JPS61112216A - Noncontacting drive type planar shift stage - Google Patents

Abstract

PURPOSE:To attain a planar shift and positioning of a sample with high accuracy by transmitting the straight advance drive to a mobile table from a drive source via a noncontacting joint and sliding both the drive table and a guide under noncontacting state. CONSTITUTION:An X table 10 has a static pressure air pad which restricts a guide shaft 11 in the up-down and front-back directions. A sample stage 16 is put on the table 10. Then the table 10 is driven forward straight by transmitting the straight advance displacement of a linear motor 19 fixed to a base to the table 10 under noncontacting state by a static pressure joint provided to said air pad. The table 10 is driven in the Y direction by linear motors 33 and 34 and static pressure joints 35 and 36 together with a Y slider having the static pressure air pads at both ends of the shaft 11 to restrice the up-down and right-left directions. The Y slider is slid within a slide guide.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a precision plane moving table driven by non-contact driving.

In particular, it can be used to precisely move a sample in a plane in ultra-precision processing equipment such as exposure of fine patterns on semiconductors, and it can be used to eliminate external vibrations and thermal effects, thereby improving accuracy. This invention relates to a contact-driven planar moving table.

[Background of the invention]

Conventionally, wafer moving tables of semi-shield exposure equipment, probe moving tables or sample moving tables of three-dimensional coordinate measuring instruments, etc.
Various methods have been used for mechanisms that require high straight running accuracy, positioning accuracy, and rigidity, such as work stands and tool stands for precision processing machine tools. Currently, the most common and proven drive mechanism uses a feed screw 1 and a motor 2, as shown in FIG.

This converts the rotational displacement of the motor 2 into a linear displacement via the feed screw 2 and nut 3, and transmits this to the driven table.Recently, with improvements in motor performance and feed screw accuracy, precision Most commonly used as a feeding mechanism.

However, the wafer moving table in semiconductor exposure equipment.

A moving table for workpieces or tools such as ultra-precision grinders and lathes,
Furthermore, in the moving tables of precision measuring instruments such as straightness measuring instruments, heat and vibration from the drive system of 0.05 μm or less, as well as posture errors during movement of the driven object, can significantly affect machining accuracy and measurement accuracy. To influence.

This conventional drive system using a feed screw and motor is no longer applicable.

That is, since the feed screw method shown in FIG. The slider 4 is always subject to external fluctuations when traveling on the slide shaft 6 due to play in the slider 4 and errors in the running direction of the slider 4 and the mounting parallelism of the feed screw 1.

In addition, the feed screw drive system has many mechanical elements and connecting parts, so the rigidity of the drive system is low.

In addition, dust prevention measures are essential for accurate feeding, so it cannot be said to be optimal as an ultra-precision feeding mechanism.

[Purpose of the invention]

An object of the present invention is to provide a non-contact drive type planar moving table that solves the above-mentioned conventional problems and allows for highly accurate planar feeding and positioning of a sample without being affected by vibration or heat from the drive unit. Our goal is to provide the following.

[Summary of the invention]
1 In order to achieve the above object, the present invention transmits the linear driving force from the drive source to the moving table via a non-contact joint in order to avoid vibration transmission and heat conduction, and
The structure is such that the movable table slides between the guide and the guide without contact using static pressure guidance.

On the other hand, after moving the moving table by a certain amount of steps, in order to maintain that position for a certain period of time, by stopping the air supply to either the upper or lower air pad of the static pressure guide, the air pad pressure of the other air pad is The movable table is pressed against the guide and fixed.

This movable table has a structure in which hydrostatic bearing pads are provided at both ends of the guide so that the table can move linearly in a direction orthogonal to the guide. Note that conventional general methods can be used for the non-contact driving method and the positioning and fixing method after movement at this time.

Further, the linear drive source for moving the moving table along the guide is fixed to the base, and when movement perpendicular to the guide occurs, the moving table is configured to run parallel to the air pad surface of the static pressure joint. I can do it.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

FIG. 2 is a plan view showing the configuration of the plane moving table of this embodiment, and FIG. 3 is a cross-sectional view taken along the line AA in FIG.

This plane moving table includes an X table 10 that slides straight in the direction of arrow X, a guide shaft 11 that guides the table, and
It is composed of a slide guide 12 that guides both ends of a guide shaft 11 in order to slide straight in the Y direction orthogonal to the direction.

The details of the structure of each part are as follows.

The X table 10 is a static pressure air pad configured to restrain the guide shaft 11 from four directions: top, bottom, front and back.

Each X upper putt 2. X lower pad 13. It has a box-shaped structure with an X front pad 14° and an X rear pad 15, on which a sample stage 16 on which a sample such as a semiconductor wafer is placed, and a laser mirror 17 that serves as a reference for measuring the position of the X table 10 are placed. There is. The linear drive of the X-table IO is such that the linear displacement of the linear motor 19 fixed to the base 18 is transmitted to the X-table 10 in a non-contact manner by a static pressure joint 21 provided with air pads 20 on both sides perpendicular to the direction of movement. ing. A DC or AC servo motor can be used as the linear motor 19, and in this embodiment, a movie magnet type linear motor is used in which the linear coil 22 is fixed and the magnet 23 is moved by applying a current to it and generating a magnetic field. is using. However, a moving coil type linear motor that fixes the magnet 23 and moves the coil 22 may be used, or any other suitable drive source may be used.

As shown in the third diagram, the static pressure joint 21 is located on the lower surface of the The air pad 20 is arranged between the bearing plates 24 with a small gap therebetween.

This air pad 20 is fixed to a magnet 23 of the linear motor 19.

As shown in FIG. 2, in order to slide the X table 10 together with the guide shaft 11 in the Y direction, a Y
A slider 2a is provided. The static pressure air pads each consist of a Y upper pad 25, a Y lower pad 26, a Y left pad 27, and a Y right pad 28 (FIG. 3). This Y air slider 29 is structured to slide within the slide guide 12.

Note that the slide guide 29' includes an upper plate 30, a side plate 31. It is composed of a base plate 32,
It may be manufactured by integral processing.

Drive in the Y direction is driven by linear motors 33, 3 as in the X direction.
4 and static pressure joints 35 and 36. Static pressure joint 35°3
6 is composed of an air pad 37, 38 and two bearing blocks 39, 40, 41, 42 fixed to the guide shaft 11 with a small gap between the surfaces opposite the air pads 37, 38 (FIG. 2). In addition, the air pads 37 and 38 are attached to each magnet 43.
．． 44, and is moved straight by linear coils 45 and 46. In addition, the linear motor 19, 33, 34 always generates a constant attraction force (several to several tens of kgf) between the magnet and the coil, so it is necessary to support it.
) 1, and in order to keep the gap between the magnet and the coil constant, the magnet 23, 43, 46 is guided in a straight line by the rolling guide rear guide 47, 48, 49 (the third
), in this case the magnet 23.43.46 may receive mechanical micro-vibrations (0.1-1.2 μl 11) from the rolling guide rear guide 47.48.49, but the static pressure joint 21 Due to .33.34, the vibration is significantly (
175 to 1/10).

Next, the air piping route supplied to each static pressure air bearing and the method of controlling the plane moving table will be described with reference to FIGS. 3 and 4. FIG. 4 is a sectional view taken along the line BB in FIG. 3, and shows the state before positioning at section 4■ in FIG. 4 and after positioning at the same section <4II.

As shown in FIGS. 3 and 4, each air piping route is 15. Putt before X 14. X lower part 12. Y left putt 27. Y right putt 28. Y upper putt 25. The static pressure joint air pads 20, 37, and 38 are supplied with compressed dry air 52 via a solenoid valve 50 through the same route. On the other hand, X lower pad 13. Compressed air is supplied to the Y lower pad 26 via the solenoid valve 51 through the same route.

FIG. 4 shows a state in which air is supplied to each air pad. At this time, the X table IO is floating with a minute gap g between it and the guide shaft 11.

Further, the Y air slider 29 is floating apart from the Y slide guide 12 with a small gap g.

This minute clearance g varies depending on the throttle system and bearing performance of the hydrostatic air bearing used, but in this example, a surface-drawn type hydrostatic bearing with high bearing rigidity and low air consumption is used. is in a floating state, and a bearing clearance g that provides maximum bearing rigidity is obtained. Note that for the sake of the following explanation, the bearing clearance g used in this example is 5±0.5 μm.

Next, a precise positioning control method of the present moving table will be explained below. In this embodiment, the position of the X table IO in the x and Y directions is measured using a laser interferometer 53 with a resolution of approximately 0.01 μm as the amount of movement of the laser mirror 17, and the CPU 5
Control is performed so that the amount of movement commanded from step 4 is achieved. Therefore, a closed loop servo formed between the linear motor controller 56 and the laser controller constitutes a system for high-speed, high-precision positioning.

For example, when exposing a sample such as a semiconductor wafer to X-rays after precisely positioning it on this moving table, it is important to keep the sample stably stationary during the exposure. It is essential to eliminate 16 minute vibrations.

Therefore, in this embodiment, after positioning the sample stage 16 at the target position g using the linear motor, as shown in part 4 of FIG.
Switch the solenoid valve 52.

That is, by stopping the supply of air to the X lower part 13 and the Y lower part 26 and opening them to the atmosphere, the X table IO is moved by the guide shaft 11 due to the air pressure of the
The Y air slider 29 is pressed against and fixed, and the Y air slider 29 is
The upper Y pad 25 is pressed against the base plate 32 by air pressure and fixed. That is, X table 10
The upper sample stage 16 is fixed to the base 18 by the above operation. What should be noted here is that the clearance between the X table 10 and the guide shaft 11 is 2 g, and the X table 10 is raised by g, but on the other hand, the Y air slider 26 is lowered by g with respect to the base plate 32, so the sample table There is no change in height during the plane movement of step 16 and after the above solid positioning clamp. For similar reasons, static pressure joints 21.3
There is also no change in relative position in the height direction between the air pad and the bearing plate 24 and bearing blocks 39 to 41 at 5°36.

Note that the above effects can be further improved by using ceramic rings as the material of all the bearings in the static air, etc. used in this embodiment.

[Effects of the Invention] 5. According to the present invention, the linear displacement of the drive source is transmitted to the movable table via the non-contact joint, and the table is fixed to the base at the target position.

When traveling, highly accurate plane movement can be achieved without being affected by vibrations from the drive system, and static stability can be achieved at the stop position without being affected by minute vibrations in the positioning servo state. 1. As shown in the example, if the linear motor is fixed on the base in a direction perpendicular to the base and the table is moved in a plane by static pressure air guided through a non-contact static pressure joint, the result will be even better. High running accuracy and high speed can be achieved.

However, it goes without saying that the present invention is not limited to the illustrated embodiment.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a conventional moving table. FIG. 2 is a plan view showing a plane moving table according to an embodiment of the present invention, FIG. 3 is a cross-sectional view taken along line A-A in FIG. 2, and FIG. 4 is a cross-sectional view taken along line B-B in FIG. FIG. 10...X table, 11...guide shaft, 29'...
Slide guide, 19.33.34... Linear motor, 29... Linear slider + 21.35.36...
- Static pressure joint, 16...sample stand.

Claims (1)

[Scope of Claims] 1. A table on which a sample stage is placed, a guide shaft that slides the sample table in a straight line using hydrostatic gas bearing guidance, and static pressure gas bearing pads provided at both ends of the guide shaft that are perpendicular to the guide shaft. In a planar moving table consisting of a guide for sliding in the direction, the linear displacement of two or more orthogonal linear drive sources fixed to the base is controlled by non-contact joints using hydrostatic gas bearings, respectively. A non-contact driven planar moving table characterized in that it is configured to transmit information to a guide shaft. 2. In the planar moving table according to claim 1,
By stopping the gas supply to the table and some of the static pressure gas bearing pads provided at the end of the guide shaft,
A non-contact driven planar moving table characterized by being provided with a clamp mechanism for fixing the table to each reference guide surface. 3. In the planar moving table according to claim 1,
A non-contact drive type planar moving table characterized by using a linear motor as a linear drive source. 4. In the planar moving table according to claim 1,
A non-contact drive type planar moving table characterized by using ceramics as the material of the static pressure gas bearing. 5. In the planar moving table according to claim 1,
A non-contact drive type planar moving table characterized by using a surface drawing type static pressure air bearing as the static pressure gas bearing.