Polarizer and microlithography projection system with a polarizer

A microlithographic projection system comprising:

• an illumination device including a light source for illuminating a mask;
• a projection lens following said illumination device for forming an image of a pattern appearing on said mask on to an image plane of said projection lens;
• and
• at least one polarizer for transforming a light beam incident along an optical axis into an exiting light beam having a prescribed distribution of locally varying polarization states over its cross-Section;
• wherein the polarizer comprises at least one birefringent element having a crystal axis and a finite axial thickness for generating a phase shift between mutually orthogonally polarized field components of transmitted light;
• wherein the illuminated cross-section of said polarizer is subdivided into numerous zones;
• wherein at least one of said zones is configured such that its transmission direction for light is inclined with respect to said crystal axis of said zone within said zone at an inclination angle greater than 0° and less than 90° and lies in a transmission plane defined by said transmission direction and said crystal axis;
• and
• wherein the axial thickness of said zone and the inclination angle are adapted such that a difference in the optical path lengths of said field components within said zone corresponds to a prescribed relative retardation upon exiting said polarizer and the orientation of the transmission plane of every such zone is prealigned such that the desired, local, preferred polarization directions exist within that zone,
• whereby the prescribed distribution of locally varying polarization states is obtained exclusively by rotating the polarization state of the incident light beam, rather than by filtering.

A method for fabricating micro-devices, comprising the following steps:

• providing a mask having a prescribed pattern;
• illuminating said mask with ultraviolet light having a prescribed wavelength using an illumination device including at least one polarizer;
• projecting an image of said pattern onto a photosensitive substrate arranged in the vicinity of the image plane of a projection lens;
• wherein the polarizer transforms a light beam incident along an optical axis into an exiting light beam having a prescribed distribution of locally varying polarization states over its cross-section;
• wherein the polarizer comprises at least one birefringent element having a crystal axis and a finite axial thickness for generating a phase shift between mutually orthogonally polarized field components of transmitted light;
• wherein the illuminated cross-section of said polarizer is subdivided into numerous zones;
• wherein at least one of said zones is configured such that its transmission direction for light is inclined with respect to said crystal axis of said zone within said zone at an inclination angle greater than 0° and less than 90° and lies in a transmission plane defined by said transmission direction and said crystal axis;
• and
• wherein the axial thickness of said zone and the inclination angle are adapted such that a difference in the optical path lengths of said field components within said zone corresponds to a prescribed relative retardation upon exiting said polarizer and the orientation of the transmission plane of every such zone is prealigned such that the desired, local, preferred polarization directions exist within that zone,
• whereby the prescribed distribution of locally varying polarization states is obtained exclusively by rotating the polarization state of the incident light beam, rather than by filtering.

A polarizer for transforming a light beam incident along an optical axis into an exiting light beam that has a prescribed distribution of locally varying polarization states over its cross-section, the polarizer comprising:

• a birefringent element having a crystal axis and a finite axial thickness for generating a phase shift between mutually orthogonally polarized field components of transmitted light;
• the illuminated cross-section of said polarizer is subdivided into numerous zones;
• at least one of said zones is configured such that its transmission direction for light is inclined with respect to said crystal axis of said zone within said zone at an inclination angle greater than 0° and less than 90° and lies in a transmission plane defined by said transmission direction and said crystal axis;
• wherein the axial thickness of said zone and the inclination angle are adapted such that a difference in the optical path lengths of said field components within said zone corresponds to a prescribed relative retardation upon exiting said polarizer and the orientation of the transmission plane of every such zone is prealigned such that the desired, local, preferred polarization directions exist within that zone, and
• wherein said birefringent element is a single-layer structure,
• whereby the prescribed distribution of locally varying polarization states is obtained by rotating the polarization state of the incident light beam.

A polarizer for transforming a light beam incident along an optical axis into an exiting light beam that has a prescribed distribution of locally varying polarization states over its cross-section, the polarizer comprising:

• a birefringent element having a crystal axis and a finite axial thickness for generating a phase shift between mutually orthogonally polarized field components of transmitted light;
• the illuminated cross-section of said polarizer is subdivided into numerous zones;
• at least one of said zones is configured such that its transmission direction for light is inclined with respect to said crystal axis of said zone within said zone at an inclination angle greater than 0° and less than 90° and lies in a transmission plane defined by said transmission direction and said crystal axis;
• wherein the axial thickness of said zone and the inclination angle are adapted such that a difference in the optical path lengths of said field components within said zone corresponds to a prescribed relative retardation upon exiting said polarizer and the orientation of the transmission plane of every such zone is prealigned such that the desired, local, preferred polarization directions exist within that zone,
• wherein said birefringement element has the crystal axis aligned roughly parallel to an optical axis of the polarizer;
• and
• wherein at least one deflecting structure is assigned to said birefringement element, said deflecting structure being designed to yield the prescribed inclination angle and inclination direction for that zones,
• whereby the prescribed distribution of locally varying polarization states is obtained by rotating the polarization state of the incident light beam.

A polarizer for transforming a light beam incident along an optical axis into an exiting light beam that has a prescribed distribution of locally varying polarization states over its cross-section, the polarizer comprising:

• a birefringent element having a crystal axis and a finite axial thickness for generating a phase shift between mutually orthogonally polarized field components of transmitted light;
• the illuminated cross-section of said polarizer is subdivided into numerous zones;
• at least one of said zones is configured such that its transmission direction for light is inclined with respect to said crystal axis of said zone within said zone at an inclination angle greater than 0° and less than 90° and lies in a transmission plane defined by said transmission direction and said crystal axis;
• wherein the axial thickness of said zone and the inclination angle are adapted such that a difference in the optical path lengths of said field components within said zone corresponds to a prescribed relative retardation upon exiting said polarizer and the orientation of the transmission plane of every such zone is prealigned such that the desired, local, preferred polarization directions exist within that zone, and
• wherein said polarizer is designed to transform incident circularly polarized light into exiting, locally linearly polarized light,
• whereby the prescribed distribution of locally varying polarization states is obtained by rotating the polarization state of the incident light beam.

A polarizer for transforming a light beam incident along an optical axis into an exiting light beam that has a prescribed distribution of locally varying polarization states over its cross-section, the polarizer comprising:

• a birefringent element having a crystal axis and a finite axial thickness for generating a phase shift between mutually orthogonally polarized field components of transmitted light;
• the illuminated cross-section of said polarizer is subdivided into numerous zones;
• at least one of said zones is configured such that its transmission direction for light is inclined with respect to said crystal axis of said zone within said zone at an inclination angle greater than 0° and less than 90° and lies in a transmission plane defined by said transmission direction and said crystal axis;
• wherein the axial thickness of said zone and the inclination angle are adapted such that a difference in the optical path lengths of said field components within said zone corresponds to a prescribed relative retardation upon exiting said polarizer and the orientation of the transmission plane of every such zone is prealigned such that the desired, local, preferred polarization directions exist within that zone, and
• wherein said polarizer is designed to transform incident light that is linearly polarized in a single direction over its entire cross-section into exiting, locally linearly polarized lights,
• whereby the prescribed distribution of locally varying polarization states is obtained by rotating the polarization state of the incident light beam.