JP2000264438A - Wafer conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly convey a conductor wafer and to easily deliver the same, without deteriorating a surface and contaminating the same with particles by providing a conveying chamber with a means for supplying an inert gas to the lower surface of a conveying plate for floating the conveying plate, and a means for moving the floated conveying plate. SOLUTION: A conveying chamber 12 is provided with a plurality of grooves 8, and Ar 14 as inert gas is introduced into these grooves 8 through a valve 11 whereby a conveying plate receives the bouyancy capable of balancing a product of the total area of the grooves 8 multiplied by the pressure of Ar 14 and a weight of a conveying plate 4, from its lower part to be floated. Then a linear motor comprising a rotor 3 and a stator 9 is driven, and the floated conveying plate 4 is conveyed in a non-contact state with the conveying chamber 12. At this time, the pressure of Ar 13 and an exhausting speed of a pump are adjusted to keep a clearance 7 between the lower surface of the floated conveying plate 4 and an upper surface of the conveying chamber 12 below a desired value. To prevent a large amoung of Ar 14 from leaking into the conveying chamber 12 through the clearance 7, a pure iron plate 2 is buried on a lower surface central part of the conveying plate 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer transfer apparatus, and more particularly, to a semiconductor wafer production line for performing various processes using many processing apparatuses such as an etching apparatus and a CVD apparatus. The present invention relates to a wafer transfer device that can effectively prevent various obstacles such as contamination or particle adhesion and transfer a semiconductor wafer in a vacuum, air, or a desired gas atmosphere.

[0002]

2. Description of the Related Art As is well known, in a conventional semiconductor device production line, a semiconductor wafer is put in a container called a mini-environment, and the inside of the container is made to have a dry air or nitrogen atmosphere. The transfer between the processing apparatuses was performed by the transfer robot.

However, since various processes are performed on a semiconductor wafer in a cassette unit, the semiconductor wafer is exposed to the air for a long time, so that the surface of the semiconductor wafer is deteriorated by oxidation or nitridation, or adhesion of organic substances or various particles. And obstacles such as pollution are likely to occur. for that reason,
When a semiconductor wafer is placed in the next processing apparatus, it is necessary to clean and clean the surface of the semiconductor wafer, and the throughput has been reduced, which has been an obstacle to further miniaturization of the semiconductor device.

In order to solve this problem, a carrier plate on which a semiconductor wafer is mounted is magnetically levitated, and is conveyed in a vacuum using a linear motor; the magnetically levitated carrier plate is conveyed by magnetic force; Three methods have been proposed in which processing is performed in a chamber called a cluster, and a plurality of such clusters are connected (multi-chamber system).

[0005]

However, since both of the above methods and the above methods perform magnetic levitation of the carrier plate,
It is necessary to arrange an electromagnet requiring a large current along the transport path. Therefore, it has been difficult not only to increase the size of the apparatus, but also to attach various mechanisms for taking out the semiconductor wafer, changing directions, moving up and down, waiting, and recognizing the wafer number.

In addition, in the above method, not only the linear motor and the heat generated by the motor generate outgas, but also the surrounding temperature rises and each component thermally expands.
The gap between the lower surface of the transfer plate and the upper surface of the transfer chamber could not be kept constant, and it was difficult to satisfactorily lift and transfer the transfer plate. In the above method, a mechanism for detecting the position and orientation of the transport plate and controlling them by an electromagnetic force is complicated and has low reliability. Further, in order to lift and transfer the transfer plate by magnetic force, it is necessary to make the wall between the electromagnet and the vacuum container thin, and as a result, a vacuum double container is required and the cost increases. .

In addition, the above method has low flexibility to process changes, for example, it is difficult to add a processing chamber when the process is changed.
Both have many problems and have not been put to practical use.

A first object of the present invention is to solve the above-mentioned problems of the prior art and to carry out various processes by moving a semiconductor wafer in a desired direction without obstruction such as surface deterioration or contamination due to adsorption of particles. An object of the present invention is to provide a wafer transfer device that can easily transfer the device to the atmosphere and the like.

A second object of the present invention is to move a semiconductor wafer in each direction, detect the location of a wafer, or wait or store an empty carrier plate without a complicated or large-sized mechanism. It is an object of the present invention to provide a low-cost wafer transfer device capable of performing such a process.

[0010]

A wafer transfer apparatus according to the present invention for solving the above problems has a transfer chamber for transferring a transfer plate on which a semiconductor wafer is mounted to a desired place or various processing apparatuses. The transfer chamber has a means for supplying an inert gas to the lower surface of the transfer plate to float the transfer plate and a means for moving the lifted transfer plate. Since the semiconductor device manufacturing line includes many various processing apparatuses, the transfer chamber is suitable for transferring a transfer plate between the processing apparatuses and removing the transfer plate from the processing apparatuses.

That is, in the present invention, the carrier plate on which the semiconductor wafer to be processed is mounted is, for example, Ar
A suitable inert gas such as (argon) is blown upward from the lower surface of the transfer plate to float, and the lifted transfer plate is transferred without contact with the transfer chamber.

In the above prior art, since the transfer plate is magnetically levitated in a vacuum, the heat generated by the operation of the linear motor does not diffuse to the outside, so that it is inevitable that the surrounding parts expand due to a rise in temperature. In addition, the gap between the lower surface of the transfer plate and the upper surface of the transfer chamber fluctuates, making it difficult to float and transfer the transfer plate satisfactorily.

However, in the present invention, instead of magnetic levitation,
The carrier plate is lifted by blowing up the inert gas from below. Therefore, heat generated from the linear motor or the like is easily dissipated to the outside via the inert gas, and generation of the released gas and thermal expansion of peripheral components are effectively prevented. Therefore, the gap between the lower surface of the transport plate and the upper surface of the transport chamber is maintained at a desired value, and the floating and transport of the transport plate are performed very easily, and the problem of the conventional method is solved. Further, since no magnetic force is used to move the lifted transport plate, a complicated and large-sized device is not required for detecting the position of the transport plate, and the problem of the above-described conventional method does not occur. Further, since means for floating and conveying the transfer plate are provided for each transfer chamber, they can follow the process variation well, and the problem of the above-mentioned conventional method is solved.

As a means for moving the above-mentioned transporting plate, a linear motor capable of transporting the transporting plate without contact with the transporting chamber is practically preferable. Although heat is generated by the operation of the linear motor, there is no problem because the generated heat is radiated to the outside through the inert gas introduced as described above.

There are several modes for introducing or supplying the above-mentioned inert gas. However, it is most practically preferable to introduce or supply the inert gas through a plurality of grooves provided in the transfer chamber. By appropriately adjusting the size, shape, or number of these grooves, the carrier plate can be floated satisfactorily. These grooves can be arranged in the direction in which the conveying plate is conveyed, but may be arranged in other directions in order to facilitate the floating of the conveying plate.

By providing a means for controlling the pressure of the inert gas to a desired value, the distance between the transfer plate and the transfer chamber is controlled to a desired value, and the transfer of the transfer plate is performed extremely well. be able to. Further, in order to carry out the floating and transport of the transport plate by introducing the inert gas without any trouble, it is preferable to have a means for evacuating the transport chamber to reduce the pressure.

By providing a valve for controlling the introduction of the inert gas into the groove in the transfer chamber, the introduction and the stop of the inert gas into the groove can be easily performed using this valve. be able to. Place a magnet at the top of this valve,
In addition, a magnetic plate can be embedded at a predetermined position on the lower surface of the transport plate. In this case, when the plate of the magnetic material comes above the valve, the magnet is attracted, the valve rises, the valve opens, and the inert gas is introduced into the groove. When the carrier plate moves and the magnetic plate moves away from the position above the magnet, the magnet is not attracted, so that the valve is lowered and the valve is closed, and the introduction of the inert gas is stopped. That is, the supply of the inert gas is performed only when the conveying plate is above the valve, and is not supplied at other times. The exposed lower surface of the transport plate and the lower surface of the magnetic plate are formed to be flat.

In order to perform various processes on the semiconductor wafer, it is necessary to change the transfer direction of the transfer plate, move up and down, detect the location of the wafer, or wait for the transfer plate. A mechanism for detecting the presence of a wafer or waiting for a transport plate, respectively.
It is practically advantageous to provide it adjacent to a desired transfer chamber or processing apparatus.

A mechanism for taking out the semiconductor wafer from the transport plate into the atmosphere or into a desired processing apparatus is provided.
By providing the transfer chamber in the desired transfer chamber, practical convenience is remarkably improved. Further, a sensor for recognizing the number of the semiconductor wafer is disposed in a desired transfer chamber, and means for controlling the next transfer of the semiconductor wafer by a signal from the sensor can be provided. In many cases, it is practically advantageous for transportation to such places.

[0020]

Embodiment 1 A first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG. 1 and 2 are views showing a cross section and a planar structure of the transfer chamber of the present embodiment, respectively. As is apparent from FIG. 1, a plurality of grooves 8 are formed in the transfer chamber 12, and Ar 14 is used as an inert gas in the grooves 8 as a valve 11.
Introduced via By doing so, the transport plate 4 placed thereon received a floating force from below, which balanced the product of the total area of the groove 8 and the pressure of the supplied Ar and the weight of the transport plate 4, and floated. Next, by driving a linear motor composed of the rotor 3 and the stator 9, the floating transport plate 4 was transported without contact with the transport chamber 12.

In the present embodiment, the pressure of Ar and the pumping speed of the pump were adjusted so that the gap 7 between the lower surface of the floating transfer plate 4 and the upper surface of the transfer chamber 12 was 5/100 mm or less. Further, a large amount of Ar is transferred to the transfer chamber 12 through the gap 7.
Since it is not preferable to leak into the inside, in order to prevent this, the pure iron plate 2 is buried in the center of the lower surface of the transport plate 4 as shown in FIGS. When the transport plate 4 comes over the groove 8, the valve 11 having the permanent magnet 15 at the upper portion provided at the Ar supply port 14 is pulled by the pure iron plate 2 and rises to separate from the packing 13, The valve 11 is opened and A
r is introduced from the valve 11 into the groove 8 via the gap, and the transport plate 4 floats. However, when the transport plate 4 moves and its end comes near the groove 8, the pure iron plate 2 moves away from the position above the permanent magnet 15, so that the valve 11 is lowered and closed, and Ar Installation has stopped. That is, in the present embodiment, the valve 11 is opened and the inert gas is introduced into the groove 8 only when the transfer plate 4 is above the valve 11, and when the transfer plate 4 is separated from the position, the valve 4 closes. Since the introduction of the inert gas was stopped, the inflow of extra Ar was prevented. In this embodiment, the pure iron plate 2 is used. However, the present invention is not limited to pure iron, and it goes without saying that a magnetic plate that generates an attractive force with a magnet can be widely used.

Since the conductance of the gap 7 is small and the pressure for floating the transfer plate 4 is small, the leakage amount of Ar from the groove 8 to the transfer chamber 12 is small, and the pressure rise is also small. Further, the linear motor generates heat as it rotates, but the generated heat is radiated to the outside via the Ar, so that the temperature rise of the peripheral components is effectively prevented. The gap 7 is a vacuum pump (not shown) used for exhaust.
Is adjusted to an appropriate value based on the pumping speed, pressure value, and conductance.

Since the transport speed of the transport plate 4 by the linear motor is about 100 mm / sec and the transport time is about several seconds, a pulse-like pressure rise occurs during this time, and Ar is physically adsorbed on the surface of the semiconductor wafer 1. It is inevitable.
However, since the condensation coefficient and activation energy of Ar to the semiconductor wafer 1 are small, if the supply of Ar is stopped after the transfer and the pressure of Ar is reduced, Ar on the surface of the semiconductor wafer 1 is desorbed within one second. Release and no damage occurred.

In this embodiment, the grooves 8 are arranged in a line with respect to the traveling direction 25 of the carrier plate 4. However, in order to float the carrier plate 4 in a balanced manner, the number and position of the grooves 8 are appropriately changed. You may. In this embodiment, Ar gas is used as the inert gas.
Was used, but it is not limited to Ar, and various other inert gases can be used.

In this embodiment, the weight of the transport plate 4 is 2.1.
kg, the total area of the groove 8 was 114.7 cm ² , and the pressure of Ar in the groove 8 was 1.8 kPa, a buoyancy of 2.1 kgf was obtained. When the pressure of Ar in the groove 8 is 1.8 kPa and the gap 7 is 2/100 mm, the heat conduction coefficient is 40 W / m ^2.
K, most of the pulsed input energy is transferred to the transfer chamber 12 side by the heat conduction of Ar, and it is confirmed that the linear motor and the parts around it are prevented from increasing in temperature and the minute gap 7 can be secured. Was. In this case, the leakage amount of Ar is 6 × 10 ⁻⁴ Pa · m ³ / s,
When the air is evacuated using a mechanical booster pump with a displacement of 1500 l / min and the five conveying plates 4 are simultaneously conveyed,
The pressure is from 1.3 × 10 ⁻² Pa to 1.2 × 10 ⁻¹ Pa
To 1.3 x 1
The pressure returned to a pressure close to 0 ^-2 Pa, and no trouble occurred.

After the inside of the transfer system is evacuated and evacuated,
When the transport plate 4 is transported while supplying Ar into the groove 8 without evacuating by the vacuum pump, the pressure in the transport chamber rises, but the pressure in the system is reduced to 1 atm by adjusting the supply amount of Ar. It was confirmed that there would be no particular safety problem if it was not exceeded. Since the transfer system is completely sealed, there is no possibility of contamination from the outside, and the transfer system is particularly suitable for transfer between processing apparatuses used in an atmospheric pressure atmosphere. Although the adsorption of Ar on the surface of the semiconductor wafer 1 is inevitable, there is no problem since it is quickly desorbed after the transfer as described above.

Embodiment 2 In a semiconductor device manufacturing apparatus, various processing apparatuses for performing processing in vacuum and in the atmosphere are mixed. The semiconductor wafer stored in the transfer plate is transferred under a high vacuum, enters various processing apparatuses, and is subjected to each processing. This embodiment is an example of a mechanism for taking out a semiconductor wafer from a carrier plate, and will be described with reference to FIG.

The transfer plate 4 containing the semiconductor wafer 1 enters the transfer chamber 12 and stops. The bellows 24 is used to move the outer shaft 26 of the double shaft to the upper part, thereby moving the flange 27 on which the carrier plate 4 is placed to the upper part, and by means of the packing 21 arranged on the upper surface of the flange 27, the transport chamber 12 And the upper lock chamber 17 are isolated from each other.

Next, dry nitrogen 19 is stored in the lock chamber 17.
, And the upper flange 16 is rotated slightly upward using the swing cylinder 20, and furthermore, the inner shaft 25 of the double shaft and the chuck thereon are further compressed by the compressed air 6 and the bellows 24. 18 and the semiconductor wafer 1 were pushed upward. The pushed-up semiconductor wafer 1 was received by a fork (not shown) or the like, and was transferred to an atmospheric pressure processing chamber (not shown). The transfer from the processing chamber at atmospheric pressure to the vacuum transfer system may be performed in the reverse order of the present embodiment.

In the present embodiment, since the gap between the semiconductor wafer 1 and the upper flange 16 is small, it is not necessary to reduce the usual exhaust speed to prevent the particles from adhering due to the steam aerosol. The evacuation could be performed in a short time.

When the semiconductor wafer 1 is put into a vacuum processing apparatus, nitrogen or the like is not introduced into the lock chamber 17 and
After the semiconductor wafer 1 is lifted upward using the internal shaft 25, the semiconductor wafer 1 may be inserted into a vacuum processing apparatus using a fork or the like (not shown). Although not shown, the semiconductor wafer 1 may be moved into and out of the vacuum processing chamber by taking in and out the semiconductor wafer 1 from the side of the transfer chamber 12 via a slit valve.

In the above prior art, there is no particular problem when the semiconductor wafer is transferred from a vacuum chamber to another vacuum chamber. However, when the semiconductor wafer is taken out into the atmosphere, particles are generated when a gate valve is used, and a slit valve is used. There was a problem that the atmospheric pressure chamber could not be maintained at atmospheric pressure. However, in this embodiment, the semiconductor wafer could be taken out in the vacuum chamber and the atmospheric pressure without such a problem.

Embodiment 3 While the semiconductor wafer is being processed in the processing apparatus, the transport plate needs to be on standby. FIG. 5 shows an example of a transport plate storage mechanism required for that.

A rotary table 28 is provided in the rotary chamber 22, and a linear motor including the rotor 3 and the stator 9 is mounted on the rotary table 28. When the transport plate 4 comes on the turntable 28, the turntable 28
Is rotated by 90 °, the transfer plate 4 on the turntable 28 is moved to a desired transfer chamber 12 by the linear motor. Alternatively, the transport plate 4 may be stored while being stacked using a suitable lifting mechanism (not shown). When recognizing the number of the semiconductor wafer being transported and transporting it to the next processing apparatus, a mechanism for recognizing the wafer number from inside or outside the transport system may be added in the middle of the transport system.

[0035]

As is clear from the above description, according to the present invention, semiconductor wafers can be transported between processing apparatuses and factories without fear of deterioration or contamination. Also, since the wafer is not magnetically levitated, it has many advantages such as simple structure and easy miniaturization, low manpower required for transportation, and continuous flow production. It is extremely useful for reduction, improvement in throughput, and realization of further miniaturization.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining a first embodiment of the present invention.

FIG. 2 is a plan view for explaining the first embodiment of the present invention.

FIG. 3 is an enlarged sectional view of a part of FIG. 1;

FIG. 4 is a cross-sectional view for explaining a wafer take-out mechanism.

FIG. 5 is a plan view for explaining a mechanism for storing a transport plate.

[Explanation of symbols]

1 ... wafer, 2 ... pure iron plate, 3 ... rotor, 4 ... transfer plate,
5 exhaust system, 6 compressed air, 7 gap, 8 groove, 9 stator, 10 traveling direction, 11 valve, 12 transfer chamber, 1
3: packing, 14: Ar, 15: permanent magnet, 16:
Upper flange, 17: Lock chamber, 18: Chuck, 19
... Dry nitrogen, 20 ... Swing cylinder, 21 ... Packing, 22 ... Rotating chamber, 23 ... Cylinder, 24 ... Bellows,
25 inner shaft, 26 outer shaft, 27 flange, 2
8 ... turntable, 29 ... rotary shaft.

Claims (9)

[Claims] 1. A transfer chamber for transferring a transfer plate on which a semiconductor wafer is mounted to a desired location, wherein the transfer chamber supplies an inert gas to a lower surface of the transfer plate transferred into the transfer chamber. A wafer transporting device having means for floating the transport plate and means for moving the transported plate. 2. The wafer transfer apparatus according to claim 1, wherein the inert gas is supplied to a lower surface of the transfer plate via a plurality of grooves provided in the transfer chamber. 3. A linear motor according to claim 1, wherein said means for moving said floating transport plate is a linear motor.
2. The wafer transfer device according to 1. 4. The wafer transfer device according to claim 1, further comprising means for controlling the pressure of the inert gas to a desired value. 5. The wafer transfer apparatus according to claim 1, further comprising means for exhausting the inside of the transfer chamber. 6. The transfer chamber includes a valve for controlling the introduction of the inert gas into the groove, a magnet is disposed at an upper end of the valve, and a lower surface of the transfer plate is provided. 6. The wafer transfer device according to claim 1, wherein a magnetic plate is buried at a predetermined position. 7. A mechanism for changing the transfer direction of the transfer plate, a mechanism for raising and lowering the transfer plate, or a mechanism for waiting the transfer plate is adjacent to the desired transfer chamber or the processing apparatus for the semiconductor wafer. The wafer transfer device according to any one of claims 1 to 6, wherein the wafer transfer device is provided. 8. A mechanism for taking out the semiconductor wafer from the transfer plate into the atmosphere or a desired gas atmosphere adjacent to the desired transfer chamber. The wafer transfer device according to any one of the above. 9. A semiconductor device according to claim 1, further comprising a sensor for recognizing the number of said semiconductor wafer, and means for controlling the next transfer of said semiconductor wafer by a signal from said sensor. The wafer transfer device according to claim 1.