Ventilation – Clean room
Reexamination Certificate
2001-09-26
2003-08-05
Boles, Derek (Department: 3749)
Ventilation
Clean room
C414S217100
Reexamination Certificate
active
06602127
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a plant for producing semiconductor products that includes an air supply system and production units that are configured in at least one clean room. A production plant of this type for semiconductor products is disclosed in Pat. Abstr. of Japan, Vol. 1999, No. 8, Jun. 30, 1999 (1999-06-30) Kaufmans & JP11 074193 A (Tokyo Electron Ltd.), Mar. 16, 1999 (1999-03-16).
Plants of this type can be provided in particular for processing wafers. These plants include a large number of production units, with which different production processes for processing the wafers are carried out. These production processes are, in particular, etching processes, wet chemical processes, diffusion processes and various cleaning processes, such as CMP (Chemical Mechanical Polishing). For each of these production processes, one or more production units is or are provided.
The entire processing process of the wafers is subject to strict cleanliness requirements, so that the production units are configured in a clean room or in a system of clean rooms. The clean room or the system of clean rooms is normally configured on one floor of a building.
The clean room is supplied with feed air by means of an air supply system. In this case, the feed air is introduced into the clean room from top to bottom via the ceiling of the clean room. For this purpose, the feed air is normally led as far as the ceiling of the clean room via a duct system and from there is blown downward into the clean room by means of blowing devices. In addition, lines belonging to the duct system can be led from the ceiling of the clean room to production units that are partly or completely sealed off from the rest of the clean room. The feed air is then led in the lines of the duct system to blowing devices at the production units and is blown into the interior of the respective production unit via the blowing devices.
The supply of air via the ceiling of the clean room requires a considerable energy expenditure. This is based on the fact that considerable blower outputs are needed in order to guide the feed air from the ceiling as far as the floor area of the clean room. In this case, the high energy expenditure results first from the great distance from the ceiling to the floor of the clean room. Second, the feed air is generally cooler than the waste air to be led away from the clean room. The waste air is heated by the dissipation of heat from the surrounding plants, in particular, the production units and machines for driving the transport system that feeds the wafers to the production units within the plant. The heated waste air rises upward toward the ceiling of the clean room as a result of convection. The blowing devices therefore have to operate with a high blower output in order to blow the feed air downward against the rising waste air.
The same is true of the air supply to the production units. There, the feed air first has to be guided, via the lines of the duct system, from the ceiling of the clean room and downward to the production units. The typical distances of the lines are about 2.1 m to 4.3 m. Because of the size of this distance, a considerable energy expenditure is already required to lead the feed air as far as the production units. There, the feed air is normally blown downward again from the ceiling of the production unit. This again requires a high energy expenditure, since the feed air has to be blown downward against the rising, heated waste air in the production unit.
In addition, it is disadvantageous that the feed air has to meet more or less strict cleanliness requirements, in order that the production processes in the production units can be carried out satisfactorily.
Since the wafers are processed in the area of the floor of the clean room, the cleanliness requirements on the feed air must be met there. However, this can be achieved only with a great expenditure on costs and material, since the feed air blown in from the ceiling of the clean room is mixed with the already used and contaminated waste air as it flows downward in the clean room.
Published Japanese Patent Application JP11 074193 A (Tokyo Electron Ltd.), Mar. 16, 1999 (1999-03-16) describes a production plant for semiconductor products in which the air is supplied from above. This becomes clear in particular from FIGS. 2 and 5 of this document.
FIG. 6 and, in detail, FIG. 7 of the Japanese document show a device which is neither a production plant nor a clean room, but a filter device, which can be seen at the extreme bottom left of FIG. 5. This filter device contains spray nozzles, with which the air stream that is introduced into the filter at the bottom and that rises upward is wetted with pure water for the purpose of cleaning. The water that is collected in the water collecting tank is then irradiated with UV radiation in order to kill off any germs in the water. The air is supplied to the filter device from the bottom right by an air pump and is fed by a blower at the top left into an air duct. The air duct leads the air through a wall section in the ceiling area of the room shown in FIG. 5 of this document, from where the cleaned air is fed into the production room from above.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a plant for producing semiconductor components which overcomes the above-mentioned disadvantageous of the prior art apparatus of this general type. In particular, it is an object of the invention to provide such a plant with an air supply system that can supply feed air with the required cleanness in the most efficient and cost-effective manner.
With the foregoing and other objects in view there is provided, in accordance with the invention, a plant for producing semiconductor products that includes at least one clean room having a floor and a plurality of production units that are configured in the clean room. The plurality of the production units define processing locations for processing semiconductor products. The processing locations are located near the floor of the clean room. The plant also includes an air supply system for directly feeding in feed air at the processing locations.
In the air supply system, the supply of air is provided via the floor of the clean room. A significant advantage of this air supply system is that, as a result, the circulation of feed air and waste air caused by the force of gravity is utilized, so that the feed air is made available, with little energy expenditure, at the locations for processing the semiconductor products.
These locations for processing the semiconductor products, in particular the different production units and transport devices and transfer stations of a transport system for transporting the semiconductor products, are located close to the floor of the clean room. The feed air therefore has to cover only a short distance from the floor of the clean room as far as the locations for processing the semiconductor products, so that only a low energy expenditure is needed for this purpose. This effect is further reinforced by the fact that the heated waste air rises upward in the clean room, and therefore does not have to be displaced by the feed air fed from the floor of the clean room.
In accordance with an added feature of the invention, the upwardly flowing waste air can be disposed of in this case via the ceiling of the clean room. This too is possible with little energy expenditure, so that extracting waste air by means of the convection of the waste air within the clean room is assisted.
In the air supply system, the feed air is fed in immediately at the processing locations of the semiconductor products, in the area of the floor. This feed air is cooler than the surrounding waste air which, as a result of convection, rises up to the ceiling of the clean room. This ensures that, in the area of the processing locations of the semiconductor products, there is virtually only cleaned feed air, and the feed air does not mix with the waste air in this are
Boles Derek
Greenberg Laurence A.
Infineon - Technologies AG
Locher Ralph E.
Stemer Werner H.
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