Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-11-19
2003-11-04
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S099000, C700S116000, C700S121000
Reexamination Certificate
active
06643558
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an installation for processing wafers.
These types of installations contain a number of processing units, with which various fabricating steps for processing wafers are carried out. The fabricating steps include etching processes, wet chemical processes, diffusion processes, and various purifying techniques such as CMP (Chemical Mechanical Polishing). One or more processing units are provided for each of these fabricating steps. In addition, measuring units are provided, wherein the quality of the wafer processing can be checked. These measuring units are expediently utilized to check all essential fabricating steps which are executed in the processing units.
The overall fabrication process is subject to stringent purity requirements, for which reason the processing units and measuring units are disposed in a clean room or a system of clean rooms.
The wafers are supplied to the individual processing units and measuring units in a predetermined batch size by way of a transport system. To accomplish this, the wafers are transported in transport containers, which are implemented in the form of cassettes, for instance, whereby the transport containers each accept an equal number of wafers. The wafers are also delivered out by way of the transport system after being processed in the fabrication and measuring units, whereby they are borne in the same transport containers. Typically, 25 wafers are combined into one batch in each transport container.
The transport system includes a conveyor system, which is constructed in the form of roll conveyors, for instance. The transport system additionally includes a storage system with a plurality of stores for storing transport containers with wafers.
In prior art wafer processing installations, a batch of wafers is combined in a transport container and fed through all fabrication and measuring units of the installation via the transport system. The batch remains attached to the respective transport container. This means that wafers from different batches are not mixed.
To process the wafers, a respective transport container containing a batch is fed to a processing unit or measuring unit via a loading and unloading station. After the wafers are processed in the fabrication or measuring unit, the batch is output to the transport system again via the loading and unloading station in the same transport container.
The transport containers with the wafers are successively fed to the individual fabrication and measuring units according to the order of the individual fabrication and measuring processes. This is problematic, because the individual fabrication and measuring units have different processing capacities. This is particularly ascribable to the fact that in some fabrication and measuring units a number of wafers can be processed in parallel, while in other fabrication and measuring units only individual wafers can be processed. For example, in furnace processes a number of wafers can be supplied to the furnace of a processing unit simultaneously. In measuring units, on the other hand, wherein an optical inspection is performed, the wafers are processed individually.
In order to guarantee an optimally high capacity utilization of the apparatus in spite of this problem, an optimally high number of transport containers with wafers are output to the transport system. The disadvantage of this is that a substantial stock of wafers is located in the apparatus. But such large material stocks in the apparatus are extremely cost-intensive. In addition, because such a large number of transport containers cannot be fed through the apparatus continuously, it is necessary to provide a plurality of stores for temporarily storing the transport containers.
Stores such as these are typically constructed as stockers. A stocker consists of a storage system wherein the wafers are stored under clean-room conditions. Stockers such as these are extremely cost-intensive owing to the large constructional outlay. Furthermore, stockers require a substantial amount of space in the clean room, which raises the cost of the installation still further.
These measures notwithstanding, owing to the different processing capacities it is impossible to prevent substantial wait times and associated downtimes in individual fabrication and measuring units. This, of course, leads to long throughput times of the wafers through the apparatus. Typical throughput times for wafer processing installations are in the range of 40 to 60 days.
U.S. Pat. No. 5,083,364 and German published patent application DE 37 35 449 A1 disclose a fabrication installation for wafers which is built from several interchangeable transport modules, processing modules, and check modules. Each processing module includes at least one processing station, one deposit and one handling device.
The wafers are sent in via the transport system in a first cassette. The handling device removes the wafers from the first cassette and feeds them to the processing stations and deposits. In the check module, unusable wafers are captured and potentially collected in a second cassette. The second cassette can serve for the temporary storage of the unusable wafers. Alternatively, the unusable wafers are channeled out of the check module. The flawless wafers are collected in cassettes and output on the transport module.
U.S. Pat. No. 5,803,932 describes a processing installation for processing wafers. That processing installation includes a loading/unloading section, a processing section and an interface section. In addition, a transport device and at least two waiting sections are provided.
The transport device is located between the loading/unloading section and the interface section. A number of processing units, which form processing sections, are disposed on either side of the transport device.
The wafers are transported on the transport device either in the direction of the loading/unloading section or in the direction of the interface section.
U.S. Pat. Nos. 6,050,768 and 6,129,496 (see German patent application DE 198 16 151 A1) relate to a control method for an automatic transporter of a semiconductor wafer cassette transport device. The transporter transports a semiconductor wafer cassette to an inlet port of a storage device under the control of a host computer.
Japanese patent application JP 08268512 A relates to a storage unit for storing substrates. The storage unit includes a sorting unit with the aid of which the substrates are automatically sorted and sent in and out of the storage unit in cassettes.
German patent application DE 198 26 314 A1 teaches a test device for automatically testing integrated circuits (IC). To carry out the tests, a plurality of testing heads are provided at a test table. A transport device for transporting individual ICs is provided at the test table. The transport device includes arms that are movable on rails and that include a gripper head for picking up the ICs.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a wafer processing installation, which overcomes the abovementioned disadvantages of the heretofore-known devices and methods of this general type and which achieves an optimally short throughput time of the wafers through the installation given an optimally high utilization of the capacity of the fabrication and measuring units.
With the foregoing and other objects in view there is provided, in accordance with the invention, an installation for processing wafers, comprising:
a configuration of processing units (e.g., fabrication units for executing individual fabricating steps and measuring units for checking the results of the fabricating steps) disposed in one of more clean rooms;
a transport system interconnecting the processing units for transporting wafers to and from the processing units, wherein the wafers are combined into variable batch quantities, adapted to capacities of at least one of the processing units and the transport system, in transport batches for t
Huber Ronald
Klaebsch Rolf-Arno
Garland Steven R.
Greenberg Laurence A.
Infineon - Technologies AG
Locher Ralph E.
Picard Leo
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