JP2694597B2 - Centrifuge with unbalance correction mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifuge with an unbalance correction mechanism used for dehydrating and drying a cleaned semiconductor substrate such as a wafer by centrifugal force.

[0002]

2. Description of the Related Art In an integrated circuit manufacturing line for a wafer which is a semiconductor substrate, a plurality of wafers are passed through various steps in a state where they are accommodated in a cassette, and defective products in each step are appropriately removed. In the vicinity of the final stage of the line, cleaning processing is performed in cassette units, followed by dehydration and drying in a centrifuge.

The centrifuge in this case is generally equipped with a rotary table 1 which is rotated at a high speed as shown in FIG. 6, and its use is to accommodate a plurality of cleaned wafers w. After fixing the cassette 2 to a specific position on the rotary table 1, the rotary table 1 is rotated.

[0004]

In each of the cassettes fixed to the rotary table of the conventional separator described above, defective wafers are removed in the middle of the manufacturing line, so that the same number of wafers are always accommodated in the same arrangement. Therefore, if the cassette after the cleaning process is immediately fixed to the rotary table and the table is rotated,
Vibration due to imbalance due to uneven distribution of wafers may occur and damage the wafer.

Therefore, in the prior art, after the dummy wafers are replenished to the nonexistent portions of the wafers of the respective cassettes automatically or artificially by the robot, and the apparent number and arrangement of the wafers of the respective cassettes are made the same. I am trying to fix the cassette of to the rotary table,
Such handling is wasteful and impairs the efficiency of processing.

An object of the present invention is to provide a centrifuge with an unbalance correction mechanism that can easily solve such problems.

[0007]

In order to achieve the above object, according to the present invention, a rotary table driven around a rotation center axis is covered at an arbitrary specific diameter position on a circumference around the rotation center axis. In addition to providing a fixing means for fixing a pair of cassettes containing the processed material, an imbalance correcting mechanism is symmetrically provided on each side of the table having the diameter as a boundary. A weight whose height position substantially coincides with the height of the center of gravity of the cassette is guided in the diametrical direction, and a weight which is designed to displace the weight to a required position by inputting an appropriately generated unbalance correction signal. And a position adjusting actuator.

At this time, the weight position adjusting and operating device displaces the weight in a position corresponding to the screw mechanism for displacing the weight, the speed reduction transmission mechanism for transmitting the rotation of the motor to the screw mechanism, and the unbalance correction signal. And a computer control device for rotating the motor as described above.

[0009]

The weight position adjusting and actuating device receives the unbalance correction signal and displaces the weight by an appropriate amount, and the static and dynamic parts of the rotating part due to the difference in the quantity and arrangement of the objects to be processed housed in each cassette. It will be possible to eliminate the actual imbalance. Therefore, it is not necessary to replenish the conventional dummy wafer. This imbalance is solved by fixing a pair of cassettes containing the object to be processed at a specific diameter position on the circumference centered on the rotation center axis on the rotation table driven around the rotation center axis. Fixing means are provided, and the unbalance correction mechanism is symmetrically provided on each side of the table with the diameter as a boundary, and the weight of the unbalance correction mechanism is displaced at a height position substantially corresponding to the height of the center of gravity of the cassette. It is relatively easy to perform by simply displacing the weight in a straight line because of what is done.

Further, in the weight position adjusting operation device,
The computer control device rotates the motor by an appropriate amount according to the required unbalance correction signal, and this rotation is transmitted to the screw mechanism by the reduction transmission mechanism, and the screw mechanism displaces the weight by the wedge action of the screw. The screw mechanism and the speed reduction transmission mechanism function to position the weight accurately and firmly.

[0011]

1 to 5 relate to an embodiment of the present invention and will be described below with reference to these drawings.

The rotary table 1 is driven around a rotation center axis 3, and a wafer as an object to be processed is placed at an arbitrary specific diameter d position on a circumference centered on the rotation center axis 3. A pair of cassettes 2, 2 accommodating w ...
There are provided fixing means 4, 4 for fixing the.

Here, the cassette 2 has been used conventionally, and accommodates a plurality of wafers w ...

The fixing means 4 may be appropriately formed, but it is designed so that the cassette 2 can be easily attached and detached. For example, a fitting for connecting the cassette 2 and the rotary table 1 to each other is provided. The device is provided with a pin or the like for restricting the careless separation of the both.

However, 5 and 5 are unbalance correction mechanisms symmetrically arranged on each side of the rotary table 1 with the diameter d as a boundary, and each unbalance correction mechanism 5 is a main body fixed to the rotary table 1. A casing 5a and a weight g which is guided through the guide rail 6 fixed to the casing 5a in the diameter d direction at a height position substantially corresponding to the height of the center of gravity of the cassettes 2, 2. A weight position adjusting and actuating device 7 is provided for inputting an unbalance correction signal and displacing the weight g to a required position.

The weight position adjusting and actuating device 7 has a screw mechanism 8 for displacing the weight g, a speed reduction transmission mechanism 10 for transmitting the rotation of the motor 9 to the screw mechanism 8, and an outside of the rotary table 1. And a computer control device 11 for rotating the motor 9 so that the weight g is displaced to a position corresponding to an unbalance correction signal (positional information) input from the other side.

The dicing screw mechanism 8 has a body casing 5a.
In addition to providing a screw shaft 13 erected via bearings 12, 12 at a specific position of the nut shaft 14, a nut body 14 is screwed into the screw shaft 13 via a ball to form a ball screw, and the nut body 14 is used as a nut holder. It is assumed to be fixed to the weight g via 14a.

The deceleration transmission mechanism 10 has the following structure. That is, the bearing 1 is placed at a specific position on the body casing 5a.
A rotary shaft 16 is installed in parallel with the screw shaft 13 through 5, 15, and a sprocket 17 is fixed to one end of the rotary shaft 16, and a sprocket 18 is fixed to one end of the screw shaft 13 as well. Hang the chain 19 between the sprockets 17 and 18. On the other hand, the reduction gear 20 is fixed to the main body casing 5a, and the large gear 21 is attached to the input shaft 20a of the reduction gear 20.
And the sprocket 22 is fixed to the output shaft 20b. The large gear 21 meshes with the small gear 24 fixed to the output shaft 9a of the motor 9 fixed to the main body casing 5a through the support piece 23, and the sprocket 2
A chain 26 is wound around the sprocket 25 fixed to the rotary shaft 16.

The computer control unit 11 has a built-in microcomputer and is fixed to the control unit main body 2 via a support piece 27 fixed to the main body casing 5a.
8, a rotation amount detection device 29 for detecting the rotation amount of the motor 9, and a position detection device 30 for detecting the position of the weight g. At this time, the rotation amount detecting device 29 fixes the disk 31 having a large number of notches on the periphery to the shaft obtained by extending the output shaft 9a of the motor 9 and detects the notches, and the transmission type sensor 32. Is provided so that the number of the notches that have passed through the 32 sensors can be counted when the motor 9 rotates. Further, the position detecting device 30 includes a detected piece 30a fixed to the weight g.
And three transmissive sensors 34a, 3a fixed to the body casing 5a via a support piece 33 to detect this.
4b and 34c, one sensor 34a is adapted to detect that the weight g is located at the reference position, and the other sensors 34b and 34c are adapted to detect that the weight g has reached the limit position. There is.

An example of use of the separator of the present invention constructed as above and its operation will be described. The cassettes 2 and 2 are fixed on the rotary table 1 as shown in FIG. 1 by a robot or the like after undergoing various manufacturing steps in a state of containing a plurality of wafers w. At this time, since the defective wafer w is removed from each cassette 2 in the previous process, the number of wafers to be accommodated and the arrangement thereof may be different.

By the way, the number of wafers w of these cassettes 2 and 2 is detected in the previous step, and this number is stored in the control computer of the manufacturing line.

On the basis of this stored information, the computer can operate the cassettes 2 and 2 fixed to the rotary table 1.
Weight g in relation to the number and arrangement of the wafers w,
Numerical information indicating what position g should be displaced is output, and the numerical information thus obtained is input to the computer control devices 11 and 11 as an imbalance correction signal.

If the number and arrangement of the wafers w in the pair of cassettes 2 and 2 are the same, the computer controllers 11 and 11 indicate that the weights g and g should be located at the reference position. Numerical information is input as an imbalance correction signal, which allows the position detection device 3
The same control device 11, 11 which grasps the current position of the weights g, g by the related operation of the sensor 34a of 0 and the rotation amount detection device 29 determines in what direction the weights g, g should be moved. A judgment is made to rotate the motor 9 by a required amount in a required direction and move it to a reference position. At this time, the rotation of each motor 9 passes through the gears 24, 21, the speed reducer 20, the chain 26, the rotary shaft 16 and the chain 19 and then the screw shaft 1
3, the screw shaft 13 moves the weight g through the nut body 14.

On the other hand, when the number and arrangement of the wafers w in the pair of cassettes 1 and 1 are not the same, the computer controller 11 determines the optimum position of the weights g, g corresponding to the difference in the number and arrangement of the wafers at that time. Numerical information represented is input as an imbalance correction signal, whereby the control devices 11, 11 move the weights g, g to the position corresponding to the input numerical information by the same operation as described above. Become.

After the weights g have been positioned in this way and static and dynamic imbalance of the rotary parts such as the rotary table 1 have been eliminated, the rotary table 1 is rotated at a high speed, and during this rotation. , The cleaning liquid attached to the wafers w is separated to the outside of the rotary table 1 by the centrifugal force, so that the wafers w are efficiently dried.

While the rotary table 1 is rotating, centrifugal forces act on the weights g, g and the cassettes 2, 2.
These centrifugal forces act at approximately the same height and are in a balanced state on a plane orthogonal to the rotation center axis 3,
These centrifugal forces do not generate couples along the vertical surface and are in a dynamic balanced state, and not only vibration of the rotary table 1 in the radial direction of rotation but also vibration of its thrust (vertical direction). Suppressed.

Thus, the wafer w of the pair of cassettes 2, 2
When the dehydration / drying process of ... Is completed, rotation of the rotary table 1 is stopped, and thereafter, the same operation as described above is repeated.

The above-mentioned operation can be continuously and fully automatically performed, but a partial manual operation is optional.

In the above embodiment, the position of the weight g is determined by the unbalance correction signal based on the number of wafers w accommodated in each cassette 2 and the arrangement thereof. A synchronous sensor or a vibration sensor is provided in the bearing portion of the rotation center shaft 3 to continuously detect the vibration state of the table 2 during rotation, and the position of the weight g is continuously determined by an imbalance correction signal calculated based on this detection information. Alternatively, the position of the weight g may be determined by the unbalance correction signal of the former before the rotary operation of the rotary table 1 and the unbalance of the latter may be determined during the rotary operation of the table 1. It is also possible to adjust the position of the weight g with a correction signal.

[0030]

According to the present invention having the above-described structure, it is possible to reduce the difference in the quantity and the arrangement of the objects to be processed (wafers) accommodated in each cassette by the simple means of automatically linearly displacing the weights. Not only static imbalance caused but also dynamic imbalance is achieved, and not only radial vibration of the rotary table 1 but also vibration in the thrust direction can be prevented, improving the processing efficiency of dehydration and drying. I will get it.

According to the second aspect of the invention, the weight can be accurately and firmly positioned by the action of the speed reduction transmission mechanism and the screw mechanism.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of a centrifuge according to the present invention.

FIG. 2 is a plan view showing an unbalance correction mechanism of the centrifugal separator.

FIG. 3 is a partial cross-sectional view of a side view of the imbalance correction mechanism.

FIG. 4 is a front view showing the inside of the imbalance correction mechanism.

FIG. 5 is a view showing a weight position detection device of the imbalance correction mechanism.

FIG. 6 is a diagram showing a conventional centrifuge.

[Explanation of symbols]

 d Specific diameter position g Weight w Wafer (object to be processed) 1 Rotary table 2 Cassette 3 Rotation center axis 4 Fixing means 5 Imbalance correction mechanism 7 Weight position adjustment actuating device 8 Screw mechanism 9 Motor 10 Deceleration transmission mechanism 11 Computer control device

Claims (2)

(57) [Claims] 1. A pair of cassettes for accommodating an object to be processed are fixed to a rotary table driven around a rotation center axis at an arbitrary specific diameter position on a circumference around the rotation center axis. Along with the fixing means, an unbalance correction mechanism is symmetrically provided on each side of the table with the diameter as a boundary, and the unbalance correction mechanism has a height position substantially corresponding to the height of the center of gravity of the cassette in the diametrical direction. And a weight position adjusting and actuating device for displacing the weight to a required position by inputting an imbalance correction signal generated appropriately. Centrifuge with correction mechanism. 2. The weight operating device includes a screw mechanism for interlocking displacement of the weight, a speed reduction transmission mechanism for transmitting the rotation of the motor to the screw mechanism, and an unbalance correction signal supplied from the outside of the rotary table. The centrifuge with an imbalance correction mechanism according to claim 1, further comprising a computer control device for rotating the motor so that the weight is displaced to a position corresponding to the position information of the above. Machine.