Supporting system in exposure apparatus

Details Supporting system in exposure apparatus Supporting system in exposure apparatus

2001-02-16

2003-12-16

Adams, Russell (Department: 2851)

Photocopying

Projection printing and copying cameras

Detailed holder for photosensitive paper

C355S075000, C355S053000, C318S649000, C310S012060

Reexamination Certificate

active

06665053

ABSTRACT:

FIELD OF THE INVENTION AND RELATED ART
This invention relates to a supporting system suitably usable, for example, in a fine-motion stage of a wafer stage incorporated into a semiconductor exposure apparatus.
FIG. 28
is a perspective view of a wafer rough-motion stage of a supporting system used in a semiconductor exposure apparatus. In this wafer rough-motion stage, a Y yaw guide
202
is fixed on a base table
201
, and a Y stage
203
which is guided by a side face of the Y yaw guide
202
and a top face of the base table
201
is slidably supported on the base table
201
by means of an air slide (not shown) along a Y direction. The Y stage
203
consists mainly of four components, that is, two X yaw guides
204
, a Y large slider
205
and a Y small slider
206
. The Y large slider
205
is opposed to the side face of the Y yaw guide
202
and the top face of the base table
201
, through air pads (not shown) provided at the side and bottom faces thereof. The Y small slider
206
is opposed to the top face of the base table
201
through air pads (not shown) provided at the side face thereof. With this structure, the Y stage
203
as a whole is supported on the top face of the base table
201
and the side face of the Y yaw guide
202
, slidably in the Y direction.
On the other hand, an X stage
210
is guided by the top face of the base table
201
and the side faces of the two X yaw guide
204
which are components of the Y stage
203
. The X stage
210
is provided so as to surround the X yaw guide
204
of the Y stage
203
, around the X axis. The X stage
210
is supported slidably, in the X direction, by means of an air slide (not shown). The X stage
210
consists mainly of for components, that is, two X stage side plates
211
, an X stage top plate
212
at the top end, and an X stage bottom plate
213
. The bottom plate
213
is opposed to the top face of the base table
201
through air pads (not shown) which are provided at the bottom face of the bottom plate. The two X stage side plates
211
are opposed to the side faces of the two X yaw guides
204
, which are components of the Y stage
203
, through air pads (not shown) provided at the side faces of the side plates The bottom face of the X stage top plate
212
and the top face of the X yaw guide
204
, as well as the top face of the X stage bottom plate
213
and the bottom face of the X yaw guide
204
are kept out of contact with each other. With this structure, the X stage
210
as a whole is supported at the side faces of the two X yaw guides
204
and the top face of the base table
201
, slidably in the X direction.
As regards the driving mechanism, there are multiple-phase coil switching type linear motors
214
and
215
, one for X driving and two for Y driving. A stator
216
comprises a plurality of coils
217
arrayed in the stroke direction and being inserted into a frame
218
. A movable element
219
comprises a magnet unit of box shape. In accordance with the position of the movable element
219
, electric currents are selectively applied to coils
217
of the stator
216
, whereby a thrust is produced. Mounted on the top of the X stage top plate
212
is a fine-motion stage
221
shown in
FIGS. 29 and 30
.
The fine-motion stage
221
serves to position a wafer W (workpiece) placed on the X stage top plate
212
, with respect to Z tilt and &thgr; direction. By means of three Z suspension driving units
222
-
1
to
222
-
3
provided at the peripheral portion, the wafer stage top plate
223
is supported and positioned with respect to Z tilt direction. A universal joint
224
provided at the central portion serves to confine the freedom to prevent shift of the wafer stage top plate
223
in X and Y directions.
The Z suspension driving units
222
-
1
to
222
-
3
each comprises an air cylinder
226
for supporting the weight of the wafer stage top plate
223
, and a Z linear motor
230
for applying a force, in the Z direction, to the wafer stage top plate
223
.
The Z linear motor
230
comprises a flat coil
231
having a major or lengthwise side parallel to a horizontal line, four magnets
232
opposed, through a gap, to the major side of the flat coil
231
, and two yokes
233
for circulating the magnetic flux of the magnets
232
. The flat coil
231
is fixed to the X stage top plate
212
, and the magnets
232
and the yokes
233
are fixed as a unit to the wafer stage top plate
223
. As an electric current is applied to the flat coil
231
, a force in the Z direction operates between the coil
231
and the integral structure of the magnet
232
and the yoke
233
.
The air cylinder
226
comprises a supporting rod
227
and a rubber film
228
. The rubber film
228
is provided at the lower portion of the wafer stage top plate
223
, and it serves to define an air chamber
229
between the lower portion of the top plate
223
and the supporting rod
227
. Airs are supplied through a supply port, not shown. The supporting rod
227
has an end fixed to the flat coil
231
, and the other end is coupled to the rubber film
228
. As a result, the weight of the wafer stage top plate
223
is supported from the X stage
210
and through the flat coil
231
, the supporting rod
227
and the air chamber
229
. The air chamber
229
provides a soft spring in the Z direction, so that vibration in the Z direction can be substantially blocked.
The Z linear motor
230
does not bear the function of weight support but it operates solely for the position control. With this structure, an electric current which nay otherwise cause a problem of heat generation is not flown thereto.
The universal joint
224
comprises an outer ring
236
fixed to the X stage top plate
212
, an inner ring
237
fixed to the wafer stage top plate
223
, and a guide
238
for slidably guiding the outer and inner rings
236
and
237
. The guide
238
may comprise an air guide, for example, having an air gap of a few microns. This air gap has a ring-like shape, and the inner ring
237
and the outer ring
236
as well as the X stage top plate
212
and the wafer stage top plate
223
are guided for slidable motion along the Z and &thgr; directions. The height of the guide
238
in the Z direction is set lower, such that motion of the inner and outer rings
234
and
236
as well as the top plates
212
and
223
in the the direction is allowed.
Although not shown in the drawings, a mechanism similar to the Z linear motor
230
, including a flat coil
231
having a major or lengthwise side parallel to the vertical line, is provided, so that the wafer stage top plate
223
can be moved in the &thgr; direction.
Mounted on the side face of the wafer stage top plate
223
is a square mirror (not shown) which enables precision measurement of the position, in six-axis direction, of the wafer stage top plate
223
by use of a laser interferometer.
In the structure described above, in conventional exposure apparatuses, a wafer W is precisely positioned with respect to the X, Y, Z, &thgr; and tilt directions, by means of a control system (not shown) and by applying appropriate electric control to coils of rough-motion x, rough-motion Y, fine-motion Z
1
, fine-motion Z
2
, fine-motion Z
3
and fine-motion &thgr;. Then, an exposure process is performed by using exposure means (not shown), whereby a pattern of an original (not shown) is sequentially printed on a wafer W.
SUMMARY OF THE INVENTION
In accordance with an aspect of the present invention, there is provided a supporting system, comprising: a carrying nicer for carrying thereon a workpiece; and a supporting mechanism having a magnet, for supporting a weight of said carrying member; wherein a supporting force to be provided by said magnet does not change with a shift of said carrying member along a plane perpendicular to a direction in which the weight is supported.
The supporting mechanism may have a magnet and a magnetic member, wherein said magnet and said magnetic member may differ from each other in respect to a size in a direction perpendicular to a direction in which a

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