radiation-sensitive material layer and a refractive index of the material layer of the mask where 0.8<β<1.2
8 . The optical arrangement according to claim 4 , further comprising an illumination system configured to introduce radiation into the material layer of the mask, wherein the optical arrangement is configured to allow only a portion of the radiation that is scattered at structures in the material layer of the mask to enter into the projection optical unit.
9 . The optical arrangement according to claim 8 , wherein the structures in the material layer of the mask are reflective.
10 . The optical arrangement according to claim 8 , wherein the illumination system is configured to generate dark field illumination.
11 . The optical arrangement according to claim 1 , wherein the mask has a holographic structure configured to at least partly compensate for spherical aberrations along the thickness direction of the radiation-sensitive material layer.
12 . The optical arrangement according to claim 11 , wherein the holographic mask has a diffraction grating configured to diffract radiation from an illumination system into the projection optical unit.
13 . The optical arrangement according to claim 1 , wherein the mask is displaceable in a direction perpendicular to an object plane of the projection optical unit by a magnitude of more than 3 λ/NA O 2 , and/or the light-sensitive material layer is displaceable perpendicular to an image plane of the projection optical unit by a magnitude of more than 3 λ/NA B 2 ,
where λ is a wavelength of the radiation used during operation of the optical arrangement, NA B is an image-side numerical aperture of the projection optical unit, and NA 0 denotes an object-side numerical aperture of the projection optical unit.
14 . The optical arrangement according to claim 1 , further comprising an illumination system configured to produce a relative numerical aperture σ of less than 0.1.
15 . The optical arrangement according to claim 1 , wherein the optical arrangement is configured to be used with radiation having a wavelength of 400 nm or less.
16 . The optical arrangement according to claim 1 , wherein the projection optical unit has an image-side aperture of 1.2 or more.
17 . The optical arrangement according claim 1 , further comprising an immersion liquid is between a last optical element of the projection optical unit and the radiation-sensitive material layer.
18 . A mask configured to be used in the optical arrangement of claim 1 , the mask having a holographic structure configured to form a three-dimensional radiation pattern, the holographic structure at least partly compensating for spherical aberrations along the thickness direction of the radiation-sensitive material layer.
19 . A method, comprising:
operating a projection exposure apparatus for microlithography by:
forming a three-dimensional radiation pattern; and
imaging the three-dimensional radiation pattern into a radiation-sensitive material layer,
wherein, while forming the three-dimensional radiation pattern and/or imaging the three-dimensional radiation pattern, spherical aberrations at least within a first plane and a second plane, which are located at different positions along a thickness direction of the radiation-sensitive layer, are compensated for to generate a stigmatic image of the three-dimensional radiation pattern in the radiation-sensitive material layer.
20 . The method according to claim 19 , further comprising, prior to imaging, displacing the mask perpendicular to an object plane and/or displacing the radiation-sensitive material layer perpendicular to an image plane of a projection optical unit used during imaging, by an amount defined in a manner dependent on the mask respectively chosen.