JPH02118491A - Static pressure air bearing xy stage - Google Patents

Abstract

PURPOSE:To hole the accuracy of constant pitching irrelevantly to the moving positions of X and Y stages by installing plural units which restrains the vertical directions of the X and Y stages respectively on the same substrate directly and independently of one another. CONSTITUTION:The X and Y stages 6 and 2 slide on the stage substrate 1 along yaw guides 7 and 3 consisting of static pressure air bearing units 8 and 4 for right-left restraint. Further, the X and Y stages 6 and 2 are restrained vertically by static pressure air bearing units 10 and 5 for up-down restraint installed directly on the substrate 1. Thus, the units 10 and 5 which support the weight of the X and Y stages 6 and 2 and restrain their up-down directions are installed on the same substrate 1 independently of each other. so there is no difference in floating quantity between the right and left static pressure bearings and invariably stable moving speeds are obtained. Further, attenuation ability due to disturbance is high and the vertical rigidity can be increased because of the use of the units 10 and 5.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an XY stage with high movement accuracy using a static pressure gas bearing, used in precision measuring instruments, etc., particularly in the vertical direction perpendicular to the XY table surface. It concerns regulatory measures.

[Prior Art] As shown in FIG. 4, an XY stage using a conventional hydrostatic gas bearing has a first stage 102 on a substrate 101.
A second stage (for example, an X stage) is attached via two vertical and horizontal restraint units 103a and 103b, and a second stage (Y stage) 104 is mounted on top of it via two vertical and horizontal restraint units 1.05a and 1.05a, respectively. 105b.

As another conventional example, as shown in FIG. 6, there is a type in which a stage 201 is floated on a vehicle and slid on a substrate 200 via a static pressure gas bearing 202 without being restrained vertically.

[Problem to be solved by the invention] However, in the above conventional example, FIGS.
As shown in FIG. 2, when the second stage 104 moves to the left end or right end, that is, when an eccentric load is applied to the first stage 102, a difference in flying height occurs between the two left and right hydrostatic gas bearings 103a. This has a disadvantage in that it adversely affects the movement accuracy (mainly pitching accuracy) of the second stage 104. That is, as shown in FIG. 5(C), the pitching displacement S, , S due to the movement of the upper stage 104
2 occurs, and the surface of the stage 104 cannot be maintained at a constant level. Further, in the case of a mere floating type without vertical restraint as shown in the conventional example of FIG. 6, there was a drawback that the damping ability due to disturbance was poor and the rigidity was low.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a hydrostatic gas bearing XY stage that always maintains constant pitching accuracy regardless of the stage's movement position and has high rigidity.

[Means and effects for solving the problem] According to the invention, in an XY stage using static pressure gas bearings, static pressure gas bearing units for restraining the vertical directions of the X and Y stages are respectively mounted on the same substrate. By directly installing the X stage, there is no need for the Y stage to support the weight of the X stage, and unlike conventional two-stage XY stages, changes in the center of gravity of the upper stage prevent the static pressure gas bearing of the lower stage from tilting. This ensures that the υ movement accuracy (mainly pitching accuracy) of the upper stage (here, the X stage) is highly accurate and constant regardless of its position.

Furthermore, in the present invention, a plurality of static pressure gas bearing units that support the weight of the X and Y stages and restrain the vertical direction are installed independently on the same board, so that the weight of the X stage is (in this case, the Y stage), an eccentric load acts on the hydrostatic gas bearing as in the conventional example, and a difference in the flying height of the left and right hydrostatic gas bearings occurs. As a result, it is possible to always obtain stable movement accuracy.

Furthermore, since static pressure gas bearings of the type that are restrained in the vertical direction are used for each of the XY stages, the damping ability due to external disturbances is high, and it is also possible to increase the rigidity in the vertical direction.

Embodiment FIGS. 1, 2, and 3 show a first embodiment of the present invention, and FIG. 1 is a partially sectional external perspective view that best represents the features of the present invention. In the figure, 1 is a stage board;
2 is Y stage (first stage or lower stage)
, 3 is a yaw guide for the Y stage 2, 4 is a static pressure gas bearing guide unit for moving the Y stage 2 along the yaw guide 3, 5 is a static pressure gas bearing unit for floating and vertically restraining the Y stage 2, 5a and 5b are guide members for vertical restraint forming the static pressure gas bearing unit l-5, and 5c are three guide members each attached to the upper and lower surfaces of the Y stage forming the static pressure gas bearing unit 5. It is a porous pad. 6 is the X stage (second stage or upper stage), 7 is the yaw guide of the X stage 6 which is suspended and fixed to the X stage 6, and 8 is installed on the Y stage 2 with the yaw guide 7 for the X stage in between. 9 is a motor for driving the X stage, 10 is a static pressure gas bearing unit for floating and vertically restraining the X stage 6, and 10a is a square constituting the static pressure gas bearing unit 10. It is a movable member that is shaped like a plate and can slide between the substrate 1 and a guide member 10b, which will be described later, with porous members 10d and 10e, which will be described later, attached to the lower and upper surfaces, respectively. 10b is a member constituting the static pressure gas bearing unit 10 and serving as an upper guide for vertical restraint. 10c is a member that constitutes the static pressure gas bearing unit 10, is mounted on the substrate 1, and holds the upper guide member 10b. 10d is a disc-shaped porous member that constitutes the static pressure gas bearing unit 10 and is attached to the lower surface of the movable member 10a. 10e is a rectangular porous member that constitutes the static pressure gas bearing unit 10 and is attached around the upper surface of the movable member 10a. 11 is the upper surface of the movable member 10a and a leg member 12 to be described later.
It is a cylindrical member that connects the porous members 10d and 10e and has supply holes provided therein for supplying pressurized gas to the porous members 10d and 10e.

Reference numeral 12 denotes a cylindrical leg member that connects the X stage and the cylindrical member 11 and serves as the three legs of the X stage.

Next, the operation of the XY stage having the above configuration will be explained.

The Y stage 2 is driven by a motor (not shown) and can move in the longitudinal direction of the yaw guide 3. The direction is regulated in the lateral direction by a yaw guide 3 mounted on the substrate 1 and a hydrostatic gas bearing unit 4 suspended and fixed to the Y stage across the yaw guide 3. The vertical direction is controlled by a porous pad 5C attached to the upper and lower surfaces of the Y stage and upper and lower guide members 5a and 5b. The X stage 6 is driven by a motor 9 and is movable along the longitudinal direction of a yaw guide 7 which is suspended and fixed below the X stage and is disposed orthogonal to the Y stage yaw guide 3.

Yaw guide 7 is used to regulate the direction of the X stage in the lateral direction.
This is achieved by a static pressure gas bearing unit 8 installed on the Y stage across the yaw guide 7, and the vertical direction is controlled by a substrate 1 and attached to this substrate 1 via a holding member 10c. Upper guide member 10b
The plate material 10a and the porous member 1 contained between
0d and 10e.

Here, the static pressure gas bearing unit 10 for vertical restraint of the X stage
This will be explained in more detail based on Figure 2. As described above, the static pressure gas bearing unit 10 includes each member 10a.
, 10b, 10c, 10d, 10e, and 11, the number of which is three. Its function is to raise the X stage 6 several microns above the substrate 1 by blowing out pressurized gas between the porous member 10d and the substrate 1, and to apply pressure between the porous member 10e and the upper guide plate 10b. It is a method of vertical restraint by blowing out gas.
Regarding the lateral direction, this refers to the XY directions 2 on the substrate 1 (in this embodiment, the movable range in the XY force directions is the range i, +jZ2 shown in FIG. 2).

Furthermore, the most significant feature of the present invention is that the static pressure gas bearing unit 10 for vertically restraining the X stage is provided directly on the substrate 1 instead of on the Y stage. In other words, as described in the conventional example, the movement accuracy of the X stage, especially the pitching accuracy, changes depending on the position of the X stage, which occurs when the upper, lower, left, and right restraint parts of the X stage are placed on the Y stage. This can happen (because it moves eight times over the fixed substrate 1) and is always stable.

Next, the effects of the arrangement of the units will be explained.

As shown in the plan view of FIG. 3, three vertical restraint units of the X and X stages are each arranged to form a triangle. Therefore, it is possible to make the stage compact in terms of space, and since it is mounted on the same substrate 1, it also has the effect of reducing the height of the entire stage compared to the conventional example. There is.

Next, to describe the characteristics regarding the static pressure gas bearings for vertical restraint of each XY stage, as shown in FIG. 2, in the X stage, porous members 10e are provided on the upper and lower surfaces of the plate material foa, respectively.

The supply pressures to the porous members 5c (P+ and P2, respectively) to the X stage can be controlled separately, and the supply pressures (P3 and P4, respectively) to the porous members 5c provided on the upper and lower surfaces of the X stage can be controlled independently. The main point is that each supply path is separate so that it can be controlled variably. This makes it possible to change the flying height of each vertical restraint unit depending on the load.

The embodiment of the present invention has a static pressure gas bearing configuration in which a porous material for pressurized gas jetting is attached to the movable side of the vertical restraint unit of the X and X stages, but this is attached to the fixed side, and the movable part is a simple flat plate. It may also have a shape such as a disk or a disk. Furthermore, the aperture type is not limited to the porous type, and other types such as self-restriction or surface aperture may be used.

Further, the vertical restraint method of the X stage may be made into a unit similar to that of the X stage.

Further, the shape of the vertical restraint unit of the X stage may be any shape other than square or round as long as it has a degree of freedom of movement in the X and Y directions.

[Effect of the invention] As explained above, in the XX stage,
By independently installing a plurality of units that restrain the stage in each vertical direction and directly installing them on the same substrate, the following effects can be obtained.

(1) X stage fJ! The IJM degree (mainly pitching accuracy) is always stable regardless of the position of the X stage.

(2) It has a large damping ability against disturbances and high rigidity.

(3) The height of the XX stage can be lowered to make it more compact.

[Brief explanation of drawings]

Fig. 1 is a partial cross-sectional external perspective view of the XX stage in which the present invention is implemented, Fig. 2 is a partial cross-sectional side view of the X and the upper and lower restraint portions of the X stage, and Fig. 3 is a partial cross-sectional side view of the XX stage in which the present invention is implemented. A plan layout diagram of the vertical restraint unit, Figure 4 is an external perspective view of a conventional XX stage, and Figure 5 (a
) (b) and (C) are explanatory diagrams showing changes in pitching accuracy depending on the position of the X stage, and FIG. 6 is a side view of another conventional stage. 1: Stage board, 2: X stage (first stage), 3: Yaw guide for X stage, 4: Static pressure gas bearing unit for X stage left and right restraint, 5. Static pressure gas bearing unit for X stage vertical restraint, 5a , 5b: Vertical restraint member for X stage, 5c, porous pad, 62 X stage, 7 Yaw kite for x stage, 8: Hydrostatic gas bearing unit for left and right restraint of X stage, 9: Motor for driving X stage, 10: Static pressure gas bearing unit for vertical restraint of X stage, 10a: Movable plate material forming the static pressure gas bearing unit for vertical restraint of X stage, 10b: Upper side forming static pressure gas bearing unit for vertical restraint of X stage Guide plate, 10c: Upper guide plate holding member configuring the static pressure gas bearing unit for vertical restraint of the X stage, 10d, 10e:
Porous member, ■I: Cylindrical member, 12 Leg member. Figure Figure

Claims (6)

[Claims] (1) A substrate, an X stage that slides on the substrate along an X-direction guide means made of a hydrostatic gas bearing, and an X stage that slides on the substrate along a Y-direction guide means made of a hydrostatic gas bearing. a Y stage; an X stage vertical restraint means comprising a static pressure gas bearing for vertically regulating the X stage; and a Y stage vertical restraining means comprising a static pressure gas bearing for restraining the Y stage in the vertical direction. A hydrostatic gas bearing XY stage, characterized in that the X stage vertical restraint means and the Y stage vertical restraint means are each directly installed on the same substrate. (2) Each of the X stage vertical restraint means and the Y stage vertical restraint means consists of a movable body that moves integrally with each X and Y stage, and a fixed guide member placed between the movable body from above and below. , the fixed guide member is fixed on the substrate, and pressurized gas is ejected between the fixed guide member and a moving body above and below the fixed guide member to constitute a static pressure gas bearing. The static pressure gas bearing XY stage described in item 1. (3) The hydrostatic gas bearing XY stage according to claim 2, wherein the pressurized gas jetting portions are provided on the fixed guide member sides above and below the movable body. (4) The hydrostatic gas bearing XY stage according to claim 2, wherein the pressurized gas jetting portions are provided on both upper and lower surfaces of the movable body so as to face the fixed guide member. (5) The pressurized gas supply systems for the upper and lower static pressure gas bearings of the moving body are separate systems, and the pressure of the pressurized gas for the upper and lower static pressure gas bearings can be controlled separately. A hydrostatic gas bearing XY stage as described in Range 2. (6) Each of the X stage vertical restraint means and the Y stage vertical restraint means is provided in the form of a triangle at three locations on each X and Y stage, and the orientation of the apex angle of the triangle on the X stage side and the Y stage Claim 1, characterized in that each of the three X-stage vertical restraint means and the Y-stage vertical restraint means is provided in a shape in which both triangles are overlapped with the apex angles of the side triangles reversed. The static pressure gas bearing XY stage described in item 1.