JPH09250544A - Bearing device and bearing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To try to enhance dynamic characteristics, and to enlarge a driving stroke. SOLUTION: In the bearing device provided with a static pressure bearing means which supports a supporting surface 7 provided for the side surface of a supporting means 2 erected over a disc board 1, and a guiding surface provided for a holding board 4 so as to be faced to the supporting surface together in a noncontacting manner, let the guiding surface be formed out of the inner circumferential surface or the outer circumferential surface of a cylindrical guiding member 3 which is integral with the disc board 4, and let a bearing gap formed out of a space between the supporting surface and the guiding surface be narrow at a place close to the center with respect to the axial direction parallel with the supporting surface, and also be made wider as it goes up to the outer periphery of a bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing apparatus suitable for a positioning apparatus such as a projection exposure apparatus used for semiconductor lithography, various precision processing machines or various precision measuring instruments, and a positioning apparatus using the bearing apparatus. is there.

[0002]

2. Description of the Related Art In a projection exposure apparatus used in semiconductor lithography, various precision processing machines, various precision measuring instruments, etc., it is required to position a substrate such as a wafer to be exposed, an object to be processed or an object to be measured with high accuracy. In addition, in recent years, it has been desired to speed up the positioning in order to improve the throughput.

FIG. 10 and FIG. 11 are plan and sectional views, respectively, showing a conventional top stage for focusing and finally performing fine movement positioning of a substrate such as a wafer with respect to a projection lens system in a projection exposure apparatus. The stage E ₀ has a disc-shaped holding plate 104 having a suction surface (not shown) for sucking a substrate such as a wafer by a vacuum suction force or the like on its surface. The holding plate 104 is a top plate of an XY stage (not shown). It is supported by a plurality of first piezoelectric elements 105 on 101. One end of each of the first piezoelectric elements 105 is elastically coupled to the annular member 103 adjacent to the outer peripheral edge of the holding plate 104 by an elastic hinge 105a, and the other end of each first piezoelectric element 105 is elastic. Hinge 105
The holding plate 10 is elastically coupled to the top plate 101 via b.
4 and the annular member 103 are elastically coupled by a plurality of first leaf springs 103a, and the outer peripheral edges of the plurality of support members 102 and the annular member 103 which are integral with the top plate 101 are respectively a plurality of. Is elastically connected by the second leaf spring 103b.

The first piezoelectric element 105 expands and contracts by a drive current supplied individually to move the holding plate 104 toward and away from the top plate 101, and change the relative inclination angle between the two. Further, the holding plate 104 has a protruding arm 104a that penetrates the opening 103c of the annular member 103 and extends outward in the radial direction.
And a second piezoelectric element 106 is provided between the protruding arm 103d provided on the annular member 103.
By the expansion and contraction of 06, the holding plate 104 and the annular member 103 are relatively rotated. That is, the holding plate 104 is reciprocally moved along an axis (hereinafter, referred to as “Z axis”) perpendicular to the surface of the top plate 101 by driving the first piezoelectric elements 105 by the same amount, respectively. The tilt angle with respect to the plane perpendicular to the Z axis, that is, the flatness is adjusted by individually changing the driving amount of each of the piezoelectric elements 105. Further, the rotation angle around the Z axis is adjusted by driving the second piezoelectric element 106. The wafer (not shown) held on the holding plate 104 is focused and finally positioned by such fine adjustment.

However, according to the above conventional technique,
When the second piezoelectric element is coupled to the annular member that is moved by the first piezoelectric element, a large imbalance occurs in the mass of the annular member, and when it is desired to drive the first and second piezoelectric elements at the same time. The generated vibrations are coupled to each other, the dynamic characteristics are significantly reduced, and the positioning accuracy is impaired. Therefore, there is a problem that the positioning by the top stage cannot be speeded up.

Further, since the annular member, the holding plate, and the support member, which is integral with the top plate, and the annular member are connected by the leaf springs respectively, if the driving amount of each piezoelectric element is large, these leaf springs The reaction force may deform the annular member or the supporting member, which may lower the positioning accuracy. In addition, there is a problem that it is impossible to drive a long stroke in the Z-axis direction.

As an invention replacing the above-mentioned conventional example, there is Japanese Patent Publication No. 6-267823 by the present inventors. This is a holding plate having a guide surface facing a supporting surface of a supporting means which is integral with the base plate, a static pressure bearing means for supporting the supporting surface and the guiding surface in a non-contacting manner, and the holding plate as described above. The first drive means for moving along the axis parallel to the support surface, and the second drive means for rotating the holding plate around the axis parallel to the support surface, and the first drive means and The second driving means is individually supported on the base. The guide surface may be an inner peripheral surface or an outer peripheral surface of a cylindrical guide member that is integral with the holding plate. Further, the first drive means may have at least three drive devices respectively connected to different portions of the holding plate in the circumferential direction. Positioning of the holding plate in the axial direction and the rotation direction is performed by the first and second driving means, respectively.

[0008]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 6-267
The invention described in No. 823 is made in view of the problem which the said prior art has. (EN) Provided is a positioning device in which it is easy to speed up positioning because there is no possibility of generating large vibrations during driving, and in addition, the positioning accuracy does not deteriorate even when the driving amount is large. However, the hydrostatic bearing means exemplified here has a configuration in which a plurality of porous bearing pads that are cylindrical and are replaced with that are arranged, and include an axis (cylindrical central axis) parallel to the support surface of the bearing guide surface. The cross-sectional shape is straight. Therefore,
When adjusting the tilt angle with respect to a plane perpendicular to the central axis of the holding plate, the bearing clearance and the bearing height dimension limit the tilt angle.

To increase the inclination angle, it is necessary to enlarge the bearing gap, which reduces the bearing rigidity in the radial direction and deteriorates the dynamic characteristics of the positioning device. On the other hand, in order to improve the bearing rigidity, it is necessary to narrow the bearing gap, and the tilt angle stroke becomes smaller. Further, as the positioning device becomes larger, the hydrostatic bearing means must be made larger, but it becomes difficult to integrally form the cylindrical porous bearing.

A first object of the present invention is to provide a holding plate having a guide surface facing the supporting surface of the supporting means provided upright on the bed,
In a bearing device having a hydrostatic bearing means for supporting the support surface and the guide surface in non-contact with each other, the guide surface being an inner peripheral surface or an outer peripheral surface of a guide member integral with a holding plate, It is to achieve the contradictory performance of improvement and expansion of drive stroke.

A second object of the present invention is to provide a manufacturable bearing structure for an increase in size of the device.

A third object of the present invention is to provide a hydrostatic bearing having high rigidity.

[0013]

In order to achieve the above first and third objects, in the first aspect of the present invention, the bearing gap formed by the gap between the support surface and the guide surface of the hydrostatic bearing is used. The means is narrow in the vicinity of the center in the axial direction parallel to the support surface and widens toward the outer edge of the bearing.
In the above configuration, the bearing rigidity in the radial direction can be improved and the dynamic characteristics can be improved without sacrificing the stroke of the holding plate (static pressure bearing) in the inclination angle direction. In order to achieve the above-mentioned second object, a second aspect of the present invention is characterized in that the hydrostatic bearing means is composed of a plurality of members divided in a cylindrical circumferential direction. With the above configuration, it is possible to make a large-sized cylindrical porous bearing.

[0014]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a vertical cross-sectional view showing a positioning device according to a first embodiment of the present invention in an axial cross section. A positioning device E1 of this embodiment is a top plate of an XY stage of a known projection exposure apparatus. A certain base 1, a fixed member 2 that is a cylindrical supporting means that is integrally provided on the base 1, a cylindrical guide member 3 that fits loosely on the outer peripheral surface that is the supporting surface, and a guide member 3 of the guide member 3. A holding plate 4 integrally connected to the upper end of the figure and a holding plate 4
Z linear motors 5a-5c (however, motors 5b and 5c are not shown) which are three first driving means for moving the holding board 4 relative to the base board 1 It has a θ linear motor 6 which is a second driving means, and a wafer (not shown) is sucked onto the surface of the holding plate 4 by a vacuum suction force. The outer peripheral surface of the fixed member 2 and the guide member 3
And the inner peripheral surface which is the guide surface of the stationary member 2 by the static pressure of the pressurized fluid ejected from the porous pad 7 which is the annular porous throttle type static pressure bearing means held on the outer peripheral surface of the fixed member 2. Since the holding plate 4 is supported in a non-contact manner, the holding plate 4 is reciprocally movable along the central axis (hereinafter, referred to as “Z axis”) of the fixed member 2 and the guide member 3 and is rotatable about the Z axis. Is. Further, the porous pad 7 can be inclined with respect to the Z-axis within a range allowed by the bearing gap, and by reducing the dimension of the porous pad 7 in the Z-axis direction, the allowable value of the inclination angle with respect to the Z-axis can be reduced. Can be bigger. Further, most of the weight of the guide member 3, the holding plate 4 and the wafer adsorbed by the guide member 3 is biasing means formed by the step 2 a provided on the fixed member 2 and the step 3 a provided on the guide member 3. It is supported by the pressure of the pressurized fluid in the preload chamber 8.

FIG. 3 is a schematic plan view showing the apparatus of FIG. 1 with the holding plate 4 removed, and FIG. 2 shows the apparatus of FIG.
It is sectional drawing shown by the cross section seen from the -C line. FIG.
[Fig. 4] is a sectional view showing a section taken along line AB of Fig. 3.
As shown in FIG. 2, the guide member 3 has internal passages 7a and 8a for supplying a pressurized fluid to the porous pad 7 and the preload chamber 8, respectively, and the lower end of the guide member 3 and the fixing member 2 shown in FIG. A labyrinth seal 8b is formed between them.
The distance between the porous pad 7 and the guide member 3 is about 7 μm, and the distance between the labyrinth seals 8b is about 15 μm.

As shown in FIGS. 2 and 3, the Z linear motors 5a-5c are arranged outside the guide member 3 at equal intervals in the circumferential direction. The mover 5d of each of the Z linear motors 5a to 5c is a cylindrical frame body having a permanent magnet on its inner surface, and the frame body is fixed to the outer peripheral surface of the guide member 3, and each Z
The stators 5e of the linear motors 5a to 5c are coils fixed to the support 1a that is integral with the base 1, and are connected to a predetermined drive circuit by wiring (not shown) to adjust the amount of current supplied from the drive circuit. Accordingly, it is driven in the Z-axis direction. If the amount of current supplied to each of the Z linear motors 5a to 5c is the same, the holding plate 4 moves in the Z-axis direction while maintaining its flatness, and the amount of current supplied to each of the Z linear motors 5a to 5c. Can be changed individually to change the flatness of the holding platen 4, that is, the inclination angle with respect to the Z axis.

As shown in FIG. 3, the θ linear motor 6 is arranged between any two Z linear motors 5a to 5c adjacent to each other, and as shown in FIGS. It is a cylindrical frame body having a permanent magnet on the inner surface, and the frame body is fixed to the outer peripheral surface of the guide member 3. The stator 6b of the θ linear motor 6 is a support 1b that is integral with the base 1.
Is a coil fixed to the holding plate 4, and is connected to a predetermined drive circuit by a wiring (not shown). The mover 6b is driven in the circumferential direction of the holding plate 4 in accordance with the amount of current supplied from the driving circuit. Rotate around the Z axis.

As shown in FIG. 1, the base 1 has first non-contact type displacement sensors 9a to 9c adjacent to the Z linear motors 5a to 5c, and each displacement sensor 9a to 9c is a holding plate 4.
Has a detection end opposed to the lower surface in the figure, and detects a change in the position of the holding plate 4 in the Z-axis direction. Further, as shown in FIG. 3, the base 1 has a pair of second non-contact type displacement sensors 10a and 10b facing one side edge of the holding plate 4, both of which are held by the difference in their outputs. The rotation angle of the board 4 around the Z axis is detected. First and second displacement sensors 9a-9c and 1
By feeding back the outputs of 0a and 10b to the above-mentioned drive circuit, the fine movement positioning of the holding plate 4 can be automatically performed.

FIGS. 4 and 5 are enlarged partial sectional views showing a part of the apparatus of FIG. 1 in an enlarged manner. As shown in FIG.
The cross-sectional shape of the porous pad 7 is such that the gap formed between the outer peripheral surface of the porous pad 7 and the inner peripheral surface of the guide member 3 is narrow near the center of the bearing portion in the Z direction and widens toward the bearing end portion. It has such a shape. Here, as for the size of the bearing gap, h ₁ and h ₂ are about 7 μm, and the minimum size h ₀ is 3 μm.
It is about μm. A graph P ₁ is a pressure distribution diagram of the bearing gap portion, the vertical axis indicates the position of the bearing portion in the Z-axis direction, and the horizontal axis indicates the pressure in the bearing gap portion.

Graph P ₀ is a pressure diagram when the cross-sectional shape of the porous bearing is a rectangle represented by a broken line k. Comparing the respective maximum pressure values, the graph P ₁ is higher, and the hydrostatic bearing showing such a pressure distribution is a hydrostatic bearing having high rigidity in the radial direction (radial direction of the bearing).

In this embodiment, the Z linear motors 5a to 5c and the θ linear motor 6 are individually supported on the base 1, and the holding plate 4 and the base 1 are not in contact with each other. There is no fear that large vibration will occur during the movement of the board 4. Further, since the preload chamber 8 supports most of the weight of the holding plate 4 and the held wafer, the driving force of the Z linear motors 5a to 5c and the θ linear motor 6 can be small.

When the flatness of the holding plate 4 is changed, that is, when the inclination angle with respect to the Z axis is changed, the dimension of the bearing gap of the porous pad 7 is changed accordingly.
Although the gap size of the labyrinth seal 8a and the gap size of the permanent magnets and coils of each of the Z linear motors 5a to 5c and the θ linear motor 6 change, in a positioning device that performs focusing and final positioning of the exposure device. Since such a change is minute, the porous pad 7
There is no possibility that the guide member 3 comes into contact with the guide member 3, the performance of the labyrinth seal 8a is significantly deteriorated, or the drive amount of the linear motor is significantly limited. That is, normally, the minimum gap of the linear motor is about 1 to 2 mm, and for example, as shown in FIG. 5, the diameter d of the bearing surface of the porous pad 7, the dimension W in the Z-axis direction, and the central portion of the bearing gap. The dimension h ₀ of
When the dimensions of both ends of the bearing gap are h ₁ and h ₂ , d = 20
If 0 mm, W = 20 mm, and the fine adjustment amount α of the inclination angle of the holding plate 4 is 3 × 10 ⁻⁴ rad, the variation amount (h ₁ −h ₂ ) / 2 of the size of the bearing gap is about 3 μm. (The amount of change in h ₀ is small enough to be ignored). As described above, the gap dimensions h ₁ and h ₂ of the porous pad 7 are set to 7 μm and the labyrinth seal gap dimension is set to 15 μm. The above-mentioned troubles such as contact between the porous pad 7 and the guide member 3 do not occur. The stroke length of the mover of each linear motor can be up to about 5 mm.

FIG. 6 shows a hydrostatic bearing portion of a positioning device according to a second embodiment of the present invention. In this embodiment, instead of the porous bearing 7 of the first embodiment, the cross section is convex. An annular porous pad 71 having the above shape is provided on the fixing member 2. The step size S of the protrusion is about 4 μm.

FIG. 7 shows the hydrostatic bearing portion according to the third embodiment. In this embodiment, instead of the porous bearing 7 of the first embodiment, an annular cross section having an arc shape is used. This is a configuration in which the porous pad 72 is provided on the fixing member 2. Dimension U is 4μ
m.

As shown in these examples, the cross-sectional shape of the porous pad should be such that the gap of the hydrostatic bearing portion is narrow near the center of the bearing portion in the Z direction and widens toward the end of the bearing. For example, it is possible to design a static bearing with high rigidity in the radial direction (radial direction of the bearing).

FIG. 8 and FIG. 9 show a fourth embodiment. Instead of the annular porous pad 7, a circumferential direction (θ
A plurality of porous pads 73 divided into (directions) are provided on the fixing member 2. The joints of the porous pads 73 are sealed by the adhesive 101. In order to increase the rigidity of the hydrostatic bearing in the radial direction (radial direction), it is necessary to increase the diameter dp of the bearing surface of the porous pad, but it is difficult to increase the size of the integrally formed porous member. Be restricted. Although the divided structure slightly lowers the static pressure bearing rigidity in the radial direction as compared with the annular integrated structure, it is possible to cope with an increase in the diameter of the static pressure bearing (increase in diameter dp).

[0027]

In the positioning device using the bearing device of the present invention, the bearing rigidity in the radial direction can be improved without sacrificing the stroke of the holding plate (hydrostatic bearing) in the direction of the inclination angle. Is easy to
In addition, the positioning accuracy does not decrease even if the driving amount is large. Therefore, when it is used in an exposure apparatus, highly accurate transfer, printing, etc. in the exposure apparatus are easy.

Further, since it is possible to make a large-sized cylindrical porous bearing, it is possible to provide a positioning device which can cope with an increase in the size of a wafer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention in a cross section taken along the line AB of FIG.

FIG. 2 is a sectional view showing a first embodiment of the present invention in a section taken along the line A-C in FIG.

FIG. 3 is a schematic plan view showing a first embodiment of the present invention with a holding plate removed.

FIG. 4 is an enlarged partial sectional view showing an enlarged part of the first embodiment of the present invention.

FIG. 5 is an enlarged partial sectional view showing an enlarged part of the first embodiment of the present invention.

FIG. 6 is an enlarged partial sectional view showing an enlarged part of the second embodiment of the present invention.

FIG. 7 is an enlarged partial sectional view showing an enlarged part of the third embodiment of the present invention.

FIG. 8 is a perspective view showing a porous pad according to a fourth embodiment of the present invention.

9 is an enlarged partial sectional view showing an enlarged part of the porous pad of FIG.

FIG. 10 is a schematic plan view showing a conventional example.

11 is a cross-sectional view taken along the line EE of FIG.

[Explanation of symbols]

1: base plate, 2: fixed member, 3: guide member, 4: holding plate,
5a, 5b, 5c: Z linear motor, 6: θ linear motor, 7, 71, 72, 73: porous pad, 8: preload chamber, 9a, 9b, 9c, 10a, 10b: displacement sensor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01L 21/027 H01L 21/30 503A 21/68 B23Q 1/14 C Z 1/26 E

Claims (7)

[Claims] 1. A hydrostatic bearing means for supporting, in a non-contact manner, a support surface provided on a side surface of a support means provided upright on a bed and a guide surface provided on a holding disk facing the support surface. In the bearing device having the above-mentioned, the guide surface is an inner peripheral surface or an outer peripheral surface of a cylindrical guide member which is integral with a holding plate, and a bearing gap formed by an interval between the support surface and the guide surface is the support. A bearing device characterized by narrowing in the vicinity of the center with respect to the axial direction parallel to the surface and widening toward the outer edge of the bearing. 2. A hydrostatic bearing means for supporting, in a non-contact manner, a support surface provided on a side surface of a support means provided upright on a base and a guide surface provided on a holding board facing the support surface. A plurality of members in which the guide surface is an inner peripheral surface or an outer peripheral surface of a cylindrical guide member that is integral with a holding plate, and the hydrostatic bearing means is divided in a cylindrical circumferential direction. A bearing device comprising: 3. The bearing device according to claim 1, wherein the hydrostatic bearing means is a porous throttle type bearing. 4. A holding plate having a guide surface opposed to a support surface provided on a side surface of a support means provided upright on a bed, and a hydrostatic bearing for supporting the support surface and the guide surface in a non-contact manner. Means, first driving means for moving the holding disc along an axis parallel to the support surface, and second driving means for rotating the holding disc about an axis parallel to the support surface. ,
An axial direction in which the guide surface is an inner peripheral surface or an outer peripheral surface of a cylindrical guide member that is integral with a holding plate, and a bearing gap formed by a gap between the support surface and the guide surface is parallel to the support surface. On the other hand, the positioning device is characterized in that it narrows near the center and widens toward the outer edge of the bearing. 5. A holding plate having a guide surface opposed to a support surface provided on a side surface of a support means provided upright on a bed, and a hydrostatic bearing for supporting the support surface and the guide surface in a non-contact manner. Means, first driving means for moving the holding disc along an axis parallel to the support surface, and second driving means for rotating the holding disc about an axis parallel to the support surface. ,
The guide surface is an inner peripheral surface or an outer peripheral surface of a cylindrical guide member which is integral with a holding plate, and the hydrostatic bearing means is composed of a plurality of members divided in a cylindrical circumferential direction. Positioning device. 6. The positioning device according to claim 4, wherein the static pressure bearing means is a porous throttle type bearing. 7. The positioning device according to claim 4, wherein the first drive means and the second drive means are individually supported by the base.