Material or article handling – Movable rack having superposed – charge-supporting elements,...
Reexamination Certificate
2001-09-25
2003-09-23
Pert, Evan (Department: 2829)
Material or article handling
Movable rack having superposed, charge-supporting elements,...
Reexamination Certificate
active
06623231
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a plant for producing semiconductor products.
Plants of this type can be constructed in particular as a plant for processing wafers. These plants contain a large number of production units, with which different production processes can be carried out. The production processes are, in particular, etching processes, wet chemical methods, diffusion processes and different cleaning processes, such as a chemical mechanical polishing (CMP) process. For each of the processes, one or more production units are provided, in which various production steps in a production process are carried out.
In addition, plants of this type contain a large number of measuring units. In the measuring units, the quality of processing of one or more production steps in a production process is checked.
The entire production process is subject to strict cleanness requirements, so that the production units and the measuring units are disposed in a clean room or in a system of clean rooms.
The wafers are supplied to the individual production units by a transport system, in predetermined batch sizes in cassettes. In addition, the outward transport of the cassettes following the processing of the wafers is carried out by the transport system.
The transport system typically has a conveyor system that, for example, is constructed in the form of roller conveyors. Here, the cassettes with the wafers are transported lying on the roller conveyors. Alternatively, the conveyor system can also contain continuous conveyors, suspension conveyors or the like.
Such conveyor systems run linearly through the clean room. In order to ensure the supply of the cassettes with the wafers to the production units, the conveyor systems branch in a suitable way. In this way, a more or less self-contained network of roller conveyors is produced within the clean room.
In order to ensure an adequate supply of wafers to the production units and the measuring units, the transport system additionally has a storage system, which has a specific number of storage units that are distributed suitably over the clean room. Storage units of this type are typically constructed as stockers, which are attached to the conveyor system. Temporarily stored in the stockers in each case is a predefined number of cassettes with wafers. The cassettes with wafers are removed from the stockers in a suitable number as required and, via the conveyor system, are supplied to the production units and the measuring units.
The disadvantage in this case, however, is that storing the cassettes with wafers in the stockers is very time-consuming and costly.
In the publication titled “What Gain from Small Batch Manufacturing”, by George Horn and William A. Podgorski in “Semiconductor Fabtech”, 8th Edition, a plant structure is proposed with which the number of stockers can be reduced.
The transport system described there contains, in addition to a conveyor system, a plurality of local process buffers. In this case, a process buffer is in each case assigned to a plurality of identical production units that in each case process the same production steps in a production process. In addition, storage units with larger storage capacities are provided for a plurality of production units and measuring units supplementing a production process, if corresponding storage capacities are required for such production processes. The production processes include, for example, diffusion processes.
Although, in a plant of this type, stockers are no longer needed, the expenditure of time for storing the cassettes with wafers and removing them again is still considerable. Depending on the processing capacities of the production unit and measuring units, cassettes have to be stored temporarily in a sufficient number in the local process buffers and in the storage units that are used to supply the production units and measuring units of a production process. The cassettes have to be removed from the storage unit again and assigned to the respective production units and measuring units, in order that they can be supplied to the production units and the measuring units via the conveyor system.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a plant for producing semiconductor products which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which provides the simplest, most efficient and cost-effective supply of semiconductor products possible to the individual production and measuring units.
With the foregoing and other objects in view there is provided, in accordance with the invention, a plant for producing semiconductor products such as wafers. The plant includes at least one clean room and a plurality of processing stations disposed in the clean room. Each of the processing stations contains at least one unit selected from the group consisting of production units and measuring units, and a production buffer for storing the semiconductor products. The production buffer is disposed directly at the unit. Each of the processing stations also has a handling device for automatic delivery and outward transport of the semiconductor products to and from the production buffer. A conveyor system interconnects the processing stations.
The plant according to the invention has the configuration of processing stations. Each of the processing stations has at least one production or measuring unit and also a production buffer, disposed on the latter, for the storage of semiconductor products. Also provided is a handling device, which is likewise a constituent part of the processing station. By the handling device, the delivery of the semiconductor products to the production buffer, and the outward transport of the products from the buffer are respectively carried out automatically.
The individual processing stations are interconnected via a conveyor system, via which the semiconductor products are transported between the individual processing stations.
The significant advantage of the plant according to the invention is that the semiconductor products are delivered to production buffers that are disposed directly at the production or the measuring units. From the production buffers, the semiconductor products can therefore be fed directly into the production or measuring units, without any further removal from the storage unit and supply via further transport devices being necessary. Saving transport devices of this type leads to a significant saving in costs. It is particularly advantageous here that, in the process station, no storage systems such as stockers or local process buffers are provided, from which temporarily stored semiconductor products have to be removed, sorted out and supplied to the various production or measuring units. Instead, the semiconductor products on the production buffers can already be assigned to the respective production or measuring units.
Storing the semiconductor products in the production buffers therefore leads to a considerable saving in costs and to simplification of the material flow in the plant, as a result of omitting stockers and local process buffers.
A further advantage can be seen in the fact that the production buffers can be attached directly to the production or measuring units, in a space-saving way, which leads to a low requirement for space for the plant.
Finally, it is advantageous that the transport of the semiconductor products within a processing station can be carried out very quickly and without the use of any personnel. The handling device, which can be constructed in particular as a robot or rack server, automatically supplies the semiconductor products delivered by the conveyor system to the production buffers and also ensures that they are transported away to the conveyor system. In addition, the removal of semiconductor products from a production buffer, subsequent insertion into the production or measuring unit and the subsequent removal are preferably carried out automatically by robots, gripper
Mayback Gregory P.
Pert Evan
LandOfFree
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