Imaging optical system
AssigneeCarl Zeiss SMT GmbH
InventorHans-Juergen Mann
Life of this patent
Estimating the term…
Abstract
The disclosure generally relates to imaging optical systems that include a plurality of mirrors, which image an object field lying in an object plane in an image field lying in an image plane, where at least one of the mirrors has a through-hole for imaging light to pass through. The disclosure also generally relates to projection exposure installations that include such imaging optical systems, methods of using such projection exposure installations, and components made by such methods.
Claims36
An imaging optical system, comprising:
- a plurality of mirrors configured to image an object field in an object plane into an image field in an image plane, at least one of the mirrors comprising a reflective surface surrounding a through-hole,
- wherein during use of the imaging optical system:
- first and second regions of the reflective surface reflect imaging light;
- and
- imaging light passes through the through-hole;
- and
- wherein:
- the through-hole is between the first and second regions of the reflective surface;
- the imaging optical system has a reduction magnification level of at least four times;
- and
- a reflection surface of at least one mirror is in the form of a free-form surface which cannot be described by a rotationally symmetrical function.
A projection exposure installation, comprising:
- an imaging optical system comprising a plurality of mirrors configured to image an object field in an object plane in an image field in an image plane, at least one of the mirrors comprising a reflective surface surrounding a through-hole, and the imaging optical system having a reduction magnification level of at least four times;
- and
- a system configured to direct illumination light to the object field of the imaging optical system,
- wherein during use of the imaging optical system:
- first and second regions of the reflective surface reflect imaging light;
- and
- imaging light passes through the through-hole;
- and
- wherein:
- the through-hole is between the first and second regions of the reflective surface;
- the projection exposure installation is a microlithography projection exposure installation;
- and
- a reflection surface of at least one of the plurality of mirrors is a free-form surface which cannot be described by a rotationally symmetrical function.
A method of using a projection exposure installation, the method comprising:
- using an imaging optical system of the projection exposure installation to project a structure of a reticle onto a light-sensitive layer, the imaging optical system comprising a plurality of mirrors configured to image an object field in an object plane in an image field in an image plane, at least one of the mirrors comprising a reflective surface surrounding a through-hole, and the imaging optical system having a reduction magnification level of at least four times,
- wherein the projection exposure installation further comprises a system configured to direct illumination light to the object field of the imaging optical system, and a reflection surface of at least one of the plurality of mirrors is a free-form surface which cannot be described by a rotationally symmetrical function, and
- wherein using the imaging optical system to project the structure of the reticle onto the light-sensitive layer comprises:
- reflecting imaging light from first and second regions of the reflective surface, the through-hole being between the first and second regions of the reflective surface;
- and
- passing imaging light through the through-hole.
Dependencies are inferred from the claim text.