JP3037999B2 - Two-dimensional motor stage device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a precision XY stage, and more particularly to an ultra-precision XY stage driven by a moving magnet.

As the degree of integration of semiconductor integrated circuit devices increases, higher standards are required for semiconductor manufacturing technology. The pattern line width is less than 1 μm, and is approaching 0.1 μm from submicron. With the decrease in line width, a stage device for positioning a semiconductor wafer is required to have an accuracy superior to the line width by at least one digit, and preferably by at least two digits.

[Prior Art] Conventionally, as a precision stage device for two-dimensionally driving an object, first, an X-axis having a servomotor and a ball screw for driving in the X-axis direction which is one direction in a plane.
XY with a stage formed and a Y stage with a ball screw and a servomotor for driving in the Y-axis direction superimposed on it
The stage is known.

However, ball screws cannot completely eliminate backlash or backlash. Further, in order to transmit the driving force generated by the servomotor to the object, the power must be transmitted via a power transmission mechanism or a guide mechanism on the way, and the generated driving force cannot be transmitted 100% to the object. From another viewpoint, this means that the driving force that cannot be used causes some mechanical member or the like to be distorted or elastically deformed. That is,
This causes a decrease in accuracy.

As described above, it is difficult to achieve a positioning accuracy of about 0.1 μm or less depending on the mechanism.

In order to realize the high precision required in semiconductor manufacturing technology, various stage devices have been studied. However, various systems have their own problems.

[Problems to be Solved by the Invention] As described above, it has been difficult to realize an ultra-precision XY stage having a positioning accuracy of, for example, 0.1 μm with a precision stage device using a servomotor and a ball screw.

An object of the present invention is to provide a stage device suitable for achieving ultra-precision accuracy.

[Means for Solving the Problems] According to one aspect of the present invention, there are provided a yoke formed of a magnetic material and defining a two-dimensional plane, and a number of permanent magnets arranged in a grid on the yoke. A plurality of permanent magnets arranged at a constant pitch in each of the X direction and the Y direction, and permanent magnets adjacent to each other in the X direction or the Y direction expose magnetic poles of opposite polarities; And a stage arranged above the plurality of permanent magnets and an X-direction drive unit including n (n is an integer of 2 or more) X coil groups supported by the stage. In addition, each of the X coil groups is arranged within a range of one pitch in the Y direction of the permanent magnet, and is constituted by at least two X coils arranged in the Y direction. X-direction pin of the permanent magnet 1 /
an X-direction drive unit, which is displaced in the X direction by n, and m units (m is 2) supported by the stage.
Represents the above integer. A) a Y-direction drive unit including the Y-coil group, wherein each of the Y-coil groups is arranged within a range of one pitch in the X-direction of the permanent magnet;
A drive unit for Y direction, which is constituted by at least two Y coils arranged in the X direction, wherein the Y coil group is displaced in the Y direction by 1 / m of a pitch of the permanent magnet in the Y direction; And driving the stage by Lorentz force acting on the coil when the coil is energized in a magnetic field formed by the plurality of permanent magnets.
A three-dimensional motor stage device is provided.

According to another aspect of the present invention, a yoke formed of a magnetic material and defining a two-dimensional plane, a plurality of permanent magnets arranged in a grid on the yoke, the yoke and the plurality of permanent magnets A stage disposed above a magnet, and a plurality of coils supported by the stage, and when energized, generate a driving force for driving the stage in the X or Y direction together with the plurality of permanent magnets. There is provided a two-dimensional motor stage device including a plurality of coils and a driving mechanism for driving the yoke in X and Y directions.

[Action] By attaching a coil group to the stage and applying a magnetic force to the coil group, a force is directly applied to the stage.
The driving force transmission system can be simplified.

As a device for applying a magnetic field to the coil group, permanent magnets arranged in a grid pattern at a constant pitch in the X direction and the Y direction on the yoke are used.
A uniform thrust can be generated in the X direction and the Y direction by a coil group including a plurality of coils arranged at a pitch of.

Further, by moving the yoke, an optimum thrust can be obtained in the vicinity of the positioning target position, and highly accurate positioning can be performed.

Thus, a precise two-dimensional motor stage device is formed.

Embodiment FIG. 1 schematically shows an X-ray exposure apparatus incorporating a stage device according to an embodiment of the present invention.

X-rays are emitted from the SOR device as accumulated orbital emission (SOR) light, and travel from right to left in the figure. In order to perform exposure using this SOR light, the semiconductor wafer is arranged vertically, and a stage device for mounting and driving the semiconductor wafer is configured to move two-dimensionally in a vertical plane.

A main body base 8 is installed at the position where the SOR light is emitted, and a mask 11 is arranged on a fine movement stage 9 mounted on the main body base 8. The SOR light emitted from an emission window (not shown) is patterned through a mask 11 and travels to a wafer 12. The fine movement stage 9 is supported on the main body base 8 via a fine movement driving element 10 such as a piezoelectric element. In the illustrated configuration, fine movement stage 9 has a degree of freedom in a direction perpendicular to the plane of the drawing and in a direction inside the drawing. A semiconductor wafer 12 is supported by a wafer chuck 21 on the main stage 3 by vacuum suction or the like so as to face the mask 11. The main stage 3 is a suction type air pad 4
Thus, it is supported on the main body base 8. The suction type air pad 4 is a pad which is attracted by a magnetic attraction to a magnetic base by incorporating a magnet, for example, and which repels by blowing air (or other gas) to float on the base. In addition, it is possible to slide on the main body base 8 with very little friction. The air pad 4 is coupled to the main stage 3 via an adjusting unit 22 such as a laminated piezoelectric element, and the attitude of the main stage 3 can be controlled by the adjusting unit 22.

Since the main stage 3 is arranged vertically, it receives a force in a direction parallel to the main body base 4 by gravity. In order to support this force, a counter force cylinder 6 is provided, and a main stage 3 is provided via an air bearing 5.
It supports the lower part and enables movement almost equivalent to weightlessness.
The main stage 3 is driven by a plurality of coil groups 2 provided on the side opposite to the semiconductor wafer 12. The coil group 2 is arranged on the surface of the main stage 3 in a predetermined pattern. A plurality of permanent magnets 1 are arranged in a grid on the two-dimensional plane of the yoke 13 so as to face these coil groups. The yoke 13 is formed of a magnetic material such as iron, and is supported on another main body base 7 facing the main body base 8. The main body base 7 does not need to be magnetic,
For example, it may be made of stone such as granite. Of course, a magnetic material such as iron can also be used. The yoke 13 is
As shown in the figure, the position on the main body base 7 can be changed by the yoke driving actuator 14.

The main stage 3 is supported on the main body base 8 via the air pad 4 and the adjusting means 22, and changes its position by a force acting on the coil 2. The force acting on the coil 2 is generated by applying a current to the coil 2 in a magnetic field generated by the permanent magnet 1 disposed opposite to the coil 2. In this way, a force for driving the main stage is generated from the back side of the main stage.

FIG. 2 schematically shows the arrangement of permanent magnets and coils for generating a driving force for driving the main stage 3 of such a semiconductor exposure apparatus, taking a two-phase arrangement drive unit as an example.

FIG. 2 is a plan view showing the relationship between the distribution of the permanent magnets on the yoke 13 of the semiconductor exposure apparatus and the coil group 2 on the main stage 3 moving thereon. The yoke 13 has a rectangular shape, and is supported on the main body base 7 via yoke driving actuators 14 and 15. The yoke driving actuator 14 drives the yoke 13 in the X direction. Also,
The yoke driving actuators 15-1 and 15-2 include a yoke.
13 is driven in the Y direction. Each actuator and yoke 13
Are connected so as not to transmit a force in directions other than the driving direction. These actuators 14 and 15 are formed by, for example, a laminated piezoelectric element or a linear motor. On the yoke 13, a large number of permanent magnets 1 are arranged two-dimensionally.
These permanent magnets 1 are arranged at a constant pitch in the X direction and the Y direction, for example. In the illustrated configuration, permanent magnets are arranged in a matrix arrangement of seven columns in the horizontal direction and seven rows in the vertical direction, and adjacent permanent magnets are arranged so as to alternately expose magnetic poles of opposite polarity. Therefore, the lines of magnetic force generated from the end surface of the permanent magnet 1 on the yoke 13 almost terminate on the adjacent permanent magnets 1 in the X direction and the Y direction.

FIG. 2 shows the arrangement of the coil 2 on the main stage 3 so as to overlap with the permanent magnet. These coils 2
They are arranged at half the pitch of the permanent magnets.

For example, two sets of Y coils 16a1, 1 and 16b1 are:
The permanent magnets are arranged at one pitch in the X direction. The Y coil 16a1 is composed of two permanent magnets separated by one pitch in the Y direction.
It consists of two coils. Y coil 16b1 is Y
In this configuration, the use coil 16a1 is shifted in the X direction by half the pitch of the permanent magnet. In the arrangement shown, two coils of the Y coil 16b1 are arranged on the N pole and the S pole of the permanent magnet.

The Y coils 16c1 and 16d1 on the right in FIG.
It has the same configuration as 16d1. Two coils of the Y coil 16d1 are arranged on the north pole and the south pole.

In the figure, Y coils 16a2, 16b2, 16c2, 16
d2 has the same configuration as the upper Y coils 16a1, 16b1, 16c1, and 16d1, but is arranged shifted in the Y direction by half the pitch of the permanent magnets. In the illustrated arrangement, the lower Y
The coils of the use coils 16a2, 16b2, 16c2, 16d2 are all arranged in a region where there is no permanent magnet in the Y direction.

In the illustrated configuration, the Y coils 16b1 and 16d1 are arranged on the magnets, and can exert a driving force.

When the main stage is shifted by 1/2 pitch in the X direction, Y
The coils for use 16a1 and 16c1 are arranged on the magnet, so that the driving force can be exhibited.

When the main stage is shifted by 1/2 pitch in the Y direction from the state shown in the figure, the Y coils 16a1, 16b1, 16c1, 16d1 are arranged between the magnets in the Y direction. Coil for Y 16
b2 and 16d2 are placed on the magnet instead, and can exert the driving force.

Further, when the main stage is shifted by a half pitch in the X direction, the Y coils 16a2 and 16c2 are arranged on the magnets so that the driving force can be exerted.

That is, since the coils are arranged at a pitch that is half the pitch of the permanent magnets, four coils correspond to one thrust source.

In order to drive the main stage in the X direction, X coils 17a, 17b, 17c, 17d are arranged. One of these four coils is arranged on the magnet,
The driving force can be demonstrated.

Although shown in a simplified manner, the number of coil sets and the number of magnets can be arbitrarily increased.

As described above, the coil group 1 includes the X direction and the Y direction, respectively.
It has a portion that is displaced by half a pitch in the direction, and is arranged such that there is a coil that generates a driving force in an optimal state even if the stage moves in any direction with respect to the yoke.

FIG. 3 is a diagram for schematically explaining the principle of driving force generation by a coil.

A plurality of permanent magnets 1 are arranged on the yoke 13 so that their polarities are alternately inverted, and magnetic flux vectors are distributed between adjacent permanent magnets. The X coil 17c and the Y coils 16a1 and 16b cross these magnetic flux vectors.
1, 16c1 and 16d1 are arranged. In the case of FIG. 3, in order to drive the stage in a direction perpendicular to the plane of the paper, a current in a direction indicated by an arrow may be applied to the Y coils 16b1 and 16d1 arranged on the magnet. The Lorentz force acting on the coil exerts a force from the back to the front of the paper. It is not necessary to supply a current to the Y coils 16a1 and 16c1 disposed between the magnets. Here, in the lower side and the upper side of the Y coils 16b1 and 16d1, a force in the opposite direction acts, but the magnetic flux vector is distributed on the lower side so as to be sufficiently higher than the upper side. Will be generated. The two sides of the Y coil generate forces in directions opposite to each other and do not contribute to driving. Therefore, the force acting on the coil is determined mainly by the Lorentz force acting on the coil side (lower side in the configuration shown) closer to the permanent magnet.

In the coil disposed between the permanent magnets, the magnetic flux vector is mainly directed in the horizontal direction, so that it is difficult to obtain an effective driving force depending on the lower side and the upper side even when a current flows. In addition, since a force in the opposite direction acts on the side, it is difficult to obtain an effective driving force.

The driving principle is the same for the X coil 17c. Since the direction in which the current flows rotates by 90 °, the generated force also rotates by 90 ° and becomes the X direction.

When the stage moves half a pitch in the horizontal direction in the figure, the coils 16b1 and 16d1 placed on the permanent magnet are now placed in the gap between the permanent magnets, and are placed in the gap until then. The coils 16a1 and 16c1 that have been set are now positioned on the permanent magnet. In this case, the coil that has generated the driving force until now is brought into a rest state, and a current is applied to the coil that has been in the rest state so as to generate the driving force. In this way, the stage can be driven continuously. By arranging the coils in three or more phases, it is possible to generate the driving force more continuously.

Referring to FIG. 4, drive force generation when the stage is driven in the X, Y, and θz directions is schematically shown.

2, it is assumed that the permanent magnets are arranged at a predetermined pitch in the X direction and the Y direction, and the coils are arranged to face these permanent magnets and at a half pitch thereof. In this case, four coils can be arranged in one unit in the XY plane of the permanent magnet. For this reason, for generating driving force in one direction, four sets of coils are used as one unit as a substrate.

In FIG. 4 (A), four sets of Y coils 16a1, 16
The b1, 16a2, and 16b2 constitute one unit of the Y-direction coil, and can generate a Y-direction driving force regardless of the state of the relative relationship between the permanent magnet and the coil. Similarly, the other four sets of Y coils 16c1, 16d1, 16c2, and 16d2 also constitute one unit of the Y-direction drive coil. Also, four sets of X coils
17a, 17b, 17c, and 17d constitute a base unit that generates a driving force in the X direction. When the stage 3 is driven in the Y direction, a current is applied to the coils on the magnets of the Y coils of each unit to generate a driving force in the Y direction, so that the stage 3 can be driven in the Y direction.

When the stage 3 is driven in the X direction, FIG. 4 (B)
As shown in (1), an electric current is applied to the coil above the magnet in the X coil unit to generate a driving force in the X direction. Regardless of the state of the four X coils 17a, 17b, 17c, and 17d in the drawing, one of them is disposed on a permanent magnet. Directional driving force can be generated.

When rotating around the Z-axis, as shown in FIG. 4 (C), certain Y coils such as 16a1, 16b1, 16a
2, 16b2 so that an upward force is generated,
A current is applied to any of the other Y coils, for example, 16c1, 16b1, 16c2, 16d2, so that a downward force or an upward force smaller than the above force is generated. in this way,
The stage 3 receives a rotating force in the XY plane by supplying a current to the different Y coils so as to generate a moment force on the stage. The main purpose of the stage 3 is to move the stage 3 in the X and Y directions, and the rotation around the Z axis is limited to the minute rotation used when correcting an unintended displacement or the like.

Thus, by arranging coils in a multi-phase manner on a plurality of two-dimensionally arranged permanent magnets, it is possible to ensure that the coils are arranged on the permanent magnets. By selectively supplying an electric current to a coil disposed on the permanent magnet, a driving force can be effectively generated, and movement in the X direction or the Y direction can be performed.

In this example, the two-phase motor is shown with the coil shifted by 1/2 pitch. However, if necessary, a multi-phase of two or more phases such as a three-phase motor with coil shifted by 1/3 pitch is also possible. .

In the present invention, the torque ripple during driving is suppressed as much as possible, and a polyphase method is adopted as a method of obtaining a uniform thrust, but it is not necessarily the case that the magnet and the coil at the target position of the stage have a positional relationship that generates an optimum thrust. Not exclusively. When positioning the stage at the target position, positioning with higher thrust characteristics of the motor enables more accurate positioning.

With reference to FIG. 5, a driving method involving driving of the yoke will be described.

The yoke is moved before or during the stage movement by the actuators 14, 15-1, and 15-2 so that the coil and magnet have the positional relationship between the coil and the magnet that can obtain the optimal thrust from the given stage target, magnet and coil pitch. Move to the planned location. This movement must be completed before the stage reaches the target position. From this 14
And 15 actuators require a stroke of at least the pitch of the magnet.

The stage reaches the target value while switching the coil to be energized.

Although the case of the vertical stage has been described, it will be obvious to those skilled in the art that the horizontal stage can be driven in the same manner.

According to the configuration described above, thrust can be directly generated on the coil fixed to the stage, and the power transmission system can be omitted, so that high motion accuracy can be secured. That is, backlash and backlash in the power transmission system can be prevented.

Further, since the X-direction thrust, the Y-direction thrust, and the θz-direction thrust can directly act on the stage, the stage can be freely moved in a two-dimensional plane.
Regardless of the position of the stage, substantially uniform driving force can be generated.

The guide system required in the conventional stage can be omitted, and it is easy to obtain a compact, lightweight, high-speed, high-precision stage device.

Since it is easy to apply a force directly to the stage, the response to disturbance is increased, and the energy efficiency can be improved.

The stage devices described above require a wide range of two-dimensional stages, such as semiconductor manufacturing devices such as SOR exposure devices, precision machines and machines in general, IC bonders, IC testers, ultra-precision machines, robots, laser machines, XY plotters, etc. Can be used in the field.

Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[Effects of the Invention] As described above, according to the present invention, since a force can be directly applied to the stage moving in a plane,
A highly accurate stage can be obtained.

By setting the pitch of the coils attached to the stage to be an integral fraction of the pitch of the two-dimensionally arranged permanent magnets, one of the coils is always arranged on the permanent magnet,
By applying a current to the coil, an effective force can be generated, a uniform force can be generated, and the stage can be accurately driven.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a semiconductor exposure apparatus incorporating a stage device according to an embodiment of the present invention. FIG. 2 is a view for explaining the arrangement of permanent magnets and coils in the semiconductor exposure apparatus of FIG. FIG. 3 is a driving principle diagram for explaining the force generated in the coil of FIG. 1, and FIGS. 4 (A), (B) and (C) show the stage in the Y direction,
FIG. 5 is a schematic diagram for explaining a method of driving in the X direction and the θz direction. FIG. 5 is a graph for explaining driving in a two-phase arrangement accompanied by driving of a yoke. In the drawing, 1 ... permanent magnet, 2 ... coil 3 ... main stage 4 ... suction air pad 5 ... air bearing 6 ... counter force cylinder 7, 8 ... body base 9 ... fine movement stage 10 ... ... Fine drive element 11... Mask 12... Semiconductor wafer 13... Yoke 14, 15... Yoke driving actuator 16... Y coil 17... X coil 21.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02K 41/03 G05D 3/00 G12B 5/00

Claims (2)

(57) [Claims] 1. A yoke formed of a magnetic material and defining a two-dimensional plane, and a plurality of permanent magnets arranged in a grid on the yoke, with a constant pitch in each of the X and Y directions. A plurality of permanent magnets disposed so that permanent magnets adjacent to each other in the X direction or the Y direction expose magnetic poles of opposite polarities; and a plurality of permanent magnets disposed above the yoke and the plurality of permanent magnets. A stage, and an X-direction drive unit including n (n represents an integer of 2 or more) X coil groups supported by the stage, wherein each of the X coil groups is The permanent magnet is constituted by at least two X coils arranged within a range of one pitch in the Y direction and arranged in the Y direction.
An X-direction drive unit, wherein the X-direction drive units are arranged in the X direction by 1 / n of a pitch of the permanent magnet in the X direction, and m (m is two or more) supported by the stage A drive unit for the Y direction provided with a Y coil group of the permanent magnet, wherein each of the Y coil groups is disposed within a range of one pitch of the permanent magnet in the X direction, and And at least two Y coils arranged in
And a Y-direction drive unit, which is arranged in the Y-direction by a pitch of 1 / m in the Y-direction of the permanent magnet, wherein the plurality of permanent magnets form a magnetic field. A two-dimensional motor stage device for driving the stage by Lorentz force acting on the coil when the coil is energized. 2. A yoke formed of a magnetic material and defining a two-dimensional plane; a plurality of permanent magnets arranged in a grid on the yoke; and arranged above the yoke and the plurality of permanent magnets. And a plurality of coils supported by the stage, and when energized, the stage is moved together with the plurality of permanent magnets by X
A two-dimensional motor stage device comprising: a plurality of coils for generating a driving force for driving in the direction or the Y direction; and a driving mechanism for driving the yoke in the X and Y directions.