EP1128217A2
Expired / Lapsed
EP
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Method of measuring aberration in an optical imaging system
Assignee: ASML Netherlands BV
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Filing: 2001-02-21
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Granted: —
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Expires: 2021-02-21
Abstract
Abstract A method of determining aberration of an optical imaging system comprises measuring at least one parameter, such as position of best-focus and/or lateral position, of an image formed by the imaging system. This is repeated for a plurality of different illumination settings of the imaging system, and from these measurements at least one coefficient, representative of aberration of said imaging system, is calculated.
Inventors
- 👤 Hans Van Der Laan
- 👤 Marco Hugo Petrus Moers
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 01:26
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70591; G03F7/706
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
140 words
A method of determining aberration of an optical imaging system
comprising: a radiation system for supplying a projection beam of radiation; a support structure for supporting patterning means, the patterning means
serving to pattern the projection beam according to a desired pattern; a substrate table for holding a substrate; and a projection system for projecting the patterned beam onto a target portion of
the substrate; the method comprising the step of: patterning the projection beam with said patterning means, and characterized by the steps of: measuring at least one parameter of an image formed by the projection
system, for a plurality of different settings of said radiation system and/or said
projection system; and calculating at least one coefficient, representative of aberration of said
imaging system, on the basis of said at least one parameter measured at said plurality
of settings.
Claim 2
Dependent Claim
17 words
A method according to claim 1, wherein said plurality of different settings
comprise different numerical aperture settings.
Claim 3
Dependent Claim
28 words
A method according to claim 1 or 2, wherein said plurality of different
settings comprise different settings of pupil filling at a pupil plane in the imaging
system.
Claim 4
Dependent Claim
30 words
A method according to claim 1, 2 or 3, wherein said plurality of different
settings comprise different illumination modes selected from the group comprising
disc-shaped, annular, quadrupolar, dipolar and soft-multipolar.
Claim 5
Independent Claim
29 words
A method according to any one of the preceding claims, wherein said
plurality of different settings comprise telecentric and non-telecentric illumination
settings, or a plurality of non-telecentric illumination settings.
Claim 6
Independent Claim
25 words
A method according to any one of the preceding claims, wherein said at least
one parameter is the position of best focus of said image.
Claim 7
Independent Claim
23 words
A method according to any one of the preceding claims, wherein said at least
one parameter is the lateral position of said image.
Claim 8
Independent Claim
34 words
A method according to any one of the preceding claims, wherein said
plurality of different settings are selected such that the variation in the or each at least
one measured parameter is substantially maximized.
Claim 9
Independent Claim
61 words
A method according to any one of the preceding claims, wherein said
plurality of different settings are selected such that the variation in said at least one
measured parameter resulting from aberration represented by one or more of said
coefficients is substantially zero, whilst the variation in said at least one parameter as
the function of a desired coefficient is non-zero.
Claim 10
Independent Claim
47 words
A method according to any one of the preceding claims, further comprising
the step of calculating a theoretical variation, for each of said plurality of different
illumination settings, of the or each measured parameter as a function of a small
change in said at least one coefficient.
Claim 11
Independent Claim
31 words
A method according to any one of the preceding claims, wherein said at least
one coefficient is calculated by multiple regression or a least-square fit of a set of
simultaneous equations.
Claim 12
Independent Claim
19 words
A method according to any one the preceding claims, wherein said at least
one coefficient is a Zernike coefficient.
Claim 13
Dependent Claim
165 words
A lithographic projection apparatus for projecting a patterned beam of
radiation onto a substrate provided with a radiation-sensitive layer, the apparatus
comprising: a radiation system for providing a projection beam of radiation; a support structure for supporting patterning means, the patterning means
serving to pattern the projection beam according to a desired pattern; a substrate table for holding a substrate; a projection system for projecting the patterned beam onto a target portion of
the substrate; and illumination setting means for providing a plurality of different illumination
settings of said radiation system and/or said projection system; characterized by further comprising: measuring means for measuring at least one parameter of a projected image
formed by the projection system; control means for selecting a plurality of different illumination settings at
which said measuring means takes measurements; and calculation means for calculating at least one coefficient, representative of
aberration of said projection and/or radiation system, on the basis of said at least one
parameter measured by said measuring means.
Claim 14
Dependent Claim
18 words
An apparatus according to Claim 13, wherein the support structure comprises
a mask table for holding a mask.
Claim 15
Dependent Claim
14 words
An apparatus according to Claim 13, wherein the radiation system comprises
a radiation source.
Claim 16
Independent Claim
170 words
A method of manufacturing a device using a lithographic projection
apparatus, comprising the steps of: (a) providing a substrate that is at least partially covered by a layer of radiation-sensitive
material; (b) providing a projection beam of radiation using a radiation system; (c) using patterning means to endow the projection beam with a pattern in its
cross-section; (d) using a projection system to project the patterned beam of radiation onto a
target portion of the layer of radiation-sensitive material, and characterized by the steps of: measuring, prior to step (d), at least one parameter of an image formed by the
projection system, for a plurality of different settings of said radiation system and/or
said projection system; calculating at least one coefficient, representative of aberration of said
projection and/or radiation system, on the basis of said at least one parameter
measured at said plurality of settings; correcting for said aberration on the basis of said at least one calculated
coefficient, to reduce aberration of an image projected by said projection system.
Claim 17
Dependent Claim
28 words
A method according to claim 16, wherein said correction step comprises
correcting for changes in lateral and/or best-focus position of said image when
changing between different illumination settings.
Claim 18
Dependent Claim
12 words
A device manufactured according to the method of claim 16 or 17.
References Cited (Backward Citations)
No citation records indexed.
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