Extreme-UV lithography system

Patent · Mon Jan 01 00:00:00 EST 2001

OSTI ID:873699

Replogle, William C ^[1]; Sweatt, William C ^[2]

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1. Livermore, CA
2. Albuquerque, NM

A photolithography system that employs a condenser that includes a series of aspheric mirrors on one side of a small, incoherent source of radiation producing a series of beams is provided. Each aspheric mirror images the quasi point source into a curved line segment. A relatively small arc of the ring image is needed by the camera; all of the beams are so manipulated that they all fall onto this same arc needed by the camera. Also, all of the beams are aimed through the camera's virtual entrance pupil. The condenser includes a correcting mirror for reshaping a beam segment which improves the overall system efficiency. The condenser efficiently fills the larger radius ringfield created by today's advanced camera designs. The system further includes (i) means for adjusting the intensity profile at the camera's entrance pupil or (ii) means for partially shielding the illumination imaging onto the mask or wafer. The adjusting means can, for example, change at least one of: (i) partial coherence of the photolithography system, (ii) mask image illumination uniformity on the wafer or (iii) centroid position of the illumination flux in the entrance pupil. A particularly preferred adjusting means includes at least one vignetting mask that covers at least a portion of the at least two substantially equal radial segments of the parent aspheric mirror.

• Research Organization: Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
• DOE Contract Number: AC04-94AL85000
• Assignee: EUV LLC (Livermore, CA)
• Patent Number(s): US 6225027
• OSTI ID: 873699
• Country of Publication: United States
• Language: English

Related Subjects

extreme-uv
lithography
photolithography
employs
condenser
series
aspheric
mirrors
incoherent
source
radiation
producing
beams
provided
mirror
images
quasi
curved
line
segment
relatively
image
camera
manipulated
fall
aimed
virtual
entrance
pupil
correcting
reshaping
beam
improves
overall
efficiency
efficiently
fills
larger
radius
ringfield
created
advanced
designs
means
adjusting
intensity
profile
ii
partially
shielding
illumination
imaging
mask
wafer
example
change
partial
coherence
uniformity
iii
centroid
position
flux
particularly
preferred
vignetting
covers
portion
substantially
equal
radial
segments
parent
particularly preferred
mask image
extreme-uv lithography
entrance pupil
substantially equal
intensity profile
beam segment
parent aspheric
mirror images
field created
aspheric mirrors
aspheric mirror
incoherent source
mirror image
coherent source
correcting mirror
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