JPS6039045A - Table driving mechanism - Google Patents

Abstract

PURPOSE:To improve the rise-up action moving speed of a table when it is reciprocated, by providing a motor continuously rotated in the forward direction and that in the reverse direction so as to selectively transmit their rotation to a driving mechanism by a clutch. CONSTITUTION:In order to inspect a defect in a pattern of a photomask or the like used in the manufacturing process of a semiconductor device, the defect of the mask pattern is detected by placing a structure 26 to be inspected on X Y tables 3, 5 and reciprocating the structure in a direction X while moving it in a direction Y so as to be scanned by a detecting device. A moving direction of the X table 3 is switched by providing a motor 13 of forward rotation and a motor 15 of reverse rotation for reciprocating motion in the direction X so as to selectively transmit the rotation of the both motors to a feed screw 8 by electromagnetic clutches 17, 18. In this way, the accuracy of inspection is improved by improving the rise-up action of a moving speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to table driving technology, and more particularly to table driving technology suitable for semiconductor manufacturing equipment, such as appearance inspection equipment for samples such as photomasks and reticles.

[Background technology]

2. Description of the Related Art One of the manufacturing processes for semiconductor devices is a new appearance inspection process for inspecting whether or not defects have occurred in patterns of photomasks and reticles formed using photolithography technology. This horizontal placement of the external appearance is now almost automated, and while the specimen to be inspected, such as a photomask or reticle, is placed on an XY table and moved in the X and X directions, it is The pattern of the sample is detected by relatively scanning the pattern detection system using light, etc. by moving the sample, and the detected pattern information is compared with pattern design M/T data to inspect the pattern (appearance). (For example, Japanese Patent Laid-Open No. 53
(Refer to Publication No.-117978).

By the way, the aforementioned XY table in this type of device usually has an X drive section and an X drive section, and when scanning the sample with respect to the pattern detection system, it continuously moves back and forth in the A method of moving in small steps is used. Particularly when moving in the X direction, the table can be moved back and forth by controlling the rotation direction of a drive motor provided in the X drive section in forward and reverse directions.

However, in such an X-direction movement method, the forward and reverse speeds of table movement in the X-direction may differ depending on the slightly different rotational speeds of the drive motor in forward and reverse rotations. Since the motor rotation is stopped at the time of switching, the speed at the time of start-up, that is, when the table changes direction, becomes low, and a uniform table speed cannot be obtained. If such speed unevenness occurs, when comparing the M/T data in the pattern detection system with the detected data, the data on the sample side will be inconsistent in time with respect to the M/T data obtained at a uniform speed. Since the timings of comparison between the two do not match, accurate comparison, that is, observation of accuracy becomes impossible.

For this reason, in the past, the drive motor circuit was controlled so that the rotational speeds in forward and reverse directions were equal, but since the forward and reverse rotations were switched frequently and at high speeds, there was a problem in that a response delay occurred, and It is extremely difficult to achieve stabilization of the rise rate at times.

[Purpose of the invention]

An object of the present invention is to provide a table drive mechanism that can keep the speed of a reciprocating table constant and stable.

Another object of the present invention is to provide a table drive mechanism for an appearance inspection apparatus that is capable of performing an appearance inspection of a sample with high precision by making the reciprocating speed of the table constant and stable.

The above seven objects and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, a forward rotation motor and a reverse rotation motor are respectively connected to a table that is reciprocated, and each motor is provided with a clutch that can cut off transmission of rotational force, and the clutch is configured to be selectively activated. This makes it possible to reciprocate the table while continuously rotating each motor, thereby easily achieving constant and stable table movement speed.

〔Example〕

FIGS. 1 and 2 show an embodiment in which the present invention is applied to a photomask appearance inspection apparatus, with FIG. 1 being a plan view and FIG. 2 being a front view. In the figure, reference numeral 1 denotes a base, on which a pair of rails 2゜2 extending in the X direction are laid, on which an X table 3 is mounted so that it can move in the X direction. A pair of rails 4.4 extend in the Y direction on top, and a Y table 5 is mounted so as to be movable in the Y direction.

The X-table 3 has a drive piece 6 integrally formed on one side thereof 17, and the drive piece 6 has a worm shaft 8 supported at both ends by bearings 7.7 fixed to the base 1. They are screwed together. This worm shaft 8 is connected to the X table 3.
It extends in the X direction along one side, and therefore, when the worm shaft 8 is rotated, the drive piece 6, that is, the X table 3 screwed thereon, moves forward according to the direction of rotation of the worm shaft. Or it will be returned. Further, the worm shaft 8 has large-diameter gears 9 and 10 fixed to each end thereof, and these gears 9 and 10 are connected to each other.
．． 10 are meshed with small-diameter drive gears 11 and 12, respectively. One drive gear [1] is a forward rotation motor 13.
The rotation output shaft 14 of each motor is connected to the other drive gear 12, and the rotation output shaft 16 of a reverse rotation motor 15 that rotates in the opposite direction to the normal rotation motor 13 is connected to the other drive gear 12.
An electromagnetic clutch 17.18 that can turn on and off the transmission of rotational force is interposed between 4.16 and 13.16, so that the rotational force of each motor 13.15 can be transmitted or not transmitted to each drive gear 11.12. ing.

On the other hand, a drive piece 19 is similarly provided on the Y table 5, and is screwed onto a worm shaft 20 supported on the X table 3 in the Y direction. The worm shaft 20 has bearings 21, 2
A gear 2 that can be rotated by 1 and is fixed to one end.
2 is meshed with a gear 24 rotated by a motor 23. For example, a pulse motor is used for this motor 23.

The normal rotation motor 13. Reverse motor 15° clutch 17, 18. The motor 23 is connected to a control circuit 25,
Electrical control is performed here.

On the other hand, a sample to be visually inspected, for example, a photomask 26, is placed on the Y table 5, above which a pattern detection system 27 is fixedly supported by an apparatus fixing part (not shown) using an optical means. The system projects visible light onto the surface of the photomask 26 and detects the photomask pattern using the transmitted light.The pattern horizontal use system 27 has a comparison section with the M/T data, and the detection This pattern is M/
By comparing with the T data, it is possible to inspect whether the pattern is good or bad.

According to the above configuration, in the control circuit 25, the normal rotation motor 13
The reverse rotation motor 15 is controlled so that it always rotates continuously at a constant speed. In this case, since each motor is continuously rotated, problems such as responsiveness do not occur, and therefore it is easy to control the rotational speed of each motor 13, 15 to match and to be constant. If the control circuit 25 performs pressure control so that the clutches 17 and 18 can be selectively turned on or off, for example, if only the clutch 17 of the normal rotation motor 13 is turned on, the rotation output shaft 14 of the normal rotation motor 13 The worm shaft 8 is rotated forward through the gear 11.9, and the X table 3 is moved forward in the X direction to the left in the figure.

When the X table 3 has moved all the way to the left, if the clutch 17 is turned off and the clutch 18 is turned on, the rotational force of the rotational output shaft 16 of the reversing motor 15 is transferred to gear 1.
2°10 to the worm shaft 8.
Reverse. As a result, the X table 3 is
It will be moved back in the direction. This operation prevents speed unevenness during start-up due to the motor stopping rotation, speed unevenness due to speed differences between forward rotation and reverse rotation of the motor, and achieves the effect of reciprocating movement at a constant and stable speed. I can do it.

On the other hand, if the motor (pulse motor) 23 is operated at the time of direction switching in synchronization with the reciprocating movement of the Then, the Y table 5 is further moved slightly in the Y direction. As a result, the photomask 26 on the Y table 5 is moved as shown in FIG. 3 together with the movement of the X table, and the entire surface is scanned by the pattern detection system 27 for pattern inspection or appearance inspection. will be carried out. Therefore, since the photomask can be scanned at a constant and stable speed with respect to the pattern detection system, overlay comparison with M/T data can be suitably performed, and accurate and highly accurate inspection can be performed.

〔effect〕

(1) Since the continuously rotating forward motor and reverse motor are connected to the table by switching between them using a clutch and configured to transmit rotational force, the rotational speed of the motor can be easily controlled. In both cases, the table can be reciprocated at a constant and stable speed without being affected by uneven startup speed of the motor.

(21) Since the normal rotation motor and the reverse rotation motor are switched by a clutch, the table movement direction can be easily controlled by simply switching the control signal to the clutch.

(3) Since the reciprocating speed of the table can be kept constant and stable, a transverse strain device that scans and inspects the external appearance of the sample on the table can achieve accurate and highly accurate external appearance when compared with M/T data. Tests can be carried out.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, a belt means may be used in place of the worm shaft, and a mechanical or hydraulic clutch may be used in place of the disengaged electromagnetic clutch. Further, the arrangement may be such that the X table and the Y table are exchanged. In addition, a worm shaft is provided on one side of the table and the other side, and a motor that rotates in the forward direction or a motor that rotates in the reverse direction is connected to the worm shaft through a gear etc. to operate in the direction of the worm shaft. It's okay.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to the visual inspection equipment for semiconductor devices, which is the background field of application, but the invention is not limited thereto. It can be applied to the reciprocating table mechanism of equipment that requires

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a schematic plan view for explaining scanning of a photomask (sample). 3...X table, 5 ...Y table, 8...worm shaft, 9-12...gear, 13-gear forward rotation motor, 1
5... Reverse motor, 17.18... Electromagnetic clutch,
2゜...Worm shaft, 23...Motor, 25...
Control circuit, 26... Sample (photomask), 27...
Pattern detection system. Ma 255

Claims (1)

[Claims] 1. In a table drive mechanism configured to reciprocate the table by a drive motor, a motor that continuously rotates in the forward direction and a motor that continuously rotates in the reverse direction are provided, respectively. A table drive mechanism characterized in that a clutch capable of interrupting power transmission is provided between each of the motors and the table, and the clutch is configured to be selectively actuated. 2. The table drive mechanism according to claim 1, wherein an electromagnetic clutch is interposed on each rotating shaft of each motor, and each rotating shaft is gear-coupled with a worm shaft for moving the table. 3. The table is a table on which a sample of the visual inspection device is placed, and the motors, clutches, etc. are incorporated in an X drive unit that reciprocates in the X direction, as described in claim 1 or 2. table drive. 4. The table has an X drive unit that moves the table stepwise in the Y direction.