JPS6036221A - Thin plate transferring device - Google Patents

Abstract

PURPOSE:To reduce the adhesion of dust, etc. onto the surface of a thin plate and as well to reduce the cost of power consumption for air-purification around a device for transferring a thin plate such as, for example, a semiconductor wafer, etc., by laying means for heating the thin plate. CONSTITUTION:Air from a compressor is fed into a pressure equalizing chamber 14, and then is blown out from an air blow-out port 18 onto a conveying surface for floating up a thin plate 24 from the conveying surface 32 so that the thin plate 24 is conveyed. In this case, an infrared ray heater 30 is laid in the upper section of the pressure equalizing chamber 14. Further, the conveying surface 32 is formed of a transparent glass material having a low infrared-ray absorption coefficient. Further, the thin plate 24 on the process of conveyance is heated by the heat radiation of the above-mentioned heater 30 so that the temperature of surface of the thin plate 24 is made higher than the atmosphere temperature therearound due to the heat transmission of the thin plate itself. With this arrangement, a space which contains no dust is formed in the close vicinity of the surface of the thin plate 2, thereby the adhesion of dust onto the surface of the thin plate 2 may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thin plate transport device for transporting, for example, a semiconductor wafer.

[Background of the invention]

For example, in a semiconductor manufacturing process, a semiconductor element goes through various steps until it is completed, and it is well known that a wafer transfer device is used to efficiently transfer the steps.

A conventional wafer conveying device of this type is shown in FIGS. 1 and 2. In FIGS. 1 and 2, a wafer transfer device pressure equalization chamber 14 is connected to the compressor 10 via a console air supply duct 12. As shown in FIGS. The upper part of this pressure equalization chamber 14 serves as a wafer transfer surface 16. On the wafer transfer surface 16, a large number of air outlets 18 in two parallel rows are opened diagonally to the transfer surface 16. The air outlet 18 is connected to the pressure equalization chamber 14 .

In the wafer transfer device having such a configuration, air compressed by the compressor 10 is supplied to the supply duct 1.
2 to the pressure equalization chamber 14 and further blown out from the air outlet 18. For this reason, the wafer process equipment 2
The wafer 24 to be transferred from 0 to the wafer processing device 22 is transported along the wafer transfer surface 16 in a state in which it is lifted by 0.5 to 1+ m above the wafer transfer surface by the air blown out from the air outlet 18. It has become.

In addition, as another conventional example, as shown in FIGS. 3 and 4, in each figure, a base 110 supports a conveyance table 112, and a drive motor attached to the base 110. A drive pulley 116 is fixed to the motor shaft 114,
Further, a drive pulley 118 is rotatably attached to the conveyance table 112. A drive belt 120 is passed around the drive pulleys 116 and 118, and the drive pulley 1
At 16, two conveyor belts 122 and 124 extend over the rack along the conveyance direction. Therefore, the drive motor 114
The rotation is transmitted to the conveyor belts 122, 124 via the drive boo 9116, the drive belt 120, and the drive pulley 118, so that the wafers 126 placed on the conveyor belts 122, 124 are conveyed.

In such a process of transporting the wafer 24.126, if dust, mist, etc. adhere to the wafer 24.126 and become foreign matter, it may cause defective products.
It is necessary to prevent dust floating above or dust generated from the wafer 24.126 from wandering around on the surface of the wafer 24.126. For this reason, conventionally, a high-performance dust collector was installed on the ceiling of the room where the wafer transport equipment was installed so as to cover the entire equipment, and by blowing clean air over the entire equipment, the 24.126 wafer surface was removed. Measures are taken to prevent dust from adhering to the

However, with such conventional equipment, due to fluctuations in the concentration distribution of airborne dust in the airflow, localized high-concentration airborne dust areas may occur, making it difficult to keep the product sufficiently clean. The drawback was that product defects were likely to occur. In addition, as mentioned above in conventional equipment, clean air must be constantly blown out over the entire surface of the wafer transfer device from the dust collector installed on the ceiling. Air filters have the drawback of high pressure loss, high power requirements for blowers, and extremely high equipment operating costs.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin plate conveying device which eliminates the above-mentioned conventional drawbacks, reduces the adhesion of dust and the like to the surface of thin plates such as wafers, and reduces air cleaning power costs.

[Summary of the invention]

The present invention has confirmed through experiments that when there is a temperature gradient between the surface of an object and the air, objects floating in the air migrate along the temperature gradient, and the object adheres to the surface of the wafer during wafer transport. As a means to reduce the amount of dust generated, for example, infrared heating is used to raise the temperature of the wafer surface to a temperature higher than that of the air.

[Example of departure J]

The present invention will be explained below using examples.

FIG. 5 is a schematic diagram showing an embodiment of the thin plate conveying device according to the present invention. Components having the same reference numerals as in FIGS. 1 and 2 have the same functions. The configuration in Figure 5 that differs from that in Figure 1 is that an infrared heater 3o is installed above the pressure equalization chamber 14, and the wafer transfer surface 32 is made of transparent glass with low absorption of infrared rays. It is in.

In this way, during the process of transporting the wafer 24, the wafer 24 will not be heated by the thermal radiation of the infrared heater 3o, and furthermore, the surface of the wafer 24 will be exposed to the surrounding atmosphere due to the heat conduction of the wafer 24 itself. The temperature of the air inside becomes hotter. Here, in order to heat the wafer 24 using radiation heat transfer by infrared rays, only the wafer 24 is heated while the temperature of the air in the surrounding atmosphere remains unchanged, and there is a gap between the surface of the wafer 24 and the air in the surrounding atmosphere. This is to form a temperature gradient. Therefore, for example, when heating the wafer 24 using an electric heater or the like, the air in the surrounding atmosphere also becomes high temperature, which is not appropriate.

Therefore, when a temperature gradient exists in the nitrogen gas containing dust, the dust is given a larger momentum by the medium gas molecules than the lower temperature side, and the dust moves toward this lower temperature region, which is a phenomenon of thermophoresis. will occur. Therefore, a space containing no dust is created in the close vicinity of the surface of the heated object. FIG. 6 is a graph showing the relationship between the rate of reduction in dust adhesion to the surface of the wafer 24 and the temperature difference between the surface temperature of the wafer 24 and the air temperature of the surrounding atmosphere.

Here, the reduction rate of dust adhesion refers to the relative value of the number of dust adhering to the wafer 24 when the surface temperature of the wafer 24 and the ambient air temperature are equal, and the number of dust adhering when a temperature difference is given.

As is clear from this relationship, as the wafer surface temperature becomes higher than the ambient temperature, the number of attached dust decreases, and for example, when the surface temperature difference ΔTs is 20°C, the number of attached dust decreases to less than half. Can be done.

Therefore, the number of dust particles adhering to the surface of the wafer 24 can be reduced by heating the substrate 24 to a higher temperature than the surrounding atmosphere using the infrared heater 30 as in the wafer transfer apparatus of this embodiment.

Therefore, if the number of adhered dust particles can be allowed to be the same as in the past, the cleanliness of the air can be lowered, and the operating cost of the equipment can be reduced by reducing the air purifying power.

w+ Figure 7 is a block diagram showing another embodiment according to the present invention. Components with the same symbols as in FIGS. 1 and 2 have the same functions. A different configuration from FIGS. 1 and 2 is that the infrared heater 30 is positioned above the wafer 24 being transported, and is supported by a support metal fitting 34 on the side surface of the transport device.

Furthermore, FIGS. 8 and 9 are configuration diagrams showing other embodiments of the present invention. In each figure, the same reference numerals as in FIGS. 2 and 3 have the same functions. 8 and 9 differ from FIGS. 2 and 3 in that a single conveyor belt 131 is passed over the drive pulley 116 along the transport direction, and the conveyor belt 131 is loaded onto the drive pulley 116. An electric heater is provided on the lower surface of the conveyor belt 131 with respect to the conveyance direction of the placed wafers 126.

Even in this case, in the conveyance process of the wafer 126, the surface of the wafer 126 is heated by the conveyor bell) 131% F4 air heater 132, and the wafer 126 is further heated, so that the surface of the wafer 126 is exposed to the surrounding air. Therefore, there is a temperature gradient in the air containing dust, and the dust is given a large momentum from the trapped gas molecules to the low temperature side, and as a result, the dust moves from the high temperature side to the low temperature side. A thermophoretic phenomenon occurs.

Although each of the embodiments described above has been described using a wafer as the object to be transported, it goes without saying that the object is not limited to this and may be, for example, a photomask.

〔Effect of the invention〕

As is clear from the above description, according to the thin plate conveying device according to the present invention, there is less dust and the like adhering to the surface of the thin plate, and the air cleaning power cost can be reduced.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing an example of a conventional thin plate conveying device, FIGS. 3 and 4 are block diagrams showing other examples of a conventional thin plate conveying device, and FIG. 5 is a block diagram showing an example of a conventional thin plate conveying device. FIG. 6 is a graph showing the effects of the present invention. FIG. 7 is a configuration diagram showing another embodiment of the present invention. FIGS. 8 and 9 are diagrams showing the effects of the present invention. 'D showing another embodiment according to
This is a J composition diagram. 10... Compressor, 12... Air supply duct,
14... Pressure equalization chamber, 16... Wafer transfer surface, 1
8... Air outlet, 20.22... Wafer processing device, 24... Wafer, 30... Infrared heater, 32... Wafer transfer surface, 34... Infrared heater support hardware, 110... Base, 112... Transport platform,
114... Drive motor, 116.118... Drive pulley, 120... Drive belt, 122.124...
Conveyor belt, 126... Wafer, 131... Conveyor belt, 132... Electric heater. Agent Tatsuyuki Unuma (and 1 other person) Figure 1 IQ Figure 2 Figure 3 Figure 5 Figure 6 Dust 0 5 Io 15 20 Surface - xi tip 757s ('c)

Claims (1)

[Claims] (1) A thin plate conveying apparatus for conveying a thin plate, characterized in that the thin plate conveying apparatus is equipped with a heating means for heating the thin plate.