Fluid reaction surfaces (i.e. – impellers) – Specific blade structure – Irregular – flanged or channel forming blade surface
Reexamination Certificate
2002-04-04
2004-05-11
Lillis, Eileen D. (Department: 3652)
Fluid reaction surfaces (i.e., impellers)
Specific blade structure
Irregular, flanged or channel forming blade surface
C414S217000, C414S270000
Reexamination Certificate
active
06733243
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an interbay transportation system for transporting a semi-processed product from a previous process step to the next process step (i.e. from one bay to another bay) in a manufacturing plant. More particularly, the present invention relates to an interbay transportation system that includes stockers (or storage shelves) for individual process steps to allow process-waiting and transportation-waiting, and transport pods (or cassettes) containing semi-processed products conveyed from the stocker for a previous process step and to the stocker for the next process step.
BACKGROUND OF THE INVENTION
A semiconductor product, such as a semiconductor memory or a microprocessor, is produced in a procedure in which many elements such as transistors and capacitors as well as wirings connecting the elements are finely and precisely formed on a semiconductor wafer having a diameter of 200 to 300 mm, the wafer is cut into individual products, and the individual cut-out products are encapsulated by resin. Thus, formation of the elements and wirings on the semiconductor wafer is significantly important for manufacturing semiconductor products, and is carried out through various and many process steps.
In each of the aforementioned process steps, a dedicated manufacturing apparatus (hereinafter referred to as process equipment) is used. As such, an interbay transportation system is necessary to transport a semiconductor wafer completed in processing by the process equipment in a previous step to the process equipment in the next process step.
Hereinafter, an example of such interbay transportation system will be described with reference to FIG.
1
.
Generally, in a semiconductor-product manufacturing plant, a plurality of rooms (each of which will be referred to as a bay) are provided in a clean room, and a plurality of process equipment are provided in each of the bays. In the example shown in
FIG. 1
, six bays (bay
1
to bay
6
) are provided in a clean room, and three or four pieces of equipment are provided in each of the bays (for example, process equipment
11
,
12
and
13
for the bay
1
).
An OHS (Over Head Shuttle)
8
is provided to perform transportation between bays, that is, interbay transportation. The OHS
8
is configured to include a guide rail circularly visiting the individual bays, and OHS vehicles
80
travelling along the guide rail. A plurality of semiconductor wafers (for example, 25 pieces) are housed in one pod, loaded onto the OHS vehicle
80
, and carried from one bay to another. Ordinarily, a plurality of the pods (for example, 2 pods) can be loaded onto the OHS vehicle
80
.
A storage shelf (which will be referred to as a stocker) is provided for each of the bays to receive from the OHS vehicle the pod (semiconductor wafers) that is to be processed in the bay, and to hand a process-completed pod to the OHS vehicles. In the example shown in
FIG. 1
, stockers
10
to
60
are provided for the respective bays
1
to
6
.
Hereinafter, a practical interbay transportation will be described using FIG.
2
.
A pod (semiconductor wafers) to be processed by process equipment
11
is loaded onto an OHS vehicle
80
and transported to a bay
1
. Then, the pod is stored in a stocker
10
for the bay
1
(see an arrow
101
in FIG.
2
). An intrabay transportation system, which is provided in the bay
1
, takes out the pod from the stocker
10
, and then feeds it into the process equipment
11
(see an arrow
102
in FIG.
2
). Upon completion of processing in the process equipment
11
, the intrabay transportation system returns the process-completed pod to the stocker
10
(see an arrow
103
in FIG.
2
).
Subsequently, the process-completed pod is transported to the next process step. Description is made hereinbelow assuming that process equipment
53
executes the next process step. An OHS
8
transports the process-completed pod to a bay
5
, and the pod is stored into a stocker
50
(see an arrow
104
in FIG.
2
). An intrabay transportation system in the bay
5
takes out the pod from the stocker
50
, and then feeds it into the process equipment
53
(see an arrow
105
in FIG.
2
). Upon completion of processing in the process equipment
53
, the intrabay transportation system returns the process-completed pod to the stocker
50
(see an arrow
106
in FIG.
2
).
The OHS
8
takes out the process-completed pod from the stocker
50
, and then transports the pod to a stocker
20
for the next process step (see an arrow
107
in FIG.
2
). Thereafter, in the same manner, transportation of a pod (semiconductor wafers) and processing in the process equipment are iterated, thereby allowing the manufacture of semiconductor products to proceed.
In the interbay transportation system described above, a request is issued to cause the pod to be transported to the next process step (for example, the stocker
50
) when the process-completed pod in the previous process equipment is returned to a stocker (for example, the stocker
10
). In response, the OHS vehicle travels to the stocker
10
, receives the pod, and then transports the pod to the stocker
50
.
At this time, the stocker
50
may be full for some reasons. That is, pods to be processed by process equipment in the bay
5
are increased, or process equipment(s) in the bay
5
has malfunctioned. In such a case, when a free space for one pod occurs, transportation from the stocker
10
to the stocker
50
is immediately started. Therefore, non-urgent transportation takes place and hinders high-urgency transportation. Furthermore, the full loading capacity of the OHS vehicle cannot be used up, so that the transportation efficiency is reduced.
In addition, as has already been described, although the OHS vehicle has the capacity of transporting the plurality of pods, a transportation request is issued in units of one pod. Therefore, unless processing for the second pod is timely completed, the OHS vehicle transports only a single pod, and thereby, the transportation efficiency is also reduced. If the transportation request is issued after completion of processing of the second pod to avoid the problem, a wait time can occur in process equipment of the next step because the pod is not timely transported thereto, thereby reducing the operation rate of the process equipment.
SUMMARY OF THE INVENTION
In order to solve the above-described problems, an interbay transportation system of the present invention includs bays in which process equipment are provided, stockers provided for the individual bays, and a vehicle traveling through the stockers for transporting a semi-processed product from one of the stockers to another, and is characterized in that timing to start transportation is determined according to the operation status of the process equipment and the number of semi-processed products in the stocker.
Moreover, an interbay transportation system according to the present invention includes bays in which process equipment are provided, stockers provided for the individual bays, and a vehicle traveling through the stockers for transporting a semi-processed product from one of the stockers to another, and furthermore, a buffer stocker in which a semi-processed product is temporary shelved.
Further, a method of interbay transportation according to the present invention is associated with an interbay transportation system including bays in which process equipment are provided, stockers provided for the individual bays, and a vehicle capable of loading a plurality of semi-processed products. Semi-processed products are transported from a stocker of a bay including process equipment for a previous process step to a stocker for a bay including process equipment for the next process step by the vehicle. In the method of the present invention, a comparison is performed between a time by completion of processing in the process equipment in the next process step and a time of transportation between the stockers. Following the result of the comparison, transportation by the vehicl
Ogata Ryoji
Ohtsuka Hirofumi
Yanaru Taichi
Johnson R. B.
Leydig , Voit & Mayer, Ltd.
Lillis Eileen D.
Renesas Technology Corp.
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