EP0744641A2
Expired / Lapsed
EP
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An illumination system and method employing a deformable mirror and defractive optical elements
Assignee: SVG Lithography Systems Inc
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Filing: 1996-05-15
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Granted: —
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Expires: 2016-05-15
Abstract
Abstract An illumination system for use in photolithography using a laser or radiation beam source. A deformable mirror is used to shape the beam of laser radiation to obtain global uniformity. A profile sensing means is used to detect any global non-uniformities. The output of this sensing means is fed to a controller for calculating a mirror contour and controlling actuators that shape the deformable mirror to obtain a globally uniform intensity. A diffractive or diffusive optical element, such as a microlens array, eliminates local non-uniformities. Movement of this element eliminates speckle caused by interference due to the coherent beam source. A uniform intensity profile and appropriate angular spread is achieved with very little transmission loss and is automatically compensated for degraded or changing source performance. The illumination system is particularly applicable to a scanning photolithography process as used in the manufacture of semiconductor substrates.
Inventors
- 👤 Stuart Stanton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 20:38
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70058; G03F7/702; G02; G02B; G02B26/00; G02B26/06; G02B26/08; G02B26/0816; G02B26/0825; G02B27/00; G02B27/48; G03F7/70141; G03F7/70216; G03F7/70258; G03F7/70266; G03F7/70358
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
107 words
An illumination system for use in lithography, comprising: a source of electromagnetic radiation; a deformable mirror; actuator means, coupled to the deformable mirror, for changing the surface contour of the deformable mirror; profile sensing means for determining an intensity profile of radiation emitted from the source; controller means, associated with the profile sensing means and the actuator means, for calculating a surface contour for the deformable mirror and controlling the actuator means; and a diffusive or diffractive optical element, whereby radiation from the source is reflected from the deformable mirror and through the at least one diffusive element resulting in improved global and local radiation intensity uniformity.
Claim 2
Dependent Claim
33 words
The illumination system of claim 1, wherein the diffusive or diffractive element is a microlens array having individual lens elements of a size roughly 1/1000 times the size of the desired uniform field.
Claim 3
Dependent Claim
15 words
The illumination system of claim 1, wherein the first diffusive or diffractive element is movable.
Claim 4
Dependent Claim
19 words
The illumination system of claim 1, wherein the first diffusive or diffractive element is movable in a single plane.
Claim 5
Dependent Claim
25 words
The illumination system of claim 1, wherein the first diffusive or diffractive element moves less than one unit size in a lateral plane during exposure.
Claim 6
Dependent Claim
18 words
The illumination system of claim 2, further comprising a second microlens array placed adjacent the first microlens array.
Claim 7
Dependent Claim
17 words
The illumination system of claim 6, wherein one of the first and second microlens arrays is movable.
Claim 8
Dependent Claim
18 words
The illumination system of claim 1, wherein the first microlens array is made of a plurality of lens.
Claim 9
Dependent Claim
19 words
The illumination system of claim 8, wherein each of the plurality of lens is 20 or less microns wide.
Claim 10
Dependent Claim
16 words
The illumination system of claim 1, wherein the deformable mirror is deformable primarily in one dimension.
Claim 11
Dependent Claim
18 words
The illumination system of claim 1, further comprising a plurality of independent actuators attached to the deformable mirror.
Claim 12
Dependent Claim
36 words
The illumination system for use in photolithography as in claim 11, wherein the number of the plurality of independent actuators is large enough to cause the surface to obtain contours that are neither flat nor spherical.
Claim 13
Dependent Claim
101 words
The illumination system of claim 1, wherein the actuator means further comprises: a first row of wire flexures attached along a first longitudinal edge of the deformable mirror; a second row of wire flexures attached along a second longitudinal edge of the deformable mirror; a first row of actuators attached to the first row of wire flexures; a second row of actuators attached to the second row of wire flexures; and the first and second rows of actuators attached to a base, and the first and second row of actuators are controlled by the controller means for deforming the deformable mirror.
Claim 14
Dependent Claim
27 words
The illumination system of claim 13, wherein each actuator in the first and second rows of actuators has a range of motion of less than 10 microns.
Claim 15
Dependent Claim
21 words
The illumination system of claim 14, wherein each actuator in the first and second rows of actuators is a piezoelectric transducer.
Claim 16
Dependent Claim
33 words
The illumination system of claim 1, wherein the first diffusive or diffractive element or microlens array is placed sufficiently close to a target plane to obtain illumination within the near field diffraction pattern.
Claim 17
Dependent Claim
106 words
An illumination system for use in photolithography, comprising: a laser or radiation beam source; a deformable mirror; actuator means, associated with the deformable mirror, for changing the surface contour of the deformable mirror; profile sensing means for determining an intensity profile of radiation emitted from the laser source; controller means, associated with the profile sensing means and the actuator means, for calculating a surface contour for the deformable mirror and controlling the actuator means; and a first microlens array, whereby radiation from the laser source is reflected from the deformable mirror and through the first microlens array resulting in improved global and local radiation intensity uniformity.
Claim 18
Dependent Claim
176 words
A laser illumination system for use in photolithography having an object and image plane, comprising: a laser source; a deformable mirror; actuator means, associated with the deformable mirror, for changing the surface contour of the deformable mirror, the actuator means capable of deforming the surface of the deformable mirror at any one location; profile sensing means for determining an intensity profile of radiation emitted from the laser source; controller means, associated with the profiler sensing means and the actuator means, for calculating a surface contour for the deformable mirror and controlling the actuator means; a first movable microlens array having a range of motion along two axes in a single plane of less than 20 microns; and a second microlens array positioned near the first microlens array, the second microlens array placed sufficiently close to a target plane to obtain illumination within the near field diffraction pattern, whereby radiation from the laser source is reflected from the deformable mirror and through the first and second microlens arrays resulting in improved global and local radiation intensity uniformity.
Claim 19
Dependent Claim
40 words
An illumination system as in claim 1, 2, 6, 16, 17, or 18, wherein said diffractive or diffusive element or microlens array has behavior dominated by diffraction of radiation and is inadequately determined by ray or refractive models or analyses.
Claim 20
Dependent Claim
36 words
An illumination system as in claim 19, wherein said diffractive or diffusive element or microlens array may include any substantially planar optical surface with phase relief or optical path modulation, with either stepwise or continuous character.
Claim 21
Dependent Claim
45 words
An illumination system as in claim 1, wherein said diffractive or diffusive element is reflective, and whereby the radiation from the source of electromagnetic radiation is reflected rather than transmitted through the diffractive or diffusive element resulting in improved global and local radiation intensity uniformity.
References Cited (Backward Citations)
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