Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2002-06-28
2004-09-14
Pyo, Kevin (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S222100, C250S338100, C340S555000
Reexamination Certificate
active
06791074
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention generally relates to a light curtain system for establishing a protective light curtain for a tool. According to further aspects, the present invention relates to a tool and to a system for processing objects, particularly for processing disklike objects such as wafers, flat panels, CDs (Compact Discs) or the like. According to yet another aspect, the present invention relates to a method for loading and/or unloading a tool using an object in a system for processing objects.
For example, such systems, tools and methods can be used to manufacture semiconductor products.
In the technical field of manufacturing and processing wafers (for example silicon disks), flat panels or CDs in semiconductor industries it is common and necessary to move such objects between different locations such as processing stations, metrology stations or the like. Moreover, there is a need to store the objects in specific storage areas, when they are not needed at the moment or before they are moved to a next station.
Usually, such objects are stored and processed under mini-environment conditions. In light of the present invention, the term mini-environment defines a localized environment created by an enclosure to isolate a product from contamination and/or people. The requirements for such mini-environments are set forth in document “Integrated Mini-environment Design Best Practices”, International SEMATECH, Technology Transfer #99033693A-ENG, SEMATECH Technology Transfer, 2706 Montopolis Drive, Austin, Tex. 78741, USA, http://www.sematech.org for example.
During transportation and any processing and storage steps or conditions, those objects are usually stored in special containers, for example, in so-called Front-Opening-Unified-Pods (FOUP).
In order to move such containers from one location to another location, they are usually carried by special vehicles that are moved along a system of tracks. The system of tracks can be mounted at the ceiling of an environment or fabrication, thus forming a so-called Overhead-Hoist-Transport-System (OHT).
When the objects reach a desired station—for example a processing station, a loading station or the like—via the transport system, they are lowered from the ceiling towards the station, where subsequently a processing step is performed. After finishing the processing step, the objects are picked up by the transport system, lifted to the ceiling of the environment and moved away from the station.
However, delivering and storing objects or containers (FOUPS) to process and/or metrology tools or the like in an automated fashion requires many safety implications for operators and material. Particularly in fabrications or pilot lines that are not fully automated, the delivery process includes both, automated steps—for example, an automated transportation by an OHT-system—and manual delivery by the operators. To protect the operators from being injured by an OHT delivery to a tool, for example, while lowering the objects from above the operator's eye level, a safety housing is typically provided around the tool. To allow automated loading as well as manual loading, the front of the safety housing is left open, thus forming a manual loadport. The manual loadport is equipped with a safety feature, for example a protective light curtain or a similar device.
Today's light curtain systems include an emitter and a receiver for infrared light beams, thus forming a protective light curtain of infrared light beams. Typically, the light curtain is activated throughout the entire operation time. Under predetermined circumstances, for example, when an object is lowered toward or lifted from a station, an interruption of the invisible light beams by an opaque object, for example by the arm of an operator, may cause an action, for example an action to stop the tool or the transport system.
However, since the protective light curtain is invisible for an operator, the operator could accidentally interrupt the protective light curtain. Present light curtain systems do not provide any mechanisms to prevent the protective light curtain from accidentally being interrupted.
Published European Patent Application EP 0 598 630 A shows a light curtain system including a first light curtain component of invisible light beams. The invisible light beams are emitted by an emitter and are directed and transmitted in parallel to each other towards a receiver. The receiver is adapted for receiving and detecting the presence or absence of the invisible light beams. The receiver is located spaced apart from the emitter, and the receiver and emitter form edges of the protective light curtain. In case one or more of the invisible light beams is/are blocked by the penetration of an opaque object, such as, the operator's arm or the like, a tool or system that is equipped with the light curtain system can be stopped.
The light curtain device known from Published European Patent Application EP 0 598 630 A further includes a number of indicator lights emitting visible light. These indicator lights are mounted adjacent to the beams of invisible light. Furthermore, a control unit is provided. The control unit operates to sense when one or more of the invisible light beams are blocked by the intrusion of an opaque object. The control unit operates indicator lights which are located adjacent the blocked beams. The visible light provides feedback to the operator, indicating where the protective light curtain is interrupted.
However, all solutions known from the prior art have several drawbacks. All solutions cannot prevent an operator from accidentally interrupting the protective light curtain that is plainly invisible. The solution according to Published European Patent Application EP 0 598 630 A only gives an indication, after the protective light curtain has already been interrupted.
For example, if those known solutions are used in the technical field of manufacturing and processing wafers as described above, an operator has no indication whether or not a loading operation is in progress. Therefore, he may accidentally interrupt the protective light curtain and thus trigger the action of stopping the manufacturing process.
Once, the conventional protective light curtain has triggered an emergency stop of the loading operation or tool operation, it takes precious time for the system to recover from this erroneous situation. The system has to be moved in slow motion back to its home position, and the system state and teach points have to be rechecked and so on. This is very time consuming.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a light curtain system for establishing a protective light curtain, a tool and a system for processing objects and a method for a loading/unloading a tool, which overcome the aforementioned drawbacks.
With the foregoing and other objects in view there is provided, in accordance with the invention, a light curtain system for establishing a protective light curtain for a tool. The light curtain system includes: a first receiver; and a first light curtain component including a first emitter for emitting invisible light beams. The invisible light beams are directed and transmitted in parallel with each other towards the first receiver. There is a second light curtain component providing visible light beams. The first receiver is adapted for receiving and detecting the presence and absence of the invisible light beams. The first receiver is located spaced apart from the first emitter. The first receiver and the first emitter define edges of the protective light curtain. The visible light beams form a part of the protective light curtain and are directed and transmitted adjacent and in parallel with the invisible light beams. The second light curtain component of the visible light beams is activated at least temporarily. The invisible light beams and the visible light beams are emitted alternately with respect to each other. At least one of the visible light bea
Hahn Sven
Lering Michael
Schulz Mathias
Greenberg Laurence A.
Infineon Technologies SC300 GmbH & Co. KG
Locher Ralph E.
Pyo Kevin
Stemer Werner H.
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