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Title: Apparatus and method for generating partially coherent illumination for photolithography

Abstract

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 themore » 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.« less

Inventors:
 [1]
  1. (Albuquerque, NM)
Issue Date:
Research Org.:
SANDIA CORP
OSTI Identifier:
872372
Patent Number(s):
5920380
Assignee:
Sandia Corporation (Livermore, CA) SNL
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
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; /355/

Citation Formats

Sweatt, William C. Apparatus and method for generating partially coherent illumination for photolithography. United States: N. p., 1999. Web.
Sweatt, William C. Apparatus and method for generating partially coherent illumination for photolithography. United States.
Sweatt, William C. Fri . "Apparatus and method for generating partially coherent illumination for photolithography". United States. https://www.osti.gov/servlets/purl/872372.
@article{osti_872372,
title = {Apparatus and method for generating partially coherent illumination for photolithography},
author = {Sweatt, William C.},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {1}
}

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