Apparatus and method for generating partially coherent illumination for photolithography

Patent · Fri Jan 01 00:00:00 EST 1999

OSTI ID:872372

Sweatt, William C ^[1]

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1. Albuquerque, NM

The present invention relates an apparatus and method for creating a bright, uniform source of partially coherent radiation for illuminating a pattern, in order to replicate an image of said pattern with a high degree of acuity. The present invention introduces a novel scatter plate into the optical path of source light used for illuminating a replicated object. The scatter plate has been designed to interrupt a focused, incoming light beam by introducing between about 8 to 24 diffraction zones blazed onto the surface of the scatter plate which intercept the light and redirect it to a like number of different positions in the condenser entrance pupil each of which is determined by the relative orientation and the spatial frequency of the diffraction grating in each of the several zones. Light falling onto the scatter plate, therefore, generates a plurality of unphased sources of illumination as seen by the back half of the optical system. The system includes a high brightness source, such as a laser, creating light which is taken up by a beam forming optic which focuses the incoming light into a condenser which in turn, focuses light into a field lens creating Kohler illumination image of the source in a camera entrance pupil. The light passing through the field lens illuminates a mask which interrupts the source light as either a positive or negative image of the object to be replicated. Light passing by the mask is focused into the entrance pupil of the lithographic camera creating an image of the mask onto a receptive media.

• Research Organization: Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
• DOE Contract Number: AC04-94AL85000
• Assignee: Sandia Corporation (Livermore, CA)
• Patent Number(s): US 5920380
• OSTI ID: 872372
• Country of Publication: United States
• Language: English

Related Subjects

apparatus
method
generating
partially
coherent
illumination
photolithography
relates
creating
bright
uniform
source
radiation
illuminating
pattern
replicate
image
degree
acuity
introduces
novel
scatter
plate
optical
path
light
replicated
designed
interrupt
focused
incoming
beam
introducing
24
diffraction
zones
blazed
surface
intercept
redirect
positions
condenser
entrance
pupil
determined
relative
orientation
spatial
frequency
grating
falling
generates
plurality
unphased
sources
seen
half
brightness
laser
forming
optic
focuses
field
lens
kohler
camera
passing
illuminates
mask
interrupts
positive
negative
lithographic
receptive
media
source light
entrance pupil
coherent radiation
incoming light
diffraction grating
light beam
optical path
scatter plate
light passing
lithographic camera
relative orientation
partially coherent
field lens
focuses light
novel scatter
coherent illumination
light falling
forming optic
generating partially
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