JPS6263228A - Stage driving device - Google Patents

Abstract

PURPOSE:To position a stage with high accuracy by keeping a driving shaft from a rotary displacing at a very small angle after electric power supply to a motor is switched off by a braking ring rotated in a body with a capstan shaft and a plate spring pressed to the ring. CONSTITUTION:A capstan shaft 13 is directly coupled to a driving shaft 11 of a motor 10 with a speed reduction gear head through a shaft coupling 12. A braking ring 16 is fixed to the capstan shaft 13, and a free end of a plate spring 17 fixed to a housing body 15 is always pressed to the braking ring 16, whereby when the rotation of the capstan shaft 13 is stopped, frictional braking is performed. Accordingly, when the electric power supply to the motor 10 is switched off, the capstan shaft 13 can be stopped at that position without differential rotary displacement.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a stage driving device using a motor, and particularly to a stage driving device that precisely drives a stage on which a mask, a reticle, or a wafer is placed, used in semiconductor manufacturing equipment.

[Background of the invention]

In recent years, as the degree of integration of ICs has increased, the line widths of patterns on masks, reticles, and wafers have become smaller, and mask patterns with a line width of 1 μm are no longer uncommon. There is. When considering an inspection device that inspects these fine lines, for example, the stage is moved so that the measuring section of the line width measurement sensor or the measuring head of the microscope is located in the center of one 1μ pattern line, and the other There is a well-known in-line inspection device that measures the distance between line widths by moving the stage again so that the center of the pattern line is located within 1μ of the pattern line. With these inspection devices,
For example, in order to position the stage so that the measuring section is within a width of 1 μ, a stage positioning ability with an accuracy of at least 0.5 μ is required.

Now, the conventional stage feeding in these inspection devices is as follows.
As shown in FIG. 3, so-called screw feeding is mainly employed in which a stage 3 is moved in a straight line by rotation of a feed screw 2 driven by a motor 1.

However, this thread feeding method has the following drawbacks.

1) Due to the nature of screw drive, the load torque is large, so a large capacity motor is required.

2) Due to the reason 1) above, the stage cannot be driven at a very high speed, and the inspection processing capacity (throughput) of the sample per unit time cannot be improved.

3) Since the stage is slightly displaced due to a change in dimensions due to a temperature change in the atmosphere around the screw fitting part, the feeding device must be housed in a so-called chamber that minimizes temperature changes.

As a feeding device that solves the above-mentioned drawbacks, there is also known a cassop drive system as shown in FIG. 4. In this system, the rotation of the motor 1 is transmitted to the cap stan 6 via the shaft coupling 5, and the rotating cap stan 6 is transferred to the stage 7.
The stage 7 is moved by pressing against the contact portion 7a of the stage 7. However, in this drive system, when power is supplied to the motor 1 to move the stage 7, there is an imbalance in the mechanical torsion force accumulated inside the motor and the contact pressure of the commutator of the brush inside the motor. Due to the rotational force acting on the commutator when the motor stops, the rotational force acting on the coil due to the unbalance of the magnetic field inside the motor (so-called conging), etc., the motor rotates by a small angle at the moment the current is turned off. As a result, there was a disadvantage that the stage moved slightly. The fine movement displacement of this stage is about 2μ to 8μ, and the stage positioning ability to position the measurement part at the center of 1μ is naturally not satisfactory, which greatly impedes operability and causes a decrease in work efficiency. It had become.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stage drive device which solves the above-mentioned drawbacks of the conventional device and is capable of positioning a stage with high precision and quickly with an extremely simple configuration.

[Summary of the invention]

In order to achieve the above object, the present invention provides a stage moving device that moves a stage via a capstan shaft that rotates together with the drive shaft of a motor, which includes a rotating member that rotates integrally with the capstan shaft, and a rotary member that rotates integrally with the capstan shaft. A spring means is provided in pressure contact with the rotating member, and the rotation of the rotating member is lightly frictionally braked. It is a technical necessity to suppress the capstan shaft so that it stops at that position without slight rotational displacement.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA in FIG. A capstan shaft 13 is directly connected to a drive shaft 11 of a motor 10 with a reduction gear head via a shaft joint 12 .

This cap stand shaft 13 has two bearings 14A, 14.
rotatably supported by the housing body 15 via B,
Further, the housing body 15 is provided with a fitting portion 15a for positioning the motor 10, and the fitting portion 15a is provided with a fitting portion 15a for positioning the motor 10.
0 is fitted and supported, the drive shaft 11 is coupled to the axial center of the capstan shaft 13 without eccentricity. Further, a brake ring 16 is fixedly installed on the capstan shaft 13 between one of the bearings 14A and the shaft coupling 12, and the brake ring 16 is made of a friction-resistant material such as bearing steel. The free end of a leaf spring 17 fixedly attached to the housing body 15 is always in pressure contact with the outer periphery, so that the rotation of the cap stand shaft 3 is frictionally braked when the cap stand shaft 3 is stopped. Furthermore, one bearing 14A and the fitting part 15a
A brake chamber 15b containing a brake ring 16 and a leaf spring 17 between the two is sealed by a dustproof cover 18.

Q On the other hand, the housing main body 15 having the motor T and the cap stun shaft 13 is held via a spring member 20 by a holding member 19 fixed to a fixed part of the stage main body (not shown). Further, the cap stun shaft 13 is configured to abut on a contact portion 22 integrated with the moving stage 21, and the contact pressure thereof is adjusted by pressing the housing body 15 with an adjustment screw 23 provided on the holding member 19. has been done. Note that the stage 21 is configured to be fast-forwarded until it reaches the target position, and then switched to slow-speed forwarding when it approaches the target position. There is almost no obedience.

Since the embodiment shown in FIG. 1 is constructed as described above, the capstan shaft 13 is rotated via the shaft coupling 12 by supplying power to the motor 10, and the capstan shaft 13 is applied with an appropriate pressure by the adjusting screw 23. The movable stage 21 moves straight through the contact portion 22 that is in pressure contact with the movable stage 21 . In this case, a frictional braking force is always applied to the capstan shaft 13 by the leaf spring 17 via the braking ring 16. This frictional braking force causes unbalance of mechanical torsion accumulated inside the motor, contact pressure of the motor's brushes on the commi-stage, unbalance of the magnetic field, etc. that occurs when the power supply to the motor 10 is cut off. Small angle rotation of the drive shaft 11 of the motor 10 can be directly suppressed. Therefore, the stage 21 together with the capstan shaft 13 stops at the position where the power supply is cut off, and does not move further.

The frictional braking force requires only a small force, about 15 gcm to 2
Experiments have demonstrated that a friction brake torque of 9 gcm is sufficient. The load on the motor due to this frictional braking is extremely small compared to the drive torque of the motor controller equipped with a reduction gearhead.
There is almost no negative effect on the drive of the stage. Rather, this substantially increases the stage's resistance to external forces, making it less susceptible to floor vibrations and providing anti-vibration effects.

Further, since the brake ring 16 and the leaf spring 17 always slide in contact with each other, there is a possibility that fine dust may be generated due to wear. However, as shown in FIG. 1, the brake ring 16 and the leaf spring 17 are housed in the brake chamber 15b that is sealed by the dustproof cover 18, so even if dust is generated, it will not leak outside. . Therefore, there is no fear of contaminating the inside of a clean room in which semiconductor manufacturing equipment and related inspection equipment are installed.

Although the stage 21 is shown to be moved only in one direction in FIG. 1, it is configured to move the stage two-dimensionally in the X and Y directions by providing a plurality of drive devices including the motor 0. You may. Further, the stage 21 may be a rotary stage that can rotate around one axis. In addition, a brake ring (rotating member) 16
is fixed to the cap stan shaft 13, but it goes without saying that it may be formed integrally with the cap stan shaft 13.

〔Effect of the invention〕

As described above, according to the present invention, minute angular rotational displacement of the drive shaft after power supply to the motor is cut off is suppressed by the brake ring that rotates integrally with the capstan shaft and the leaf spring that is pressed against the brake ring. Therefore, highly accurate positioning of the stage is possible with an extremely simple and compact structure, and throughput can be improved. Furthermore, the resistance to external force of the stage is substantially increased by the frictional braking force, which can be expected to have the effect of improving the stage's vulnerability to vibration, and it is possible to eliminate the need for a complicated mechanism for vibration resistance of the stage.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a schematic perspective view of a conventional feed screw drive device, and FIG. FIG. 1 is a schematic perspective view of a conventional shaft-driven device. [Explanation of symbols of main parts] 10 ---------- Motor 11 ------- Drive shaft

Claims (3)

[Claims] (1) A stage moving device that moves the stage via a capstan shaft that rotates together with the drive shaft of a motor, which includes a rotating member that rotates integrally with the capstan shaft and a spring means that presses against the rotating member. 1. A stage driving device, characterized in that the stage driving device is configured such that rotation of the rotating member is frictionally braked by the spring means. (2) The rotating member (16) and the spring means (17) are connected to a brake chamber (
15b). The stage drive device according to claim 1, wherein the stage drive device is provided in the stage drive device 15b). (3) The rotating member (16) is connected to the capstan shaft (
13), and the spring means is fixed to the housing body (1) rotatably supporting the capstan shaft (13).
The stage drive according to claim 1 or 2, characterized in that the stage drive comprises a leaf spring (17) having one end fixed to the rotating member (16) and the other end being in contact with the rotating member (16). Device.