EP0083394A2
Expired / Lapsed
EP
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A method and apparatus for providing a uniform illumination of an area
Assignee: International Business Machines Corp
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Filing: 1982-10-05
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Granted: —
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Expires: 2002-10-05
Abstract
Abstract Uniform illumination of a two dimensional area, such as a lithographic mask, is provided. The fan-like input beam : (50) is sent to a mirror (52), which it strikes at a grazing angle and is then reflected to the area to be illuminated. Collimation occurs to reduce the divergence of the beam in order to increase its intensity. By changing the grazing angle between the reflected beam (50) and the mirror (52) by a small amount, the reflected beam (54) will be swept across the two dimensional area. The angle is changed at a non-uniform rate which is a function of time, and is chosen so that substantially uniform illumination occurs at all points in the area to be illuminated. A particular embodiment uses a divergent x-ray beam from a synchrotron source. The divergent beam strikes a cylindrical mirror, which collimates it and directs the reflected beam to an x-ray mask plane. The mirror is moved with a nonlinear velocity in order to provide substantially uniform illumination of the mask area, and substantially uniform heating across the mask plane.
Inventors
- 👤 Warren David Grobman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 04:51
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70058; G03F7/70075; G02; G02B; G02B26/00; G02B26/08; G02B26/10
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
117 words
An apparatus for providing substantially uniform illumination across a two-dimensional area, characterised in that the apparatus comprises a source of an input beam (50) of radiation which is divergent in one direction, reflecting means (52) for reflecting said input beam of radiation including means (52) for collimating said divergent input beam and for providing a reflected output beam (54) to said area to be illuminated, means (58, 62, 64, 70, 78, 80, 82) for changing the angle between said reflected beam (54) and said reflecting means (52) in a manner to change said angle as a function of time such that substantially uniform illumination of said area will occur as said illumination is moved across said area.
Claim 2
Independent Claim
117 words
An apparatus for providing substantially uniform illumination across a two-dimensional area, characterised in that the apparatus comprises a source of an input beam (50) of radiation which is divergent in one direction, reflecting means (52) for reflecting said input beam of radiation including means (52) for collimating said divergent input beam and for providing a reflected output beam (54) to said area to be illuminated, means (58, 62, 64, 70, 78, 80, 82) for changing the angle between said reflected beam (54) and said reflecting means (52) in a manner to change said angle as a function of time such that substantially uniform illumination of said area will occur as said illumination is moved across said area.
Claim 3
Dependent Claim
44 words
An apparatus according to Claim 1, including drive means for moving said reflecting means with a velocity which varies with time such that the product of the flux in said reflected beam and the velocity of movement of said reflecting means is substantially constant.
Claim 4
Dependent Claim
76 words
An apparatus according to Claim 2, wherein-said drive means includes means for sensing the instantaneous position of said reflecting means and developing a first signal representative thereof, means for producing a reference signal indicating the desired position for said reflecting means at each instant of time, and means for comparing said first signal and said reference signal for producing an output signal for moving said reflecting means to said desired position at any instant of time.
Claim 5
Dependent Claim
30 words
An apparatus according to Claim 3, wherein the position of the illumination on said area at any point x is approximated by a quadratic expression relating said position to time.
Claim 6
Independent Claim
20 words
An apparatus according to any one of the preceding Claims, wherein said source is a synchrotron source of x-ray radiation.
Claim 7
Independent Claim
20 words
An apparatus according to any one of the preceding Claims, wherein said reflecting means is a mirror of cylindrical shape.
Claim 8
Independent Claim
20 words
An apparatus according to any one of the preceding Claims, wherein said area to be illuminated is a lithography mask.
Claim 9
Dependent Claim
53 words
An apparatus according to Claim 7, wherein the angle between said reflected beam and said reflecting means is changed as a periodic function of time with a fundamental frequency sufficiently great that the temperature rise in the plane of said lithography mask cannot quickly follow the sweep of radiation across said mask plane.
Claim 10
Independent Claim
32 words
An apparatus according to any one of the preceding Claims, wherein the distance between said source and said reflecting means is less than the distance between said reflecting means and said area.
Claim 11
Independent Claim
18 words
An apparatus according to any one of the preceding Claims, wherein said angle is less than approximately 2°.
Claim 12
Independent Claim
109 words
A method for providing substantially uniform illumination of a two dimensional area with a beam (50) of radiation which is divergent in one direction, characterised in that the method comprises sending said beam (50) from a source to a reflecting means (52) from which it is reflected to said area to be illuminated, collimating said beam to provide a collimated reflected beam (54) to said area, changing the angle between said reflected beam (54) and said reflecting means (52) in a manner to change said angle as a function of time such that substantially uniform illumination of said area will occur as said illumination is moved across said area.
Claim 13
Independent Claim
109 words
A method for providing substantially uniform illumination of a two dimensional area with a beam (50) of radiation which is divergent in one direction, characterised in that the method comprises sending said beam (50) from a source to a reflecting means (52) from which it is reflected to said area to be illuminated, collimating said beam to provide a collimated reflected beam (54) to said area, changing the angle between said reflected beam (54) and said reflecting means (52) in a manner to change said angle as a function of time such that substantially uniform illumination of said area will occur as said illumination is moved across said area.
Claim 14
Dependent Claim
23 words
A method according to Claim 11, wherein said beam of radiation is x-ray radiation and said two dimensional area is an x-ray mask.
Claim 15
Dependent Claim
13 words
A method of Claim 11, wherein said beam of radiation is optical radiation.
Claim 16
Independent Claim
22 words
A method according to any one of claims 1 to 13, wherein said reflecting means is a mirror having a cylindrical shape.
Claim 17
Dependent Claim
34 words
A method according to Claim 14, wherein said angle is changed by moving said mirror to change the tilt of said mirror with respect to the direction of said beam incident upon said mirror.
Claim 18
Dependent Claim
44 words
A method according to Claim 11, wherein said beam is comprised of photons sent back and forth in a first plane to produce a fan of radiation, and are then swept in a direction transverse to said plane to provide illumination over said area.
Claim 19
Independent Claim
42 words
A method according to any one of Claims 11 to 16, wherein the product of the flux in said reflected beam and the velocity of movement of said angle is approximately constant with time as said reflected beam moves across said area.
Claim 20
Dependent Claim
13 words
A method according to Claim 11, wherein said angle changes linearly with time.
Claim 21
Independent Claim
38 words
A method according to any one of the preceding Claims, wherein the position of said reflected beam at any point x in said area to be illuminated is approximated by a quadratic function relating said position to time.
Claim 22
Independent Claim
32 words
A method according to any one of the preceding Claims, wherein the angle between the beam which strikes said mirror and the axis of said mirror is less than 2 0 .
Claim 23
Independent Claim
34 words
A method according to any one of the preceding Claims, wherein said angle is changed as a function of time with a fundamental frequency sufficiently high to lead to uniform heating across said area.
Claim 24
Dependent Claim
32 words
A method according to Claim 1, wherein said reflecting means is a mirror which is rotated to scan said reflected beam across said area, said mirror being oscillated with a non-uniform velocity.
Claim 25
Dependent Claim
27 words
A method according to Claim 22, wherein the distance between said mirror and said area is substantially greater than the distance between said source and said mirror.
References Cited (Backward Citations)
No citation records indexed.
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