JP3014002B2 - Precision guide stage device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a stage device, and more particularly to a stage device having a highly accurate XY stage.

2. Description of the Related Art High precision XY stages are required in semiconductor manufacturing equipment, machine tools, ultra-precision processing machines, three-dimensional measuring instruments, robots, and the like.

[Prior Art] Conventional stage devices generally achieve multidimensional degrees of freedom by stacking stages with a single degree of freedom.
For example, in the case of the XY stage, the XY stage is obtained by configuring the Y stage on the X stage.

In an apparatus for manufacturing a semiconductor device, particularly, an SOR exposure apparatus or the like, an extremely dense XY stage apparatus is required. The wafer stage on which the workpiece of such an ultra-precision stage device is mounted is guided by an ultra-precision guide member such as a slide guide or an air slide, but is mounted on a coarse movement stage using a combination of a ball screw and a linear guide. Place the stage for posture correction, straightness, yawing,
Running errors related to pitching, rolling, and the like are corrected by a posture correction stage.

In these methods, the running accuracy of each axis of the multidimensional degrees of freedom is directly represented by the attitude of the wafer stage. Further, interference between the degrees of freedom occurs, for example, such that the driving of the X axis changes the position of the Y axis.

In order to suppress these errors as much as possible, it is necessary to make the running accuracy of the stage ultra-precise, and to correct the posture with a fine movement stage or the like with high accuracy. However, there is a limit to making the running accuracy of the stage ultra-precise in the entire movable range, and the size and weight of the apparatus are increased. The posture correction by the fine movement stage also has a complicated structure when the stroke is large.

[Problems to be Solved by the Invention] As described above, according to the related art, it is inevitable that when the stage is driven in a certain axial direction, the positional accuracy in another direction is affected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a precision guide stage device that can eliminate an error generated in another direction when the stage is driven in one direction by a buffer.

[Means for Solving the Problems] A precision guide stage device according to the present invention includes a first base having a guide reference surface, a stage supported on the guide reference surface via an air pad, and a parallel with the guide reference surface. Two-dimensional driving means capable of moving in a simple plane, connecting the two-dimensional driving means and the stage, and providing the guide reference of a connecting part to the two-dimensional driving means and a connecting part to the stage. The two-dimensional driving means, the cruciform spring, and the cruciform spring having low rigidity with respect to the displacement in the normal direction of the surface, and high rigidity with respect to the displacement in the direction parallel to the guide reference plane. Stages are connected in this order in a direction normal to the guide reference plane.

[Operation] Since the stage supported on the guide reference plane via the air pad is driven by the two-dimensional driving means via the cross spring, the stage is driven by the two-dimensional driving means in the two-dimensional in-plane direction. The cross spring absorbs errors in directions other than the two-dimensional in-plane direction. For this reason, the stage can perform high-precision movement along the guide reference plane.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a side view of a precision guide stage according to an embodiment of the present invention. The X, Y, and Z directions are taken as shown in the upper left of the figure.

The base 11 and the base 35 have parallel surfaces facing each other. An X stage 14 guided by a linear guide 12 and driven by a ball screw 13 is provided on the base 11. On the X stage 14, a Y stage 18 driven by a ball screw 16 and a linear guide (not shown) is provided. In the case of this embodiment, since the Y direction is oriented in the vertical direction, a force due to gravity also acts on the driving device in the Y direction. When gravity acts, driving in the + Y direction and-
Driving in the Y direction has different characteristics. Therefore, in order to cancel this effect of gravity, a constant tension spring
17 is coupled to the Y stage 18. With this configuration,
An XY drive mechanism is configured on the base 11. That is, the Y stage 18 constitutes a two-dimensional driving means that moves within the XY plane.

A precision stage arm 22 is connected to the Y stage 18 via a cross spring 20. The cruciform spring 20 has low rigidity in the Z direction in the figure and high rigidity in the X direction and the Y direction.

 FIG. 2 is a perspective view showing a configuration example of a cross spring.

In the configuration shown in the figure, rigid members 42 and 43 are connected on a diagonal line of a leaf spring member 41, and an opening 44 is formed at the center. This cross spring is used in the direction of the rigid members 42 and 43.
It will be obvious that 20 exhibits high stiffness. However,
For example, when the rigid members 42 and 43 are relatively displaced in the Z direction, the leaf spring member 41 functions as a strip-shaped leaf spring which receives a force in the thickness direction, and easily elastically deforms. Also, the cross spring 20 against rotational freedom theta _z direction around the Z-axis show high stiffness, theta _x-direction, the rigidity is low relative theta _y-direction. As described above, the cruciform spring has low rigidity only in a predetermined direction and allows relative movement in that direction, but has high rigidity in other directions. By connecting the rigid members 42 and 43 to the two objects respectively,
One of the predetermined degrees of freedom can be selectively transmitted to the other. That is, in the case of the illustrated configuration, X direction, Y direction, the displacement of the theta _z direction is selectively transmitted.

The precision stage arm 22 is connected to the Y stage 20 at three or more positions by a cross spring 20 having high rigidity in the X and Y directions. This precision stage arm 22
A precision stage 28 is provided via a rotary bearing 26. That is, the precision stage 28 is a Y stage
18 movements in the X and Y directions are received as they are,
The movement in the Z direction is absorbed by the cross spring 20 and is not transmitted to the precision stage 28. The precision stage arm 22 is held on the base 35 by the air pad 24. The air pad 24 maintains a predetermined gap between itself and the base 35 by blowing out air.

 FIG. 3 schematically shows a configuration example of the air pad.

Most of the air pad 24 is formed of a magnetic material such as iron. Air duct in the center of air pad 24
An air outlet 46 is provided at the bottom surface. Further, an annular permanent magnet 47 is embedded, and the inner and outer peripheral surfaces thereof are separated from the periphery by a non-magnetic material 48. Therefore, when such an air pad is arranged on a base 35 formed of a magnetic material such as iron, a magnetic circuit including the magnet 47 and the base 35 is formed, and the air pad 24 is attracted to the base 35. Air duct 45 to air outlet 46
The air pad rises from the base 35 by blowing out air. In this manner, the air pad 24 floats at a predetermined interval from the surface of the base 35 by the pressure of the blown air (or other gas).

In the configuration shown in FIG. 1, the precision stage 28 can be pressed against the base 35 by the cruciform spring 20 or the like, and the air pad need not be provided with a magnet. If the force provided by the cruciform spring 20 alone is insufficient to hold the precision stage 28 on the base 35, another driving force means may be provided. The gas used for the air pad may be other than air. When an air pad as shown in FIG. 3 is used, the distance of the precision stage 28 to the base 35 is controlled by the gas pressure blown to the air pad.
In the Z direction. Thus, the precision stage 28 X-direction of the Y stage 18, the X-direction depending on the position in the Y direction, is controlled the position in the Y direction is the motion control of the theta _z-direction by the movement through the rotation bearing 26. The position in the Z direction is determined by the air pad 24 arranged on the guide reference plane of the base 35. A wafer chuck 31 is provided on the precision stage 28, and the wafer 32 is supported on the wafer chuck 31 by vacuum suction, electrostatic suction or the like. Note that X-rays are irradiated onto the wafer 32 from the SOR light duct 34.

FIG. 4 schematically shows the support of the precision stage by the air pad.

The figure shows a precision stage viewed from 34 SOR light ducts. The precision stage 28 is supported by three precision stage arms 22, and an air pad is attached to the tip of each precision stage arm 22.
24 are connected. These air pads 24 are base 35
And slide on the guide reference plane. Note that a wafer chuck 31 is provided on the precision stage 28,
Is sucked by the negative pressure. With such a configuration, the drive by the X stage 14 and the Y stage 18 is transmitted to the stage arm 22 via the three cross springs 20. The stage arm 22 supports a precision stage 28 on which the wafer chuck 31 is mounted. The air pad 4 slides on the guide reference surface of the base 35 with a constant air gap. Each of the cross spring 20 has X-direction, Y-direction, theta _z direction high rigidity, Z
Rigidity in the direction is weak, X-direction from the movement of the Y stage 18, Y-direction, movement of the theta _z-direction is accurately transmitted. However, the precision stage 28 Z-direction, theta _x-direction, the theta _y-direction is guided by the guide reference surface of the base 35, Y
Unaffected by Stage 18. That is, the displacement of the Y stage relating to these degrees of freedom is absorbed by the cross spring 20. Thus, the running accuracy error caused by the driving of the X and Y driving means is absorbed by the cross spring, and the attitude of the wafer is determined by the three air pads and the guide reference base.

In the configuration shown in FIG. 1, the precision stage 28 is Y
It is driven in the X and Y directions via the stage 18, but is not affected by its displacement in the Z direction. Precision stage 28 Z
The directional position is precisely supported by the air pad 24.
Further, since the air pad 24 provides the frictionless support to the base 35, the precision stage 28 can be driven with high accuracy. Incidentally, if necessary, a Z-direction driving means may be provided between the precision stage 28 and the wafer chuck 31. By using the Z-direction drive means for example three sets, it Z direction, theta _x-direction, also for driving the theta _y-direction.

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, the running accuracy error caused by the driving of the two-dimensional driving means is absorbed by the cross spring, and the attitude of the precision stage is determined by the air pad and the guide reference plane.

Therefore, the running error of the two-dimensional driving means does not affect the attitude of the wafer.

The rigidity as viewed from the wafer is sufficiently high, and the two-dimensional driving means and the precision stage can be positioned with high speed and high accuracy.

By using the escape by the cross spring, a simple and compact configuration can be obtained as a whole.

[Brief description of the drawings]

1 is a side view of a precision guide stage according to an embodiment of the present invention, FIG. 2 is a perspective view showing a configuration example of a cross spring in the configuration of FIG. 1, and FIG. 3 is a configuration of an air pad in the configuration of FIG. FIG. 4 is a schematic cross-sectional view showing an example, and FIG. 4 is a bottom view schematically showing an example of a support form of the precision stage in the configuration of FIG. In the figure, 11, 15… Base 12… Linear guide 13, 16… Ball screw 14… X stage 17… Constant tension spring 18… Y stage 20… Cross spring 22… Precision stage arm 24… Air pad 26 Rotating bearing 28 Precision stage 31 Wafer chuck 32 Wafer 34 SOR light duct 41 Leaf spring member 42, 43 Rigid member 44 Opening 45 Air duct 46 Air outlet 47: Magnet 48: Non-magnetic material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-102186 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23Q 1/00-1/76 G12B 5 / 00 H01L 21/68

Claims (1)

(57) [Claims] A first base having a guide reference surface; a stage supported on the guide reference surface via an air pad; and a movable member movable in a plane parallel to the guide reference surface.
A two-dimensional driving means, the two-dimensional driving means and the stage are coupled, and the rigidity of the coupling part to the two-dimensional driving means and the coupling part to the stage with respect to the displacement in the normal direction of the guide reference plane Is low,
A cross spring having high rigidity with respect to displacement in a direction parallel to the guide reference plane; and the two-dimensional driving means, the cross spring, and the stage are arranged in a direction normal to the guide reference plane. A precision guide stage device that is connected in order.