Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
2000-07-19
2003-10-28
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
C310S058000, C310S06000A, C250S492200
Reexamination Certificate
active
06639333
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
This invention relates to a linear motor and a stage system with the same, suitably usable in an apparatus such as a semiconductor exposure apparatus or a high precision processing machine wherein precise positioning is to be performed. The present invention also relates to an exposure apparatus and/or a device manufacturing method using such a linear motor or a stage system.
In an positioning system of nanometer order for use in a semiconductor exposure apparatus or a high precision processing machine, heat generation in a linear motor, which is a driving source, has an adverse influence on the positioning process. More specifically, the heat generation may cause thermal deformation of the structure of the machine and a temperature rise of air, which may result in a measurement error in a position measuring laser interferometer. It may also cause degradation of the positioning precision of the apparatus in which the linear motor is incorporated. For example, with a temperature rise of only 1° C., a low thermal expansion material (thermal expansion coefficient 1×10
−6
) of a size 100 mm may deform by 100 nm. Also, with a change of only 1° C. or less in the temperature of air at the light path of an optical-interferometer distance gauge, an error of 100 nm may be produced in the measured value. In consideration of this, some measures should be taken to prevent such temperature change and, in this respect, a linear motor has to be cooled. Particularly, any heat produced from the linear motor should be collected.
On the other hand, in order to improve the performance of an apparatus, enlargement of the output power of a linear motor has been desired. If the electric current to be supplied to coils of the motor is made larger at this end, the amount of heat generation becomes larger. It requires enlargement of the cooling capacity. The enlargement of the cooling capacity is important also with respect to prevention of damage to the coil wires or an increase in coil resistance due to a coil temperature rise.
FIG. 15
is a sectional view of a structure of a conventional linear motor having cooling means. As illustrated, the linear motor comprises a coil
1
and permanent magnets
3
fixed to yokes
2
on the opposite sides of the coil
1
. The coil
1
is surrounded by a jacket
9
, which comprises thin sheets
4
and
4
′ and a frame
5
. The coil
1
is fixed to the frame
5
by means of a fixing element
7
. The jacket
9
is structured so that a cooling medium flows through an inside space
6
thereof, to collect heat produced at the coil
1
.
FIG. 16
is a sectional view of a linear motor of another example. In this linear motor, an electric current flows through a coil
1
(lateral in
5
the drawing) disposed in a magnetic field (longitudinal in the drawing) produced by permanent magnets
3
, which are fixed to yokes
2
. In response to it, the coil
1
and the magnets
3
are relatively moved in a direction perpendicular to the sheet of the drawing. In order to collect heat produced from the coil
1
, the coil
1
is enclosed by a jacket having portions
14
and
14
′. A cooling medium flows through a clearance between the coil
1
and the jacket, by which the heat is collected. In order that the distance between the permanent magnets
3
is made smaller and the produced magnetic density is made larger for enlargement of the linear motor thrust, the jacket is made thin.
In these examples, however, if the flow rate of the cooling medium is made larger to increase the cooling capacity, the resultant pressure rise of the cooling medium may cause outward deformation of a small-thickness portion of the jacket. It may result in contact with the permanent magnet or breakage of the jacket. To avoid this, the small-thickness portion of the jacket should have a sufficient strength. To the contrary, to increase the output power of a linear motor, the distance between permanent magnets has to be made small to enlarge the magnetic density. In this respect, the small-thickness portion of the jacket should be made thin as much as possible to reduce the size of the jacket.
Further, in a case of a multiple-phase linear motor having coils being arrayed along a direction perpendicular to the sheet of the drawing of
FIG. 16
, the coil and jacket structure extends in a direction perpendicular to the sheet of the drawing. In this example, the natural frequency of the structure should be made large to reduce the adverse influence on a high-precision positioning system in which the linear motor is incorporated.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a linear motor structure and/or a stage system with the same wherein the thickness of a small-thickness portion can be kept small while the strength of the same is enlarged.
It is another object of the present invention to provide an invention to provide a linear motor structure and/or a stage system with the same wherein a coil and jacket structure has an enlarged natural vibration frequency.
It is a further object of the present invention to provide an exposure apparatus and/or a device manufacturing system that uses a linear motor structure or a stage system such as described above.
In accordance with an aspect of the present invention, there is provided a linear motor, comprising: a magnet; a coil; and a jacket having an inside comb-shaped member extending along a driving direction, wherein the coil is engaged by teeth of the comb-shaped member and wherein a cooling medium flows through an inside space enclosed by the jacket.
The comb-shaped member may include base portions provided on mutually opposed inside faces of the jacket and formed in parallel to the driving direction and to be opposed to each other, and a pillar-like portion for connecting the base portions, wherein the coil may be supported by said base portions in a floating manner while it may be held fixed by the pillar-like portion with respect to the driving direction.
The linear motor may include a plurality of coils arrayed along the driving direction partially overlapping each other, wherein each coil may have a bent end portion to avoid mutual interference of the partially overlapped portions of the coils, and wherein the coils may be disposed with their central portions placed substantially at the same level.
The jacket may have a central portion of a small thickness with an outside recessed portion, wherein the bent end portions of the coils may be disposed at the recessed portion, and wherein the central portion of small thickness may be reinforced by the recessed portion.
The jacket may serve as a guide for an element to be driven by the linear motor.
In accordance with another aspect of the present invention, there is provided a stage system, comprising: a movable stage; a linear motor having a magnet and a coil, for driving the stage; and a jacket having an inside member that is comb-shaped, extending along a driving direction, wherein the coil is engaged by teeth of the comb-shaped member and wherein a cooling medium flows through an inside space enclosed by the jacket.
In accordance with a further aspect of the present invention, there is provided an exposure apparatus, comprising: a movable stage for holding a substrate thereon; a linear motor having a magnet and a coil, for driving the stage; and a jacket having an inside member that is comb-shaped, extending along a driving direction, wherein the coil is engaged by teeth of the comb-shaped member and wherein a cooling medium flows through an inside space enclosed by the jacket.
In accordance with a yet further aspect of the present invention, there is provided a device manufacturing method, comprising the steps of: applying a photosensitive material onto a substrate; exposing the substrate by use of an exposure apparatus including a movable stage for holding a substrate thereon, a linear motor having a magnet and a coil, for driving the stage, and a jacket having an inside member that is comb shaped, extend
Kamata Shigeto
Matsuki Toshio
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Mullins Burton
LandOfFree
Linear motor stage system for use in exposure apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Linear motor stage system for use in exposure apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Linear motor stage system for use in exposure apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3116756