EP0838728A2
Expired / Lapsed
EP
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Precision stage interferometer system with air duct
Assignee: Nikon Corp
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Filing: 1997-10-22
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Granted: —
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Expires: 2017-10-22
Abstract
Abstract A local gas duct directs a temperature-controlled stream of gas across two perpendicular sets of interferometer beams which are used to measure the two dimension (X-Y) position of a precision stage in e.g. an optical lithography stepper or step and scan system, or in any other precision coordinate measuring machine. By thereby providing an additional single gas flow which is azimuthally directed across both the X and Y direction interferometer beams, the precision of the interferometric measurement is maximized. In addition, a second flow of gas is directed downvards from the local gas duct, thus providing sufficient gas circulation onto the stage when the stage is directly beneath the local duct, even though in that location the stage is otherwise blocked from receiving the main gas flow through the chamber.
Inventors
- 👤 Michael R. Sogard
- 👤 John K. Eaton
- 👤 Kyoichi Suwa
- 👤 Naoyuki Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 16:35
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/708; G03F7/70858; G03F7/70866; G03F7/70875; G03F7/70691; G03F7/70716
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
121 words
A gas circulation system for use with a location
apparatus in an enclosure with a movable object located
therein, the location apparatus including two mirrors
mounted on the movable object at an angle to one another,
and having two sources of light beams inside the enclosure,
the two sources being spaced apart and each directing at
least one light beam onto each one of the mirrors, the
circulation system comprising: a first source of gas directed through the
enclosure and across the movable object; and a second source of gas directed towards the object
at least when the object is in a central location in the
enclosure, the second source of gas directing the gas
across each of the light beams.
Claim 2
Dependent Claim
18 words
The system of Claim 1, wherein the second source of
gas includes a nozzle having a curved shape.
Claim 3
Dependent Claim
23 words
The system of Claim 1, wherein the curved shape
defines a circular sector having a span of approximately a
quarter of a circle.
Claim 4
Dependent Claim
40 words
The system of Claim 1, wherein the gas from the
second source is directed at an angle of about 25° from a
plane defined by the at least one light beam from each of
the two sources of light beams.
Claim 5
Dependent Claim
36 words
The system of claim 1, wherein gas from the second
source flows azimuthally symmetrically about a vertical
axis across each of the at least one light beam from each
of the two sources of light beams.
Claim 6
Dependent Claim
30 words
The system of Claim 2, further comprising at least
one adjustable member coupled to the nozzle to vary the
shape of the nozzle within a range of predetermined
azimuthal directions.
Claim 7
Dependent Claim
16 words
The system of Claim 2, further comprising a
plurality of spacer members extending across the nozzle.
Claim 8
Dependent Claim
15 words
The system of Claim 2, further comprising at least
one baffle disposed in the nozzle.
Claim 9
Dependent Claim
20 words
The system of Claim 1, wherein the second source of
gas is a duct having a gas filter disposed therein.
Claim 10
Dependent Claim
21 words
The system of Claim 9, wherein the duct includes a
frame formed therein, the gas filter being disposed in the
frame.
Claim 11
Dependent Claim
20 words
The system of Claim 10, wherein the frame comprises
a recess formed in an inner peripheral surface of the duct.
Claim 12
Dependent Claim
15 words
The system of Claim 9, further comprising a thermal
reservoir structure located inside the duct.
Claim 13
Dependent Claim
15 words
The system of Claim 12, wherein the thermal
reservoir structure is a porous metal material.
Claim 14
Dependent Claim
16 words
The system of Claim 2, wherein the nozzle has a
contraction ratio of at least 0.9.
Claim 15
Dependent Claim
30 words
The system of Claim 2, wherein the nozzle is
located above a plane defined by the at least one light
beam from each of the two sources of light beams.
Claim 16
Dependent Claim
18 words
The system of Claim 2, wherein the nozzle is spaced
apart from a central portion of the enclosure.
Claim 17
Dependent Claim
25 words
The system of Claim 1, further comprising a shield
interposed between the first source of gas and at least
one of the light beam sources.
Claim 18
Dependent Claim
25 words
The system of Claim 17, wherein at least one light
beam source includes a mount holding an optical element.
the shield curving around the mount.
Claim 19
Dependent Claim
55 words
The system of Claim 2, wherein the second source of
gas is a duct, the nozzle including an opening at the
extremity of the duct, further including a plurality of
holes defined by the duct to direct a third flow of gas
onto the movable object when the movable object is located
under the duct.
Claim 20
Dependent Claim
36 words
The system of Claim 19, wherein the plurality of
holes are disposed along at least one curve in the duct,
the at least one curve being shaped in accordance with a
perimeter surface of the nozzle.
Claim 21
Dependent Claim
22 words
The system of Claim 20, wherein the plurality of
holes have diameters determined in accordance with a
relative distance from the nozzle.
Claim 22
Dependent Claim
34 words
The system of claim 19, further comprising at least
one partition inside the duct defining a first plenum in
communication with the nozzle and a second plenum in
communication with the plurality of holes.
Claim 23
Dependent Claim
30 words
The system of Claim 22, further comprising a first
gas supply passage in communication with the first plenum
and a second gas supply passage in communication with the
second plenum.
Claim 24
Dependent Claim
28 words
The system of Claim 22, wherein the second plenum
is located in a portion of the duct closer to the light
beams than is in the first plenum.
Claim 25
Dependent Claim
18 words
The system of Claim 22, wherein the second plenum
is tapered in cross section immediately adjacent the
nozzle.
Claim 26
Dependent Claim
18 words
The system of Claim 23, wherein the first and
second gas supply passages are parallel to one another.
Claim 27
Dependent Claim
38 words
The system of Claim 1, further comprising a third
source of gas into the enclosure, the third source
admitting gas into the enclosure at an angle of about 90°
to a direction of the first source of gas.
Claim 28
Dependent Claim
18 words
The system of Claim 1, further comprising means for
controlling a temperature of the second source of gas.
Claim 29
Dependent Claim
12 words
The system of Claim 1, wherein the movable object
is a stage.
Claim 30
Dependent Claim
14 words
The system of Claim 22, further comprising a filter
located in the first plenum.
Claim 31
Independent Claim
103 words
A method for circulating gas in an enclosure,
wherein a movable object in the enclosure includes two
mirrors mounted on the movable object at predetermined
orientations relative to the movable object, a position of
the movable object being determined interferometrically by
directing at least one light beam onto each mirror, the
method comprising the steps of: directing a first flow of gas through the enclosure
and across the movable object; and directing a second flow of gas independent of the
first flow of gas, the second flow of gas being directed
across the at least one light beam incident on the two
mirrors.
References Cited (Backward Citations)
No citation records indexed.
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