Title: Four-mirror extreme ultraviolet (EUV) lithography projection system

Abstract

The invention is directed to a four-mirror catoptric projection system for extreme ultraviolet (EUV) lithography to transfer a pattern from a reflective reticle to a wafer substrate. In order along the light path followed by light from the reticle to the wafer substrate, the system includes a dominantly hyperbolic convex mirror, a dominantly elliptical concave mirror, spherical convex mirror, and spherical concave mirror. The reticle and wafer substrate are positioned along the system's optical axis on opposite sides of the mirrors. The hyperbolic and elliptical mirrors are positioned on the same side of the system's optical axis as the reticle, and are relatively large in diameter as they are positioned on the high magnification side of the system. The hyperbolic and elliptical mirrors are relatively far off the optical axis and hence they have significant aspherical components in their curvatures. The convex spherical mirror is positioned on the optical axis, and has a substantially or perfectly spherical shape. The spherical concave mirror is positioned substantially on the opposite side of the optical axis from the hyperbolic and elliptical mirrors. Because it is positioned off-axis to a degree, the spherical concave mirror has some asphericity to counter aberrations. The spherical concavemore » mirror forms a relatively large, uniform field on the wafer substrate. The mirrors can be tilted or decentered slightly to achieve further increase in the field size. « less

Inventors:

Cohen, Simon J ^[1]; Jeong, Hwan J ^[2]; Shafer, David R ^[3]

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+ Show Inventor Affiliations

1. Pleasonton, CA
2. Los Altos, CA
3. Fairfield, CT

Issue Date:

Sat Jan 01 00:00:00 EST 2000

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

OSTI Identifier:

873351

Patent Number(s):

6142641

Assignee:

Ultratech Stepper, Inc. (San Jose, CA); Regents of University of California (Oakland, CA)

Patent Classifications (CPCs):

G - PHYSICS G01 - MEASURING G01B - MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS

G - PHYSICS G01 - MEASURING G01M - TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES

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G - PHYSICS G01 - MEASURING G01B - MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS

G01B11/2441 - {using interferometry}
G01B11/255 - for measuring radius of curvature {

G - PHYSICS G01 - MEASURING G01M - TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES

G01M11/005 - {Testing of reflective surfaces, e.g. mirrors}

G - PHYSICS G02 - OPTICS G02B - OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS

G02B17/0657 - {off-axis or unobscured systems in which all of the mirrors share a common axis of rotational symmetry}

G - PHYSICS G03 - PHOTOGRAPHY G03F - PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES

G03F7/70233 - {Optical aspects of catoptric systems}
G03F7/70258 - {Projection system adjustment, alignment during assembly of projection system
G03F7/70591 - {Testing optical components

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DOE Contract Number:  

W-7405-ENG-48

Resource Type:

Patent

Country of Publication:

United States

Language:

English

Subject:

four-mirror; extreme; ultraviolet; euv; lithography; projection; directed; catoptric; transfer; pattern; reflective; reticle; wafer; substrate; light; path; followed; dominantly; hyperbolic; convex; mirror; elliptical; concave; spherical; positioned; optical; axis; opposite; mirrors; relatively; diameter; magnification; hence; significant; aspherical; components; curvatures; substantially; perfectly; shape; off-axis; degree; asphericity; counter; aberrations; forms; uniform; field; tilted; decentered; slightly; achieve; increase; size; wafer substrate; spherical concave; spherical shape; optical axis; extreme ultraviolet; concave mirror; spherical mirror; convex mirror; reflective reticle; uniform field; light path; mirror forms; convex spherical; elliptical concave; /359/