Microlithographic illumination method and a projection lens for carrying out the method

A projection lens for a microlithographic projection system for imaging a pattern arranged in an object plane onto an image plane of the projection lens employing light that contains a first light ray having a first polarization direction and a second light ray having a second polarization direction that differs from the first polarization direction,

• the projection lens comprising optical components that may be illuminated by transmitted light rays at varying angles of incidence, the optical components including at least one mirror having a mirror surface inclined with respect to the optical axis and arranged between the object plane and the image plane;
• wherein a difference in the length of a first optical path traversed by the first light ray and a second optical path traversed by the second light ray occurs within at least one region of the image plane due to the optical configuration of the optical components;
• the projection lens further comprising at least one optical correction means for correcting for differences in the optical path length of the light rays by altering at least one of the first optical path and the second optical path;
• the optical correction means being configured such that the difference in the optical path length occurring at the image plane is largely independent of the angles of incidence of the light rays on the optical components.

A method for fabricating a projection lens comprising optical components and being usable for transmitting light containing a first light ray having a first polarization direction and a second light ray having a second polarization direction that differs from the first polarization direction, wherein the optical components may be illuminated by a transmitted light beam containing light rays having differing angles of incidence on the optical components and wherein a difference in the lengths of a first optical path traversed by the first light ray and a second optical path traversed by the second light ray occurs within at least one region of the image plane of the projection lens due to the optical configuration employed, wherein the method comprises:

• configuring the projecting lens using the optical components, the optical components including at least one birefringent optical component transited by the light beam and contributing to the difference in lengths of the first and second optical path through birefringence;
• transmitting light beams through the projection lens, wherein the light beams contain a first light ray and a second light ray that is orthogonally polarized with respect to the first light ray;
• determining wavefronts for light rays transmitted by the projection lens, wherein a first wavefront for the first light ray and a second wavefront for the second light ray are determined in accordance with their polarizations, and the wavefronts are employed for determining differential wavefronts;
• creating at least one optical correction means in accordance with the differential wavefronts, wherein the optical correction means are configured for compensating for the differences in the lengths of the optical paths such that the differential wavefronts will be largely independent of their angles of incidence on the optical components due to the compensation for the differences in the lengths of the optical paths when the optical correction means is installed in the projection lens;
• and
• installing that optical correction means in the projection lens.

An optical corrector for installation in a projection lens for a microlithographic projection system for imaging a pattern arranged in an object plane onto an image plane of the projection lens employing light that contains a first light ray having a first polarization direction and a second light ray having a second polarization direction that differs from the first polarization direction, the projection lens comprising optical components that may be illuminated by transmitted light rays at varying angles of incidence, the optical components including at least one birefringent optical component transited by the light and contributing to the difference in length of the first and second optical path through birefringence,

• wherein a difference in the length of a first optical path traversed by the first light ray and a second optical path traversed by the second light ray occurs within at least one region of the image plane due to the optical configuration of the optical components,
• the optical corrector being adapted for correcting for differences in the optical path length of the light rays by altering at least one of the first optical path and the second optical path,
• the optical corrector being configured such that the difference in the optical path length occurring at the image plane is largely independent of the angles of incidence of the light rays on the optical components.

A method for manufacturing semiconductor devices or other types of micro-devices comprising:

• arranging a mask having a prescribed pattern in the object plane of a projection lens;
• illuminating the mask using ultraviolet light;
• and
• using a projection lens to project an image of the pattern onto a photosensitive substrate situated in the vicinity of the image plane of the projection lens;
• wherein the projection lens comprises optical components illuminated by transmitted light rays at varying angles of incidence,
• wherein a difference in the length of a first optical path traversed by a first light ray having a first polarization direction and a second optical path traversed by a second light ray having a second polarization direction that differs from the first polarization direction occurs within at least one region of the image plane due to the optical configuration of the optical components, the optical configuration including at least one birefringent optical component transited by the first light ray and the second light ray, and contributing to the difference in the lengths of the first and second optical path through birefringence,
• wherein the projection lens further comprises at least one optical correction device that corrects differences in the optical path length of the light rays by altering at least one of the first optical path and the second optical path, and
• wherein the optical correction device is configured to render the difference in the optical path length occurring at the image plane substantially independent of the angles of incidence of the light rays on the optical components.

A method for manufacturing semiconductor devices or other types of micro-devices comprising:

• arranging a mask having a prescribed pattern in the object plane of a projection lens;
• illuminating the mask using ultraviolet light;
• and
• using a projection lens to project an image of the pattern onto a photosensitive substrate situated in the vicinity of the image plane of the projection lens;
• wherein the projection lens is a catadioptric projection lens having at least one mirror having a mirror surface at least partly inclined with respect to the optical axis and arranged between the object plane and image plane;
• and
• wherein the projection lens comprises optical components illuminated by transmitted light rays at varying angles of incidence, wherein a difference in the length of a first optical path traversed by a first light ray having a first polarization direction and a second optical path traversed by a second light ray having a second polarization direction that differs from the first polarization direction occurs within at least one region of the image plane due to the optical configuration of the optical components;
• wherein the projection lens further comprises at least one optical correction device that corrects differences in the optical path length of the light rays by altering at least one of the first optical path and the second optical path;
• wherein the optical correction device is configured to render the difference in the optical path length occurring at the image plane substantially independent of the angles of incidence of the light rays on the optical components;
• and
• wherein the optical correction means are configured for creating a substantially linear gradient of the phase shift, whereby a tilting of wavefronts running through the projection lens is at least partly compensated.