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Title: Critical illumination condenser for x-ray lithography

Abstract

A critical illumination condenser system is disclosed, particularly adapted for use in extreme ultraviolet (EUV) projection lithography based on a ring field imaging system and a laser produced plasma source. The system uses three spherical mirrors and is capable of illuminating the extent of the mask plane by scanning either the primary mirror or the laser plasma source. The angles of radiation incident upon each mirror of the critical illumination condenser vary by less than eight (8) degrees. For example, the imaging system in which the critical illumination condenser is utilized has a 200 {micro}m source and requires a magnification of 26. The three spherical mirror system constitutes a two mirror inverse Cassegrain, or Schwarzschild configuration, with a 25% area obstruction (50% linear obstruction). The third mirror provides the final pupil and image relay. The mirrors include a multilayer reflective coating which is reflective over a narrow bandwidth. 6 figs.

Inventors:
;
Issue Date:
Research Org.:
Univ. of California (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
619396
Patent Number(s):
5737137
Application Number:
PAN: 8-617,719
Assignee:
Univ. of California, Oakland, CA (United States)
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Resource Relation:
Other Information: PBD: 7 Apr 1998
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; OPTICAL SYSTEMS; MASKING; MICROELECTRONIC CIRCUITS; EXTREME ULTRAVIOLET RADIATION; LASER-PRODUCED PLASMA

Citation Formats

Cohen, S J, and Seppala, L G. Critical illumination condenser for x-ray lithography. United States: N. p., 1998. Web.
Cohen, S J, & Seppala, L G. Critical illumination condenser for x-ray lithography. United States.
Cohen, S J, and Seppala, L G. Tue . "Critical illumination condenser for x-ray lithography". United States.
@article{osti_619396,
title = {Critical illumination condenser for x-ray lithography},
author = {Cohen, S J and Seppala, L G},
abstractNote = {A critical illumination condenser system is disclosed, particularly adapted for use in extreme ultraviolet (EUV) projection lithography based on a ring field imaging system and a laser produced plasma source. The system uses three spherical mirrors and is capable of illuminating the extent of the mask plane by scanning either the primary mirror or the laser plasma source. The angles of radiation incident upon each mirror of the critical illumination condenser vary by less than eight (8) degrees. For example, the imaging system in which the critical illumination condenser is utilized has a 200 {micro}m source and requires a magnification of 26. The three spherical mirror system constitutes a two mirror inverse Cassegrain, or Schwarzschild configuration, with a 25% area obstruction (50% linear obstruction). The third mirror provides the final pupil and image relay. The mirrors include a multilayer reflective coating which is reflective over a narrow bandwidth. 6 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {4}
}