Photocopying – Projection printing and copying cameras – Step and repeat
Reexamination Certificate
1997-10-22
2001-02-06
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Step and repeat
C355S075000
Reexamination Certificate
active
06184970
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a transporting system and more particularly, to a transporting system for transporting an exposure master plate, such as a reticle or a photomask.
Using an exposure apparatus (e.g., a stepper), a circuit pattern formed on a reticle is exposed to light so as to transfer the image of the circuit pattern onto a wafer coated with a photoresist layer, thereby forming the circuit pattern on the wafer. In general, multiple layers of circuit patterns are superimposed on the wafer during exposure, and a plurality of different types of reticles having different patterns are successively used during the exposure process.
In order to interchange the multiple reticles promptly, several types of transporters that are capable of transporting master plates (e.g., reticles) in an efficient fashion have been proposed. For example, Japanese Patent Application Laid-Open No. 7-321179 and corresponding U.S. Patent Application Ser. No. 08/445,170 disclose such a transporter that retrieves a master plate from a container, carries the master plate from the container to the exposure stage, and returns the master plate into the container. The container is installed in an exposure apparatus to accommodate one or more master plates.
With this type of transporter, it must be confirmed in advance (i) that the master plates are actually stored in the container, and (ii) which master plate is stored at which position. To this end, the operator has to check that the master plates are in the container, the positions of the master plates, the type and the capacity of the container, and so on. In the automatic transporting mode, the operator generally specifies the positions of the master plates and gives directions for transporting the master plates.
In this context, the operator may make a mistake in his directions. For instance, if the operator mistakenly gives a direction to retrieve a master plate from an empty position, a transport error occurs because the transporter moves to the empty place to receive a nonexisting master plate. In such a case, the operation of the exposure apparatus and the production line stops. Conversely, if the operator issues directions to return the master plate to a position at which another master plate is stored, the two master plates strike each other, and the expensive master plates can be damaged.
Transport errors may also occur when a container is replaced with another container that stores different master plates in different positions. If the operator forgets to update the directions for the new container, a master plate that is being returned to an empty position in the former container may collide with another master plate that is stored in the same position in the other container. This then is another type of scenario in which the master plates can be damaged.
To eliminate transport errors caused by the operator, optical sensors for detecting whether a master plate is stored in each position of the container have been proposed. Reticles, however, which serve as the master plates, are made of a transparent material, such as quartz, and are made in the shape of a flat plate (referred to as a quartz glass plate). Because most of the light passes through this quartz reticle, it is difficult for a transmission-type optical sensor to determine its presence, i.e., the presence of a master plate.
Furthermore, several types of containers, including a single-plate container and a multiple-plate container, are used in an exposure apparatus. The automatic transporting mode cannot be successfully performed unless the type of container is identified. If a direction is made under the assumption of a multiple-plate container when a single-plate container is used then a transport error or a collision between two master plates may occur.
SUMMARY OF THE INVENTION
The present invention was conceived to overcome these problems and aims to provide a master plate transporting system that can automatically detect the presence/absence and the position, if present, of a master plate in a container and that can automatically determine the type of container.
In particular, the present invention aims to provide a master plate transporting system that is suitable for an exposure apparatus in which transparent master plates, such as reticles, are stored in a container. The present invention additionally aims to provide a master plate transporting system that can detect the presence and the position of transparent master plates in a reliable manner and transport the master plates accurately.
In order to achieve these and other objects, in one aspect of the invention, a master plate transporting system is designed to transport a master plate between a master plate container, which stores one or more master plates, and a processing system for executing prescribed processes using the master plate. The master plate transporting system has an edge detector for detecting the edge of the master plate stored in the container to determine if there is a master plate in the container. Because the presence/absence of the master plate is determined based on the edge detection, the transporting system is able to detect the presence of the master plates accurately even if a plurality of master plates are stacked in the container.
Preferably, the edge detector includes a light-emitting system for emitting light toward the container, a light-receiving system for receiving the light reflected from the edge of a master plate, and a determination unit that determines that master plates are stored in the container when the receiving system receives the reflected light. Because the edge of the master plate is used for optical detection, the presence of the master plate is reliably detected even if the master plate is a transparent glass plate, like a reticle used in an exposure apparatus.
If a plurality of master plates are stacked in the container, it is preferable for the master plate transporting system to have a position detector for detecting the vertical position of each master plate. In this arrangement, the presence and the position of the master plate are simultaneously detected.
The master plate transporting system further includes a controller for controlling the transporting action in response to the detection result of the edge detector.
In another aspect of the invention, a master plate transporting system is designed to transport a master plate between a master plate container and a processing system for executing prescribed processes using the master plate. The master plate container stores one or more master plates and is interchangeable with other master plate containers having different sizes depending on the number of master plates in them. The master plate transporting system also has a size detector for detecting the size of the master plate container in order to perform transport control according to the size of the container.
If the size difference between master plate containers is a difference in height, depending on the number of master plates stacked in the container, the size detector detects the size of the master plate container based on the height of the containers.
REFERENCES:
patent: 4265440 (1981-05-01), Shibazaki et al.
patent: 4776462 (1988-10-01), Kosugi et al.
patent: 4974166 (1990-11-01), Maney et al.
patent: 4984953 (1991-01-01), Nakazato et al.
patent: 4999671 (1991-03-01), Iizuka
patent: 5097421 (1992-03-01), Maney et al.
patent: 5126946 (1992-06-01), Ko
patent: 5380138 (1995-01-01), Kasai et al.
patent: 5414974 (1995-05-01), Van De Ven et al.
patent: 5442163 (1995-08-01), Nakahara et al.
patent: 5570990 (1996-11-01), Bonora et al.
patent: 5671057 (1997-09-01), Kawai
patent: 5684599 (1997-11-01), Shimoyama et al.
patent: 5727685 (1998-03-01), Laganza et al.
patent: 5747221 (1998-05-01), Kim et al.
patent: 5785309 (1998-07-01), Halup et al.
patent: 5909030 (1999-06-01), Yoshitake et al.
patent: 4-340245 (1992-11-01), None
Patent Abstract of Japan, vol. 096, No. 004, Apr. 30, 1996 and JP 07 321179 A (Nikon Corp.), Dec. 8, 1995
Endo Yutaka
Nakahara Kanefumi
Nishikata Akio
Adams Russell
Nguyen Henry Hung
Nikon Corporation
Nixon & Vanderhye P.C.
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