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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:
 [1];  [2];  [3]
  1. (Pleasonton, CA)
  2. (Los Altos, CA)
  3. (Fairfield, CT)
Issue Date:
Research Org.:
Lawrence Livermore National Lab. (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) LLNL
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/

Citation Formats

Cohen, Simon J, Jeong, Hwan J, and Shafer, David R. Four-mirror extreme ultraviolet (EUV) lithography projection system. United States: N. p., 2000. Web.
Cohen, Simon J, Jeong, Hwan J, & Shafer, David R. Four-mirror extreme ultraviolet (EUV) lithography projection system. United States.
Cohen, Simon J, Jeong, Hwan J, and Shafer, David R. Sat . "Four-mirror extreme ultraviolet (EUV) lithography projection system". United States. https://www.osti.gov/servlets/purl/873351.
@article{osti_873351,
title = {Four-mirror extreme ultraviolet (EUV) lithography projection system},
author = {Cohen, Simon J and Jeong, Hwan J and Shafer, David R},
abstractNote = {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 concave 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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {1}
}

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