JPH02225857A - Ball screw device - Google Patents

Abstract

PURPOSE:To move a movable stage device at high speed with high accuracy and enable the usage thereof in the vacuum atmosphere without troubles by providing a ceramics feeding ball screw, a ceramics ball nut to be threadedly engaged with that screw and a power transmitting coupling connected to a motor. CONSTITUTION:A motor 8 of a Y stage 10 drives to rotate a ball screw 5 through a coupling 7 to feed a ball nut 4 forward and backward, and an X-stage 2 is moved forward and backward. The stage 2 is displaced within a horizontal surface with the movement on flat surfaces 19, 20 without fine movement in Z direction, and the movement in Y direction is regulated by a guide 9. On the other hand, a motor 17 of a basic board 18 drives to rotate a ball screw 15 through a coupling 16, and the stage 10 is moved forward and backward. The stage 10 is accurately displaced in Y direction on flat surfaces 21, 22 with the regulation by a guide 9. The fluctuation against the change of temperature is hard because of the low thermal conductivity and the low thermal expansion coefficient of the ceramics material, and an oil free type sliding surface and an oil free type turning surface can be formed to enable the usage in the vacuum atmosphere.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a ball screw device, particularly a projection exposure apparatus, which transmits the driving force of a motor to a movable body when moving the movable body along a guide. The present invention relates to a ball screw device that is incorporated into a movable stage device that is applied to an electron beam lithography device or a semiconductor manufacturing device such as a wire bonder.

[Prior art] Conventional ball screw devices are based on AI type, Ti type, or M type.
Each part is constructed using G-based light alloy and other metal materials.

[Problem that the invention seeks to solve] However,
These metal materials have problems in terms of rigidity, deformation due to temperature changes, wear resistance, rust prevention, etc. In particular, when the stage device is used in a vacuum atmosphere, the use of lubricants is restricted, which further deteriorates the wear resistance.

Furthermore, when a ball screw device is incorporated into a highly accurate movable stage device such as that used in the semiconductor manufacturing field, maintaining its accuracy is a very difficult problem considering the aging of metal materials.

The present invention was made in view of these circumstances, and its purpose is to solve the problems of the prior art described above, and to enable high-speed and highly accurate movement of a movable stage device.
For example, an object of the present invention is to provide a ball screw device that can be used without problems even in a vacuum atmosphere.

[Means for solving the problem] In order to achieve this objective, the ball screw device of the present invention has the following features:
It has a ceramic feed ball screw, a ceramic lx ball nut containing a built-in ball that screws into the feed ball screw, and a power transmission coupling that connects the drive shaft of the motor to the feed ball screw. ing. This reduces the weight of each part and improves wear resistance. Furthermore, when incorporated into a movable stage device, the movable stage can be moved at high speed and with high precision, and can also be used in a vacuum atmosphere.

Furthermore, problems in terms of rigidity, deformation due to temperature changes, rust prevention, aging, etc. have also been solved.

[Example] Hereinafter, the present invention will be described in detail using an illustrated example of the XY stage device according to the present invention.

In FIG. 1, reference numeral 1 denotes a chuck made of alumina ceramics, and a silicon wafer or sample placed thereon is vacuum-adsorbed. Although not shown in the figure, the wafer chuck 1 is provided with an opening for vacuum suction and a duct connected to a vacuum pump. 2 is an X stage made of alumina ceramics, which transports the 5 chucks 1 in the X direction. 3 is a sliding member made of alumina ceramics or whose sliding surface is further coated with Teflon, and is provided on the inner surface of the X stage 2. Reference numeral 4 denotes a ceramic pole nut for applying a feeding force to the X stage 2, which is connected to the X stage 2 via a coupling member, and contains a ceramic ball or a nonmetallic ball such as ruby or sapphire.

5 is a ball screw for feeding ceramics, and is screwed into the pole nut 4. 6 is a ceramic housing for holding the ball screw 5;
It houses a bearing made of non-metallic material such as ruby sapphire to receive the vibration. 7 is a power transmission coupling made of ceramics, one side of the coupling 7 is connected to the ball screw 5, and the other side is connected to the drive shaft of a motor 8 that drives the X stage. Reference numeral 9 denotes a ceramic linear sliding guide for regulating the movement of the X stage 2. One side of the sliding guide 9 contacts the transfer guide 23 (see Fig. 23), and the other side contacts the sliding member 3. come into contact with

Next, 10 is a Y stage made of ceramics, which supports the protrusions 2° and 2' of the X stage 2, and is connected to an X direction sliding guide 9. 11 is a sliding member made of ceramics or further coated with Teflon, and is provided inside the Y stage 10. Reference numeral 12 denotes a ceramic linear sliding guide for regulating the movement of the Y stator 10, which is coupled to a ceramic base 18. 13 and 14 are ceramic ball screws 1 for feeding in the Y direction.
The housing 13.14 is made of ceramic and houses a bearing made of a ceramic material or a non-metallic material such as ruby sapphire. Although not shown in the figure, the pole nut is screwed into the ball screw 15, and the Y stage 1
Fixed inside 0.

A coupling 16 for power transmission is made of ceramics and is coupled to a motor 17 that drives the Y stage 10. 19 to 22 are sliding surfaces of ceramics that have been lapped to give a mirror finish to the flat surfaces;
0 supports the lower protrusions 2° and 2° of the X stage 2, and the sliding surfaces 21° and 22 support the lower protrusions 10'l of the Y stage 10.
O.

We support each of them.

2 and 3 each show a Tachibana structure for supporting the stage 2.10, and in FIG. In FIG. 3, 25 is a ceramic air bat when an air bearing is used, and a pneumatic duct (not shown) is connected to the air bat 25. Furthermore, among these parts,
Conventional alloy members may be used for the parts other than the sliding part and the transfer part depending on the purpose.

With the above configuration, when the motor 8 fixed to the Y stage 1o is driven, the ball screw 5 rotates via the coupling 7, and the ball nut 4, which is screwed with the ball screw 5, is sent back and forth to be fixed. The X stage 2 can be moved back and forth in the X direction. By moving on the planes 19 and 20, the X stage 2 is displaced in the Z direction in the horizontal plane without slight movement, and the movement in the Y direction is regulated by the guide 9.

On the other hand, if the motor 17 fixed to the base 18 is driven,
The ball screw 15 rotates via the coupling 16, and the Y
The stage 10 can be moved back and forth in the Y direction. Y stage 1
0 moves on planes 21 and 22, is regulated by a guide 12, and is accurately displaced in the Y direction.

In this embodiment, ceramic is used as the coupling coupling 7.16 because it has high rigidity and low inertia and can reduce vibration transmission from the feeding device.

[Effects of the Invention] As described above, according to the present invention, the weight of each part can be reduced without reducing its rigidity, and the low thermal conductivity and low coefficient of thermal expansion of the ceramic material makes it possible to reduce the weight of each part, and to resist changes in the ambient atmosphere temperature due to the low thermal conductivity and low coefficient of thermal expansion of the ceramic material. Since it is possible to provide a ball screw device that does not easily fluctuate, it is possible to improve the precision of the stage device.

Furthermore, according to the present invention, wear resistance can be improved, problems such as ringing that occur with metals are less likely to occur, and a non-lubricated sliding surface or transfer surface can be constructed, so it can be used even in a vacuum atmosphere, for example. This makes it possible to provide a ball screw device. Further, according to the present invention, the change over time of the ball screw device can be made extremely small, so when it is incorporated into a stage device, high stage accuracy can be maintained for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the XY stage device incorporating the ball screw device of the present invention, FIG. 2 is a cross-sectional view showing the main part of the embodiment shown in FIG. 1, and FIG. It is a sectional view showing a modification of . In the figure, 2 is the X stage, 4 is the pole nut, 5 is the ball screw, 8 is the X stage drive motor, 9 is the X guide, 1
0 is a Y stage, 12 is a Y guide, 17 is a motor for driving the Y stage, and 18 is a base. Figure 3

Claims (4)

[Claims] (1) It has a feed ball screw made of ceramics, a ball nut made of ceramics containing a built-in ball that screws into the feed ball screw, and a power transmission coupling that connects the drive shaft of the motor with the feed ball screw. A ball screw device featuring: (2) The ball screw device according to claim 1, wherein the ball is made of a non-metallic material. (3) The ball screw device according to claim 2, wherein the balls are made of ceramics, ruby, or sapphire. (4) The ball screw device according to claim 1, wherein the power transmission coupling is made of ceramics.