Data processing: generic control systems or specific application – Specific application – apparatus or process – Article handling
Reexamination Certificate
1998-09-10
2001-06-26
Ellis, Christopher P. (Department: 3651)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Article handling
C700S214000, C414S937000
Reexamination Certificate
active
06253118
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a substrate transport apparatus for use with a substrate processing system for performing varied treatments (e.g. film-forming, prebaking, exposure, development and postbaking) in a photolithographic process of substrates such as semiconductor wafers or glass substrates for liquid crystal displays. Specifically, the invention relates to a substrate transport method and apparatus for transferring substrates through a buffer section having a plurality of storages for temporarily storing the substrates, between a processing unit for performing varied treatments before and after an exposing process and an exposure unit for performing the exposing process.
(2) Description of the Related Art
A conventional substrate transport apparatus of the type noted above transfers substrates between the processing unit and exposure unit through a buffer section having a plurality (e.g. 50 stages) of storages for temporarily storing the substrates. This apparatus includes a first substrate transport device for transporting the substrates between the processing unit and buffer section, and a second substrate transport device for transporting the substrates between the buffer section and exposure unit.
This apparatus operates as follows, for example.
In the buffer section, the first to 25th storages counted from the bottom act as a feed buffer, and the 26th to 50th storages as a return buffer. The feed buffer stores unexposed substrates to be transported to the exposure unit. The return buffer stores exposed substrates transported from the exposure unit.
A first unexposed substrate having a film formed thereon and prebaked in the processing unit is received by the first transport device and deposited on the first (lowermost) storage of the feed buffer. Next, a second substrate is received by the first transport device and deposited on the lowermost one of the vacant storages (i.e. the second storage) of the feed buffer. In this way, each succeeding substrate treated in the processing unit is deposited on a next lower storage of the feed buffer.
The second transport device transfers the substrates, successively in the order of deposition, from the feed buffer to the exposure unit. Of the first and second substrates deposited as above, for example, the first substrate is first transferred to the exposure unit.
The first substrate exposed in the exposure unit is received by the second transport device, and deposited in the return buffer (e.g. the 26th and lowermost storage in the return buffer) of the buffer section. Next, the second substrate is deposited on the lowermost one of the vacant storages (e.g. the 27th storage immediately above the 26th storage). In this way, each succeeding substrate exposed in the exposure unit is deposited on a next lower storage of the return buffer.
The first transport device receives the substrate deposited first in the return buffer if there are substrates therein, and transfers it to the processing unit. The substrate transferred to the processing unit is developed therein.
The above substrate transporting mode absorbs a difference in throughput between the processing unit and exposure unit.
The conventional apparatus with the above construction has the following drawback.
When one of the first and second transport devices transports a substrate to or from the buffer section, the other substrate transport device cannot transport a substrate to or from not only the same storage but the two storages adjacent that storage. This is because the storages are arranged close to one another, and the two transport devices could interfere with each other in their vertical movements. Thus, the transport operation may be retarded. A waiting time is caused with the first or second transport device to lower throughput.
To avoid the above inconvenience, it is conceivable to arrange the storages at increased intervals. Then, naturally, only a reduced number of substrates could be stored, and the buffer section would have an increased height, requiring the transport devices to be movable to an increased height.
SUMMARY OF THE INVENTION
The present invention has been made having regard to the state of the art noted above, and its object is to provide a substrate transport method and apparatus employing a novel order for storing substrates to avoid a wasteful waiting time occurring in substrate transport, thereby to improve throughput.
The above object is fulfilled, in one aspect of the present invention, by a substrate transport method comprising the steps of:
depositing a first substrate in a buffer section having a plurality of storages for temporarily storing substrates to transfer the substrates between a processing unit for performing various substrate treatments before and after an exposing process and an exposure unit for performing the exposing process, by actuating a first substrate transport device for transporting the substrates between the buffer section and the processing unit and/or a second substrate transport device for transporting the substrates between the buffer section and the exposure unit; and
depositing a second substrate on one of the storages next but at least one to a storage on which the first substrate is stored.
When storing substrates in the buffer section to transfer the substrates between the processing unit and exposure unit, each substrate is deposited on a storage spaced across at least one storage from a storage on which a preceding substrate is stored. While one of the first and second substrate transport devices is depositing a substrate on a storage, the other transport device can fetch a preceding substrate from a nearby storage. There is no possibility of interference between the two transport devices since the preceding substrate is stored adjacent but at least two storages away from the storage receiving the new substrate. Thus, even when a substrate is being deposited, a different substrate may be fetched from a nearby position. Such substrate transport does not involve a wasteful waiting time.
Thus, the substrates may be transported efficiently between the processing unit and exposure unit to achieve improved throughput.
In another aspect of the invention, a substrate transport apparatus is provided, which comprises:
a processing unit for performing various substrate treatments before and after an exposing process;
an exposure unit for performing the exposing process;
a buffer section having a plurality of storages for temporarily storing substrates to exchange the substrates with the exposure unit;
a first substrate transport device for exchanging the substrates with the processing unit and depositing and fetching the substrates on/from the storages;
a second substrate transport device for exchanging the substrates with the exposure unit and depositing and fetching the substrates on/from the storages; and
a control device for controlling the first substrate transport device and the second substrate transport device to deposit each of the substrates on one of the storages next but at least one to a storage on which a preceding substrate is stored.
The control device controls the first and second substrate transport devices such that, when storing substrates in the buffer section, each substrate is deposited on a storage spaced across at least one storage from a storage on which a preceding substrate is stored. While one of the first and second transport devices is depositing a substrate on a storage, the other transport device can fetch a preceding substrate from a nearby storage. There is no possibility of interference between the two transport devices since the preceding substrate is stored adjacent but at least two storages away from the storage receiving the new substrate. Thus, even when a substrate is being deposited, a different substrate may be fetched from a nearby position. Such substrate transport does not involve a wasteful waiting time.
Thus, the substrates may be transported efficiently between the processing unit and exposure unit to a
Dainippon Screen Mfg. Co,. Ltd.
Ellis Christopher P.
Ostrolenk Faber Gerb & Soffen, LLP
Tran Khoi H.
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