Photocopying – Projection printing and copying cameras – Distortion introducing or rectifying
Reexamination Certificate
2000-06-09
2004-06-15
Fuller, Rodney (Department: 2851)
Photocopying
Projection printing and copying cameras
Distortion introducing or rectifying
C355S055000, C359S695000, C359S811000, C359S813000, C359S823000, C359S826000
Reexamination Certificate
active
06750947
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a driving apparatus suitable for precise position adjustment of members and an exposure apparatus including this driving device and, more particularly, to a driving device for adjusting the optical characteristics, such as magnification, aberration, and distortion, of a projection optical system which can be mounted on an exposure apparatus and the like, and an exposure apparatus including this driving device. The present invention is applicable to an optical apparatus serving as an additional optical system in an exposure apparatus, such as a semiconductor exposure apparatus, for accurately forming an image when projecting and exposing the image of an original plate (e.g., a mask and reticle) onto a target (e.g., a wafer), and an exposure apparatus including this optical apparatus.
BACKGROUND OF THE INVENTION
A semiconductor exposure apparatus transfers different patterns formed on a plurality of original plates (reticles) onto a silicon wafer (substrate) in an overlaying manner. To form a high-integration circuit, an increase in not only resolution performance but also overlay accuracy is indispensable.
Factors causing overlay errors in the semiconductor exposure apparatus are classified into an alignment error, image distortion, and magnification error. The alignment error is reduced by adjusting the positions of the original plate (reticle) and the substrate (wafer) relative to each other. The magnification error can be adjusted by moving at least one optical element of the projection optical system in the direction of the optical axis. When moving the optical element in the direction of the optical axis, components other than the moving direction, particularly parallel eccentricity and a tilt error, of the optical element should be kept small.
Conventionally, as a projecting magnification adjusting device for a semiconductor exposure apparatus, an optical element moving device having a mechanism using parallel leaf springs is proposed (Japanese Patent Laid-Open No. 9-106944).
FIGS. 17A and 17B
are plan and sectional views, respectively, of a conventional optical element moving device.
As shown in
FIGS. 17A and 17B
, the conventional optical element moving device has a movable table
1
for holding an adjustment lens
7
which adjusts the magnification, aberration, and the like of an optical system, and a cell
8
which supports the adjustment lens
7
, and a stationary table
2
which forms part of the stationary portion of the projection optical system. A driving element
4
is comprised of bellows
9
and the like. One end of the driving element
4
is fixed to the stationary table
2
, and the other end thereof is fixed to a clamp top plate
5
connected to the movable table
1
. The movable and stationary tables
1
and
2
are connected to each other through a spring mechanism having a plurality of sets of opposing leaf springs
3
and a plurality of leaf spring retainers
6
for supporting the leaf springs
3
. The driving element
4
is arranged in a gap between the plurality of sets of leaf springs
3
arranged on the movable table
1
to be equidistant from its center and symmetric with respect to an optical axis
20
.
FIG. 18
shows the driving element
4
in detail.
The driving element
4
is constituted by the bellows
9
and two flanges
10
a
and
10
b.
The flange
10
a
is connected to the clamp top plate
5
at the gap between a plurality of sets of leaf springs
11
. The other flange
10
b
is arranged in the stationary table
2
to transmit an air pressure applied to the interior of the bellows
9
to the movable table
1
.
When a heavy, large-diameter movable portion such as a lens is driven by a mechanism utilizing leaf springs, since the eigenfrequency is low, the movable portion is largely vibrated by a disturbance or the like. To improve the transfer performance of the exposure apparatus, the mechanism desirably has a high eigenfrequency.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a high-precision driving device.
A driving device according to the first aspect of the present invention comprises a first member, an annular second member arranged outside the first member, an annular first plate for connecting the first and second members to each other, an annular second plate for connecting the first and second members to each other, and a fluid controller for supplying or exhausting a fluid into or from a space surrounded by the first and second members and the first and second plates, thereby moving the first and second members relative to each other. As a result, at least one of the first and second members can be driven at high precision.
A volume in the space can change as the first and second members move relative to each other.
The first and second members can move relative to each other in a direction substantially parallel to an axial direction of the annular second member. The first and second members can move relative to each other in a direction substantially parallel to a direction of gravity.
The first and second plates preferably have different shapes.
Either one of a
1
≠a
2
and b
1
≠b
2
is preferably satisfied where a
1
is an inner diameter of a portion of the second member at which the second member is connected to the first plate, a
2
is an inner diameter of a portion of the second member at which the second member is connected to the second plate, b
1
is an outer diameter of a portion of the first member at which the first member is connected to the first plate, and b
2
is an outer diameter of a portion of the first member at which the first member is connected to the second plate. In this case, (a
1
−b
1
) and (a
2
−b
2
) are further preferably substantially equal to each other.
A gas such as an inert gas is preferably used as the fluid.
The fluid controller preferably has a pressure control valve for controlling a pressure in the space.
The driving device preferably has a sensor for detecting a relative distance or displacement between the first and second members. The fluid controller preferably controls the pressure control valve, which controls the pressure in the space, on the basis of an output signal from the sensor. A target for the sensor preferably has an annular shape. A fixing member for fixing either one of the first and second plates to either one of the first and second members preferably also serves as the target for the sensor. The fixing member may have a portion formed by welding a metal to a nonconductive material. The sensor may be arranged in the space. The sensor may be, e.g., an electrostatic capacitance sensor.
The driving device preferably has a damper between the first and second members. The damper may have a piston, cylinder, and viscous substance. The damper may be arranged in the space.
The first member may have a step structure on its outer side surface. The second member may have a step structure on its inner side surface.
The first and second members may move relative to each other within a range having as one boundary a position where rigidity of the first and second plates and a mass of at least one of the first and second members balance with each other. Alternatively, the first and second members may move relative to each other within a range including a position where rigidity of the first and second plates and a mass of at least one of the first and second members balance with each other.
A driving device according to the second aspect of the present invention for driving a first member and an annular second member, which is arranged outside the first member, relative to each other, comprises an annular electrode formed on at least one of the first and second members, and a detector for detecting a change in electrostatic capacitance concerning the electrode upon movement of the electrode, thereby detecting positions of the first and second members relative to each other. As a result, since the electrostatic capacitance concerning the electrode can be increased, the change in el
Ebinuma Ryuichi
Mizuno Makoto
Tomita Hiroyuki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Fuller Rodney
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